Polymorphisms in Toll-like receptor 4 (TLR4) are associated with protection against leprosy

Accumulating evidence suggests that polymorphisms in Toll-like receptors (TLRs) influence the pathogenesis of mycobacterial infections, including leprosy, a disease whose manifestations depend on host immune responses. Polymorphisms in TLR2 are associated with an increased risk of reversal reaction, but not susceptibility to leprosy itself. We examined whether polymorphisms in TLR4 are associated with susceptibility to leprosy in a cohort of 441 Ethiopian leprosy patients and 197 healthy controls. We found that two single nucleotide polymorphisms (SNPs) in TLR4 (896G>A [D299G] and 1196C>T [T399I]) were associated with a protective effect against the disease. The 896GG, GA and AA genotypes were found in 91.7, 7.8 and 0.5% of leprosy cases versus 79.9, 19.1 and 1.0% of controls, respectively (odds ratio [OR] = 0.34, 95% confidence interval [CI] 0.20-0.57, P < 0.001, additive model). Similarly, the 1196CC, CT and TT genotypes were found in 98.1, 1.9 and 0% of leprosy cases versus 91.8, 7.7 and 0.5% of controls, respectively (OR = 0.16, 95% CI 0.06--.40, P < 0.001, dominant model). We found that Mycobacterium leprae stimulation of monocytes partially inhibited their subsequent response to lipopolysaccharide (LPS) stimulation. Our data suggest that TLR4 polymorphisms are associated with susceptibility to leprosy and that this effect may be mediated at the cellular level by the modulation of TLR4 signalling by M. leprae.

Contact calls of common marmosets (Callithrix jacchus): influence of age of caller on antiphonal calling and other vocal responses

Marmosets, as do many other primates, live in forest environments, are group living and constantly at risk of predation. Retaining contact with one another is therefore a matter of survival. We ask here whether their contact calls (phee and twitter vocalizations) are in some way ordered acoustically by sex or age and whether the calls of older marmosets elicit different responses than those of younger marmosets. In our study, marmosets (2-14 years) were visually isolated from conspecifics and the vocal responses to each isolated caller by other marmosets in the colony were recorded. Vocal responses to phee calls largely consisted of phee calls and, less commonly, twitter calls. No differences between the responses to calls by males and females were apparent. However, we found a strong positive and significant correlation between the caller's age and the percentage of its phee calls receiving a phee response, and a significant negative correlation between the caller's age and the percentage of its phee calls receiving a twitter response. The older the marmoset, the more antiphonal calling occurred. Two-syllable phee calls were emitted more often by older marmosets (10-14 years) than by younger ones (2-6 years). Hence, we have found age-dependent differences in phee-call production and a consistent change in the response received across the adult life-span. This age-dependent effect was independent of kinship relations. This is the first evidence that marmosets distinguish age by vocal parameters alone and make social decisions based on age.

Serum amyloid type A may be a predictor of restenosis

BACKGROUND

Elevation of acute phase proteins [C-reactive protein (CRP) and serum amyloid type A (SAA)] has been demonstrated in unstable angina with an adverse clinical prognosis.

HYPOTHESIS

The study was undertaken to determine the effect of angioplasty on the levels of SAA and the correlation with postangioplasty restenosis.

METHODS

In a university-affiliated tertiary medical center, a prospective case study was undertaken in 55 patients who underwent successful percutaneous transluminal coronary angioplasty (PTCA) of a single coronary lesion for angina pectoris. Three groups of patients were clinically characterized according to Braunwald's classification of anginal syndrome: Group A: class III; Group B: class I; Group C: stable angina. Serum amyloid type A was measured by an ELISA method before PTCA and after 24 h, 1, and 3 months. Patients were followed clinically for 12 months. A thallium stress perfusion scan was performed 3 months after PTCA and coronary angiography was repeated in patients with an abnormal thallium perfusion scan.

