Relapse Risk and Safety of Long-Term Tocilizumab Use Among Patients With Giant Cell Arteritis: A Single-Enterprise Cohort Study

OBJECTIVE

To evaluate the safety and efficacy of tocilizumab (TCZ) in giant cell arteritis (GCA) in a large North American cohort.

METHODS

Patients with GCA treated with TCZ between January 1, 2010, and May 15, 2020, were retrospectively identified. Kaplan-Meier methods were used to estimate time to TCZ discontinuation and time to first relapse after TCZ discontinuation. Poisson regression models were used to compare annualized relapse rates before, during, and after TCZ use. Age- and sex-adjusted risk factors associated with relapse on and off TCZ and development of adverse events of significant interest (AESIs) were examined using Cox models.

RESULTS

One hundred fourteen patients (60.5% female) were included with mean (SD) age 70.4 (8.2) years. Median duration from GCA diagnosis to TCZ start was 4.5 months. Median overall duration of TCZ treatment was 2.3 years. Relapse rate prior to TCZ start (0.84 relapses/person-year) was 3-fold reduced while on TCZ (0.28 relapses/person-year; P < 0.001) but increased to 0.64 relapses/person-year after TCZ discontinuation. Fifty-two patients stopped TCZ after a median of 16.8 months; 27 relapsed after discontinuation (median: 8.4 months; 58% relapsed within 12 months). Only 14.9% of patients stopped TCZ because of AESIs. Neither dose/route of TCZ, presence of large-vessel vasculitis, nor duration of TCZ therapy prior to discontinuation predicted relapse after TCZ stop.

CONCLUSION

TCZ is well tolerated in GCA, with low rates of discontinuation for AESIs. However, relapse occurred in > 50% despite median treatment > 12 months. Since the duration of TCZ prior to discontinuation did not significantly affect subsequent risk of GCA recurrence, further research is needed to determine the optimal duration of therapy.

Immune responses and disease biomarker long-term changes following COVID-19 mRNA vaccination in a cohort of rheumatic disease patients

Introduction

The longitudinal responses towards multiple doses of COVID-19 mRNA vaccines in patients with systemic autoimmune diseases remain incompletely understood. While observational studies suggested the safety of COVID-19 mRNA vaccines in rheumatic disease patients, laboratory evidence is lacking.

Methods

Here we evaluated seroreactivity, clinical manifestions, and multiple disease biomarkers after 2 or 3 doses of COVID-19 mRNA vaccines in a cohort of patients with rheumatic diseases.

Results

Most patients generated high SARS-CoV-2 spike-specific neutralizing antibodies comparable to those in healthy controls after 2 doses of mRNA vaccines. The antibody level declined over time but recovered after the third dose of the vaccine. Patients with systemic lupus erythematosus (SLE) or psoriatic arthritis (PsA) remained without significant flares post-vaccination. The changes in anti-dsDNA antibody concentration and expression of type I interferon (IFN) signature genes were highly variable but did not show consistent or significant increases. Frequency of double negative 2 (DN2) B cells remained largely stable.

Discussion

Our data provide experimental evidences indicating the efficacy and safety of repeated COVID-19 mRNA vaccination in rheumatic disease patients.

Lower Frequency of Comorbidities Prior to Onset of Giant Cell Arteritis: A Population-Based Study

OBJECTIVE

To assess the frequency of comorbidities and metabolic risk factors at and prior to giant cell arteritis (GCA) diagnosis.

METHODS

This is a retrospective case control study of patients with incident GCA between January 1, 2000, and December 31, 2019, in Olmsted County, Minnesota. Two age- and sex-matched controls were identified, and each assigned an index date corresponding to an incidence date of GCA. Medical records were manually abstracted for comorbidities and laboratory data at incidence date, 5 years, and 10 years prior to incidence date. Twenty-five chronic conditions using International Classification of Diseases, 9th revision, diagnosis codes were also studied at incidence date and 5 years prior to incidence date.

RESULTS

One hundred and twenty-nine patients with GCA (74% female) and 253 controls were identified. At incidence date, the prevalence of diabetes mellitus (DM) was lower among patients with GCA (5% vs 17%; P = 0.001). At 5 years prior to incidence date, patients were less likely to have DM (2% vs 13%; P < 0.001) and hypertension (27% vs 45%; P = 0.002) and had a lower mean number (SD) of comorbidities (0.7 [1.0] vs 1.3 [1.4]; P < 0.001) compared to controls. Moreover, patients had significantly lower median fasting blood glucose (FBG; 96 mg/dL vs 104 mg/dL; P < 0.001) and BMI (25.8 vs 27.7; P = 0.02) compared to controls. Multivariable logistic regression analysis revealed negative associations for FBG with GCA at 5 and 10 years prior to diagnosis/index date.

CONCLUSION

DM prevalence and median FBG and BMI were lower in patients with GCA up to 5 years prior to diagnosis, suggesting that metabolic factors influence the risk of GCA.

Immune responses and disease biomarker long-term changes following COVID-19 mRNA vaccination in a cohort of rheumatic disease patients

Objective

To evaluate seroreactivity and disease biomarkers after 2 or 3 doses of COVID-19 mRNA vaccines in a cohort of patients with rheumatic diseases.

Methods

We collected biological samples longitudinally before and after 2-3 doses of COVID-19 mRNA vaccines from a cohort of patients with systemic lupus erythematosus (SLE), psoriatic arthritis, Sjogren's syndrome, ankylosing spondylitis, and inflammatory myositis. Anti-SARS-CoV-2 spike IgG and IgA and anti-dsDNA concentration were measured by ELISA. A surrogate neutralization assay was utilized to measure antibody neutralization ability. Lupus disease activity was measured by Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). Expression of type I interferon signature was measured by real-time PCR. The frequency of extrafollicular double negative 2 (DN2) B cells was measured by flow cytometry.

Results

Most of the patients generated high SARS-CoV-2 spike-specific neutralizing antibodies comparable to those in healthy controls after 2 doses of mRNA vaccines. The antibody level declined over time but recovered after the third dose of the vaccine. Rituximab treatment substantially reduced antibody level and neutralization ability. Among SLE patients, no consistent increase in SLEDAI scores was observed post-vaccination. The changes in anti-dsDNA antibody concentration and expression of type I IFN signature genes were highly variable but did not show consistent or significant increases. Frequency of DN2 B cells remained largely stable.

