Raza Ali Naqvi

Disruption of HLA-DR raft, deregulations of Lck-ZAP-70-Cbl-b cross-talk and miR181a towards T cell hyporesponsiveness in leprosy.

Leprosy, a chronic human disease, results from infection of Mycobacterium leprae. Defective CMI and T cell hyporesponsiveness are the major hallmark of M. leprae pathogenesis. The present study demonstrates immunological-deregulations that eventually lead to T cell anergy/hyporesponsiveness in M. lepare infection. We firstly, evaluated the membrane fluidity and antigen-presenting-lipid-raft (HLA-DR) on macrophages of leprosy patients using fluorescence anisotropy and confocal microscopy, respectively. Increased membrane fluidity and raft-out localizations of over-expressed HLA-DR towards BL/LL pole are pinpointed as major defects, may be leading to defective antigen presentation in leprosy. Furthermore, altered expression and localization of Lck, ZAP-70, etc. and their deregulated cross talks with negative regulators (CD45, Cbl-b and SHP2) turned out to be the major putative reason(s) leading to T cell hyporesponsiveness in leprosy. Deregulations of Lck-ZAP-70 cross-talk in T cells were found to be associated with cholesterol-dependent-dismantling of HLA-DR rafts in macrophages in leprosy progression. Increased molecular interactions between Cbl-b and Lck/ZAP-70 and their subsequent degradation via ubiquitinization pathway, as result of high expression of Cbl-b, were turned out to be one of the principal underlying reason leading to T cell anergy in leprosy patients. Interestingly, overexpression of SHP2 due to gradual losses of miR181a and subsequent dephosphorylation of imperative T cell signaling molecules were emerged out as another important reason associated with prevailing T cell hyporesponsiveness during leprosy progression. Thus, this study for the first time pinpointed overexpression of Cbl-b and expressional losses of miR-181 as important hallmarks of progression of leprosy.

CD4+CD25+ T regs with acetylated FoxP3 are associated with immune suppression in human leprosy

Leprosy is a chronic human disease that results from infection of Mycobacterium leprae. T reg cells have been shown to have important implications in various diseases. However, in leprosy, it is still unclear whether T regs can mediate immune suppression during progression of the disease. In the present study, we have proposed the putative mechanism leading to high proportion of T reg cells and investigated its significance in human leprosy. High levels of TGF-β followed by adaptation of FoxP3(+) naive and memory (CD4(+)CD45RA(+)/RO(+)) T cells were observed as the principal underlying factors leading to higher generation of T reg cells during disease progression. Furthermore, TGF-β was found to be associated with increased phosphorylation-mediated-nuclear-import of SMAD3 and NFAT towards BL/LL pole to facilitate FoxP3 expression in these cells, the same as justified after using nuclear inhibitors of SMAD3 (SIS3) and NFAT (cyclosporin A) in CD4(+)CD25(+) cells in the presence of TGF-β and IL-2. Interestingly, low ubiquitination of FoxP3 in T reg cells of BL/LL patients was revealed to be a major driving force in conferring stability to FoxP3 which in turn is linked to suppressive potential of T regs. The present study has also pinpointed the presence of CD4(+)CD25(+)IL-10(+) sub class of T regs (Tr1) in leprosy.

Th3 immune responses in the progression of leprosy via molecular cross-talks of TGF-β, CTLA-4 and Cbl-b.

Leprosy is a chronic human disease; primarily affecting skin, peripheral nerves, eyes, testis etc. Comprehensive-expressional-profiling of Th1-Th2-Th3 associated markers (84 genes) using qRT-PCR array, negated the previously prevailing notion, Th2 bias towards multibacillary stage of leprosy. High production TGF-β further supported the dearth of any immune response(s) in leprosy progression. Over expression of Cbl-b, could emerge as plausible reason for contributing T cell hyporesponsiveness, possibly by degradation of T cells signaling molecules. Anti-TGF-β treatments further confirm the TGF-β-dependent-Cbl-b overexpression in multibacillary patients. Diminished Cbl-b expression in CTLA-4 knockout studies using siRNA, provided other evidence towards T cell hyporesponsiveness. Further, high T cell proliferation and IL-2 production in PBMC cultures treated with anti-TGF-β and siRNA offers here a strategy to revert T cell hyporesponsiveness by downregulating Cbl-b expression in leprosy. Thus, this study negates Th2 bias and substantiates molecular cross-talk amongst TGF-β-CTLA-4-Cbl-b eventually leads to M. leprae persistence.

