AB1094 SAFETY AND EFFICACY OF VACCINES FOR SARS-CoV-2 IN PATIENTS WITH RHEUMATIC AND IMMUNE-MEDIATED INFLAMMATORY DISEASES: DATA FROM THE ARGENTINEAN REGISTRY SAR-CoVAC

Background

Currently there is little information on the efficacy and safety of SARS-CoV-2 vaccination in patients with immune-mediated diseases and/or under immunosuppressive treatment in our country, where different types of vaccines and mix regimens are used. For this reason, the Argentine Society of Rheumatology (SAR) with the Argentine Society of Psoriasis (SOARPSO) set out to develop a national register of patients with rheumatic and immune-mediated inflammatory diseases (IMIDs) who have received a SARS-CoV-2 vaccine in order to assess their efficacy and safety in this population.

Objectives

To assess SARS-CoV-2 vaccine efficacy and safety in patients with rheumatic and IMIDs.

Methods

SAR-CoVAC is a national, multicenter and observational registry. Adult patients with a diagnosis of rheumatic or IMIDs who have been vaccinated for SARS-CoV-2 were consecutively included between June 1st and September 17th, 2021. Sociodemographic data, comorbidities, underlying rheumatic or IMIDs, treatments received and their modification prior to vaccination and history of SARS-CoV-2 infection were recorded. In addition, the date and place of vaccination, type of vaccine applied, scheme and indication will be registered. Finally, adverse events (AE), as well as SARS-CoV-2 infection after the application of the vaccine were documented

Results

A total of 1234 patients were included, 79% were female, with a mean age of 57.8 (SD 14.1) years. The most frequent diseases were rheumatoid arthritis (41.2%), osteoarthritis (14.5%), psoriasis (12.7%) and spondyloarthritis (12.3%). Most of them were in remission (28.5%) and low disease activity (41.4%). At the time of vaccination, 21% were receiving glucocorticoid treatment, 35.7% methotrexate, 29.7% biological (b) Disease Modifying Anti-Rheumatic Drugs (DMARDs) and 5.4% JAK inhibitors. Before vaccine application 16.9% had had a SARS-CoV-2 infection.

Regarding the first dose of the vaccine, the most of the patients (51.1%) received Gam-COVID-Vac, followed by ChAdOx1 nCoV-19 (32.8%) and BBIBP-CorV (14.5%). In a lesser proportion, BNT162b2 (0.6%), Ad26.COV2.S (0.2%) and CoronaVac (0.2%) vaccines were used. Almost half of them (48.8%) completed the scheme, 12.5% were mix regimenes, the most frequent being Gam-COVID-Vac / mRNA-1273. The median time between doses was 51days (IQR 53).

More than a quarter (25.9%) of the patients reported at least one AE after the first dose and 15.9% after the second. The flu-like syndrome and local hypersensitivity were the most frequent manifestations. There was one case of mild anaphylaxis. No patient was hospitalized. Altogether, the incidence of AE was 246.5 events/1000 doses. BBIBP-CorV presented significantly lower incidence of AE in comparison with the other types of vaccines. (118.5 events/1000 doses, p<0.002 in all cases)

Regarding efficacy, 63 events of SARS-CoV-2 infection were reported after vaccination, 19% occurred before 14 days post-vaccination, 57.1% after the first dose (>14 days) and 23.8% after the second. In most cases (85.9%) the infection was asymptomatic or had an outpatient course and 2 died due to COVID-19.

Conclusion

In this national cohort of patients with rheumatic and IMIDs vaccinated for SARS-CoV-2, the most widely used vaccines were Gam-COVID-Vac and ChAdOx1 nCoV-19, approximately half completed the schedule and in most cases homologously. A quarter of the patients presented some AE, while 5.1% presented SARS-CoV-2 infection after vaccination, in most cases mild.

Disclosure of Interests

None declared

POS1204 SARS-CoV-2 INFECTION AFTER VACCINATION IN PATIENTS WITH RHEUMATIC DISEASES FROM ARGENTINA

Background

Patients with rheumatic diseases (RD) have been excluded from SARS-CoV-2 vaccine trials. Though data appear to show safety and efficacy, mostly evidence remains in mRNA vaccines. However in our country, adenovirus and inactivated vaccines, as well as heterologous schemes are frequently used.

Objectives

To describe clinical characteristics and outcomes of SARS-CoV-2 infection after vaccination in patients with RD from de the SAR-CoVAC registry and to compare them with patients who got infected before vaccination. Additionally, factors associated with COVID-19 unfavorable outcome were assessed.

Methods

Adult patients with RD who have been vaccinated for SARS-CoV-2 were consecutively included between June 1st and December 21st, 2021. Confirmed SARS-CoV-2 infection (RT-PCR o serology) was reported by the treated physician. Infection after an incomplete scheme was defined when the event was diagnosed at least 14 days after first dose; and after a complete scheme when it occurred > 14 days after second dose. Homologous scheme is defined by two same doses of vaccine and heterologous by two different doses. Patients with previous SARS-CoV-2 infection were excluded. To compare SARS-CoV-2 infection characteristics in not vaccinated patients, subjects from the SAR-COVID registry, which includes patients with RD and SARS-CoV-2 infection, were matched 2:1 by gender, age and RD.

WHO-Ordinal Scale ≥5 was used to define unfavorable infection outcome. Descriptive statics, Chi2 test, Fischer test, T test and ANOVA were used.

Results

A total of 1350 patients from the SAR COVAC registry were included, 67 (5%) presented SARS-CoV-2 infection after vaccination. The later were mostly (72%) females with a mean age of 57 (SD 15) years old. The most frequent RD were rheumatoid arthritis (41%), psoriatic arthritis (12%) and systemic lupus erythematosus (10%). At vaccination, most of them (75%) had low disease activity or remission, 19% were taking steroids, 39% methotrexate, 27% bDMARDs and 6% JAK inhibitors.

A total of 11 (16%) patients had SARS-CoV-2 infection <14 days after the first vaccine dose, 39 (58%) after an incomplete scheme and 17 (25 %) following a complete one. In the incomplete scheme group, 59% received Gam-COVID-Vac, 31% ChAdOx1 nCov-19 and 10% BBIBP-CorV; and in patients with complete scheme 47%, 24% and 29%, respectively. No event was reported after a complete heterologous scheme. No significant differences regarding sociodemoghraphic characteristics, RD, disease treatment, type of vaccine and regimen was found between in those with infection and those without it.

After vaccination only 8 (12%) of the patients who got infected had an unfavorable course, 88% of them following an incomplete scheme (5 received Gam-COVID-Vac, 1 ChAdOx1 nCov-19 and 1 BBIBP-CorV) and one subject after a complete homologous Gam-COVID-Vac scheme. Having an unfavorable outcome of SARS-CoV-2 infection was associated to: male gender [63% vs 24%, p=0.036], older age [mean 70 years (SD 7) vs 55 years (SD 15), p=0.005], being Caucasian [100% vs 54%, p=0.018], higher education [mean 17 years (SD 4) vs 12 years (SD 4), p=0.010], the presence of comorbidities [100% vs 39%, p=0.001, having pulmonary disease [37% vs 5%, p=0.019], dyslipidemia [63% vs 17%, p=0.011] and arterial hypertension [63% vs 24%, p=0.036], RD, treatments, disease activity and types of vaccines received were comparable between groups.

When comparing patients with and without vaccination prior SARS-CoV-2 infection, those who received at least one dose of vaccine had less frequently severe COVID-19 (12% vs 24%, p=0.067) and presented lower mortality due to COVID-19 (3% vs 6%, p=0.498). However these differences did not reach statistical significance.

Conclusion

In the SAR-CoVAC registry 5% of the patients had SARS-CoV-2 infection after vaccination, most of them mild and 25% after a complete scheme. Any vaccine was associated with severe COVID-19. When comparing with non-vaccinated patients, those with at least one dose, had less frequently severe disease and died due COVID-19.

Disclosure of Interests

None declared

POS0508 PREDICTORS OF PERSISTENT DISEASE IN EARLY ARTHRITIS: 12 MONTHS RESULTS

Background

Early arthritis is an inflammatory disease with the potential to progress to persistent arthritis, such as established Rheumatoid Arthritis (RA) or other articular disease, to resolve spontaneously or remain undifferentiated for indefinite periods of time.

Objectives

To identify predictors of persistent RA after 12 months follow up in the Argentinean early arthritis clinic (CONAART).

Methods

We conducted an observational, prospective longitudinal study, including patients with early arthritis (at least 1 swollen joint with <2 years of evolution) who had at least one year of follow-up.

Sociodemographic and clinical data and characteristics of the disease were recorded at baseline, at 3, 6 and 12 months. After 1 year of follow-up, each patient was classified according to diagnosis: self-limited arthritis, persistent non-erosive arthritis, or persistent erosive arthritis.

The association between the different predictors of diagnosis at 12 months was evaluated using multiple logistic regression, adjusted by potential confounders. Rheumatoid Factor (RF) and Anti Citrullinated Peptide Antibodies (ACPA) were included in separate models in order to avoid multicollinearity. A value of p<0.05 was considered significant.

Results

We included 839 patients, 83% females, mean age of 57±14 years and mean disease duration of 8.2±6.2 months; 67.5% were rheumatoid factor positive and 59% ACPA positive. Disease characteristics at baseline were DAS28 5.1±1.4, swollen joints 6±5, erythrocyte sedimentation rate (ESR) 34±25 mm/h, C Reactive Protein (CRP) 4±6 and Health Assessment Questionnaire-Argentinean (HAQ-A) 1.2±0.8.

After 12 months follow up, 11% of the patients were diagnosed as self-limited disease, whereas 89% were diagnosed as persistent disease. For the persistent disease, 34% presented radiograph erosions and therefore were catalogued as persistent erosive disease.

The seropositivity for both, RF and ACPA, together with baseline DAS28, were the variables independently associated with the development of persistent disease at 12 months. [Model 1a: RF OR 2.33 (95% CI 1.44, 3.78) and DAS28 1.27 (1.06, 1.52); Model 2a: ACPA 2.61 (1.38, 4.93) and DAS28 1.59 (1.24, 2.04)]. (Table 1).

Table 1.

Predictors of Persistent Rheumatoid Arthritis at 12 months

OutcomesPersistent RAPersistent RAPersistent RAPersistent RAOR (95 IC)OR (95 IC)OR (95 IC)OR (95 IC)Model 1aModel 1bModel 2aModel 2bn708708507507Age (years)0.99 (0.98, 1.01)0.99 (0.98, 1.01)0.99 (0.97, 1.01)0.99 (0.97, 1.01)Female gender1.06 (0.57, 2.00)1.06 (0.56, 1.99)0.72 (0.30, 1.71)0.72 (0.30, 1.70)RF positive2.33 (1.44, 3.78)***2.45 (1.52, 3.98)***--ACPA positive--2.61 (1.38, 4.93)**2.63 (1.39, 4.98)**DAS28 at baseline1.27 (1.06, 1.52)**1.59 (1.24, 2.04)***Categorical DAS28  MDA (vs LDA)-1.81 (0.85, 3.86)^-2.86 (1.68, 6.99)*  HDA (vs LDA)-2.83 (1.30, 6.15)^-6.39 (2.42, 16.82)***

^ p<0.1, * p<0.05, ** p<0.01, *** p<0.001

RF, Rheumatoid Factor; ACPA, Anti Citrullinates Protein Antigen; DAS28, Disease activity Score-28; LDA, low disease activity; MDA, moderate disease activity; HDA, high disease activity.

In the patient prediction model, it can be observed that a patient with female gender, ACPA negative, and a low activity at baseline (DAS28 <3.1) presents a 62.3% of likelihood of developing persistent arthritis after 12 months, while a male patient, ACPA positive, with a high baseline activity level, the probability of having persistent disease rises to 97.5%. (Figure 1)

Figure 1.

Matrix prediction model. Probability of diagnosis of Persistent Rheumatoid Arthritis after 12 months of follow-up. Colors represents predictive probability of achieving the outcome as follow: grey: 0-69.9%; blue: 70.0-89.9%; purple: 90.0-100%.

DAS28, Disease Activity Score 28; LDA, low disease activity; MDA, Moderate Disease Activity; HDA, High Disease Activity.

Conclusion

Predictors of persistent arthritis after 12 months of follow up since AT diagnosis were RF and ACPA seropositivity and higher baseline disease activity level.