Conclusion

Rheumatic disease patients without rituximab treatment have robust antibody responses toward COVID-19 mRNA vaccination. Disease activity and disease-associated biomarkers remain largely stable over 3 doses of vaccines, suggesting that COVID-19 mRNA vaccines may not exacerbate rheumatic diseases.

KEY MESSAGES

Patients with rheumatic diseases mount robust humoral immunity towards 3 doses of COVID-19 mRNA vaccines.Disease activity and biomarkers remain stable following 3 doses of COVID-19 mRNA vaccines.

Immune And Inflammatory Mechanisms Mediate Cardiovascular Diseases From Head To Toe

Practitioners have long recognized the involvement of inflammation in certain acute cardiovascular diseases such as endocarditis, myocarditis, and pericarditis. Attention to the participation of immune and inflammatory mechanisms in chronic cardiovascular diseases has generally lagged. Yet, these pathways contribute to a broad swath of clinically important cardiovascular conditions, both acute and chronic. Understanding of these complex mechanisms can aid specialists in cardiovascular research and practice immeasurably by providing new concepts and illuminating new diagnostic and therapeutic strategies. The collection of essays presented in this focused issue of Cardiovascular Research aims to promote this goal.

THU0310 CASE–CONTROL SEROPREVALENCE STUDY ON THE ASSOCIATION BETWEEN BARTONELLA INFECTION AND ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY-ASSOCIATED VASCULITIS

Background:

Bartonellosis is an emerging anthropozoonosis caused by infection with intracellular Gram-negativeBartonellaspecies. It leads to necrotizing granulomas and endothelial damage and causes acute and chronic human diseases, such as cat scratch disease, bacillary angiomatosis and endocarditis. Endocarditis due toBartonella henselaeandB. quintanais reported to produce anti-neutrophil cytoplasmic antibodies (ANCAs) that disappear with effective antimicrobial treatment.

Objectives:

Hypothesizing a role forBartonellainfection in ANCA-associated vasculitis (AAV), which also includes granulomatous and vascular inflammation, we studied the seroprevalence of 5Bartonellaspecies in patients with AAV.

Methods:

The study used plasma samples from patients with granulomatosis with polyangiitis and microscopic polyangiitis that were enrolled in the Rituximab for AAV (RAVE) trial and from healthy controls living in the United States. Western blot assays were used for serological testing of infection withB. quintana,B. henselaeHouston-1,B. elizabethae,B. vinsoniisubsp.berkhoffiiandB. alsatica. The associations of positive serology results and AAV were expressed as odds ratios (OR). Clinical characteristics of seropositive and seronegative patients, assessed by the BVAS/WG instrument, were compared. These comparisons were done for 9 organ systems; in case they showed differences withP<0.10, the corresponding organ system-specific clinical features were also analyzed. Statistical analysis was performed using Fisher’s exact test or Student’s t-test, as appropriate.

Results:

We analyzed blood samples of 187 patients with AAV (collected at start of the trial) and of 127 controls. There were no significant differences between the cases and controls for mean age (P=0.148) and proportion of males (P=0.36).Bartonellaspp. serological testing was positive for 112 (60%) cases and 40 (31%) controls (OR 3.25 [95% CI 2.02–5.22],P<0.001). Significant associations were also found within subsets of PR3-AAV (OR 4.00 [95% CI 2.37–6.76],P<0.001), MPO-AAV (OR 2.18 [95% CI 1.17–4.06],P=0.017), newly-diagnosed (OR 3.89 [95% CI 2.21–6.86],P<0.001) and relapsing disease (OR 2.86 [95% CI 1.65–4.98],P<0.001). Species-specific positive serological testing was found in particular againstB. henselae(cases: 27%, controls: 0.8%; OR 39.93 [95% CI 5.42–293.90];P<0.001). Compared to AAV patients without seropositivity forBartonellaspp., AAV patients testing seropositive forBartonellaspp. had significantly more bloody nasal discharge (P=0.046), sinus involvement (P=0.035) and conjunctivitis/episcleritis (P=0.016).

Conclusion:

This study reveals higher seroprevalence ofBartonella, especiallyB. henselae, in patients with AAV than in healthy controls. Although cross-reactivity ofBartonellawith other microorganisms cannot be excluded, these results may support an etiopathogenic role ofBartonellainfection in AAV that deserves further investigation.

Disclosure of Interests:

Alfred Mahr Consultant of: Celgene, Speakers bureau: Roche, Chugai, Sophie Edouard: None declared, Divi Cornec: None declared, Solange GONZALEZ-CHIAPPE: None declared, Jörg Goronzy: None declared, Philippe Guilpain: None declared, Carol Langford: None declared, Pierre-Yves Lévy: None declared, Peter A. Merkel: None declared, Paul Monach: None declared, E. William St. Clair: None declared, Philip Seo: None declared, Robert Spiera Grant/research support from: Roche-Genetech, GSK, Boehringer Ingelheim, Chemocentryx, Corbus, Forbius, Sanofi, Inflarx, Consultant of: Roche-Genetech, GSK, CSL Behring, Sanofi, Janssen, Chemocentryx, Forbius, Mistubishi Tanabe, Cornelia Weyand: None declared, John H. Stone Grant/research support from: Roche, Consultant of: Roche, Didier Rauolt: None declared, Ulrich Specks: None declared

Response to Comment on "Diversification of the antigen-specific T cell receptor repertoire after varicella zoster vaccination"

In our repertoire studies of varicella zoster virus-specific T cells, we used very stringent computational criteria to keep contamination with T cell receptor sequences from bystander-activated T cells to a minimum.