FoxP3 provides competitive fitness to CD4+CD25+ T cells in leprosy patients via transcriptional regulation

Leprosy is a chronic infectious disease caused by Mycobacterium leprae. FoxP3 have been shown to have important implications in various diseases. The present study describes the mechanism of action of FoxP3 in CD4+CD25+ T cells derived from leprosy patients. Increased molecular interactions of FoxP3 with histone deacetylases 7/9 in the nucleus of CD4+CD25+ T cells derived from borderline lepromatous leprosy/lepromatous leprosy (BL/LL) patients were found to be responsible for FoxP3‐driven immune suppression activities during the progression of leprosy. Further, downregulation of CTLA‐4 and CD25 genes in siFoxP3‐treated PBMCs derived from BL/LL patients elucidated the transcription‐activating nature of FoxP3. This observation was supported by direct binding of FoxP3 to the promoter region of the CTLA‐4 and CD25 genes, and FoxP3s molecular interaction with histone acetyl transferases. The study also revealed that the increased expression of miR155 in CD4+CD25+ cells from BL/LL governs the competitive fitness of these cells. Again, reduced Annexin V & propidium iodide staining and Nur77 expression, and concomitantly increased Ki‐67 positivity suggested that CD4+CD25+ cells derived from BL/LL patients are more competitively fit than those from borderline tuberculoid leprosy/tuberculoid leprosy and healthy controls. Taken together, the study shows the orchestration of FoxP3 leading to competitive fitness of Treg cells in leprosy.

IL-10 production from dendritic cells is associated with DC SIGN in human leprosy

The defective antigen presenting ability of antigen presenting cells (APCs) modulates host cytokines and co-stimulatory signals that may lead to severity of leprosy. In the present study, we sought to evaluate the phenotypic features of APCs along with whether DC SIGN (DC-specific intercellular adhesion molecule-grabbing nonintegrin) influences IL-10 production while moving from tuberculoid (BT/TT) to lepromatous (BL/LL) pole in leprosy pathogenesis. The study revealed an increased expression of DC SIGN on CD11c⁺ cells from BL/LL patients and an impaired form of CD83 (∼50 kDa). However, the cells after treatment with GM-CSF+IL-4+ManLAM showed an increased expression of similar form of CD83 on DCs. Upon treatment with ManLAM, DCs were found to show increased nuclear presence of NF-κB, thus leading to higher IL-10 production. High IL-10 production from ManLAM treated PBMCs further suggested the role of DC SIGN in subverting the DCs function towards BL/LL pole of leprosy. Anti-DC SIGN treatment resulting in restricted nuclear ingression of NF-κB as well as its acetylation along with enhanced T cell proliferation validated our findings. In conclusion, Mycobacterium leprae component triggers DC SIGN on DCs to induce production of IL-10 by modulating intracellular signalling pathway at the level of transcription factor NF-κB towards BL/LL pole of disease.

Association of TNF-α-(308(GG)), IL-10(-819(TT)), IL-10(-1082(GG)) and IL-1R1(+1970(CC)) genotypes with the susceptibility and progression of leprosy in North Indian population.