Disclosure of Interests

None declared.

AB1123 EFFICACY AND SAFETY OF SARS-CoV-2 THIRD VACCINE IN PATIENTS WITH RHEUMATOID ARTHRITIS WHO DID NOT RESPOND AFTER PRIMARY TWO-DOSE REGIMEN

Background

Vaccination for COVID-19 is an essential tool to fight the pandemic. Evidence suggests that patients with immune mediated inflammatory diseases (IMIDs) have less response. The application of a booster shot is a strategy that has been implemented in this population, however there is scarce information about its efficacy.

Objectives

To assess the humoral and cellular immune response after a third dose of SARS-CoV-2 vaccine in patients with rheumatoid arthritis (RA) with undetectable antibodies titles after primary regimen of two doses.

Methods

Observational study. Patients with RA (ACR/EULAR 2010 criteria) from two rheumatology centers, ≥18 years old, with no seroconversion after two doses of SARS-CoV-2 vaccine, who received a third dose of either mRNA or vector-based vaccines (BNT162b2 or ChAdOx1 nCoV-19) were included. Anti-SARS-CoV-2 IgG antibodies, neutralising activity and T cell responses were assessed between 21 and 40 days after the third dose. Sociodemographic data, comorbidities, treatment, vaccine applied and the presence of adverse events (AE) were recorded. Statistical analysis: descriptive analysis. Chi2 or Fischer test and T test.

Results

A total of 21 non-responder patients were included, all of them females with a mean age of 63.7 years (SD 11,6) and mean disease duration of 15.8 years (SD 8). Most of them (81%) reported comorbidities, being the most frequent arterial hypertension, obesity and dyslipidemia. At vaccination time, 6 (28.6%) were receiving glucocorticoids, 3 of them ≥10 mg/day, 17 c-DMARDs (methotrexate 57.1%) and 18 (85.1%) b-DMARDs, 6 abatacept (ABT) and 4 rituximab (RTX).

Regarding the primary vaccination regimen, 13 (61.9%) received two doses of BBIBP-CorV, 3 (14.3%) Gam-COVID-Vac, 3 (14.3%) ChAdOx1 nCoV-19 and 2 (9.5%) a mix regimen of Gam-COVID-Vac/mRNA-1273. The majority (95.2%) received BNT162b2 vaccine and only one of them ChAdOx1 nCoV-19, with a mean time between the second and third dose of 151,4 days (SD 46,4). After the third dose, 90.5% of the patients presented detectable anti-SARS-CoV-2 IgG and 76.2% presented neutralizing activity. The median of neutralizing antibodies titers was 1/12 (IQR 1/7-1/48). Both patients who did not present detectable antibodies were obese, recieved BBIBP-CorV during the primary regimen and BNT162b2 as the third dose, one of them was taking methotrexate and ABT and the other one RTX. Compared to other treatments, ABT and RTX was associated with no neutralizing activity in 4 (80%) patients and lower titers of neutralizing antibodies [median 1/3 (IQR 0-1/20) vs median 1/8 (IQR 1/4-1/128), p=0.197].

A T-cell response was present in 41.2% of all patients after the second dose, increasing to 75% after the third dose. The use of ABT was associated with a lower frequency of T-cell response (80% vs 20%, p=0.014).

Sixteen (76.1%) patients reported at least one AE, 66.7% injection site reaction and 25% flu-like syndrome.

Conclusion

In this RA cohort who failed to seroconvert after two doses of SARS-CoV-2 vaccine, 90.5% presented detectable anti-SARS-CoV-2 IgG and 75% T-cell responce after a third dose. The use of ABT was associated with a lower frequency of T-cell response. This data highlights the importance of a third vaccine in this group of patients.

Disclosure of Interests

None declared

POS1238 GLUCOCORTICOIDS, RITUXIMAB AND THE PRESENCE OF INTERSTITIAL LUNG DISEASE ARE ASSOCIATED WITH POOR OUTCOMES OF THE SARS-COV-2 INFECTION IN PATIENTS WITH RHEUMATOID ARTHRITIS: DATA FROM THE NATIONAL REGISTRY SAR-COVID

Background

High disease activity, treatment with glucocorticoids (GC) and rituximab (RTX), have been related to worse outcomes of COVID-19.

Objectives

To assess the clinical characteristics and severity of the SARS-CoV-2 infection in patients with rheumatoid arthritis (RA) included in the SAR-COVID registry and to identify factors associated with poor outcomes.

Methods

SAR-COVID is a national, longitudinal and observational registry. Patients of ≥18 years old, with diagnosis of RA (ACR-EULAR criteria 2010) who had confirmed SARS-CoV-2 infection (RT-PCR or positive serology) were included between 13-8-20 and 31-7-21. Sociodemographic and clinical data, comorbidities, disease activity and treatment at the moment of the SARS-CoV-2 infection were collected. Additionally, infection symptoms, complications, medical interventions and treatments for COVID-19 were registered. Infection severity was assessed using the WHO-ordinal scale (WHO-OS)1. A cut-off value of ≥5 identified patients with severe COVID-19 and those who died.

Statistical analysis: Descriptive statistics. Chi2 or Fischer test, Student T test or Mann-Whitney and Kruskal Wallis or ANOVA, as appropriate. Multiple logistic regression model.

Results

A total of 801 patients were included, with a mean age of 53.1 ± 12.9 years, most of them were female (84.5%) and the median (m) disease duration was 8 years (IQR 4-14). One third were in remission and 46.4% had comorbidities, being the most frequent, hypertension (26.9 %), dyslipidemia (13.5 %), obesity (13.4 %) and diabetes (8.9%). Moreover, 3.2% had interstitial lung disease (ILD) associated with RA. At SARS-CoV-2 diagnosis, 42.5% were receiving glucocorticoids (GC), 73.9% conventional (c) disease modifying antirheumatic drugs (DMARD), 24% biologic (b) DMARD and 9.1% targeted synthetic (ts) DMARD. Among bDMARD, the most frequently used were TNF inhibitors (17%), followed by abatacept (2.8%), IL-6 inhibitors (2.4%) and rituximab (RTX) (2.1%). During the SARS-CoV-2 infection, 95.8% had symptoms, 27% required hospitalization, 7.9% presented complications and 4.4% died due to COVID-19. Severe disease and death (WHO-OS≥5) was present in 7.5% of the patients. They were older (62.9±12.5 vs 52.2±12.7, p<0.001), and they had more frequently ILD (18.5% vs 2%, p<0.001), comorbidities (82.5% vs 43.7%, p<0.001), ≥2 comorbidities (60.3% vs 25.8%, p<0.001), treatment with GC (61% vs 40.7%, p=0.04) and RTX (8.3% vs 1.6%, p=0.007). Conversely, the use of cDMARD and TNF inhibitors was more frequent in patients with WHO-OS<5, nevertheless this difference was not significant. Disease activity was comparable between groups. In multivariable analysis, older age, the presence of diabetes, ILD, the use of GC and RTX were significantly associated with WHO-OS≥5 (Figure 1). Furthermore, older age (65.7±10.8 vs 52.4±12.8, p<0.001), the presence of comorbidities (87.9% vs 44.7%, p<0.001), chronic obstructive pulmonary disease (21.9% vs 5.2%, p=0.002), diabetes (30.3% vs 7.9%, p<0.001), hypertension (57.6% vs 25.6%, p<0.001), cardiovascular disease (15.6% vs 3.2%, p=0.005), cancer (9.1% vs 1.3%, p=0.001), ILD (23.3% vs 2.4%, p<0.001) and the use of GC (61.8% vs 41.4%, p=0.02) were associated with mortality. Older age [OR 1.1 IC95% 1.06-1.13] and the use of GC 5-10 mg/day [OR 4.6 IC95% 1.8-11.6] remained significantly associated with death due to COVID-19.

Figure 1.

Factors associated with severe disease and death due to COVID-19 (WHO-OS≥5) in patients with rheumatoid arthritis. Multivariable analysis. (ref.: reference; PDN: prednisone; OR: odds ratio; CI: confidence interval)

Conclusion

Treatment with RTX and GC, as well as older age, the presence of diabetes and ILD were associated with poor COVID-19 outcomes in this national cohort of patients with RA. Older patients and those taking GC had a higher mortality rate.

References

[1]World Health Organization coronavirus disease (COVID-19) Therapeutic Trial Synopsis Draft 2020.

Disclosure of Interests

None declared

POS1201 SAFETY OF SARS-COV-2 VACCINES IN PATIENTS WITH RHEUMATIC DISEASES: DATA FROM THE NATIONAL REGISTRY SAR-CoVAC FROM ARGENTINA

Background

Patients with rheumatic diseases (RD) have been excluded from SARS-CoV-2 vaccine trials, though data appear to show safety and efficacy, mostly evidence remains in mRNA vaccines. In our country, adenovirus-vector, inactivated and heterologous scheme vaccines are frequently used.

Objectives

To describe the safety of SARS-CoV-2 vaccines in patients with RD from the national registry SAR-CoVAC and to assess sociodemographic and clinical factors associated to AE and disease flares after vaccination.

Methods

Adult patients with RD who have been vaccinated for SARS-CoV-2 from de Argentine Society of Rheumatology Vaccine Registry (SAR-CoVAC) were consecutively included between June 1st and December 21st, 2021, This is a national multicentric observational registry that includes patients that have received at least one dose of any SARS-CoV-2 available vaccines in Argentina. Data is voluntarily collected by the treating physician. Naranjo scale was use to assess the association between the AE and vaccination.

Homologous and heterologous schedules were defined according to whether both vaccines received were the same or different, respectively. Descriptive statics, Chi2 test, Fischer test, T test, ANOVA and multivariate regression logistic model were used.

Results

A total of 1679 patients, with 2795 SARS-CoV-2 vaccine doses were included. Vaccines more frequently used were: Gam-COVID-Vac (1227 doses, 44%), ChAdOx1 nCov-19 (872 doses, 31%), BBIBP-CorV (482 doses, 17%) and mRAN-1273 (172 doses, 6%). Altogether, 510 EA were experienced by 449 (27%) patients. Pseudo-flu syndrome was the most frequent (11%), followed by injection site reaction (7%). They were significantly more frequent after the first dose in comparison to the second one (13% vs 7% and 9% vs 5%, respectively, p<0.001 in both cases). All were mild or moderate and no patient was hospitalized due to an AE. One case of moderate anaphylaxis was reported by a patient who received Gam-COVID-Vac. No cases of vaccine-induced thrombotic thrombocytopenia were observed. There were 25 disease flares reported, 17 (68%) cases of arthritis. Among patients with two doses, those with heterologous schedule presented AE more frequent after the second dose (39% vs 17%).

Total incidence of EA was 182.5 events/10 00 doses, it was significantly lower for BBIBP-CorV (105.9 events/1000 dosis, p<0.002 for all cases). The higher incidence of AE was observed for mRAN-1273 (261.6 events/1000 doses) and ChAdOx1 nCov-19 (232.8 events/1000 doses).

Patients with AE were younger [mean 55 years (SD 14) vs 59 years (SD 14), p <0.010], not Caucasian ethnicity [48% vs 35%, p<0.001], had higher education level [mean 13.8 years (SD 4) vs 11.9 years (SD 5), p<0.001], were more frequently employed [54% vs 44%, p<0.001], lived mostly in urban area [99% vs 95% p <0.001, had more frequently dyslipidemia [38% vs 28% p 0.012], and less frequently arterial hypertension [49% vs 65%, p<0.001]. Systemic lupus erythematosus [11% vs 7%, p=0.039] and Sjögren syndrome [6% vs 1.8%, p<0.001] were more frequent among them, while non inflammatory diseases were less prevalent [19% vs 31%, p<0.001]. They were taking steroids [24 vs 18%, p=0.007], antimalarials [17% vs 10%, p<0.001] and methotrexate [41% vs 31%, p <0.001] more frequently.

In the multivariable analysis, mRAN-1273 and ChAdOx1 nCov-19 were associated with AE, while BBIBP-CorV with lower probability of having one. (Figure 1)

Figure 1.

Variables associated with the development of AE. Multivariate logistic regression model

Conclusion

The incidence of AE was 1825 events/1000 doses, were significantly higher for mRAN-1273 and ChAdOx1 nCov-19 and lower for BBIBP-CorV. Most common AE was pseudo-flu syndrome. Female sex, being younger, higher education level, ChAdOx1 nCov-19 and mRAN-1273 vaccines, the use of methotrexate and antimalarials were related of EA in patients with RD.