RESULTS

Serum amyloid type A levels > 100 micrograms/ml could identify Group A patients with a high sensitivity and specificity (r = 0.85 and 0.86, respectively). Of the patients studied, 75% increased their SAA level 24 h after angioplasty. An increase of SAA by > 100% was associated with an increased risk of restenosis, with a relative risk of 6.4 (p < 0.05).

CONCLUSION

Increased levels of SAA characterize patients with unstable angina pectoris with a high specificity and sensitivity. Levels of SAA that increase > 100% 24 h after angioplasty may serve as a marker of restenosis.

The morphology of echinoid phagocytes and mouse peritoneal macrophages during phagocytosis in vitro

The morphology of mouse peritoneal macrophages and echinoid phagocytes during phagocytosis in vitro was studied. A striking similarity in the function of the foreign surface receptor is found in the two systems. Glutaraldehyde-treated erythrocytes attached randomly over the entire surface of the cells and were internalized without circumferential attachment between the particles and the phagocyte membrane. The particles seemed to sink directly into the cytoplasm of the cells. Tannin-treated erythrocytes were phagocytosed by the echinoid cells in a similar mode. The complement-coated erythrocytes were attached only in the perinuclear area of the echinoid phagocyte's membrane, but the morphology of their internalization was similar to that mediated by the foreign surface receptor. A circumferential attachment between the particles and the phagocyte membrane did not seem necessary. This is also the case for mouse peritoneal macrophages.

Teat preference for suckling in common marmosets: relationship to side of being carried and hand preference

Mother-infant interaction in common marmosets ( Callithrix jacchus jacchus ) was scored for the first 60 days post parturition. Teat preference was compared to hand preference for picking up and holding food over the same ages and at 18 months. All infants, except one, exhibited strong preferences for one of the mother's teats. Preference for a teat was maintained when twins suckled separately as well as together. Infants suckled separately for a mean 42% of the time of all suckling bouts being observed. There was a significant correlation between teat preference and the side of being carried by the mother. This correlation was maintained despite the fact that the father also carried the infants. There was no significant relationship between teat preference and hand preference from 0 to 2 months or later life.

Resolving appendicitis: role of CT

BACKGROUND

We assessed the role of computed tomography (CT) in the resolution of appendicitis.

METHODS

This was a retrospective study over 2.5 years involving 155 patients and 172 CT scans for suspected appendicitis in an emergency setting.

RESULTS

Sixty-nine studies were positive for appendicitis by CT criteria. Of these, 53 underwent surgery: 48 were positive for appendicitis, four had other pathologies (two with colon cancer, one with colitis, one with infectious enteritis), and one had a normal appendix that was removed. Three of the 69 patients were released or left the emergency room against medical advice. Twelve patients demonstrated acute appendicitis by CT criteria but were treated conservatively because their clinical conditions were stable; four of those patients had follow-up CT that showed resolution of findings. Six patients were followed clinically, without recurrence of symptoms, and two were lost to follow-up.

CONCLUSION

Resolving appendicitis is an entity that should be considered in a patient who has signs positive for appendicitis on CT but is doing well clinically. CT positive for appendicitis does not necessarily indicate surgery, and the decision for operation should depend on clinical and radiologic features.

Self-reported health status of immigrants from the former Soviet Union in Israel

BACKGROUND

A mass influx of immigrants from the former Soviet Union to western countries and Israel followed the demise of the Soviet Bloc at the beginning of the 1990s. It was expected that these immigrants would have a higher morbidity and mortality rate similar to that in the former USSR.

OBJECTIVES

To measure and compare self-reported diseases, subjective health and health services utilization of a representative sample of veteran Israeli Jews and immigrants from the former USSR.

METHODS

A cross-sectional survey of Israeli adults was performed by telephone interviews. The survey included 793 Israeli Jews, of whom 124 were immigrants from the former USSR who arrived in Israel after 1989 (response rate 52%).