On-farm Campylobacter and Escherichia coli in commercial broiler chickens: Re-used bedding does not influence Campylobacter emergence and levels across sequential farming cycles

Limitations in quality bedding material have resulted in the growing need to re-use litter during broiler farming in some countries, which can be of concern from a food-safety perspective. The aim of this study was to compare the Campylobacter levels in ceca and litter across three litter treatments under commercial farming conditions. The litter treatments were (a) the use of new litter after each farming cycle; (b) an Australian partial litter re-use practice; and (c) a full litter re-use practice. The study was carried out on two farms over two years (Farm 1, from 2009–2010 and Farm 2, from 2010–2011), across three sheds (35,000 to 40,000 chickens/shed) on each farm, adopting three different litter treatments across six commercial cycles. A random sampling design was adopted to test litter and ceca for Campylobacter and Escherichia coli, prior to commercial first thin-out and final pick-up. Campylobacter levels varied little across litter practices and farming cycles on each farm and were in the range of log 8.0–9.0 CFU/g in ceca and log 4.0–6.0 MPN/g for litter. Similarly the E. coli in ceca were ∼log 7.0 CFU/g. At first thin-out and final pick-up, the statistical analysis for both litter and ceca showed that the three-way interaction (treatments by farms by times) was highly significant (P < 0.01), indicating that the patterns of Campylobacter emergence/presence across time vary between the farms, cycles and pickups. The emergence and levels of both organisms were not influenced by litter treatments across the six farming cycles on both farms. Either C. jejuni or C. coli could be the dominant species across litter and ceca, and this phenomenon could not be attributed to specific litter treatments. Irrespective of the litter treatments in place, cycle 2 on Farm 2 remained Campylobacter-free. These outcomes suggest that litter treatments did not directly influence the time of emergence and levels of Campylobacter and E. coli during commercial farming.

Serpin treatment suppresses inflammatory vascular lesions in temporal artery implants (TAI) from patients with giant cell arteritis

Giant cell arteritis (GCA) and Takayasu’s disease are inflammatory vasculitic syndromes (IVS) causing sudden blindness and widespread arterial obstruction and aneurysm formation. Glucocorticoids and aspirin are mainstays of treatment, predominantly targeting T cells. Serp-1, a Myxomavirus-derived serpin, blocks macrophage and T cells in a wide range of animal models. Serp-1 also reduced markers of myocardial injury in a Phase IIa clinical trial for unstable coronary disease. In recent work, we detected improved survival and decreased arterial inflammation in a mouse Herpesvirus model of IVS. Here we examine Serp-1 treatment of human temporal artery (TA) biopsies from patients with suspected TA GCA arteritis after implant (TAI) into the aorta of immunodeficient SCID (severe combined immunodeficiency) mice. TAI positive for arteritis (GCA^pos) had significantly increased inflammation and plaque when compared to negative TAI (GCA^neg). Serp-1 significantly reduced intimal inflammation and CD11b⁺ cell infiltrates in TAI, with reduced splenocyte Th1, Th17, and Treg. Splenocytes from mice with GCA^pos grafts had increased gene expression for interleukin-1beta (IL-1β), IL-17, and CD25 and decreased Factor II. Serp-1 decreased IL-1β expression. In conclusion, GCA^pos TAI xenografts in mice provide a viable disease model and have increased intimal inflammation as expected and Serp-1 significantly reduces vascular inflammatory lesions with reduced IL-1β.

Role of increased guanosine triphosphate cyclohydrolase-1 expression and tetrahydrobiopterin levels upon T cell activation

Tetrahydrobiopterin (BH(4)) is an essential co-factor for the nitric-oxide (NO) synthases, and in its absence these enzymes produce superoxide (O(2)(·-)) rather than NO. The rate-limiting enzyme for BH(4) production is guanosine triphosphate cyclohydrolase-1 (GTPCH-1). Because endogenously produced NO affects T cell function, we sought to determine whether antigen stimulation affected T cell GTPCH-1 expression and ultimately BH(4) levels. Resting T cells had minimal expression of inducible NOS (NOS2), endothelial NOS (NOS3), and GTPCH-1 protein and nearly undetectable levels of BH(4). Anti-CD3 stimulation of T cells robustly stimulated the coordinated expression of NOS2, NOS3, and GTPCH-1 and markedly increased both GTPCH-1 activity and T cell BH(4) levels. The newly expressed GTPCH-1 was phosphorylated on serine 72 and pharmacological inhibition of casein kinase II reduced GTPCH-1 phosphorylation and blunted the increase in T cell BH(4). Inhibition of GTPCH-1 with diaminohydroxypyrimidine (1 mmol/liter) prevented T cell BH(4) accumulation, reduced NO production, and increased T cell O(2)(·-) production, due to both NOS2 and NOS3 uncoupling. GTPCH-1 inhibition also promoted TH(2) polarization in memory CD4 cells. Ovalbumin immunization of mice transgenic for an ovalbumin receptor (OT-II mice) confirmed a marked increase in T cell BH(4) in vivo. These studies identify a previously unidentified consequence of T cell activation, promoting BH(4) levels, NO production, and modulating T cell cytokine production.

TCR tuning by homeostatic cytokines — implication for autoimmunity (101.16)

In animal models, lymphopenia and the associated function of homeostatic cytokines (HC) set the stage for autoimmunity. This model is relevant for rheumatoid arthritis (RA) which has defects in T cell homeostasis due to a failure in DNA repair and which responds to JAK inhibition. We have previously shown that RA T cells have a hyperreactive ERK response which impairs the induction of anergy. Here, we examined whether HC tune TCR activation thresholds by calibrating the ERK rheostat. RA T cells exhibited increased levels of phosphorylated STAT3 and STAT5 indicating in vivo activity of IL-21/IL6 and IL-7/IL-15. Incubation of healthy donor T cells with IL-7, IL15 or IL21 prior to anti-CD3/CD28 stimulation augmented ERK activation and expression of activation markers (CD69, CD40L) and cytokines (TNFα, IFNγ and IL-17). Preincubation with IL-1β or TNFα did not exert an effect. In DR4 healthy donors, HC priming facilitated responses to self-antigens such as citrullinated vimentin peptide. The effect of HC lasted for less than 3 hours and was sensitive to PI3K inhibition suggesting a non-transcriptional PI3K mediated priming of the ERK pathway. HC dose titration showed a bimodal distribution in pERK consistent with an on-off switch characteristic of a positive feedback loop. Allosteric binding of RAS-GTP to SOS is known to induce such an on-off switch. Indeed, HC incubation increased active RAS. We propose that HC lower the threshold for autoimmune responses by priming of SOS.