References

[1]Sattui SE et al. Early experience of COVID-19 vaccination in adults with systemic rheumatic diseases: results from the COVID-19 Global Rheumatology Alliance Vaccine Survey. RMD Open 2021;7.

Disclosure of Interests

None declared

POS0953 PERIPHERAL ARTHRITIS AND HIGHER DISEASE ACTIVITY LEAD TO MORE FUNCTIONAL IMPAIRMENT IN AXIAL SPONDYLOARTHRITIS: LONGITUDINAL ANALYSIS FROM ESPAXIA

Background:

Preserving functional ability is among the main goals when treating patients with axSpA. Higher disease activity, reduced axial mobility, and increase spinal radiographic damage, and smoking status have shown to be longitudinally associated with functional worsening. The presence of peripheral arthritis has also been associated with worse functional ability during follow-up, though not in a true longitudinal analysis.

Objectives:

To investigate whether peripheral arthritis together with disease activity independently contribute to functional impairment over time in patients with axSpA and to evaluate if there are contextual factors modifying this relationship.

Methods:

Patients with axSpA from the ESPAXIA cohort were followed-up annually over 7 years. Physical function was assessed by the self-reported questionnaire BASFI, disease activity by ASDAS and peripheral arthritis was also recorded. The association between BASFI (outcome), peripheral arthritis and ASDAS (main variables of interest) over time was tested in generalized estimating equations (GEE) models. Models were autoregressive, i.e. adjusted for BASFI 1 year earlier, to allow for a truly longitudinal interpretation. Interactions between each of ASDAS and peripheral arthritis with contextual factors were tested.

Results:

185 patients were included (77 % male, mean age 42 (SD 13), mean disease duration 9.4 (SD 9.6) years. Mean baseline ASDAS was 2.3 (1.4), mean BASFI 3.9 (2.7) and 17% presented peripheral arthritis during the first visit. After a mean of 3.7 (2.4) years of follow-up, ASDAS and peripheral arthritis independently contributed to explaining BASFI changes over time. Contextual factors did not modify either of the relationships. A true longitudinal relation was proved with the autoregressive GEE model, showing that, adjusted for age, gender, spinal mobility and use of NSAIDs, an increase of one ASDAS unit led to a BASFI 0.48 units higher (ß 0.48 [95% CI 0.39-0.57]), and the presence of peripheral arthritis, to a BASFI 0.44 units higher (ß 0.44 [0.08-0.8]) (Table 1). A gradient was found for ASDAS disease activity states: ASDAS low disease activity (vs ASDAS inactive disease) with an increase in BASFI of 0.67 (0.35-0.98) units compared to ASDAS very high disease activity (vs ASDAS inactive disease) with a BASFI increase of 2.30 (1.90-2.72) units. (Figure 1) No interaction was found between peripheral arthritis and disease activity on BASFI, and similarly, no interactions were found between either ASDAS or peripheral arthritis with age, gender, educational level, smoking status, job type or comorbidities on BASFI.

Table 1.

Factors longitudinally associated with BASFI

AssessmentModel with ASDAS continuousß (95% CI)n=179Model with ASDAS categoricalß (95% CI)n=179Previous BASFI (0-10)0.47 (0.41 to 0.52) †0.44 (0.39 to 0.50)†Age (years)0.007 (-0.005 to 0.02)0.008 (-0.004 to 0.02)Male gender (vs female gender)-0.42 (-0.79 to -0.06) †-0.38 (-0.74 to -0.02)†Peripheral arthritis0.44 (0.08 to 0.80) †0.38 (0.03 to 0.74) †ASDAS-CRP0.48 (0.39 to 0.57) †-ASDAS-CRP categoricalModerate vs inactive disease-0.67 (0.35 to 0.98) †High vs inactive disease-1.70 (1.37 to 2.02) †Very high vs inactive disease-2.30 (1.90 to 2.72) †BASMI (0-10)0.32 (0.24 to 0.41) †0.32 (0.23 to 0.40) †NSAIDs (%)0.38 (0.09 to 0.66) †0.37 (0.09 to 0.64) †

† Significant at p<0.05.

Figure 1.

Longitudinal relationship between ASDAS and BASFI

Conclusion:

Peripheral arthritis and higher disease activity independently lead to more functional impairment in axSpA. Contextual factors do not modify these relationships.

Disclosure of Interests:

Dafne Capelusnik Speakers bureau: BMS, Grant/research support from: Pfizer, Sofia Ramiro Speakers bureau: Lilly, MSD, Novartis, UCB, Consultant of: AbbVie, Lilly, MSD, Novartis, UCB, Sanofi, Grant/research support from: MSD, Emilce Edith Schneeberger Speakers bureau: Abbvie, BMS, Janssen, Eli Lilly, Boehringer Ingelheim, Pfizer, Grant/research support from: Pfizer, Gustavo Citera Speakers bureau: Abbvie, BMS, Janssen, Pfizer, Grant/research support from: Pfizer, BMS, Janssen

POS0312 HOW DOES THE PRESENCE OF DEPRESSION IMPACT ON DISEASE ACTIVITY SCORES IN PATIENTS WITH RHEUMATOID ARTHRITIS?

Background:

Depression is present in up to half of patients with Rheumatoid Arthritis (RA). The association between this mood disorder and disease activity scores, including DAS28, SDAI and CDAI, has previously been described by various authors.

Objectives:

The aim of our study was assessed the effect of depression on the components of different disease activity scores.

Methods:

We performed a cross-sectional study of consecutive adults with RA, according to ACR/EULAR 2010 criteria. Sociodemographic data, comorbidities and current treatment were recorded. Disease activity was evaluated using DAS28-ESR, DAS28-CRP, SDAI and CDAI. Depression was assessed using PHQ-9 questionnaire. The PHQ-9 values were categorized in 4 groups as follows: 5 to 9, 10 to 14, 15 to 19, 20 or greater, represents mild, moderate, moderate/severe, and severe depression, respectively. A cutoff value of 10 or greater was set to define major depression. Statistical analysis: Student´s T, ANOVA and Chi2 tests. Multiple logistic regression.

Results:

Two hundred fifty eight patients were included, with a median (m) disease duration of 9 years (IQR 3.6-16.7). The m PHQ-9 score was 6 (IQR 2-12.3) and the prevalence of major depression was 33.7%. Patients with major depression had more tender and swollen joint count (TJC and SJC) (mean 4.9±4.3 vs 2.3±3.7, p<0.0001 and 2.9±3.3 vs 1.7±3.4, p=0.009), more pain (VAS [cm] mean 5.6±2.7 vs 3.3±2.6, p<0.0001), higher patient and physician global assessment (PGA and PhGA) (VAS [cm] mean 5.4±2.9 vs 3.1±2.5, p<0.0001 and 4.4±2.7 vs 2.4±2.4, p<0.0001) and CRP (mean 1.7±3.3 vs 0.7±1.1 mg/dl, p=0.01). ESR values were higher in the group with major depression, but the difference did not reach significance. Disease activity was higher in the depression group by all scores: DAS28-ESR (mean 4.3±1.4 vs 3.3±1.3, p<0.0001), DAS28-CRP (mean 3.9±1.4 vs 2.8±1.7, p<0.0001), SDAI (mean 19.2±12.7 vs 10.3±10.1, p<0.0001) and CDAI (mean 17.6±10.9 vs 9.6±9.9, p<0.0001). While 41 (15.9%) patients had high disease activity according to DAS28-ESR, only 34 (13.2%) had SDAI>26.

In the multivariate analysis, evaluating the association of major depression with the different components of DAS28-ESR, DAS28-CRP, SDAI and CDAI, we observed that the presence of this mood disorder remained significantly associated with higher PGA in all the scores. In addition, a significant association was seen with higher TJC in both DAS28 scores.

Conclusion:

Patients with major depression had higher disease activity. It´s presence has a significantly association with the subjective items of the disease activity scores, particularly PGA. CRP value was the only objective component associated with depression.

Disclosure of Interests:

Carolina Ayelen Isnardi Speakers bureau: Bristol Myers Squibb, Janssen, Grant/research support from: Pfizer, Emilce Edith Schneeberger Speakers bureau: Abbvie, Amgen, Bristol Myers Squibb, Janssen, Eli Lilly, Boehringer Ingelheim, Pfizer, Genzyme, Grant/research support from: Pfizer, Dafne Capelusnik Speakers bureau: Bristol Myers Squibb, Grant/research support from: Pfizer, Marcela Bazzarelli: None declared, Laura Barloco: None declared, Eliana Soledad Blanco: None declared, Alejandro Benitez Speakers bureau: Abbvie, Novartis, Amgen, Federico Benavidez: None declared, SANTIAGO SCARAFIA: None declared, María Alicia Lazaro Speakers bureau: Abbvie, Rodolfo Perez Alamino Speakers bureau: Pfizer, Abbvie, Amgen, Bristol-Myers-Squibb, Lilly, Janssen, Novartis, Federico Colombres: None declared, María Paula Kohan: None declared, Julia Sosa: None declared, Luciana Gonzalez Lucero: None declared, Ana Lucía Barbaglia: None declared, Hernan Maldonado Ficco Speakers bureau: Pfizer, Abbvie, Jansen, Novartis, Bago, Bristol, Eli Lilly., Consultant of: Pfizer, Abbvie, Novartis, Jansen, Bago, Eli Lilly., Gustavo Citera Speakers bureau: Abbvie, Bristol-Myers-Squibb, Lilly, Jansen, Gema, Pfizer, Roche, Grant/research support from: Pfizer

POS1005 ASSESSMENT OF DAREA AND MODIFIED DAREA IN AN ARGENTINIAN-GUATEMALAN REACTIVE ARTHRITIS COHORT

Background:

Reactive Arthritis (ReA) is an inflammatory joint disease and, as in rheumatoid or psoriatic arthritis, composite indices are the most useful tools to measure disease activity. The Disease Activity Index for Reactive Arthritis (DAREA) is the only developed index for ReA, which requires a 66/68 joint count and CRP for its assessment, the latter being difficult to acquire in our setting. Therefore, we developed a simplified index, the modified DAREA (DAREAm), with a lower joint count and ESR for its evaluation.

Objectives:

1) To evaluate the DAREA and the DAREAm in a cohort of patients with diagnosis of ReA and post-infectious arthritis 2) To assess the correlation of the DAREA and DAREAm with several clinical variables, functional capacity and quality of life in a cohort of patients with ReA.

Methods:

Patients with diagnosis of ReA (Calin’79) and post-infectious arthritis were included. Demographic data were collected, patient´s pain and global assessment were evaluated through a visual analog scale (VAS) and a 3-point scale (no pain = 0, mild = 1, moderate = 2, severe = 3), physician´s global assessment, morning stiffness (MS) and VAS fatigue. Functional capacity was assessed by HAQ and quality of life according to EuroQol-5 dimensions (EQ-5D), and the activity indices DAS28, DAREA and DAREAm were calculated. Statistical analysis: a descriptive analysis of the variables and correlation between numerical variables with Spearman rank correlation were performed.

Results:

57 patients were included, 53 with diagnosis of ReA, the majority post urogenital (63%) and gastrointestinal (17%), and 4 with diagnosis of post-infectious arthritis. Fifty six percent were male, mean age: 40 years old (SD ± 14) and median ReA duration: 15 months (IQR 2-45). The number of painful and swollen joints in a 66/68 joint count showed a median of 2 (IQR 0-3) and 1 (IQR 1-2) respectively. Median VAS pain 43 (IQR 15-70), patient´s disease activity 40 (IQR 20-60) and physician´s 40 (IQR 20-60), MS 10 (IQR 0-50) and fatigue 30 (IQR 0-80). Median DAS28 3.6 (IQR 2.3-4.3), DAREA 7.4 (IQR 2.5-10.6), DAREAm 8.6 (IQR 4.6-12.7), HAQ 0.625 (IQR 0.125-1). The dimensions with the greatest compromise in the EQ-5D were pain/discomfort (63%) and anxiety/depression (51%), and the median VAS EQ-5D was 60 (IQR 32-80). DAREA correlated with DAREAm (rs= 0.89; p <0.001), DAS28 (rs= 0.84; p <0.001), medical VAS (rs= 0.60; p <0.001), MS (rs= 0, 50; p <0.001), HAQ (rs= 0.53; p <0.001), VAS fatigue (rs= 0.57; p <0.001) and mobility subscales of the EQ5D (rs= 0.56; p <0.001), pain/discomfort (rs= 0.49; p <0.001) and anxiety/depression (rs= 0.61; p <0.001). The DAREAm correlated with DAS28 (rs= 0.93; p <0.001), physician VAS (rs= 0.58; p <0.001), fatigue VAS (rs= 0.53; p <0.001), HAQ (rs= 0 .51; p <0.001) and the EQ5D subscales: mobility (rs= 0.64; p <0.001), pain/discomfort (rs= 0.56; p <0.001) and anxiety/depression (rs= 0.66; p <0.001)

Conclusion:

This is the first study that assess activity indices in a cohort of patients with ReA. The DAREAm demonstrated a very good correlation with both DAREA and DAS28. We encourage the use of this simplified index in daily practice to evaluate patients with ReA.