RESULTS

The immigrants reported a higher rate of diseases and sub-optimal health after adjustment for other variables. However, no excess in health services utilization was reported. A time trend of reporting sub-optimal subjective health was observed: the longer the immigrants spent in Israel the more their reporting patterns resembled those of immigrants who arrived in Israel before 1970. Those who arrived after 1994 more frequently reported having a chronic disease.

CONCLUSIONS

Acculturation seems to have been the main effect on the immigrants' health, together with a healthy migrant effect at the beginning of the 1990s. The immigrants' health was worse in the later years of the immigration wave, partially reflecting the poor state of health in the former Soviet Union compared to Israel.

Autologous Schwann cells drive regeneration through a 6-cm autogenous venous nerve conduit

Peripheral nerve regeneration is a complex series of events, involving bi-directional interactions between regenerating axons and Schwann cells. These authors have demonstrated in their laboratory that nerves will regenerate through a 3-cm autogenous venous nerve conduit (AVNC) in an animal model and, with Dr. David Chiu, a similar distance in the human. They have shown that the upper limit of nerve regeneration in an empty AVNC was 3 cm, with no evidence of nerve growth at the 6-cm mark (no-growth model). Most recently, they have demonstrated rapid growth at 1 month in a 3-cm AVNC filled with Schwann cells, compared to poor-to-no-regrowth at 1 month in controls. While, in theory, Schwann-cell-derived growth factor should be sufficient to supplant the requirement for Schwann cells, in practice, therapies with growth factors have failed in clinical trials, with some resulting in severe morbidity and mortality for the subjects. The present study showed excellent nerve regeneration through a 6-cm AVNC with the addition of autologous Schwann cells, breaking the barrier in the previous no-growth model. In the first stage, autologous Schwann cells were harvested from the contralateral peroneal nerve of the rabbit and expanded in culture. The Schwann cells were purified to >99 percent homogeneity using differential adhesion and antibody-compliment-mediated cytolysis. In the second stage, 6 cm of gluteal vein were harvested and used as a conduit that was filled with either Matrigel or a slurry of Matrigel and 10(6)/ml autologous Schwann cells (n=6 control and 6 experimental animals). The non-donor side peroneal was exposed and transected, leaving a gap of 6 cm. The filled gluteal vein graft (AVNC) was then anastomosed to the proximal and distal peroneal nerve stumps, and the rabbits were allowed to recover. Four months postoperatively, the animals were subjected to transcardiac perfusion with EM grade fixative. The grafts were analyzed at the light and electronmicroscopic levels, and showed excellent growth of nerve at 6 cm, the distal end of the AVNC.

The immunomodulatory effects of thalidomide on human immunodeficiency virus-infected children

The safety and immune effects of low-dose thalidomide treatment (3 mg/kg/day for 28 days) were evaluated in a study involving 8 South African human immunodeficiency virus (HIV)-infected children. The children were 7-69 months old and in disease stages A1-C3. Thalidomide therapy did not affect virus load, even though none of the children was receiving antiretroviral therapy. Thalidomide stimulated CD8+ T cells in peripheral blood, which increased expression of the activation markers CD38 and human leukocyte antigen DR and of the memory cell marker CD45RO. The frequency of HIV gag-specific CD8+ T cells in peripheral blood increased in 3 of 4 children who were evaluated during treatment with thalidomide. Clinical adverse events were mild. In this study, thalidomide was found to be safe and well tolerated and caused significant immunomodulation at a low dose. This is the first report describing use of an oral drug that may enhance HIV-specific CD8+ T cell function in HIV-infected children.

General subjective health status or age-related subjective health status: does it make a difference?

This study examines the agreement between two subjective health measures, a general question on subjective health and an age-related question on subjective health. The study identifies specific groups differing in their answer to the two questions. These measures are used frequently in health-related studies where a short measure is needed to estimate health. Therefore, it is important to understand how the population estimates its health. The study based on 793 telephone interviews shows that among respondents aged 65-75 with no reported diseases and those with less than 12 years of education with no reported diseases, the agreement between the two questions was poor. These two groups reported better health when they were asked to compare their health to people of their age and sex. Excellent agreement between the two questions was reported in those aged 55-64 with no diseases. The respondents having more years of education reported better health than the less educated but only when using the age-related subjective health measure. These findings demand caution when using different wordings in questions on subjective health in non-homogeneous populations.