Regulation of T-cell receptor signaling by activation-induced zinc influx (109.21)

Zinc is a trace element that is essential for innate and adaptive immune responses. In addition to being a structural element of many proteins, zinc also functions as a neurotransmitter and an intracellular messenger. Although cytoplasmic zinc concentrations are strictly controlled, temporal or spatial changes in bioavailable zinc may influence the activity of several enzymes, including kinases and phosphatases. In this study, we provide evidence that zinc functions as an ionic signaling molecule after T-cell activation. Cytoplasmic zinc concentrations increased within one minute after TCR triggering by super antigen presented by myeloid dendritic cells. In contrast to activation-induced calcium influx, increased zinc concentrations were compartmentalized in the subsynaptic area. The zinc increase was dependent on the extracellular zinc concentrations and was inhibited by silencing the plasma membrane zinc transporter Zip6 consistent with influx from extracellular compartments. Increased zinc availability augmented ZAP70 phosphorylation, inhibited SHP-1 recruitment to the T cell signaling complex, slowed down Lck rephosphorylation at position 505 and sustained calcium influx. As a result, increased extracellular zinc bioavailability facilitated the induction of T cell proliferative responses to suboptimal stimuli. We propose that zinc calibrates TCR activation thresholds by inhibiting negative feedback mechanisms in TCR signaling.

Extra-telomeric function of telomerase in rheumatoid arthritis (101.2)

Telomerase, an enzyme that adds DNA onto telomeric ends is upregulated in T lymphocytes upon antigen recognition. How telomerase affects T-cell function is unknown. In patients with the autoimmune syndrome rheumatoid arthritis (RA) induction of T-cell telomerase is impaired and associated with premature immunosenescence. To suppress telomerase activity healthy naïve CD4 T cells were stimulated through the T-cell receptor and transfected with control or hTERT-specific siRNA. Telomerase inhibition significantly increased p53 mRNA (p=0.05) and p53 protein (p=0.002). Pro-apoptotic BH3-only proteins were selectively upregulated; PUMA was increased (p=0.04), Noxa and Bim remained unaffected. hTERT silencing doubled frequencies of apoptotic cells. In RA T cells hTERT expression was spontaneously reduced (p&lt;0.0001); immunostaining localized most of the protein to the cytoplasm (p=0.002). Upon TCR ligation RA T cells had higher levels of p53, phosp53 and PUMA. p53 or PUMA knockdown effectively rescued RA T cells from apoptosis. hTERT over-expression suppressed p53 and PUMA and normalized cellular yield. p53 and PUMA silencing did not correct hTERT expression, placing telomerase upstream of the p53-pathway. In conclusion, T-cell telomerase has extra-telomeric functions and regulates life-death decisions after antigenic stimulation. In patients with rheumatoid arthritis, the survival-protective function of telomerase is defective, causing T cell loss and proliferative stress.

Mechanisms of defective T cell-dependent B cell responses with age (104.17)

The ability to generate immune responses after vaccinations declines with age. Efforts to improve vaccine responses have focused on identifying immunogenic vaccines and novel adjuvants. We hypothesized that signaling pathways in T cells can be directly targeted to optimize responses in the elderly. Gene expression profiling of CD4 memory T cell from 65 to 85 year-old compared to young adults stimulated with myeloid dendritic cells plus superantigen showed an overexpression of the dual-specific phosphatase 4 (DUSP4) on days 2 and 3 in the elderly which was confirmed by qPCR (p&lt;0.001), Western blotting (p=0.03) and DUSP4 promoter reporter gene assays (p&lt;0.001). Overexpression of DUSP4 in young T cells shortened CD40L (p&lt;0.001) and ICOS (p&lt;0.001) expression and decreased IL-4 (p&lt;0.001), IL-17A (p&lt;0.001) and IL-21 (p&lt;0.001) production. Conversely, DUSP4 silencing increased expression. Improvement was more pronounced in elderly T cells for CD40L (p&lt;0.001), IL-4 (p=0.007) and IL-21 (p=0.04). CD4 memory T cells from 65 to 85 year-old individuals failed to support differentiation of young adult B cells into CD38+IgD- B cells in vitro (p=0.004). DUSP4 silencing in CD4 T cells restored this ability (p=0.02). The role of DUSP4 expression in CD4 T cells in regulating T cell-dependent B cell responses was confirmed in in vivo studies using CD4 knockout mice reconstituted with DUSP4 overexpressing or control OT-II CD4 T cells and in healthy volunteers undergoing influenza vaccination.

Chronic Stimulation of the DNA Repair Enzyme DNA-PKcs Impairs T-Cell Survival in Rheumatoid Arthritis (RA) (135.7)

Patients in RA have premature aging of the immune system, with accumulation of pro-inflammatory and tissue-destructive T cells. Accelerated immune senescence has been attributed to chronic T cell loss. Naïve T cells in RA have a defect in repairing damaged DNA. We have examined whether chronic stimulation of DNA repair mechanisms affects T cell survival in RA. Naïve CD4+CD45RA+ T cells from RA patients had a higher load of double-stranded DNA breaks (p=0.0005) and spontaneous apoptosis rates (p=0.03) than in healthy controls. High DNA damage failed to upregulate the ATM-p53 axis. Instead, the transcript and protein levels of the DNA repair enzyme DNA-PKcs were elevated. Induction of DNA-PKcs was disease-specific and not found in patients with SLE. Knocking down DNA-PKcs transcription or inhibiting enzyme activity with a kinase inhibitor normalized T cell apoptosis rates in patients. Activation of DNA-PKcs was correlated with stimulation of SAPK/JNK pathway. Inhibition of either DNA-PKcs or JNK suppressed the pro-apoptotic protein Bim and protected T cells from apoptotic death. T cells in RA patients accumulate damaged DNA, causing chronic induction of repair activity. DNA double-strand breaks are recognized by a ATM-independent pathway involving DNA-PKcs. Due to the activation of the JNK-Bim death signaling cascade, RA T cells are apoptosis sensitive. Therapeutic blockade of DNA-PK-dependent cell death machinery could help rejuvenate the immune system of RA patients.