Disclosure of Interests:

None declared.

[Idiophatic inflammatory myophaties: its asociation with liver disorders]

The aspartate aminotransferase (SGOT) and alanine aminotransferase (SGPT) are sensitive indicators of liver damage. While the TSGOT is also found in other organs, the SGPT is considered an enzyme specific liver. However, some authors state that the TGP can rise also in cases of muscle injury. Furthermore, there are reports in the literature suggesting the association of idiopathic inflammatory myopathies (IIM) with viral hepatitis.

OBJECTIVE

To determine the frequency of abnormal liver function tests in patients with idiopathic inflammatory myopathies, evaluate possible associationsto liver diseases, determine its relationship with elevation of muscle enzymes and whether these patients have particular clinical and / or serological characteristics.

MATERIAL AND METHODS

Consecutive patients older than 16 years diagnosed with DM / PM according to Bohan and Peter criteria during 1999-2000 were included. Patients with other connective tissue disease (CTD) were excluded. Demographic data were recorded, characteristics of the disease, laboratory data and elevated liver enzymes and muscle during the course of the disease. Serologic tests were performed for viral hepatitis B and C and confirmatory tests (HBV-DNA and HCV-RNA by PCR). Autoantibodies were determined: ANA (antinuclear antibody) by Hep II, ASMA (anti smooth muscle antibody), AMA (anti-mitochondrial antibodies) and LKM (Liver Kidney Microsomal) by mouse wound, MSA (myositis-specific antibodies) by ELISA. Patients who had abnormal liver tests underwent hepatic ultrasonography. For statistical analysis, descriptive statistics, categorical variables were compared by Fisher's exact test.

RESULTS

We included 27 patients, of whom 22 had sufficient data for analysis. Mean age 47.95 years ± 16, 18 female (81.8%) and mean disease duration 8.09 ± 5.6 years. With regard to liver enzymes, 14/22 patients (63.3%) had elevated SGPT and 11/22 (50%) elevated SGOT, 10 of these patients also had elevated SGPT concomitantly. In the 10/15 (66.7%) abdominal ultrasonography showed abnormalities, 8 patients had liver hyperechogenicity, 4 cholelithiasis and 1 patient hepatomegaly. No patient bearing of HBV or HCV. The 8 patients with liver hyperechogenicity matched the 8 patients with isolated elevation of SGPT/SGOT. As for the 10 patients who had both elevated liver enzymes (SGPT and SGOT), only one case could be explained by liver disease (patient ASMA +). However in the 15 cases studied, elevations of SGPT and / or SGOT coincided with outbreaks of myositis,findingconcomitant apparent liver disease in only 9 of them.

CONCLUSIONS

In this study, elevated transaminases, including the TGP, was observed concomitantly with the activity of myositis. Approximately half of these cases could not be associated with coexisting liver disease, which could be attributed to injury to muscle secondary to inflammatory myopathy.

The influence of intravascular fluid volume on the permeability of newborn and adult mouse lungs to ultrastructural protein tracers

The permeability of the alveolar-capillary membrane of newborn and adult mice to horseradish peroxidase (HRP) and catalase was studied by means of ultrastructural cytochemistry, and the permeability to ferritin was studied by electron microscopy. The influence of varying volumes of intravenously injected fluid on the rate of leakage of the tracers from pulmonary capillaries was examined. The tracers were injected intravenously and the mice were sacrificed at timed intervals. Experiments on newborn mice with intranasally instilled HRP were also done. The tissues were fixed in formaldehyde-glutaraldehyde fixative. Chopped sections were incubated in Graham and Karnovsky's medium for peroxidase and in a modification of this medium for catalase. Tissues were postfixed in OsO₄ and processed for electron microscopy. In both newborn and adult mice, the ready passage of peroxidase through endothelial clefts was dependent on the injection of the tracer in large volumes of saline. When the tracer was injected in small volumes of saline, its passage through endothelial clefts was greatly reduced. Endothelial junctions of newborn mice were somewhat more permeable to HRP than those of adult mice. In all animals, alveolar epithelial junctions were impermeable to HRP. Catalase and ferritin did not pass through endothelial junctions. Intranasally instilled HRP in newborn mice was taken up by pinocytotic vesicles and tubules of flat alveolar cells.

Ultrastructural basis for alveolar-capillary permeability to protein

The intravenous injection into mice of small volumes (less than 0.1 ml) of peroxidatic enzymes of molecular weight of 40 000 daltons or greater results in little if any penetration of these probe molecules into endothelial junctions. The injection of cytochrome c (12 000 daltons), on the other hand, results in the localization of this tracer in some but not all endothelial junctions. When horseradish peroxidase (EC 1.11.1.7) is injected in a large volume of saline (0.5 ml), reaction product is present in endothelial junctions and basement membrane, but is prevented from entering the alveolar space by zonulae occludentes between epithelial cells. These experiments indicate that although endothelial junctions, under physiological conditions, are largely impermeable to molecules the size of horseradish peroxidase, and presumably most serum proteins, they are labile and susceptible to stretching if intravascular pressure is increased. Freeze-fracture studies show that pulmonary capillary endothelial junctions are composed of one or at the most two strands which show areas of discontinuity. Epithelial junctions, by contrast, are composed of a continuous, complex network of anastomosing fibres. These observations confirm physiological experiments which indicate that it is the pulmonary epithelium rather than the endothelium which determines the permeability properties of the alveolar-capillary membrane to lipid-insoluble molecules. Bidirectional pinocytic transport is an additional mechanism whereby lipid-insoluble molecules are transported across both endothelial and epithelial layers. The relative contribution of this transport mechanism to the total amount transported remains to be established.

Glycoprotein E of varicella-zoster virus enhances cell-cell contact in polarized epithelial cells

Varicella-zoster virus (VZV) infection involves the cell-cell spread of virions, but how viral proteins interact with the host cell membranes that comprise intercellular junctions is not known. Madin-Darby canine kidney (MDCK) cells were constructed to express the glycoproteins gE, gI, or gE/gI constitutively and were used to examine the effects of these VZV glycoproteins in polarized epithelial cells. At low cell density, VZV gE induced partial tight junction (TJ) formation under low-calcium conditions, whether expressed alone or with gI. Although most VZV gE was intracellular, gE was also shown to colocalize with the TJ protein ZO-1 with or without concomitant expression of gI. Freeze fracture electron microscopy revealed normal TJ strand morphology in gE-expressing MDCK cells. Functionally, the expression of gE was associated with a marked acceleration in the establishment of maximum transepithelial electrical resistance (TER) in MDCK-gE cells; MDCK-gI and MDCK-gE/gI cells exhibited a similar pattern of early TER compared to MDCK cells, although peak resistances were lower than those of gE alone. VZV gE expression altered F-actin organization and lipid distribution, but coexpression of gI modulated these effects. Two regions of the gE ectodomain, amino acids (aa) 278 to 355 and aa 467 to 498, although lacking Ca(2+) binding motifs, exhibit similarities with corresponding regions of the cell adhesion molecules, E-cadherin and desmocollin. These observations suggest that VZV gE and gE/gI may contribute to viral pathogenesis by facilitating epithelial cell-cell contacts.

Inducible expression of claudin-1-myc but not occludin-VSV-G results in aberrant tight junction strand formation in MDCK cells

Occludin and 18 distinct members of the claudin family are tetra-span transmembrane proteins that are localized in cell-specific tight junctions (TJs). A previous study showed that expression of chick occludin in Madin-Darby canine kidney (MDCK) cells raised transepithelial electrical resistance (TER) and, paradoxically, increased mannitol flux. In the present study, we employed epitope tagged canine occludin expression, under the control of the tetracycline repressible transactivator, to determine the extent to which the unexpected parallel increase in TER and mannitol flux was related to a structural mismatch between avian and canine occludins, which are only 50% identical. To determine whether the paradoxical changes in permeability was specific to occludin, we assessed the effect of over-expressing epitope tagged murine claudin-1. Our data revealed that over-expression of either of the epitope tagged mammalian tight junction proteins increased TER, mannitol and FITC-dextran flux. We observed a 2- and up to 5.6-fold over-expression of occludin-VSV-G and claudin-1-myc, respectively, with no change in ZO-1, endogenous occludin or claudin-1 expression. Confocal microscopy revealed that occludin-VSV-G, claudin-1-myc and ZO-1 co-localized at the TJ. In addition, claudin-1-myc formed aberrant strands along the lateral cell surface without an underlying ZO-1 scaffold. In fracture labeled replicas these strands consisted of claudin-1-myc with little accompanying occludin. These observations suggest that in epithelial cells claudin-1 can assemble into TJ strands without the participation of either ZO-1 or occludin. The proximity of the myc tag to the COOH-terminal YV sequence of claudin-1 appeared to interfere with its interaction with ZO-1, since over-expression of non-tagged claudin-1 increased TER but had a minimal effect on solute flux and no aberrant strands formed. From our data we conclude that differences in structure between avian and mammalian occludin do not account for the observed paradoxical increase in mannitol flux. Levels of ZO-1 remained unchanged despite substantial increases in induced TJ integral protein expression, suggesting that an imbalance between levels of ZO-1 and occludin or claudin-1 leads to altered regulation of pores through which non-charged solute flux occurs. We suggest that ion and solute flux are differentially regulated at the TJ.

Inhibiting cadherin function by dominant mutant E-cadherin expression increases the extent of tight junction assembly

Previous studies have shown that induction of cadherin-mediated cell-cell adhesion leads to tight junction formation, and that blocking cadherin-mediated cell-cell adhesion inhibits tight junction assembly. Here we report analysis of tight junction assembly in MDCK cells overexpressing a mutant E-cadherin protein that lacks an adhesive extracellular domain (T151 cells). Mutant E-cadherin overexpression caused a dramatic reduction in endogenous cadherin levels. Despite this, tight junction assembly was extensive. The number of tight junction strands observed by freeze-fracture electron microscopy significantly increased in T151 cells compared to that in control cells. Our data indicate that the hierarchical regulation of junctional complex assembly is not absolute, and that inhibition of cadherin function has both positive and negative effects on tight junction assembly.

Restoration of tight junction structure and barrier function by down-regulation of the mitogen-activated protein kinase pathway in ras-transformed Madin-Darby canine kidney cells

In the Madin-Darby canine kidney epithelial cell line, the proteins occludin and ZO-1 are structural components of the tight junctions that seal the paracellular spaces between the cells and contribute to the epithelial barrier function. In Ras-transformed Madin-Darby canine kidney cells, occludin, claudin-1, and ZO-1 were absent from cell-cell contacts but were present in the cytoplasm, and the adherens junction protein E-cadherin was weakly expressed. After treatment of the Ras-transformed cells with the mitogen-activated protein kinase kinase (MEK1) inhibitor PD98059, which blocks the activation of mitogen-activated protein kinase (MAPK), occludin, claudin-1, and ZO-1 were recruited to the cell membrane, tight junctions were assembled, and E-cadherin protein expression was induced. Although it is generally believed that E-cadherin-mediated cell-cell adhesion is required for tight junction assembly, the recruitment of occludin to the cell-cell contact area and the restoration of epithelial cell morphology preceded the appearance of E-cadherin at cell-cell contacts. Both electron microscopy and a fourfold increase in the transepithelial electrical resistance indicated the formation of functional tight junctions after MEK1 inhibition. Moreover, inhibition of MAPK activity stabilized occludin and ZO-1 by differentially increasing their half-lives. We also found that during the process of tight junction assembly after MEK1 inhibition, tyrosine phosphorylation of occludin and ZO-1, but not claudin-1, increased significantly. Our study demonstrates that down-regulation of the MAPK signaling pathway causes the restoration of epithelial cell morphology and the assembly of tight junctions in Ras-transformed epithelial cells and that tyrosine phosphorylation of occludin and ZO-1 may play a role in some aspects of tight junction formation.