Chronic use of non-steroidal anti-inflammatory drugs does not alter colonic mucosa of patients without diarrhoea

BACKGROUND

Several types of colitis can be NSAID-induced, but whether chronic use of NSAIDs alters colonic mucosa in patients without diarrhoea is not known.

PATIENTS AND METHODS

Biopsy specimens of rectal mucosa were taken in six patients with rheumatoid arthritis without diarrhoea receiving NSAIDs (group 1, n=6). Patients with rheumatoid arthritis without diarrhoea not receiving NSAIDs (group 2, n=9), and patients undergoing surveillance colonoscopy (group 3, n=23) served as controls. In all patients from the three study groups, intraepithelial lymphocyte count and apoptotic cell count were assessed, and sub-epithelial collagen band thickness was measured. Leucocyte population of lamina propria was evaluated semi-quantitatively. HLA-DR and CD25 expression of mucosal cells was appreciated by immunohistochemistry.

RESULTS

Intraepithelial lymphocyte count was in the normal range in all three group patients, and not statistically different between groups. Apoptotic epithelial cell count was not different between groups. Sub-epithelial collagen band thickness was normal in all the patients. No patient had a marked infiltration of lamina propria by leucocytes, and HLA-DR and CD25 were normally expressed in all patients.

CONCLUSION

These results from a small sample of patients suggest that patients without diarrhoea receiving NSAIDs on a long-term basis do not develop microscopic or inflammatory colitis.

Similarity of the song nuclei of male and female Australian magpies (Gymnorhina tibicen)

The organisation of the song control nuclei of the Australian magpie (Gymnorhina tibicen), a species with highly complex song, was investigated. In contrast to most of the songbirds studied so far, the Australian magpie sings throughout the year and both males and females sing. All of the forebrain song nuclei, including the high vocal centre (HVC), the robust nucleus of the archistriatum (RA), Area X and the lateral and medial magnocellular nuclei of the anterior neostriatum (lMAN and mMAN) were found to be well developed in both male and female magpies. Consistent with the known vocal competence of juvenile magpies, all of the song nuclei were also well-developed in juvenile magpies (2--3 months old). HVC in both male and female magpies consists of a rostrolateral and a caudomedial region. The ventromedial part of RA differs from the dorsolateral part by having medium-sized neurons packed in higher density. The HVC to RA projections were labelled anterogradely by DiI and DiA. However, no HVC to Area X projections were labeled by DiI or DiA, suggesting a possible difference from songbirds studied previously.

Income inequality, the psychosocial environment, and health: comparisons of wealthy nations

BACKGROUND

The theory that income inequality and characteristics of the psychosocial environment (indexed by such things as social capital and sense of control over life's circumstances) are key determinants of health and could account for health differences between countries has become influential in health inequalities research and for population health policy.

METHODS

We examined cross-sectional associations between income inequality and low birthweight, life expectancy, self-rated health, and age-specific and cause-specific mortality among countries providing data in wave III (around 1989-92) of the Luxembourg Income Study. We also used data from the 1990-91 wave of the World Values Survey (WVS). We obtained life expectancy, mortality, and low birthweight data from the WHO Statistical Information System.

FINDINGS

Among the countries studied, higher income inequality was strongly associated with greater infant mortality (r=0.69, p=0.004 for women; r=0.74, p=0.002 for men). Associations between income inequality and mortality declined with age at death, and then reversed among those aged 65 years and older. Income inequality was inconsistently associated with specific causes of death and was not associated with coronary heart disease (CHD), breast or prostate cancer, cirrhosis, or diabetes mortality. Countries that had greater trade union membership and political representation by women had better child mortality profiles. Differences between countries in levels of social capital showed generally weak and somewhat inconsistent associations with cause-specific and age-specific mortality.