Loss of miR-181a-mediated DUSP6 repression increases the TCR threshold of naive CD4 T cells in the elderly (85.11)

With increasing age, the ability of the immune system to respond to vaccination with a CD4 T cell response and the production of antibodies declines. The decline is only partially explained by a loss of naïve and central memory CD4 T cells due to thymic involution. Naïve CD4 T cells are present in sufficient, albeit compared to young adults reduced frequencies in most elderly suggesting that additional functional defects are important. In these studies, we compared naïve CD45RO- CD4+ T cells from 20 to 35 (n=117) and 70 to 85 (n=80) year-old healthy adults. Elderly T cells were less responsive to superantigen/dendritic cell (p&lt;0.001) stimulation. Signaling studies by PhosFlow showed reduced ERK (p&lt;0.0001), but normal ZAP70 phosphorylation in the first 5 minutes after stimulation, suggesting a selective age-related defect in the ERK pathway. In murine systems, DUSP6 has been implicated in differentiation-dependent TCR threshold calibration. In Western blot studies, DUSP6 protein was increased in elderly CD4 T cells (p=0.02), however, DUSP6 transcription was not different suggesting a defect in posttranscriptional regulation. Expression of miR-181a that binds to the DUSP6 3′UTR was decreased in elderly naïve CD4 T cells. Overexpression of miR-181a downregulated DUSP6 expression and restored ERK responses in elderly CD4 T cells. Our data suggest that loss of miR181a in naïve CD4 T cells increases the TCR threshold and contributes the immune defect in the elderly.

Induction of hypertension and peripheral inflammation by reduction of extracellular superoxide dismutase in the central nervous system

The circumventricular organs (CVOs) lack a well-formed blood-brain barrier and produce superoxide in response to angiotensin II and other hypertensive stimuli. This increase in central superoxide has been implicated in the regulation of blood pressure. The extracellular superoxide dismutase (SOD3) is highly expressed in cells associated with CVOs and particularly with tanycytes lining this region. To understand the role of SOD3 in the CVOs in blood pressure regulation, we performed intracerebroventricular injection an adenovirus encoding Cre-recombinase (5x10(8) particles per milliliter) in mice with loxP sites flanking the SOD3 coding region (SOD3(loxp/loxp) mice). An adenovirus encoding red-fluorescent protein was injected as a control. Deletion of CVO SOD3 increased baseline blood pressure modestly and markedly augmented the hypertensive response to low-dose angiotensin II (140 ng/kg per day), whereas intracerebroventricular injection of adenovirus encoding red-fluorescent protein had minimal effects on these parameters. Adenovirus encoding Cre-recombinase-treated mice exhibited increased sympathetic modulation of heart rate and blood pressure variability, increased vascular superoxide production, and T-cell activation as characterized by increased circulating CD69(+)/CD3(+) cells. Deletion of CVO SOD3 also markedly increased vascular T-cell and leukocyte infiltration caused by angiotensin II. We conclude that SOD3 in the CVO plays a critical role in the regulation of blood pressure, and its loss promotes T-cell activation and vascular inflammation, in part by modulating sympathetic outflow. These findings provide insight into how central signals produce vascular inflammation in response to hypertensive stimuli, such as angiotensin II.

Regulation of T-cell function by endogenously produced angiotensin II

The adaptive immune response and, in particular, T cells have been shown to be important in the genesis of hypertension. In the present study, we sought to determine how the interplay between ANG II, NADPH oxidase, and reactive oxygen species modulates T cell activation and ultimately causes hypertension. We determined that T cells express angiotensinogen, the angiotensin I-converting enzyme, and renin and produce physiological levels of ANG II. AT1 receptors were primarily expressed intracellularly, and endogenously produced ANG II increased T-cell activation, expression of tissue homing markers, and production of the cytokine TNF-alpha. Inhibition of T-cell ACE reduced TNF-alpha production, indicating endogenously produced ANG II has a regulatory role in this process. Studies with specific antagonists and T cells from AT1R and AT2R-deficient mice indicated that both receptor subtypes contribute to TNF-alpha production. We found that superoxide was a critical mediator of T-cell TNF-alpha production, as this was significantly inhibited by polyethylene glycol (PEG)-SOD, but not PEG-catalase. Thus, T cells contain an endogenous renin-angiotensin system that modulates T-cell function, NADPH oxidase activity, and production of superoxide that, in turn, modulates TNF-alpha production. These findings contribute to our understanding of how ANG II and T cells enhance inflammation in cardiovascular disease.

Role of the T cell in the genesis of angiotensin II induced hypertension and vascular dysfunction

Hypertension promotes atherosclerosis and is a major source of morbidity and mortality. We show that mice lacking T and B cells (RAG-1^−/− mice) have blunted hypertension and do not develop abnormalities of vascular function during angiotensin II infusion or desoxycorticosterone acetate (DOCA)–salt. Adoptive transfer of T, but not B, cells restored these abnormalities. Angiotensin II is known to stimulate reactive oxygen species production via the nicotinamide adenosine dinucleotide phosphate (NADPH) oxidase in several cells, including some immune cells. Accordingly, adoptive transfer of T cells lacking the angiotensin type I receptor or a functional NADPH oxidase resulted in blunted angiotensin II–dependent hypertension and decreased aortic superoxide production. Angiotensin II increased T cell markers of activation and tissue homing in wild-type, but not NADPH oxidase–deficient, mice. Angiotensin II markedly increased T cells in the perivascular adipose tissue (periadventitial fat) and, to a lesser extent the adventitia. These cells expressed high levels of CC chemokine receptor 5 and were commonly double negative (CD3⁺CD4⁻CD8⁻). This infiltration was associated with an increase in intercellular adhesion molecule-1 and RANTES in the aorta. Hypertension also increased T lymphocyte production of tumor necrosis factor (TNF) α, and treatment with the TNFα antagonist etanercept prevented the hypertension and increase in vascular superoxide caused by angiotensin II. These studies identify a previously undefined role for T cells in the genesis of hypertension and support a role of inflammation in the basis of this prevalent disease. T cells might represent a novel therapeutic target for the treatment of high blood pressure.