Leprosy is an infectious disease caused by M. leprae. We analyzed 48 cytokine polymorphisms in 13 (pro as well as anti-inflammatory) cytokine genes using PCR-SSP assay in 102 leprosy patients and 120 healthy controls with intent to find out a link between cytokine polymorphisms and disease susceptibility. TNF-α (-308) GG, IL-10 (-819) TT, IL-10 (-1082) GG and IL1R (+1970) CC genotypes are found to be predominant (p=0.01, p=0.02, p=0.0001 and p=0.001, respectively) in both tuberculoid as well as lepromatous leprosy patients. This observation suggests these genotypes as play the central role(s) in the progression of disease. CBA assay demonstrates the varied serum concentration of these cytokines with respect to their genotypes. The above genotypes appeared as high producer genotypes in our study. Even in presence of high produce genotypes, TNF-α level are found to be affected/masked by the presence of IL-10 in leprosy patients. Expressional masking of TNF-α is associated with the expression of IL-10 in these patients. This is one the negative impact of SNP-SNP interaction in leprosy patients. Therefore, we can conclude that cytokine gene polymorphisms determine the predisposition to the leprosy progression.

Multiple Antigen Peptide Containing B and T Cell Epitopes of F1 Antigen of Yersinia pestis Showed Enhanced Th1 Immune Response in Murine Model

Yersinia pestis is a facultative bacterium that can survive and proliferate inside host macrophages and cause bubonic, pneumonic and systemic infection. Apart from humoral response, cell‐mediated protection plays a major role in combating the disease. Fraction 1 capsular antigen (F1‐Ag) of Y. pestis has long been exploited as a vaccine candidate. In this study, F1‐multiple antigenic peptide (F1‐MAP or MAP)‐specific cell‐mediated and cytokine responses were studied in murine model. MAP consisting of three B and one T cell epitopes of F1‐antigen with one palmitoyl residue was synthesized using Fmoc chemistry. Mice were immunized with different formulations of MAP in poly DL‐lactide‐co‐glycolide (PLGA) microspheres. F1‐MAP with CpG oligodeoxynucleotide (CpG‐ODN) as an adjuvant showed enhanced in vitro T cell proliferation and Th1 (IL‐2, IFN‐γ and TNF‐α) and Th17 (IL‐17A) cytokine secretion. Similar formulation also showed significantly higher numbers of cytokine (IL‐2, IFN‐γ)‐secreting cells. Moreover, F1‐MAP with CpG formulation showed significantly high (P < 0.001) percentage of CD4+ IFN‐γ+ cells as compared to CD8+ IFN‐γ+ cells, and also more (CD4‐ IFN‐γ)+ cells secrete perforin and granzyme as compared to (CD8‐ IFN‐γ)+ showing Th1 response. Thus, the study highlights the importance of Th1 cytokine and existence of CD4+ and CD8+ immune response. This study proposes a new perspective for the development of vaccination strategies for Y. pestis that trigger T cell immune response.

Multiple antigen peptide consisting of B- and T-cell epitopes of F1 antigen of Y. pestis showed enhanced humoral and mucosal immune response in different strains of mice

Yersinia pestis is a causative agent of plague. F1 and V antigen based vaccines have shown remarkable protection in experimental animals. In order to develop epitope based immunogen, three B and one T-cell epitopes of F1 antigen with palmitate residue at amino terminal were assembled on a lysine backbone as multiple antigen peptide (MAP or F1-MAP). MAP was characterized by SDS-PAGE, immunoblot and immunoreactivity with anti F1 sera. MAP was entrapped in PLGA (polylactide-co-glycolide) microparticles and humoral, mucosal immune responses were studied after intranasal immunization with/without CpG ODN 1826 (CpG)/murabutide in different strains of mice. Serum and mucosal washes were measured for MAP specific IgG, IgA, sIgA and IgG subclasses in three strains of mice. F1-MAP showed high serum antibody and mucosal IgG and IgA peak antibody titers. MAP with CpG showed significantly high (p<0.001) peak antibody titer ranging from 102,400 to 204,800 for IgG and 6400 to 12,800 for IgA. High mucosal sIgA and its secretary component detection confirmed generation of mucosal response in intestinal and lung washes. MAP antisera also showed significant immunoreactivity with individual peptides. Moreover, antibody specific activity (IgG, IgA and sIgA) positively correlates with peak antibody titers. Predominantly IgG2a/IgG2b subclass was observed with CpG formulation but in other formulation a mixed IgG1 and IgG2a response was observed. The present study highlights the importance of multiple antigen peptide approach of F1-antigen with CpG as an alternative approach for subunit vaccine.