INTERPRETATION

Income inequality and characteristics of the psychosocial environment like trust, control, and organisational membership do not seem to be key factors in understanding health differences between these wealthy countries. The associations that do exist are largely limited to child health outcomes and cirrhosis. Explanations for between-country differences in health will require an appreciation of the complex interactions of history, culture, politics, economics, and the status of women and ethnic minorities.

A survey of sports injuries among a convenience sample of Israeli athletes

BACKGROUND

Israel lacks a systematic surveillance of sports injuries, and knowledge of risk factors and specific patterns of injury is inadequate. In order to promote prevention of sports-related injuries, the magnitude of the problem must first be identified and the incidence and severity of sports injuries described.

OBJECTIVE

To conduct a survey on previous sports injuries among a sample of Israeli athletes.

METHODS

A convenience sample of Israeli amateur athletes participating in the 1997 15th Maccabiah Games was randomly selected. The study group answered an anonymous self-administered questionnaire that included sociodemographic data, and information regarding their sports activity and sports-related injuries that had occurred during the previous 2 years.

RESULTS

The study group, aged 12-73 years (median age 21), comprised 301 consenting athletes in 28 different sports. Of these athletes 56.1% reported having had at least one injury. Most injuries (75.6%) involved the upper and lower extremities, and 37.8% of the injured sportsmen had received medical attention from a physician. Half of the athletes participated in contact sports--both collision and limited impact. This group had a much greater proportion of reported injuries in all age groups.

CONCLUSION

Surveillance of sports injuries should be expanded in order to develop appropriate prevention programs in Israel.

Remitting seronegative symmetrical synovitis with pitting edema following intravesical bacillus Calmette-Guérin instillation

Remitting seronegative symmetrical synovitis with pitting edema (RS3PE) is a rare syndrome of undetermined etiology occurring in the elderly. We describe the first case of RS3PE in a HLA-B27 positive 65-year-old man following intravesical bacillus Calmette-Guérin (BCG) instillation for bladder carcinoma. He developed symmetrical arthritis and synovitis involving wrists, knees, ankles, and metatarsophalangeal joints, with marked pitting edema of the dorsa of both hands and feet, fever, and elevated acute phase reactants. Right knee effusion revealed nonspecific sterile inflammatory fluid. He responded dramatically to nonsteroidal antiinflammatory drugs. BCG instillation may have triggered active symmetrical synovitis via local T cell activation and a T-helper-1 (Th-1)/Th-2 inflammatory profile.

TNF-α Controls Intracellular Mycobacterial Growth by Both Inducible Nitric Oxide Synthase-Dependent and Inducible Nitric Oxide Synthase-Independent Pathways

The role of TNF-alpha in the control of mycobacterial growth in murine macrophages was studied in vitro. Infection of macrophages from TNF-alpha gene disrupted (TNF-knockout (KO)) mice with recombinant Mycobacterium bovis bacillus Calmette Guérin (BCG) expressing the vector only (BCG-vector) resulted in logarithmic growth of the intracellular bacilli. Infection with BCG-secreting murine TNF-alpha (BCG-TNF) led to bacillary killing. Killing of BCG-TNF was associated with rapid accumulation of inducible NO synthase (iNOS) protein and the production of nitrite. The uncontrolled growth of BCG-vector was associated with low iNOS expression but no nitrite production. Thus, iNOS expression appears to be TNF-alpha independent but iNOS generation of NO requires TNF-alpha. In cultures of TNF-KO macrophages infected with BCG-TNF, inhibition of iNOS by aminoguanidine (AMG) abolished the killing of the bacilli. However, the growth of the organisms was still inhibited, suggesting an iNOS-independent TNF-alpha-mediated growth inhibition. To confirm this, macrophages from iNOS-KO mice were infected with either BCG-vector or BCG-TNF. As expected, no nitrite was detected in the culture medium. TNF-alpha was detected only when the cells were infected with BCG-TNF. In the iNOS-KO macrophages, the growth of BCG was inhibited only in the BCG-TNF infection. These results suggest that in the absence of iNOS activity, TNF-alpha stimulates macrophages to control the growth of intracellular BCG. Thus, there appears to be both a TNF-alpha-dependent-iNOS-dependent killing pathway as well as a TNF-alpha-dependent-iNOS-independent growth inhibitory pathway for the control of intracellular mycobacteria in murine macrophages.

