A distinct double positive IL-17A+/F+ T helper 17 cells induced inflammation leads to IL17 producing neutrophils in Type 1 reaction of leprosy patients.

Type 1 reactions (T1R) an inflammatory condition, of local skin patches in 30-40% leprosy patients during the course of MDT. IL-17A and IL-17F play an important role in regulating skin inflammation through neutrophils. In the present study, we have analyzed 18 of each T1R and Non-reactions (NR) patients through flow cytometry and qPCR. Interestingly we found that, CD3+CD4+ gated IL-17A+IL-17F+ cells were significantly high in T1R in both MLSA stimulated PBMCs and skin lesions as compared to NR leprosy patients. Hierarchical clustering analysis of gene expression showed that CXCL6, CXCL5, CCL20, CCL7, MMP13 and IL-17RB expression were significantly associated with IL-17A and IL-17F expression (Spearman r2 = 0.77 to 0.98), neutrophils and monocyte markers respectively. In this study, the inflammation noted in lesions of T1R is a different phenotype of Th17 which produce double positive IL-17A+IL17F+ and also contributes IL-17 producing neutrophils and thus would be useful for monitoring, diagnosis and treatment response before reactions episodes.

Hsp65-producing Lactococcus lactis prevents experimental autoimmune encephalomyelitis in mice by inducing CD4+LAP+ regulatory T cells.

Heat shock proteins (Hsps) participate in the cellular response to stress and they are hiperexpressed in inflammatory conditions. They are also known to play a major role in immune modulation, controlling, for instance, autoimmune responses. In this study, we showed that oral administration of a recombinant Lactococcus lactis strain that produces and releases LPS-free Hsp65 prevented the development of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. This was confirmed by the reduced inflammatory cell infiltrate and absence of injury signs in the spinal cord. The effect was associated with reduced IL-17 and increased IL-10 production in mesenteric lymph node and spleen cell cultures. Hsp65-producing-L. lactis-fed mice had a remarkable increase in the number of natural and inducible CD4+Foxp3+ regulatory T (Treg) cells and CD4+LAP+ (Latency-associated peptide) Tregs - which express the membrane-bound TGF-ß - in spleen, inguinal and mesenteric lymph nodes as well as in spinal cord. Moreover, many Tregs co-expressed Foxp3 and LAP. In vivo depletion of LAP+ cells abrogated the effect of Hsp65-producing L. lactis in EAE prevention and worsened disease in medium-fed mice. Thus, Hsp65-L.lactis seems to boost this critical regulatory circuit involved in controlling EAE development in mice.

Evidence for human CD4+ T cells in the CD1-restricted repertoire: derivation of mycobacteria-reactive T cells from leprosy lesions.

Both the CD4-CD8- (double negative) and CD4-CD8+ T cell lineages have been shown to contain T cells which recognize microbial lipid and glycolipid Ags in the context of human CD1 molecules. To determine whether T cells expressing the CD4 coreceptor could recognize Ag in the context of CD1, we derived CD4+ T cell lines from the lesions of leprosy patients. We identified three CD4+ Mycobacterium leprae-reactive, CD1-restricted T cell lines: two CD1b restricted and one CD1c restricted. These T cell lines recognize mycobacterial Ags, one of which has not been previously described for CD1-restricted T cells. The response of CD4+ CD1-restricted T cells, unlike MHC class II-restricted T cells, was not inhibited by anti-CD4 mAb, suggesting that the CD4 coreceptor does not impact positive or negative selection of CD1-restricted T cells. The CD4+ CD1-restricted T cell lines produced IFN-gamma and GM-CSF, the Th1 pattern of cytokines required for cell-mediated immunity against intracellular pathogens, but no detectable IL-4. The existence of CD4+ CD1-restricted T cells that produce a Th1 cytokine pattern suggests a contributory role in immunity to mycobacterial infection.

Modulation of protective and pathological immunity in mycobacterial infections.

Mycobacterial infections represent major problems to global health care. Tuberculosis is feared particularly because of its high mortality rates whereas in leprosy the occurrence of immunopathology, particularly nerve damage, is a major problem since the bacillus itself is relatively harmless. Thus, both effective vaccination strategies as well as novel immunomodulating regimens are warranted for the control of morbidity and mortality in mycobacterial diseases. Since CD4+ Th1 cells and type-1 cytokines play a key role both in protective immunity and immunopathology in mycobacterial infections, we here describe new pharmacological and cytokine-based strategies to regulate Th1 immunity.

Cytokine gene expression in the foot pad and spleen of BALB/cAJcl mice infected with M. leprae.

The cytokine mRNAs expressed in the foot pads and spleens of BALB/cAJcl mice infected with Mycobacterium leprae were studied by the reverse transcriptase-polymerase chain reaction (RT-PCR) method using cytokine-specific primers for interleukin-1 alpha (IL-1 alpha), -2, -4, -6, -10, -12-(p40), gamma interferon (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and TNF-beta, and then for CD4 and CD8 markers. The pattern of cytokine gene expression in the foot pad which supports M. leprae growth was different from the expression in the spleen which does not permit M. leprae multiplication in mice. Before BALB/cAjcl mice were infected with M. leprae, IL-1 alpha and TNF-beta mRNAs were expressed physiologically in the foot pad while all of the cytokine genes examined were expressed in the spleen. In the foot pads of mice inoculated with M. leprae, in addition to the physiological appearance of IL-1 alpha and TNF-beta mRNAs, these signals were intensified. TNF-alpha expression was induced by the infection. On the other hand, in the spleens of mice inoculated with M. leprae, CD4 mRNA expression disappeared on day 1 of the infection, which was accompanied by the reduced expression of IL-2, -4, -6, and -12 mRNAs. The recovery of CD4 mRNA expression at a latter stage was accompanied by a corresponding increase of the cytokine mRNA expression. It was suspected that these results might permit restricted growth of M. leprae in the foot pads of normal mice. Furthermore, our study suggests that tissue-specific, local, immunologic characteristics are important in M. leprae growth.

Flow cytometric analysis of CD2 modulation on human peripheral blood T lymphocytes by Dharmendra preparation of Mycobacterium leprae.

It has been reported previously that Mycobacterium leprae modulated CD2 on human peripheral blood T lymphocytes and that this modulation was accompanied by a marked reduction in the proliferative response of these cells to mitogens and antigens. In this study, we report that treatment of peripheral blood mononuclear cells from healthy individuals with Dharmendra preparation of M. leprae inhibited their ability to form rosettes with sheep red blood cells. Flow cytometric analysis of Dharmendra lepromin-treated cells showed that, in addition to CD2, CD4 and CD8 were modulated while the surface expression of CD3 was not affected. The specificity of CD2 modulation was confirmed by similar effects of Dharmendra lepromin on thymocytes and lymph node cells from human CD2 transgenic mice. The modulatory effect of Dharmendra lepromin was not observed at lower temperatures. Dharmendra lepromin treatment of activated T cells resulted in reduced binding of monoclonal antibodies to IL-2R and D66 epitope of CD2. The modulatory effects were not observed with Dharmendra preparation of BCG or other preparations of M. leprae. Our results indicate that certain M. leprae factor(s) specifically modulate(s) CD2, CD4, CD8 and IL-2R but not CD3 on T lymphocytes. The suppressive effect of Dharmendra lepromin on the T-cell proliferative response reported earlier may be explained by its modulatory effect on a number of T-cell surface molecules.