B and T cell epitope mapping and study the humoral and cell mediated immune response to B-T constructs of YscF antigen of Yersinia pestis

YscF antigen, a type III secretion protein has recently been shown partial protection in murine model. Five peptides of YscF antigen were predicted using DNASTAR and T-cell prediction software. Peptides were synthesised and authenticated using competitive, direct binding immunoassay with anti YscF/peptide sera raised in mice. Peptide P1 and P2 were found to be B cell epitope while P3 was minor B cell epitope. P4 peptide was a pure T cell epitope based on lymphoproliferative response, cytokines profile and T-bet expression. Furthermore, with an intention to enhance immunogenicity, three B-T constructs were designed between the above epitopes. Conjugate B1T1 and B2T1 showed higher serum IgG/IgA titre, respectively, as well as high secretory IgA plus secretory component (Sc) both in lung and intestinal washes. Also, these conjugates showed high T-cell proliferation in addition to higher Th1 type cytokines (IFN-γ and IL-2) in cells obtained from spleen, lamina propria and Peyers patches. B3T1 stimulated cells showed moderate levels of IFN-γ and IL-2 but higher levels of IL-4. This study demonstrates superior immunogen of B1T1 and B2T1 of YscF antigen to be exploited as vaccine candidate for plague.

IL-12 and IL-23 modulate plasticity of FoxP3+ regulatory T cells in human Leprosy

&NA; Leprosy is a bacterial disease caused by M. leprae. Its clinical spectrum reflects the hosts immune response to the M. leprae and provide an ideal model to investigate the host pathogen interaction and immunological dysregulation. Tregs are high in leprosy patients and responsible for immune suppression of the host by producing IL‐10 and TGF‐&bgr; cytokines. In leprosy, plasticity of Tregs remain unstudied. This is the first study describing the conversion of Tregs into Th1‐like and Th17‐like cells using in vitro cytokine therapy in leprosy patients. Peripheral blood mononuclear cells from leprosy patients were isolated and stimulated with M. leprae antigen (MLCwA), rIL‐12 and rIL‐23 for 48 h. Expression of FoxP3 in CD4+CD25+ Tregs, intracellular cytokines IFN‐&ggr;, TGF‐&bgr;, IL‐10 and IL‐17 in Tregs cells were evaluated by flow cytometry (FACS) after stimulation. rIL‐12 treatment increases the levels of pStat4 in Tregs and IFN‐&ggr; production. In the presence of rIL‐23, pStat3+ and IL‐17A+ cells increase. rIL‐12 and r—IL‐23 treatment downregulated the FoxP3 expression, IL‐10 and TGF‐&bgr; production by Tregs and enhances the expression of co‐stimulatory molecules (CD80, CD86). In conclusion rIL‐12 converts Tregs into IFN‐&ggr; producing cells through STAT‐4 signaling while rIL‐23 converts Tregs into IL‐17 producing cells through STAT‐3 signaling in leprosy patients. This study may helpful to provide a new avenue to overcome the immunosuprression in leprosy patients using in vitro cytokine. Highlightsr‐IL‐12 & r‐IL‐23 downregulate FoxP3 expression inTregs in leprosy patients.r‐IL‐12 converts Tregs into Th1 like cells in leprosy patients.r‐IL‐23 converts Tregs into Th17 like cells in leprosy patients.r‐IL‐12 & r‐IL‐23 downregulate IL‐10, TGF‐&bgr; production by T regs in leprosy.r‐IL‐12 & r‐IL‐23 enhance the expression of co‐stimulatory in leprosy patients.