Anti-psoriatic drug anthralin activates JNK via lipid peroxidation: mononuclear cells are more sensitive than keratinocytes

Anthralin is a widely used, topical therapy for psoriasis. Anti-proliferative and anti-inflammatory properties of anthralin have been identified. Little is known, however, about differential sensitivities of targeted cell types and specific mechanisms of signaling pathway activation. We demonstrate that anthralin exerts potent effects on keratinocytes and mononuclear cells through strong induction of lipid peroxidation and JNK activation, a stress-induced signal transduction pathway. Lipid peroxidation was observed rapidly and half-maximal levels of lipid peroxidation were reached at a 10-fold lower concentration of anthralin for peripheral blood mononuclear cells vs normal keratinocytes. JNK activation was detected in peripheral blood mononuclear cells at a 40-fold lower anthralin dose compared with keratinocytes. For both cell types, selected inhibitors of lipid peroxidation prevented JNK activation. This study demonstrates that mononuclear leukocytes are markedly more sensitive than keratinocytes to anthralin-induced lipid peroxidation and JNK activation. We identify anthralin as a novel and potent inducer of JNK activation and demonstrate that this process is mediated, at least in part, by lipid peroxidation which is among the earliest and most proximate, membrane-related responses to anthralin yet described.

Interferon-alpha treatment of Behçet's disease

OBJECTIVE

To determine if interferon-alpha (IFN-alpha) is effective in Behçet's disease (BD).

METHODS

Ten patients having active BD were entered into a 6 month open label trial of IFN-alpha therapy given by self-administered dose of 3 million units subcutaneously daily. Provision was made for downward or upward dosing depending on predetermined responses. Four study centers followed the same protocol. Patients having ocular or neurologic inflammation at onset of the study were excluded.

RESULTS

Seven patients completed the trial, while 3 were removed at 3 and 4 months for side effects or lack of efficacy. There was a substantial reduction in the number of oral and genital ulcers, cutaneous lesions, and articular signs and symptoms by the end of the study. Pain scores, global assessments, and prednisone dose also declined. The IFN-alpha dose at end of study averaged 1.5 million units. Significant side effects, besides the anticipated flu-like syndrome experienced by all the patients, included single instances of seizure, psychosis, psoriasis, and hyperthyroidism.

CONCLUSION

The results suggest that IFN-alpha is effective therapy for some manifestations of Behçet's disease.

Selective induction of rheumatoid factors by superantigens and human helper T cells

Production of autoantibodies specific for the Fc region of autologous IgG, called rheumatoid factors (RF), is a characteristic finding in patients with rheumatoid arthritis (RA). To study the requirements regulating the synthesis of these autoantibodies, we have cloned human helper T cells and co-cultured them with purified B cells. To mimic cognate T-B cell interaction, we have used bacterial superantigens that function by cross-linking HLA molecules on the B cell with selected T cell receptor (TCR) molecules expressing a particular polymorphism of the V beta gene segment. Data presented here demonstrate that the staphylococcal enterotoxin D (SE D), but not other bacterial superantigens, exhibits an ability to induce IgM, IgG, and especially RF production, in B cells from RA patients and normal individuals. Comparison with the polyclonal antibody production in B cell cultures driven by anti-CD3-stimulated T cell clones confirmed that SE D shifted the repertoire of secreted antibodies toward immunoglobulins with Fc binding specificity, suggesting that SE D preferentially stimulates RF+ B lymphocytes. B cells with the potential to secrete RF were highly frequent in RA patients, requiring as few as 150 peripheral B cells/culture to detect RF in the culture supernatants. SE D-induced RF synthesis was strictly dependent on the presence of selected CD4+T helper cells and required a direct membrane contact between B cells and T helper cells. Here, we propose a model that SE D selectively induces RF production depending on the availability of SE D responsive T cells in the TCR repertoire of the responder.

[Nodular panniculitis: a manifestation of Lyme borreliosis?]

Infection with Borrelia burgdorferi can induce various skin manifestations. The type of skin manifestation and the histopathological picture depend on the stage of infection and vary from local inflammatory infiltrates to chronic atrophic skin disease. Involvement of subcutaneous tissue has been observed only very rarely. We report on two patients suffering from nodular panniculitis (Pfeifer-Weber-Christian) and present evidence that the disease was caused by Borrelia burgdorferi. In one of the cases Borrelia burgdorferi was repeatedly isolated from skin and subcutaneous tissue biopsies in spite of repeated high-dose therapy with ceftriaxone, Doxycycline and cefotaxime.

Enhanced cell-mediated protection against fatal Escherichia coli septicemia induced by treatment with recombinant IL-2

Administration of rIL-2 to BALB/c mice induces a rapid, cell-mediated response that is sufficient to protect mice from a lethal i.p. dose of Escherichia coli. Mice were protected from septic death if IL-2 was administered i.p. within 1 h after the bacterial challenge. Optimal protection was provided by treating the lethally challenged mice with rIL-2 at 1 and 5 h or 1, 5, and 10 h after the bacterial challenge and was dose-dependent (greater than or equal to 5.0 x 10(5) U/kg). Furthermore, treatment of mice with anti-IL-2R antibody abolished the protective effect induced by rIL-2 administration. These data suggest that the rIL-2-induced protection against septic death in mice is mediated by a cell type expressing a functional IL-2R. One potentially important therapeutic application of rIL-2 may be to modulate the course of sepsis once the host has been exposed to potentially lethal microbial pathogens.

Enhanced cell-mediated protection against fatal Escherichia coli septicemia induced by treatment with recombinant IL-2

Administration of rIL-2 to BALB/c mice induces a rapid, cell-mediated response that is sufficient to protect mice from a lethal i.p. dose of Escherichia coli. Mice were protected from septic death if IL-2 was administered i.p. within 1 h after the bacterial challenge. Optimal protection was provided by treating the lethally challenged mice with rIL-2 at 1 and 5 h or 1, 5, and 10 h after the bacterial challenge and was dose-dependent (greater than or equal to 5.0 x 10(5) U/kg). Furthermore, treatment of mice with anti-IL-2R antibody abolished the protective effect induced by rIL-2 administration. These data suggest that the rIL-2-induced protection against septic death in mice is mediated by a cell type expressing a functional IL-2R. One potentially important therapeutic application of rIL-2 may be to modulate the course of sepsis once the host has been exposed to potentially lethal microbial pathogens.