The accumulation of dendritic cells in the lung is impaired in CD18-/- but not in ICAM-1-/- mutant mice

Bone marrow-derived dendritic cell (DC) precursors migrate via the blood stream to peripheral tissues to adopt their sentinel function. To identify factors facilitating their emigration to the lung, mutant mice deficient in E-selectin, P-selectin, E/P-selectin, ICAM-1, or CD18 and their respective controls were examined. DCs and monocytes/macrophages were immunolabeled with M5/114 and MOMA-2 mAbs, respectively, and quantified morphometrically. Of these genotypes, the numbers of DC and MOMA-2+ cells were significantly less only in the lungs of CD18-/- mice by 68 and 35% in alveolar walls and by 28 and 26% in venous walls, respectively. DCs were reduced by 30 and 41% around large and small airways, respectively, but the number of MOMA-2+ cells in these locations was not significantly different from controls. Ablation of a single gene may be associated with augmented expression of other, related gene products. Therefore, we examined the expression of VCAM-1. Increased numbers of arteries exhibited continuous luminal VCAM-1 staining in both CD18-/- and ICAM-1-/- mutants. VCAM-1 expression was absent in pulmonary capillaries and unchanged in veins. These data suggest that under nonperturbing conditions, CD18-mediated adhesion is required for the full complement of DC precursors to accumulate in the lungs. However, the defect in CD18-/- mice is partial, suggesting that CD18-independent adhesion occurs. The alternative pathway may involve VLA-4/VCAM-1 in arteries and venules but not in capillaries. The smaller defect in ICAM-1-/- mice suggests that the CD11/CD18 complex recognizes ligands other than ICAM-1 at some sites.

Complement activation in acute humoral renal allograft rejection: diagnostic significance of C4d deposits in peritubular capillaries

The distinction between acute humoral rejection (AHR) and acute cellular rejection (ACR) in renal allografts is therapeutically important, but pathologically difficult. Since AHR is probably mediated by antibodies to the donor endothelium that activate the classical complement pathway, it was hypothesized that peritubular capillary C4d deposition might distinguish this group. Renal biopsies (n = 16) from 10 patients with AHR who had acute graft dysfunction, neutrophils in peritubular capillaries, and a concurrent positive cross-match were stained for C4d by immunofluorescence. Control biopsies for comparison showed ACR (n = 14), cyclosporin A toxicity (n = 6), or no abnormality (n = 4). Peribiopsy sera were tested for anti-donor HLA antibody. C4d deposited prominently and diffusely in the peritubular capillaries in all AHR biopsies (16 of 16). IgM and/or C3 were also present in 19 and 44%, respectively. With two-color immunofluorescence, C4d was localized in basement membranes (type IV collagen+) and in the endothelium (Ulex europaeus agglutinin-I+). In ACR, no more than trace C4d was found in peritubular capillaries (P < 0.0001 versus AHR), and no patient had anti-donor HLA antibodies (0 of 8); 27% had neutrophils in peritubular capillaries. One of six biopsies with cyclosporin A toxicity had similar C4d deposits, and circulating anti-donor class I antibody was detected. Grafts with AHR were lost (40%) more often than those with ACR (0%; P < 0.02). C4d in peritubular capillary walls distinguishes AHR from ACR, is more specific and sensitive than traditional criteria, and is a potentially valuable adjunct in the diagnosis of graft dysfunction.

Connexin-occludin chimeras containing the ZO-binding domain of occludin localize at MDCK tight junctions and NRK cell contacts

Occludin is a transmembrane protein of the tight junction that functions in creating both an intercellular permeability barrier and an intramembrane diffusion barrier. Creation of the barrier requires the precise localization of occludin, and a distinct family of transmembrane proteins called claudins, into continuous linear fibrils visible by freeze-fracture microscopy. Conflicting evidence exists regarding the relative importance of the transmembrane and extracellular versus the cytoplasmic domains in localizing occludin in fibrils. To specifically address whether occludin's COOH-terminal cytoplasmic domain is sufficient to target it into tight junction fibrils, we created chimeras with the transmembrane portions of connexin 32. Despite the gap junction targeting information present in their transmembrane and extracellular domains, these connexin-occludin chimeras localized within fibrils when expressed in MDCK cells, as assessed by immunofluorescence and immunogold freeze-fracture imaging. Localization of chimeras at tight junctions depends on the COOH-terminal ZO-binding domain and not on the membrane proximal domain of occludin. Furthermore, neither endogenous occludin nor claudin is required for targeting to ZO-1-containing cell-cell contacts, since in normal rat kidney fibroblasts targeting of chimeras again required only the ZO-binding domain. These results suggest an important role for cytoplasmic proteins, presumably ZO-1, ZO-2, and ZO-3, in localizing occludin in tight junction fibrils. Such a scaffolding and cytoskeletal coupling function for ZO MAGUKs is analogous to that of other members of the MAGUK family.

Rapid reduction of MDCK cell cholesterol by methyl-beta-cyclodextrin alters steady state transepithelial electrical resistance

The role of plasma membrane lipids in regulating the passage of ions and other solutes through the paracellular pathway remains controversial. In this study we explore the contribution of cholesterol (CH) in maintaining the barrier function of an epithelial cell line using the CH-solubilizing agent methyl beta-cyclodextrin (MBCD) to stimulate CH efflux. Inclusion of 20 mM MBCD in both apical and basolateral media reduced CH levels by 70-80% with no significant effect on cell viability. Most of that decrease occurred during the first 30 min of incubation. Recovery of CH content to initial values was nearly complete 22 h after removal of MBCD. Within 30 min of adding MBCD to the culture medium, transepithelial electrical resistance (TER) increased, reaching maximum values 30-40% above controls. This early rise in TER occurred when MBCD was added to either side of the monolayer. The later rapid decline in TER was observed only when MBCD bathed the basolateral surface from which, coincidentally, CH efflux was most rapid. Freeze fracture replicas and transmission electron microscopy of monolayers exposed to MBCD for only 30 min revealed no increase in either the average tight junction (TJ) strand number or the dimensions of the lateral intercellular space. There was a statistically significant increase in the number of TJ particles associated with the E fracture face at this time. This raises the interesting possibility that during CH efflux there is a change in the interaction between TJ particles and underlying cytoskeletal elements. There was no change in staining for occludin and ZO-1. After exposing the basolateral surface to MBCD for 2 h, TER fell below control levels. The accompanying increase in mannitol flux suggests strongly that the decrease in TER resulted from an increase in the permeability of the paracellular and not the transcellular pathway. A decrease in immuno-staining for occludin and ZO-1 at TJs, a striking accumulation of actin at tri-cellular areas as well as a decline in the number of parallel strands, as seen in freeze fracture replicas, suggest that changes in cytoskeletal organization during long incubations with MBCD had physically disrupted the TJ network. Data are presented which suggest that the observed changes in paracellular permeability during CH efflux may be related to increased levels of lipid-derived second messengers, some of which may trigger changes in the phosphorylation status of TJ proteins.

VIP17/MAL, a lipid raft-associated protein, is involved in apical transport in MDCK cells

Apical proteins are sorted and delivered from the trans-Golgi network to the plasma membrane by a mechanism involving sphingolipid-cholesterol rafts. In this paper, we report the effects of changing the levels of VIP17/MAL, a tetraspan membrane protein localized to post-Golgi transport containers and the apical cell surface in MDCK cells. Overexpression of VIP17/MAL disturbed the morphology of the MDCK cell layers by increasing apical delivery and seemingly expanding the apical cell surface domains. On the other hand, expression of antisense RNA directed against VIP17/MAL caused accumulation in the Golgi and/or impaired apical transport of different apical protein markers, i.e., influenza virus hemagglutinin, the secretory protein clusterin (gp80), the transmembrane protein gp114, and a glycosylphosphatidylinositol-anchored protein. However, antisense RNA expression did not affect the distribution of E-cadherin to the basolateral surface. Because VIP17/MAL associates with sphingolipid-cholesterol rafts, these data provide functional evidence that this protein is involved in apical transport and might be a component of the machinery clustering lipid rafts with apical cargo to form apical transport carriers.

Dendritic cell precursors are enriched in the vascular compartment of the lung

The vast mucosal interface separating external from internal compartments of the lung is under the surveillance of a population of blood-borne, bone marrow-derived dendritic cells (DC) characterized by constant turnover. Because these sentinel cells process foreign antigens that have penetrated the epithelial barrier and transport them to local lymph nodes, they require continuous replenishment by blood-borne cells. In the present study, the phenotype and function of DC and their precursors isolated from the vascular compartment of the lung were examined and compared with those in vena cava blood. Intravascular leukocytes were retrieved by exhaustive perfusion of the lung vasculature. Leukocytes harvested from the subdiaphragmatic vena cava of the same animal served as a source of DC in prepulmonary blood. Typical, large, major histocompatibility class II+ antigen (MHC II+) DC constituted < 1% of leukocytes from either vascular compartment. These cells expressed intercellular adhesion molecule [ICAM]-1 and lymphocyte function-associated antigen [LFA]-1 and many were ED1(+) (lysosomal antigen in monocytes, macrophages, and some DC). No ED2(+) cells (macrophages) were identified. Very few of the circulating DC expressed the alpha-like subunit of integrin recognized by the OX62 monoclonal antibody. A striking difference appeared when neutrophil-depleted leukocytes were cultured with granulocyte macrophage colony-stimulating factor (GM-CSF) for 3 d; the number of MHC II+ DC generated from pulmonary vascular leukocytes was 76% greater than that from the vena cava population. After pulse-labeling with tritiated thymidine ([3H]TdR) followed by 3 d of culture with GM-CSF, DC from either source remained virtually unlabeled, as determined by autoradiography. On the day of harvest, DC and their precursors obtained from either vascular compartment were poor stimulators of the mixed leukocyte reaction and required GM-CSF for development of their full accessory cell capability. These data suggest that, relative to leukocytes in vena cava blood, those in the lung vascular compartment are enriched in a population of mononuclear cells that are capable of differentiating into MHC II+ DC when exposed to the appropriate growth factors, including GM-CSF. This enriched population of DC precursors could represent a source from which lung DC may be readily recruited not only to replenish the normally turning-over mucosal DC, but also to participate in inflammatory reactions occurring in the lung.

Structural and functional regulation of tight junctions by RhoA and Rac1 small GTPases

Tight junctions (TJ) govern ion and solute diffusion through the paracellular space (gate function), and restrict mixing of membrane proteins and lipids between membrane domains (fence function) of polarized epithelial cells. We examined roles of the RhoA and Rac1 GTPases in regulating TJ structure and function in MDCK cells using the tetracycline repressible transactivator to regulate RhoAV14, RhoAN19, Rac1V12, and Rac1N17 expression. Both constitutively active and dominant negative RhoA or Rac1 perturbed TJ gate function (transepithelial electrical resistance, tracer diffusion) in a dose-dependent and reversible manner. Freeze-fracture EM and immunofluoresence microscopy revealed abnormal TJ strand morphology and protein (occludin, ZO-1) localization in RhoAV14 and Rac1V12 cells. However, TJ strand morphology and protein localization appeared normal in RhoAN19 and Rac1N17 cells. All mutant GTPases disrupted the fence function of the TJ (interdomain diffusion of a fluorescent lipid), but targeting and organization of a membrane protein in the apical membrane were unaffected. Expression levels and protein complexes of occludin and ZO-1 appeared normal in all mutant cells, although ZO-1 was more readily solubilized from RhoAV14-expressing cells with Triton X-100. These results show that RhoA and Rac1 regulate gate and fence functions of the TJ, and play a role in the spatial organization of TJ proteins at the apex of the lateral membrane.