Virulence of a Mycobacterium tuberculosis clinical isolate in mice is determined by failure to induce Th1 type immunity and is associated with induction of IFN-alpha /beta

To understand how virulent mycobacteria subvert host immunity and establish disease, we examined the differential response of mice to infection with various human outbreak Mycobacterium tuberculosis clinical isolates. One clinical isolate, HN878, was found to be hypervirulent, as demonstrated by unusually early death of infected immune-competent mice, compared with infection with other clinical isolates. The differential effect on survival required lymphocyte function because severe combined immunodeficiency (SCID) mice infected with HN878 or other clinical isolates all died at the same rate. The hypervirulence of HN878 was associated with failure to induce M. tuberculosis-specific proliferation and IFN-gamma production by spleen and lymph node cells from infected mice. In addition, 2- to 4-fold lower levels of tumor necrosis factor-alpha (TNF-alpha), IL-6, IL-12, and IFN-gamma mRNAs were observed in lungs of HN878-infected mice. IL-10, IL-4, and IL-5 mRNA levels were not significantly elevated in lungs of HN878 infected mice. In contrast, IFN-alpha mRNA levels were significantly higher in lungs of these mice. To further investigate the role of Type 1 IFNs, mice infected with HN878 were treated intranasally with purified IFN-alpha/beta. The treatment resulted in increased lung bacillary loads and even further reduced survival. These results suggest that the hypervirulence of HN878 may be due to failure of this strain to stimulate Th1 type immunity. In addition, the lack of development of Th1 immunity in response to HN878 appears to be associated with increased induction of Type 1 IFNs.

[Traumatic brain injury--the National Trauma Registry]

BACKGROUND

Traumatic Brain Injury (TBI) has been established as a category in reporting systems. Uniform data systems case definition has been suggested for hospital discharge data surveillance systems cases based on ICD-9-CM diagnostic codes. These include fractures and specific mention of intracranial injuries such as contusion, laceration, hemorrhage, and concussion. Inspection of data from the Israel National Trauma Registry suggested that two diagnostic groups of very different severity and outcome were being unjustifiably combined.

AIM

To evaluate the validity of categorizing TBI into two discrete groups, using the presence of specific mention of intracranial injury and/or loss of consciousness for more than one hour as the definition of definite TBI. Possible TBI includes skull fractures with no mention of intracranial injury and/or concussion with no loss of consciousness.

METHODS

The study population includes all traumatic injuries admitted to hospital, dying in the ER or transferred to other hospitals and recorded in the 1998 Trauma Registry in all 6 level I trauma centers in Israel and two level II centers.

RESULTS

The significant difference in severity between groups supports the validity of sub-dividing the TBI classification into definite and possible subcategories. As a result, we obtain two different severity groups without measuring specific severity scores which are limited in the reporting system.

CONCLUSION

The groups were significantly different in severity, hospital resource use, immediate outcome, demographic and injury circumstances.

Acupuncture for osteoarthritis of the knee: a systematic review

OBJECTIVE

To evaluate trials of acupuncture for osteoarthritis (OA) of the knee, to assess the methodologic quality of the trials and determine whether low-quality trials are associated with positive outcomes, to document adverse effects, to identify patient or treatment characteristics associated with positive response, and to identify areas of future research.