Administration in vivo of recombinant interleukin 2 protects mice against septic death

Administration in vivo of recombinant interleukin 2 (rIL-2) to mice induces a polyclonal IgM response. When co-administered with a specific antigen, rIL-2 can enhance concentrations of murine IgM antibodies specific for the antigen by fivefold within 7 d of initial treatment. IgM antibodies that are induced after injection of rIL-2 include antibodies specific for J5, a cell wall core lipopolysaccharide (LPS) antigen that is shared by the different members of the Enterobactericeae family. We report here that mice pretreated with rIL-2 or immunized with J5 antigen 7 d before bacterial challenge were protected from septic death that is caused by intraperitoneal challenges with Escherichia coli. Optimal protection was provided by a combined J5 antigen and rIL-2 treatment. Acquisition of the rIL-2 and J5 antigen-induced protection against lethal bacterial infection coincided temporally with maximal serum IgM titers that also contained IgM antibodies specific for the J5 antigen. In passive immunization experiments, the affinity-purified IgM fraction in sera of rIL-2-treated animals was identified as necessary and sufficient for protection. The IgM-depleted serum had no protective effect. The nonspecific augmentation of host-defense mechanisms without the induction of endotoxin manifestations makes rIL-2 a potential candidate to any alternative LPS-containing vaccines for the prevention of bacterial infections by gram-negative organisms since the core LPS antigen is shared among gram-negative bacteria.

Heterogeneity of signal requirements in T cell activation within a panel of human proliferative T cell clones

Activation of T lymphocytes is initiated by receptor ligand interactions at the cell surface leading to the transduction of intracellular signals followed by the de novo synthesis and expression of T cell activation markers (including receptors for interleukin 2 (IL 2) and transferrin), production of lymphokines, and T cell proliferation. This requisite first step for activation of T lymphocytes can be mimicked in certain situations with a variety of stimuli. These include antibodies to certain integral membrane proteins, phorbol esters, and plant lectins that act as mitogens. In this paper, we report that at least two classes of human T cell clones can be distinguished based upon signal requirements necessary to induce proliferation. Although all clones analyzed expressed IL 2 receptors and secreted IL 2 after non-antigenic activation, one subset of clones did not proliferate in response to the same non-antigenic signals. In that subset, complete activation leading to proliferation required interaction of the T cell with specific antigen. The ability to subset these T cell clones into two groups did not correlate with phenotypic differences, source of the clone, nor with magnitude of intracellular calcium mobilization. By studying the stimulation requirements of these two subsets of human T cell clones through the use of specific antigen or antigen-independent stimuli, it was possible to demonstrate that different stimuli varied in their ability to induce steps of T cell activation. Analysis of reactivity of these clones to suboptimal stimulation allowed the definition of intermediate stages of T cell activation. Such intermediate stages might reflect a diversity of intracellular signaling pathways or a complexity of regulatory mechanisms distal to the events that allow intracellular calcium mobilization. Thus for the first time, it has been possible to study ordered events of T cell activation in non-transformed, antigen-dependent human T lymphocytes. The data presented in this paper suggest that T cell activation is not an all or nothing phenomenon, and there is an ordered sequence of events that can be differentiated based upon signal requirements at the T cell membrane.

Heterogeneity of signal requirements in T cell activation within a panel of human proliferative T cell clones

Activation of T lymphocytes is initiated by receptor ligand interactions at the cell surface leading to the transduction of intracellular signals followed by the de novo synthesis and expression of T cell activation markers (including receptors for interleukin 2 (IL 2) and transferrin), production of lymphokines, and T cell proliferation. This requisite first step for activation of T lymphocytes can be mimicked in certain situations with a variety of stimuli. These include antibodies to certain integral membrane proteins, phorbol esters, and plant lectins that act as mitogens. In this paper, we report that at least two classes of human T cell clones can be distinguished based upon signal requirements necessary to induce proliferation. Although all clones analyzed expressed IL 2 receptors and secreted IL 2 after non-antigenic activation, one subset of clones did not proliferate in response to the same non-antigenic signals. In that subset, complete activation leading to proliferation required interaction of the T cell with specific antigen. The ability to subset these T cell clones into two groups did not correlate with phenotypic differences, source of the clone, nor with magnitude of intracellular calcium mobilization. By studying the stimulation requirements of these two subsets of human T cell clones through the use of specific antigen or antigen-independent stimuli, it was possible to demonstrate that different stimuli varied in their ability to induce steps of T cell activation. Analysis of reactivity of these clones to suboptimal stimulation allowed the definition of intermediate stages of T cell activation. Such intermediate stages might reflect a diversity of intracellular signaling pathways or a complexity of regulatory mechanisms distal to the events that allow intracellular calcium mobilization. Thus for the first time, it has been possible to study ordered events of T cell activation in non-transformed, antigen-dependent human T lymphocytes. The data presented in this paper suggest that T cell activation is not an all or nothing phenomenon, and there is an ordered sequence of events that can be differentiated based upon signal requirements at the T cell membrane.

Gene conversion. A mechanism to explain HLA-D region and disease association

In speculating about mechanisms that might give rise to T-cell epitopes appearing within different HLA-DR frameworks, we return to the hypothesis expressed above that suggests that gene-conversion-like events might be involved in shuffling the hypervariable segments of HLA-D region exons into alternative HLA-D region frameworks where they will still be recognized by the T cell (but not typed by conventional serology or mixed lymphocyte typing) as the "disease associated" HLA product. This might well explain the lack of stringent association between rheumatoid arthritis and HLA-DR4. It is possible, through the use of such alloreactive T-cell clones, that we might eventually define subgroups based upon presumed genetic susceptibility markers, which might allow therapeutic or prognostic assignment of patients with seropositive rheumatoid arthritis.