Water transport and the distribution of aquaporin-1 in pulmonary air spaces

Recent evidence suggests that water transport between the pulmonary vasculature and air spaces can be inhibited by HgCl2, an agent that inhibits water channels (aquaporin-1 and -5) of cell membranes. In the present study of isolated rat lungs, clearances of labeled (3HOH) and unlabeled water were compared after instillation of hypotonic or hypertonic solutions into the air spaces or injection of a hypotonic bolus into the pulmonary artery. The clearance of 3HOH between the air spaces and perfusate after intratracheal instillation and from the vasculature to the tissues after pulmonary arterial injections was invariably greater than that of unlabeled water, indicating that osmotically driven transport of water is limited by permeability of the tissue barriers rather than the rate of perfusion. Exposure to 0.5 mM HgCl2 in the perfusate and air-space solution reduced the product of the filtration coefficient and surface area (PfS) of water from the air spaces to the perfusate by 28% after instillation of water into the trachea. In contrast, perfusion of 0.5 mM HgCl2 in air-filled lungs reduced PfS of the endothelium by 86% after injections into the pulmonary artery, suggesting that much of the action of this inhibitor is on the endothelial surfaces. Confocal laser scanning microscopy demonstrated that aquaporin-1 is on mouse pulmonary endothelium. No aquaporin-1 was found on alveolar type I cells with immunogold transmission electron microscopy, but small amounts were present on some type II cells.

Pulmonary response to inhaled antigen: neuroimmune interactions promote the recruitment of dendritic cells to the lung and the cellular immune response to inhaled antigen

Dendritic cells (DCs) play a critical role in capturing and presenting inhaled antigens to T lymphocytes. We report that pulmonary DCs in the Lewis rat are normally located in the lung in immediate proximity to nerve fibers that contain immunoreactive substance P (SP). Functionally, pulmonary DCs bound 125I-SP and displayed increased motility in vitro in response to graded concentrations of SP. However, SP had no effect on the accessory cell activities of DCs. To examine the role of neural influences on the pulmonary immune response to inhaled antigen, Lewis rats were pretreated with capsaicin (CAP), which damages small nerves and depletes neuropeptide stores, and then challenged intratracheally (i.t.) with hen egg lysozyme (HEL). The number and antigen-presenting cell activities of pulmonary DCs in the CAP-treated rats were comparable to those of controls up to day 14. T lymphocytes harvested from the regional lymph nodes draining the lung were effectively sensitized to HEL in both groups. However, when CAP-treated rats sensitized to HEL i.t. at day 0 were rechallenged with HEL i.t. at day 14, the lungs showed decreased numbers of OX-6+ DCs and diminished pulmonary lymphoid infiltrates compared with controls. We suggest that CAP interferes with a neural-mediated response that contributes to the accumulation of inflammatory cells during the efferent limb of the pulmonary-cell-mediated immune response in vivo.

Interferon-gamma reduces Ia+ dendritic cell traffic to the lung

MHC class II+ lung dendritic cells (DC) increase in number following treatment of animals with interferon-gamma (IFN-gamma) [Kradin et al. (1991) Am. J. Resp. Mol. Biol. 4, 210; Gong et al. (1992)J. Exp. Med. 175, 797]. To test whether this is due to increased sequestration and/or trafficking of DC to the lung, bone marrow DC from BALB/c mice were obtained by culturing bone marrow with granulocyte-macrophage colony-stimulating factor (GM-CSF). Recipient BALB/c mice were injected intraperitoneally (i.p.) for 4 days with one of the following: IFN-gamma, dexamethasone (Dex), or phosphate-buffered saline (PBS). Twenty-four hours after the last dose, they were injected intravenously (i.v.) with carboxyfluorescein (F1) -labeled DC (1 x 10(6)/mouse) and killed 4 h later. DC, double immunostained for Ia and F1, were quantified by morphometry in frozen sections of lung. The number of injected dual-labeled DC/cm2 was reduced by 90% in IFN-gamma-treated mice. By contrast, there was no significant difference between Dex- and PBS-treated animals in the number of double-labeled DC retained in pulmonary capillaries. Biodistribution and imaging studies were conducted on IFN-gamma- and PBS-treated mice using 111In-labeled DC. Reduced radioactivity in the lung was accounted for by an equivalent increase in the liver of IFN-gamma-treated mice; imaging studies confirmed these observations. Removal of >80% of alveolar macrophages (AM) by pretreatment with intratracheally administered chlodronate-loaded liposomes did not change the biodistribution of DC in IFN-gamma- and PBS-injected mice. Serum levels of tumor necrosis factor-alpha (TNF-alpha and nitrite/nitrate in IFN-gamma-treated mice were similar to those of controls. Immunostaining for inducible nitric oxide synthase (iNOS), however, revealed a 1.5-and 6-fold increase in the number of positively stained cells in the lung and liver, respectively, of IFN-gamma-treated mice; the number of iNOS-expressing cells was markedly reduced in Dex-treated animals relative to controls. To test whether the systemic treatment with IFN-gamma stimulated the cytotoxic activity of Kupffer cells, mice were injected with chlodronate liposomes 5 days before death. After treating the mice in the ensuing 4 days with IFN-gamma or PBS, biodistribution and imaging studies with 111In-labeled DC were conducted on the 5th day. After administration of chlodronate liposomes, there was a significant increase in the radioactivity detected in the lungs of IFN-gamma-injected mice but not in those of PBS- injected controls, a finding confirmed by imaging studies. We conclude that IFN-gamma treatment augmented Kupffer cell cytotoxic activity, which, in turn, effectively reduced the number of injected DC in circulation, with the result that fewer of these cells were retained in the lung vasculature. We further conclude that IFN-gamma increases the number of Ia+ lung DC by up-regulating Ia expression of resident Ia- DC precursors and not by promoting the migration of circulating DC to the lung.

Occludin is a functional component of the tight junction

Occludin's role in mammalian tight junction activity was examined by ‘labeling’ the occludin pool with immunologically detectable chick occludin. This was accomplished by first transfecting MDCK cell with the Lac repressor gene. HygR clones were then transfected with chick occludin cDNA inserted into a Lac operator construct. The resulting HygR/NeoR clones were plated on porous inserts and allowed to form tight junctions. Once steady state transepithelial electrical resistance was achieved, isopropyl- beta-D-thiogalactoside was added to induce chick occludin expression. Confocal laser scanning microscopy of monolayers immunolabeled with Oc-2 monoclonal antibody revealed that chick occludin localized precisely to the preformed tight junctions. When sparse cultures were maintained in low Ca2+ medium, chick occludin and canine ZO-1 co-localized to punctate sites in the cytoplasm suggesting their association within the same vesicular structures. In low calcium medium both proteins also co-localized to contact sites between occasional cell pairs, where a prominent bar was formed at the plasma membrane. Chick occludin was detectable by western blot within two hours of adding isopropyl- beta-D-thiogalactoside to monolayers that had previously achieved steady state transepithelial electrical resistance; this coincided with focal immunofluorescence staining for chick occludin at the cell membrane of some cells. A gradual rise in transepithelial electrical resistance, above control steady state values, began five hours after addition of the inducing agent reaching new steady state values, which were 30–40% above baseline, 31 hours later. Upon removal of isopropyl- beta-D-thiogalactoside chick occludin expression declined slowly until it was no longer detected in western blots 72 hours later; transepithelial electrical resistance also returned to baseline values during this time. While densitometric analysis of western blots indicated that the presence of chick occludin had no detectable effect on E-cadherin or ZO-1 expression, the possibility cannot be excluded that ZO-1 might be a limiting factor in the expression of chick occludin at the cell surface. To test whether expression of chick occludin affected the process of tight junction assembly, monolayers in low Ca2+ medium were treated with isopropyl- beta-D-thiogalactoside for 24 or 48 hours, before Ca2+ was added to stimulate tight junction assembly. Chick occludin did not alter the rate at which transepithelial electrical resistance developed, however, steady state values were 30–40% above control monolayers not supplemented with the inducing agent. By freeze fracture analysis, the number of parallel tight junction strands shifted from a mode of three in controls to four strands in cells expressing chick occludin and the mean width of the tight junction network increased from 175 +/- 11 nm to 248 +/- 16 nm. Two days after plating confluent monolayers that were induced to express chick occludin, mannitol flux was reduced to a variable degree relative to control monolayers. With continued incubation with the inducing agent, mannitol flux increased on day 11 to 50%, and TER rose to 45% above controls. Both of these changes were reversible upon removal of isopropyl- beta-D-thiogalactoside. These data are consistent with the notion that occludin contributes to the electrical barrier function of the tight junction and possibly to the formation of aqueous pores within tight junction strands.

Alterations in cell cholesterol content modulate Ca(2+)-induced tight junction assembly by MDCK cells

Transepithelial electrical resistance (TER), a measure of tight junction (TJ) barrier function, develops more rapidly and reaches higher values after preincubation of MDCK cells for 24 h with 2 microM Lovastatin (lova), an inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase. While this effect was attributed to a 30% fall in cholesterol (CH), possible effects of lova on the supply of prenyl group precursors could not be excluded. In the current study, strategies were devised to examine effects on TER of agents that simultaneously lower CH and increase the flux of intermediates through the CH biosynthetic pathway. Zaragozic acid, 20 microM, an inhibitor of squalene synthase known to increase the synthesis of isoprenoids and levels of prenylated proteins, lowered cell CH by 30% after 24 h, while accelerating development of TER in the same manner as lova. TER was also enhanced, despite a 23% increase in the rate of [3H]acetate incorporation into CH, when total CH was reduced by 45% during a 2-h incubation with 2 mM methyl beta-cyclodextrin (MBCD), an agent that stimulates CH efflux from cells. The fact that the rate of TER development was diminished when cell CH content was elevated by incubation with a complex of CH and MBCD is further evidence that this sterol modulates development of the epithelial barrier. Cell associated CH derived from the complex was similar to endogenous CH with respect to its accessibility to cholesterol oxidase. Lova's effect on TER was diminished when 5 micrograms/mL of CH was added to the medium during the last 11 h of incubation with lova.

Expression and function of B7-1 and B7-2 in hapten-induced contact sensitivity

We analyzed the expression and function of the co-stimulatory molecules B7-1 (CD80) and B7-2 (CD86) during contact sensitivity reactions induced by the hapten 2,4-dinitrofluorobenzene (DNFB). In the normal skin, only a few epidermal Langerhans cells or dermal dendritic cells express B7-2. In contrast, following challenge with DNFB, expression of B7-2 is up-regulated in both epidermis and dermis. Importantly, B7-1 is induced later and at lower levels compared to B7-2. Intravenous injections of anti-B7-2 mAb, but not anti-B7-1 mAb partially inhibit the hapten-induced contact sensitivity reaction. Experiments in which mice are injected differentially with anti-B7-2 mAb, either before the afferent or before the efferent phase of the contact sensitivity response, suggest that B7-2 is important for successful antigen priming.

Conjunctival biopsy in patients with Kawasaki disease

Kawasaki disease (KD) is an acute vasculitis of infants and young children that is associated with bilateral nonexudative conjunctivitis during the acute illness. Epidemiologic evidence has suggested an infectious cause but the etiology of KD remains unknown. We examined conjunctival biopsy specimens from seven patients with typical KD to characterize the pathologic changes during the acute disease. Light microscopic examination revealed nonspecific, mild inflammatory changes that included vascular dilatation, infiltration with scattered lymphocytes, increased numbers of plasma cells in the conjunctival stroma, and increased prominence of goblet cells in the epithelium. No pathogens were identified by special stains for bacteria and rickettsiae, nor were viral particles seen by electron microscopy. We conclude that the conjunctivitis of acute KD is characterized by vascular dilatation with a mild mononuclear cell response with no pathognomonic features. The conjunctiva can be readily sampled in these patients and biopsy may prove useful in selected patients to exclude other clinical entities in the differential diagnosis.