METHODS

Eight databases and 62 conference abstract series were searched. Randomized or quasi-randomized trials of all languages were included and evaluated for methodologic quality using the Jadad scale. Outcomes were pain, function, global improvement, and imaging. Data could not be pooled; therefore, a best-evidence synthesis was performed to determine the strength of evidence by control group. The adequacy of the acupuncture procedure was assessed by 2 acupuncturists trained in treating OA and blinded to study results.

RESULTS

Seven trials representing 393 patients with knee OA were identified. For pain and function, there was limited evidence that acupuncture is more effective than being on a waiting list for treatment or having treatment as usual. For pain, there was strong evidence that real acupuncture is more effective than sham acupuncture; however, for function, there was inconclusive evidence that real acupuncture is more effective than sham acupuncture. There was insufficient evidence to determine whether the efficacy of acupuncture is similar to that of other treatments.

CONCLUSION

The existing evidence suggests that acupuncture may play a role in the treatment of knee OA. Future research should define an optimal acupuncture treatment, measure quality of life, and assess acupuncture combined with other modalities.

Systemic inflammatory response with plasma C-reactive protein elevation in disk-related lumbosciatic syndrome

OBJECTIVE

To look for a systemic inflammatory response in patients with disk-related lumbosciatic syndrome by using an ultrasensitive (US) plasma C-reactive protein (CRP) assay, and to determine whether plasma CRP-US levels correlated with clinical and/or laboratory features.

PATIENTS AND METHODS

Plasma CRP was assayed using an enzyme-linked immunosorbent assay (ELISA) (detection limit, 5 microg/L) in patients with sciatica shown by computed tomography to be due to a disk herniation. Levels in 35 patients aged 23 to 64 years were compared to those in age- and sex-matched controls.

RESULTS

Mean CRP-US levels measured by ELISA were significantly higher in the patients than in the controls (1.68 vs 0.74 mg/L; P = 0.002). There was a trend toward higher CRP-US levels in the patients with more severe nerve root symptoms.

CONCLUSION

The significantly higher plasma CRP-US levels by ELISA in our patients with disk-related lumbosciatic syndrome is consistent with a systemic inflammatory response to the local nerve root impingement.

Mycobacterium tuberculosis 19-kilodalton lipoprotein inhibits Mycobacterium smegmatis-induced cytokine production by human macrophages in vitro

Vaccination of mice with Mycobacterium vaccae or M. smegmatis induces some protection against M. tuberculosis challenge. The 19-kDa lipoprotein of M. tuberculosis, expressed in M. vaccae or M. smegmatis (M. smeg19kDa), abrogates this protective immunity. To investigate the mechanism of this suppression of immunity, human monocyte-derived macrophages (MDM) were infected with M. smeg19kDa. Infection resulted in reduced production of tumor necrosis factor alpha (TNF-alpha) (P < 0.01), interleukin-12 (IL-12) (P < 0.05), IL-6 (P < 0.05), and IL-10 (P < 0.05), compared to infection with M. smegmatis vector (M. smegV). Infection with M. smeg19kDa and with M. smegV had no differential effect on expression of costimulatory molecules on MDM, nor did it affect the proliferation of presensitized T cells cocultured with infected MDM. When MDM were infected with M. smegmatis expressing mutated forms of the 19-kDa lipoprotein, including non-O-glycosylated (M. smeg19NOG), nonsecreted (M. smeg19NS), and nonacylated (M. smeg19NA) variants, the reduced production of TNF-alpha or IL-12 was not observed. When the purified 19-kDa lipoprotein was added directly to cultures of infected monocytes, there was little effect on either induction of cytokine production or its inhibition. Thus, the immunosuppressive effect is dependent on glycosylated and acylated 19-kDa lipoprotein present in the phagosome containing the mycobacterium. These results suggest that the diminished protection against challenge with M. tuberculosis seen in mice vaccinated with M. smegmatis expressing the 19-kDa lipoprotein is the result of reduced TNF-alpha and IL-12 production, possibly leading to reduced induction of T-cell activation.