T cell activation: differences in the signals required for IL 2 production by nonactivated and activated T cells

Soluble antibodies against the T3/antigen receptor complex alone are not sufficient to induce proliferation and interleukin 2 expression by T lymphocytes. An additional requirement is the presence of accessory cells (AC). In this model, AC provide at least two functions required for T cell activation: 1) the surface interaction of T3 antibodies with Fc receptors on the AC surface and 2) the production of soluble mediators such as interleukin 1 (IL 1). In the experiments reported here, these stimuli are represented by T3 antibodies immobilized onto Sepharose beads and by recombinant IL 1. In this study we investigated differences in activation requirements in resting and activated T cells. Resting T cells were represented by AC-depleted peripheral blood mononuclear cells (PBMC) or the T cell line Jurkat, which phenotypically resembles a resting T cell. Activated T cells were represented by T cell clones and the T cell line HUT 78, which express the activation molecules Ia and the IL 2 receptor (Tac). In resting cells, activation required the presence of three different signals: perturbation of the T3/antigen receptor complex by T3 antibodies, surface redistribution of T3/antigen receptor complexes, and presence of IL 1. In contrast, activated T cells require only perturbation and redistribution of T3/antigen receptor complexes and not IL 1 for the induction of proliferation or IL 2 production. Possible mechanisms of intracellular signaling for these stimuli are discussed.

T cell activation: differences in the signals required for IL 2 production by nonactivated and activated T cells

Soluble antibodies against the T3/antigen receptor complex alone are not sufficient to induce proliferation and interleukin 2 expression by T lymphocytes. An additional requirement is the presence of accessory cells (AC). In this model, AC provide at least two functions required for T cell activation: 1) the surface interaction of T3 antibodies with Fc receptors on the AC surface and 2) the production of soluble mediators such as interleukin 1 (IL 1). In the experiments reported here, these stimuli are represented by T3 antibodies immobilized onto Sepharose beads and by recombinant IL 1. In this study we investigated differences in activation requirements in resting and activated T cells. Resting T cells were represented by AC-depleted peripheral blood mononuclear cells (PBMC) or the T cell line Jurkat, which phenotypically resembles a resting T cell. Activated T cells were represented by T cell clones and the T cell line HUT 78, which express the activation molecules Ia and the IL 2 receptor (Tac). In resting cells, activation required the presence of three different signals: perturbation of the T3/antigen receptor complex by T3 antibodies, surface redistribution of T3/antigen receptor complexes, and presence of IL 1. In contrast, activated T cells require only perturbation and redistribution of T3/antigen receptor complexes and not IL 1 for the induction of proliferation or IL 2 production. Possible mechanisms of intracellular signaling for these stimuli are discussed.

Human T cell clones express functional homing receptors required for normal lymphocyte trafficking

To function efficiently in vivo, lymphocytes must circulate from the blood into lymphoid tissues and other sites of immune reaction. Herein, we show that human cytotoxic and helper T cell clones and lines, maintained in vitro with IL-2, express the functional capacity to recognize and bind to high endothelial venules (HEV), a capacity essential for lymphocyte exit from the blood, and hence for normal lymphocyte trafficking. The expression of functional homing receptors distinguishes human T cell clones from their murine counterparts, which uniformly lack receptors for HEV and are unable to migrate normally from the blood in vivo. The results raise the possibility that human T cell clones may be more effective in mediating in vivo immune responses than is suggested by murine models.

Evidence for two independent effects of oestradiol benzoate on the renin-angiotensin-aldosterone system

Plasma renin concentrations (PRC), plasma renin substrate concentration (PRS), plasma aldosterone and cortisol concentrations as well as plama renin activity (PRA) were measured in ovariectomized subjects after im administration of 10 mg oestradiol benzoate (EB).

The esterified oestrogen exerts two independent effects on the renin-angiotensin-aldosterone system.

1) 48 h after EB administration, PRS was significantly increased. Similar results were obtained for total plasma cortisol, reflecting transcortin concentration. In both cases, the increase was quantitatively related to the basal concentrations. These observations are consistent with the well known oestrogen-induced protein synthesis in the liver.

2) The elevation of PRC preceded that of PRS and was already significant 11 h after EB injection. The early rise in plasma renin activity was essentially caused by the increase in PRC, whereas an influence of the activated substrate synthesis was found later, between the 2nd and the 4th day post injection. The time course of plasma aldosterone concentration correlated well with the increased PRA.

The results provide evidence that EB has two different effects on the renin-aldosterone axis: an early one by elevating renin release and a delayed one by increasing renin substrate synthesis. Whereas the second mechanism can clearly be localized in the liver, extrarenal as well as direct renal effects of EB may be responsible for the renin stimulation.

Recognition of polymorphic H-2 domains by T lymphocytes. I. Functional role of different H-2 domains for the generation of alloreactive cytotoxic T lymphocytes and determination of precursor frequencies

In the present communication, the repertoire of alloreactive cytotoxic T lymphocytes (CTL) clones was quantitatively investigated by limiting dilution analysis and by target inhibition with a panel of monoclonal antibodies (mAb). These mAb have previously been shown to define two distinct alloantigenic domains, A and B, on the H-2Kk molecule. The Poisson distribution analysis of H-2Kk-specific CTL clones generated in a limiting dilution system revealed three CTL populations with different precursor frequencies. The high frequent population is suppressed by an unknown suppressive mechanism that allows less frequent CTL populations to become visible. Target inhibition studies with a panel of Kk-specific mAb showed that these CTL populations differ not only in their precursor frequency but also in their specificity for different H-2 epitopes on the Kk molecule. Thus clones of the high frequency population are almost exclusively specific for determinants within domain A. In contrast, the low frequency population displays predominant specificity for determinants of domain B, while the population with medium frequency is blocked equally well by mAb against either domains A or B. Each mAb blocked only a fraction of clones indicating that each CTL subpopulation may consist of a large number of clonotypes with specificity for different H-2 epitopes. The data suggest that CTL recognize basically the same polymorphic domains on the H-2Kk molecule defined by antibodies, and they show that regulatory mechanisms determine the expressed repertoire in CTL populations.