Basolateral but not apical application of protease results in a rapid rise of transepithelial electrical resistance and formation of aberrant tight junction strands in MDCK cells

In the presence of Ca2+, application of trypsin to the basolateral surface of confluent MDCK cell monolayers with formed tight junctions (TJ), induces the formation of basolaterally oriented aberrant TJ strands. Induction of aberrant TJ strands is accompanied by an increase in transepithelial electrical resistance (TER), up to 90%, which upon addition of trypsin inhibitor is maintained for up to 1 h. Thereafter TER returns slowly to baseline values. Under similar conditions, application of trypsin to the apical surface has little or no effect on either TER or the number of aberrant TJ strands. Confocal microscopy of monolayers, immunostained for ZO-1, revealed that this TJ associated cytoplasmic protein, extended below the TJ along the basolateral surface following brief exposure to trypsin. Removing Ca2+ after treatment of the monolayer with basolaterally applied trypsin resulted, after 20 min, in the increased partitioning of TJ particles onto the E fracture face, of both normal and aberrant TJ strands. Like the TJ strands themselves, therefore, aberrant strands may be linked to cytoskeletal elements. Aberrant TJ strands do not form when monolayers, maintained in low Ca2+ medium, are exposed to trypsin, suggesting that under these conditions TJ precursors, and/or trypsin-sensitive proteins regulating TJ strand assembly, are sequestered in a vesicular compartment that is inaccessible to exogenous trypsin. Prolonged exposure of the apical surface of an established, polarized epithelium with intact TJ to trypsin, had little effect on TJ integrity and did not induce aberrant strands.

The costimulatory molecule B7 is expressed in the medullary region of the murine thymus

Several laboratories, including our own, have previously shown that the B7 antigen, a glycoprotein expressed on activated B cells, macrophages and dendritic cells, can provide a potent costimulatory signal for peripheral murine T lymphocytes. In the present report we have analysed the expression and function of B7 in the murine thymus. The expression of B7 was demonstrated histochemically. B7-expressing cells were present in the thymic medulla but virtually absent from the cortex. Further analysis by immunofluorescence and flow fluorocytometry revealed that the B7-positive cells also expressed major histocompatibility complex (MHC) class II molecules. Both epithelial and dendritic cells expressed the B7 antigen. Finally, although we have demonstrated expression of mB7 in the murine thymus, we have been unable to detect a function for this antigen in this organ. The implications of these findings are discussed.

Interstitial lung macrophages interact with dendritic cells to present antigenic peptides derived from particulate antigens to T cells

When the protective structural and functional barriers of the lung are breached, immune responses must be generated in order to contain invading micro-organisms. This requires the presence of accessory cells capable of phagocytosing and presenting immunogenic peptides to either naive or sensitized T cells. In contrast to dendritic cells (DC) present in the airway epithelium, those within the lung parenchyma do not readily engulf particulates and, therefore, other mechanisms must account for their apparent ability to present immunogenic peptides derived from micro-organisms. The purpose of the present study was to determine the extent to which interstitial macrophages (IM) interact with lung DC to process and present antigenic peptides, derived from particulate, heat-killed Listeria monocytogenes (HKL), to HKL-immune T cells. Results show that highly purified Ia- lung IM avidly phagocytose fluorescent-labelled HKL, but they do not present antigen to primed T cells. Their ability to present antigen is only modestly increased following interferon-gamma (IFN-gamma) stimulation. Conversely, mature DC isolated from the lung interstitium do not phagocytose fluorescent-labelled HKL. In antigen presentation assays, however, addition of 10% (2.5 x 10(3)/ml) Ia- IM to DC and HKL results in a two- to threefold increase in antigen presentation by DC to HKL-immune T cells. Conditioned medium (CM), generated by 2.5 x 10(4)/ml IM induced to phagocytose HKL, when administered to DC and HKL-sensitized T cells without added intact HKL, resulted in brisk mitogenesis, a response that did not occur in T cells sensitized to an irrelevant antigen. Conditioned medium derived from larger numbers of IM was inhibitory. When IM phagocytosed inert polystyrene beads, the resulting CM induced modest T-cell mitogenesis, suggesting that small amounts of cytokines were released. The results indicate that in small numbers, IM augment DC function, in part, by the release of antigenic peptides which are then presented by DC to T cells. When present in numbers greater than 50% of DC, however, they inhibit DC function, probably due to the release of soluble inhibitors.

FcR+/- subsets of Ia+ pulmonary dendritic cells in the rat display differences in their abilities to provide accessory co-stimulation for naive (OX-22+) and sensitized (OX-22-) T cells

A substantial body of evidence indicates that the primary sensitization of naive T cells to inhaled antigens occurs in the regional lymph nodes, whereas secondary responses may be generated directly within lung tissue. Ia+ pulmonary dendritic cells are widely distributed within the rat lung where they can participate in the induction of the immune response to inhaled antigens. Recently, two subsets of Ia+ pulmonary dendritic cells have been distinguished based on their expression of Fc receptors (FcR), but little is known concerning their abilities to support the responses of naive or sensitized T cells. In order to address this question, pulmonary FcR+/- dendritic cells have been purified from enzymatic digests of Lewis rat lungs, based on their differential binding to heat-aggregated immunoglobulin. The FcR+/- dendritic cell subsets differed with respect to their light microscopic appearance and in their expression of non-specific esterase. Only the FcR+ subset was able to phagocytize latex beads and showed intracellular phagolysosomes by electron microscopy. Both of the FcR+/- subsets rapidly formed clusters with naive (OX-22+) and sensitized (OX-22-) T cells. However, the clusters yielded by the FcR+ subset were substantially smaller, possibly reflecting their diminished surface membrane expression of the intercellular adhesion molecule-1. The FcR+/- subsets were capable of presenting soluble and particulate antigens to OX-22- T cells. FcR+ cells were less effective than FcR- cells in promoting the proliferative response of OX-22+ T cells to concanavalin A and in the primary mixed leukocyte reaction. We conclude that the FcR+/- pulmonary dendritic cells differ in their abilities to support the responses of naive and sensitized T lymphocytes. This observation may have significance for how primary and secondary pulmonary cell-mediated immune responses are generated.

Depleting cell cholesterol alters calcium-induced assembly of tight junctions by monolayers of MDCK cells

A role for lipids in the formation of tight junctions (TJ) has been proposed. Attempts to relate changes in whole cell phospholipid composition to the formation of TJs, however, have yielded equivocal results. The object in the present study was to relate changes in TJ of MDCK cells more specifically to alterations in plasma membrane lipids. Cholesterol, which resides primarily in the plasma membrane, was reduced by 25% after incubation of cell monolayers for 24 h in a low Ca2+ medium supplemented with (1-2 microM) Lovastatin, an inhibitor of hydroxymethylglutarylcoenzyme A (HMG-CoA) reductase. This was associated with a halving of the time required for Ca2+ to induce TJ formation as monitored by transepithelial electrical resistance (TER). [3H]Mannitol flux, and morphometric measurements made on freeze fracture replicas confirm that the effects on TER reflect changes in the characteristics of the paracellular pathway. Peak and steady state values of TER were also elevated over control values. The changes in cholesterol content and the time course for TJ assembly were apparent at levels of Lovastatin which do not affect prenylation of proteins, and were prevented if 5 mM mevalonate was present along with Lovastatin. Paradoxically, despite a decrease of approximately 1/3 in the Ca concentration required to yield maximum rates of TJ assembly, 45Ca2+ uptake was actually reduced after cholesterol depletion. The data suggest that cholesterol may modulate the properties of membrane proteins and/or phospholipids which interact with Ca2+, possibly on the exoplasmic leaflet, during TJ assembly.

Cellular variability in the development of tight junctions after activation of protein kinase C

Phorbol 12-myristate 13-acetate (PMA) decreases the tight junction conductance (TJC) during the reorganization of LLC-PK1A monolayers, but has the opposite effect in LLC-PK1B4, MDCK, and MDCK4 cells. Because no protein synthesis was required for the effects of PMA on the TJC of LLC-PK1A monolayers, we conclude that the regulation of the tight junction by protein kinase C (PKC) is a posttranslational event. In LLC-PK1A monolayers with existing tight junctions, PMA produced an initial increase in the TJC that reverted later to control values despite the continuous presence of PMA and cycloheximide. The inhibitory effect of PMA on the other cell lines was not revertible. A downregulation of total PKC activity and phorbol ester receptors was only observed during the reorganization of LLC-PK1A monolayers. PMA further increases this downregulation. This indicates that the peculiar response to PMA observed in LLC-PK1A monolayers is the result of two concurrent events: 1) the early activation of the enzyme just before the reorganization of the tight junctions begin, and 2) its late downregulation induced after prolonged exposure to phorbol esters. We conclude that PKC regulates the development of the occluding junctions, but through different mechanisms dependent on the characteristics of the cells.

Structure, function, and regulation of cellular tight junctions

The tight junction (TJ) is a dynamic structure that is controlled, in part, by the activity of the cytoskeleton. It has become abundantly clear that, in the presence of Ca2+, assembly of the TJ is the result of cellular interactions that trigger a complex cascade of biochemical events that ultimately lead to the formation of an organized network of TJ elements, the composition of which remains unknown. The TJ functions both as a barrier between two fluid compartments and, to a lesser extent, as a fence between apical and basolateral membrane domains. To meet the many physiological and pathological challenges to which epithelia and endothelia are subjected, the TJ must be capable of a rapid and coordinated response, which depends on complex regulatory mechanisms. The precise characterization of the mechanisms involved in the assembly and regulation of the TJ is an area of current active investigation. However, until the biochemical composition of this structure has been defined and its gene identified, the TJ will continue to be an elusive yet tantalizing challenge to the cell biologist.

Ontogeny of Ia+ accessory cells in fetal and newborn rat lung

In the adult mammalian lung, Ia+ dendritic cells (DC) constitute a significant population of immunologically potent accessory cells that are important in the regulation of immune responses to inhaled antigens. The newborn, in most species, displays an increased susceptibility to sensitization by inhaled antigens; whether an immaturity of pulmonary accessory cells is involved has not been determined. In the present study, the ontogeny and function of these cells were examined in fetal and newborn rats. Cells identified as DC in fetal and newborn rat lungs were Ia+, C11b+/-, OX41-, OX43-, W3/13-, W3/25-, and OX8-. They were characterized ultrastructurally by an eccentric, lobulated nucleus, a paucity of lysosomes, delicate cytoplasmic processes, and abundant membrane-associated Ia. Ia+ DC were first detected within the pulmonary mesenchyme at day 15 and by day 17 of gestation they were also present within the epithelium lining airways. The appearance of Ia+ DC preceded the migration of either T4 or T8 subclasses of T cells to the lung, the latter becoming significant only after birth, when the newborn was exposed to environmental antigens. In none of the fetal or newborn animals was Ia detected on alveolar type II cells. The accessory cell function of rat pulmonary DC, isolated from fetuses at 20 and 21 days of gestation and from newborns, was tested by an autologous mixed leukocyte reaction. At 20 and 21 days of gestation, pulmonary DC were 40 and 60% as effective, respectively, in stimulating cell proliferation in purified autologous adult splenic T cells as those isolated from adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraepithelial airway dendritic cells: a distinct subset of pulmonary dendritic cells obtained by microdissection

Dendritic cells (DC), in general, and pulmonary DC, in particular, are a heterogeneous population of cells, their phenotype and function being dependent on their anatomic location, their state of activation, and the regulatory effect of locally secreted cytokines. Using a novel microdissection technique, the epithelium from the trachea and entire airway system was harvested, and the contained DC isolated at greater than 90% purity. The phenotype and function of these airway DC (ADC) was compared to DC isolated, at greater than 90% purity, from the parenchyma of the same lung. In contrast to lung DC (LDC), ADC did not express intercellular adhesion molecule 1 (ICAM-1) in situ, the amount of immune associated antigen (Ia) expressed was less (as determined by immunoperoxidase staining and immunopanning), and greater than 50% of ADC displayed Fc receptors (FcR). The majority of LDC were ICAM-1+, less than 5% expressed FcR, and all were intensely Ia+. Airway DC were most numerous in tracheal epithelium, but they were also present in small numbers in the epithelium of the most distal airways. Their numbers increased in all segments of the tracheobronchial epithelium in response to the administration of IFN-gamma. ADC were consistently more effective than LDC in presenting soluble (hen egg lysozyme) and particulate (heat-killed Listeria monocytogenes) antigens to antigen-sensitized T cells. By contrast, LDC were significantly more efficient in stimulating the proliferation of nonsensitized T cells in an autologous mixed leukocyte reaction. These data suggest that in normal animals, intraepithelial DC of airways share many attributes with Langerhans cells of the skin. Interstitial LDC, by contrast, reside in an environment where they may be exposed to a different set of regulatory factors and where they have progressed to a more advanced stage of differentiation than ADC. Both groups of DC are, however, heterogeneous, reflecting the continuous turnover that these cells undergo in the lung.

Accessory cells of the lung. II. Ia+ pulmonary dendritic cells display cell surface antigen heterogeneity

In earlier studies, we had determined that class II (Ia) major histocompatibility complex (MHC) antigen expression in the normal rat lung was limited to dendritic cells and type II alveolar cells. In order to characterize the Ia+ pulmonary dendritic cells of the lung parenchyma, Lewis rat lungs were dissected free of their major airways, enzymatically digested, and serially subjected to density centrifugation on bovine serum albumin, overnight adherence, and immunopanning with a murine anti-rat monoclonal antibody (anti-OX-6) that reacts specifically with class II (Ia) MHC antigens. The purified Ia+ pulmonary cells displayed the morphologic and functional features of dendritic accessory cells, including extended cell processes, absence of nonspecific esterase staining, minimal phagocytosis of latex beads, rapid clustering with T lymphocytes, and co-stimulation of T-cell mitogen responses. Detailed immunophenotyping by cytofluorimetry and immunohistology showed that the purified dendritic cells were Ia (OX-6)+, CD45R (OX-1)+, CD45Rb (OX-22)-, ICAM-1+, and OX-43-. As many as 50% of the cells bound heat-aggregated IgG, while a smaller percentage expressed the CD43 sialophorin antigens (W3/13) expressed by a variety of blood-derived cells, and/or the OX-41 and RMA macrophage antigens. We conclude that Ia+ dendritic cells of lung are heterogeneous with respect to their expression of surface membrane differentiation antigens and may prove to be functionally distinct with respect to their accessory activities.

Inhibition of adenine nucleotide synthesis: effect on tight junction structure and function of clone 4 MDCK cells

The formation and maintenance of tight junctions as a barrier to the diffusion of ions and other water-soluble across epithelia is an energy-dependent process. The administration of N-formyl-hydroxyaminoacetic acid (Hadacidin), an analog of aspartate and a competitive inhibitor of adenylosuccinate synthetase, has been shown to inhibit the multiplication of clone 4 MDCK cells and concomitantly reduce the levels of ATP and cAMP (J. Cell. Physiol. 140, 186-194 (1989)). When added to mitotically quiescent confluent cultures of clone 4 MDCK cells, millimolar concentrations of Hadacidin inhibited the generation of transepithelial electrical resistance (TER). In such cultures passive Na+ permeability was similar to controls indicating that the effect of Hadacidin was not on the transcellular pathway. That these cells were viable was demonstrated by their ability to exclude Trypan Blue, and the fact that they remained competent to develop steady state TER upon removal of the inhibitor. Suppression of TER was completely reversed within 48 h of replacing the Hadacidin-supplemented medium with one containing aspartate. Adenosine, but not aspartate, when added simultaneously with the drug, obviated the latter's effect on TER. A mixture of dibutyryl cAMP (db-cAMP) and theophylline was only partially effective in overcoming the effects of Hadacidin on the development of TER and, in fact, markedly delayed its development in control cultures not treated with the drug. When monolayers with established steady state TER were exposed to Hadacidin, no change was noted during the first 24 h. By 48 h, however, TER had decreased to very low values.(ABSTRACT TRUNCATED AT 250 WORDS)

Accessory cells of the lung. I. Interferon-gamma increases Ia+ dendritic cells in the lung without augmenting their accessory activities

Dendritic cells are specifically adapted to provide accessory signals for the growth of T lymphocytes. Ia+ dendritic cells are present within the normal lung; however, little is known concerning their regulation in vivo. Interferon-gamma (IFN-gamma) is a proinflammatory lymphokine that augments the expression of Ia antigens and promotes the accessory activities of a variety of cells. In order to determine whether IFN-gamma regulates pulmonary dendritic cells in vivo, Lewis rats were injected intraperitoneally with recombinant murine IFN-gamma (2 x 10(5) U/rat/day) or with buffered saline for 5 consecutive days. Following sacrifice, the lungs were excised, and the distribution and number of Ia (OX-6)+ cells was determined in situ. Dendritic cells were localized in the mucosal lining of the tracheobronchial tree, in pulmonary capillaries, as well as in the alveolar septal interstitium and subjacent to the pleural surfaces. IFN-gamma yielded a specific increase in Ia+ dendritic cells in alveolar septa and in pulmonary airways. Purified Ia+ dendritic cells from enzymatic digests of lung were excellent accessory cells for the proliferative responses of both antigen-primed and naive T lymphocytes. IFN-gamma did not, however, further augment the expression of Ia antigens or the accessory activities of pulmonary dendritic cells. These results suggest that IFN-gamma may promote pulmonary T cell-mediated inflammatory responses in vivo by increasing the number of Ia+ dendritic accessory cells in the lung.

Anti-RMA, a murine monoclonal antibody, activates rat macrophages: II. Induction of DNA synthesis and formation of multinucleated giant cells

Anti-RMA is a murine anti-rat monoclonal antibody that binds to a 120-kD surface membrane antigen expressed primarily by alveolar macrophages. Saline-lavaged alveolar macrophages (AM) formed clusters after incubation with anti-RMA. Anti-RMA produced multinucleated giant cells (MGC) in approximately 15% of adherent AM, and the F (ab')2 fragment of anti-RMA yielded MGC in approximately 9% of AM. The Fab fragment of anti-RMA did not promote MGC formation, nor did the murine anti-rat monoclonal antibodies OX41 and W3/25 (anti-CD4). Although anti-RMA produced a tenfold increase in [3H]thymidine incorporation by AM, it yielded a minimal increase in the number of AM. Autoradiography of AM stimulated with anti-RMA showed heterogeneous labeling of nuclei in MGC, suggesting that 3H-labeled AM may fuse with AM that are not actively synthesizing DNA. These findings suggest that binding of anti-RMA to AM may activate DNA synthesis, and promote clustering and fusion of AM, leading to MGC formation.

Anti-RMA: a murine monoclonal antibody that activates rat macrophages. I. Distribution and characterization of the RMA antigen

Activated macrophages participate in inflammation by eliminating foreign cells, promoting wound healing, and modulating the immune response. A murine monoclonal antibody, designated anti-rat macrophage activator (RMA), was raised against alveolar macrophages (AM) activated with interferon-gamma (IFN-gamma) and phorbol myristate acetate (PMA). The RMA antigen is expressed by resident macrophages but not by other cells. Binding to AM by anti-RMA is not competitively inhibited by the murine monoclonal antibodies MRC OX-41, OX-42, and OX-43. Surface membrane expression of RMA antigens is upregulated by lipopolysaccharide, PMA, and tumor necrosis factor-alpha but not by IFN-gamma. Stimulation of AM with anti-RMA yields distinct ultrastructural alterations, as well as de novo protein and DNA synthesis. Immunoprecipitation of [35S]methionine metabolically labeled AM yields a 120 kD protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) that is not altered by chemical reduction. We conclude that the RMA antigen is macrophage specific and that binding of anti-RMA to AM promotes functional activities in a subset of these cells.

Interaction of native and chemically modified albumin with pulmonary microvascular endothelium

The ability of native and chemically modified bovine serum albumin (BSA) to maintain normal pulmonary microvascular permeability was tested in "bloodless," fluorocarbon emulsion exchange transfused rats. Wet-to-dry weight ratios (W/D) of whole lung and morphometric estimates of the amount of ferritin transported to basement membrane were used to assess changes in water flux and macromolecular transport, respectively. Native and modified BSA in capillary walls were localized by immunogold techniques. Arginine residues of BSA were blocked with cyclohexanedione (CHD-BSA), and lysine residues were modified either by succinylation (Succ-BSA) or reductive methylation. Succinylation and CHD modification of BSA caused alterations in antigenicity and trypsin sensitivity; succinylation reduced the isoelectric point (pI). Whereas administration of either CHD-BSA or Succ-BSA increased the W/D, transport of ferritin to basement membrane was greater in the presence of Succ-BSA than CHD-BSA. By contrast, infusion of reductively methylated BSA in which modified lysines altered neither antigenicity nor pI, resulted in a W/D and amount of ferritin in basement membranes comparable to that of BSA. Binding of CHD-BSA and Succ-BSA to endothelial glycocalyx appeared to be reduced relative to native BSA and reductively methlyated BSA. The lowered pI of Succ-BSA may have contributed to its reduced binding; reductively methylated BSA with an unaltered pI was present in the glycocalyx. These data are consistent with a role for positively charged arginine residues in the interaction of albumin with the glycocalyx. The W/D of animals perfused with BSA was higher than those reported for rats perfused with complete rat serum proteins. This is consistent with the notion that serum factors, in addition to albumin, are required to maintain normal microvascular permeability.

Reduction of adenine nucleotide content of clone 4 MDCK cells: effects on multiplication, protein synthesis, and morphology

The antitumor agent hadacidin (N-formyl-hydroxyamino-acetic acid), at 4 mM, inhibited the multiplication of clone 4 Madin Darby canine kidney (MDCK) cells within 24 hr. Growth resumed rapidly upon replacement of hadacidin with aspartate, an observation consistent with the drug's action as a competitive inhibitor of adenylosuccinate synthetase, an enzyme in adenine nucleotide biosynthesis. Data indicate that the drug-treated cells were arrested in S phase of the cell cycle. Accompanying inhibition of multiplication was a 16-fold increase in the area occupied by the cells and a refractoriness to release by treatment with trypsin. None of these changes occurred when 0.5 mM adenosine was included in the incubation mixture containing the inhibitor. Hadacidin decreased the adenosine triphosphate (ATP) and cyclic adenosine monophosphate (cAMP) content of the cells as well as the rate at which 3H-leucine was incorporated into protein. In the presence of 1 mM dibutyryl cAMP and theophylline, the drug had no effect on cell division and protein synthesis. The data suggest that, in clone 4 MDCK cells, the effects of hadacidin are mediated by diminishing the level of cAMP.

Antigen-independent binding of T-cells by dendritic cells and alveolar macrophages in the rat

The antigen-independent binding of CD4+ T-lymphoblasts by alveolar and peritoneal macrophages and splenic dendritic cells (DC) was compared. DC formed clusters with T-lymphoblasts within 30 min at 37 degrees C, whereas alveolar and peritoneal macrophages did not. Antigen-independent binding developed between macrophages and CD4+ blasts by 4 h at 37 degrees C. Binding by alveolar macrophages was trypsin sensitive, magnesium dependent, serum independent, and cold insensitive, whereas binding by DC required serum and was inhibited by cold. Cluster formation (cell aggregates greater than 250 microns 2) by macrophages and CD4+ blasts was increased by interferon-gamma and phorbol esters, but diminished by lipopolysaccharide. However, each of these factors increased cluster formation by blasts with DC. Efforts to promote antigen-independent binding of T cells by Ia+ macrophages did not alter their poor accessory cell capacities. The role of cluster formation in accessory cell activities was examined. Inhibitors of DC clustering, including trypsin, paraformaldehyde, and tunicamycin, abrogated the ability of DC to support antigen presentation and lectin-mediated proliferation. It is concluded that rapid antigen-independent binding to T-cells is a distinct property that is restricted to DC. Exposure to LPS may down regulate nonproductive binding of T-cells to alveolar macrophages. Our data further suggest that accessory cell activities in the rat are not a function of alveolar macrophages and may be limited to specialized Ia+ cells of dendritic lineage.

Angioedema induced by a peptide derived from complement component C2

Synthetic peptides that correspond to the COOH-terminal portion of C2b enhance vascular permeability in human and guinea pig skin. In human studies, 1 nmol of the most active peptide of 25-amino acid residues produced substantial local edema. A pentapeptide and a heptapeptide corresponding to the COOH-terminal sequence of C2b each induced contraction of estrous rat uterus in the micromole range; a peptide of 25 amino acids from this region induced a like contraction of rat uterus at a concentration 20-fold lower than the smaller peptides. The vascular permeability of guinea pig skin was enhanced by doses of these synthetic peptides in a similar fashion as that observed for the concentration of rat uterus. The induction of localized edema by intradermal injection in both the guinea pig and the human proceeds in the presence of antihistaminic drugs, suggesting that there is a histamine-independent component to the observed increase in vascular permeability. Cleavage of C2 with the enzymic subcomponent of C1, C1s, yields only C2a and C2b, and no small peptides, whereas cleavage of C2 with C1s and plasmin yields a set of small peptides. These plasmin-cleaved peptides are derived from the COOH terminus of C2b, and they induce the contraction of estrous rat uterus.