India International Center for Excellence in Research

National Institute Of Allergy And Infectious Diseases

Investigators

Linked publications, trials & patents

Abstract

In the past year, we have completed a number of studies on the pathogenesis of Strongyloidiasis and LF and the immunology of tuberculosis. We are also continuing our studies on TB - helminth co-infection and immune responses in TB and TB-diabetes. Strongyloidiasis and LF pathogenesis: A. Elevated Systemic Levels Of Eosinophil, Neutrophil And Mast Cell Granular Proteins In Strongyloides Stercoralis Infection That Diminish Following Treatment Infection with the helminth parasite Strongyloides stercoralis (Ss) is commonly clinically asymptomatic that is often accompanied by peripheral eosinophilia. Granulocytes are activated during helminth infection and can act as immune effector cells. Plasma levels of eosinophil and neutrophil granular proteins provide an indirect measure of granulocyte degranulation and are markedly increased in many helminth-infected patients. We sought to examine the levels of eosinophil, neutrophil and mast cell activation-associated granule proteins in asymptomatic Ss infection and to understand their kinetics following anthelmintic therapy. To this end, we measured the plasma levels of eosinophil cationic protein, eosinophil derived neurotoxin, eosinophil peroxidase, eosinophil major basic protein, neutrophil elastase, myeloperoxidase, neutrophil proteinase-3, mast cell tryptase, leukotriene C4 and mast cell carboxypeptidase-A3 in individuals with asymptomatic Ss infection (INF) or without Ss infection (UN). We also measured the levels of all of these analytes in infected individuals following definitive treatment of Ss infection. We show that INF individuals have significantly higher plasma levels of eosinophil cationic protein, eosinophil derived neurotoxin, eosinophil peroxidase, eosinophil major basic protein, elastase, myeloperoxidase, mast cell tryptase, leukotriene C4 and carboxypeptidase-A3 compared to UN individuals. Following treatment of Ss infection, each of these granulocyte-associated proteins drop significantly. Our data suggest that eosinophil, neutrophil and mast cell activation may play a role in the response to Ss infection. B. Elevated Systemic And Parasite Antigen Stimulated Levels Of Type III IFNs In A Chronic Helminth Infection And Reversal Following Anthelmintic Treatment Type III IFNs are important players in immunity to viral and bacterial infections. However, their association with helminth infections has not been examined. To explore the association of Type III IFNs with Strongyloides stercoralis (Ss) infection, we examined the systemic levels of IL-28A, IL-28B, IL-29 in Ss infected (INF, n=44), helminth uninfected (UN, n=44) and in post treatment INF individuals. We also examined the levels of IL-28A, IL-28B and IL-29 in whole blood culture supernatants stimulated with Ss somatic antigens or LPS. Finally, we performed correlations of systemic Type III IFN levels with absolute numbers of dendritic cells subsets. Ss infection is characterized by elevated systemic levels of IL-28A, IL-28B and IL-29 in comparison to UN individuals and a significant reduction following anthelmintic treatment. Ss infection is also characterized by elevated levels of unstimulated or Ss antigen stimulated levels of IL-28A, IL-28B and IL-29 and a significant reduction following treatment. In addition, Ss infection is characterized by increased numbers of plasmacytoid and myeloid dendritic cells in comparison to UN individuals, with a significant reduction following anthelmintic treatment of INF individuals. Finally, Ss infection exhibits a significant positive correlation between the systemic levels of IL-28A and IL-28B and the numbers of plasmacytoid dendritic cells. Thus, Ss infection is characterized by elevations in systemic and antigen induced levels of Type III IFNs, which is positively associated with the numbers of plasmacytoid dendritic cells and reversed upon anthelmintic treatment. Tuberculosis Studies: A. Coexistent helminth infection mediated modulation of chemokine responses in latent tuberculosis Coexistent helminth infections are known to modulate T cell and cytokine responses in latent infection with Mycobacterium tuberculosis (Mtb). However, their role in modulating chemokine responses in latent tuberculosis (LTB) has not been explored. Since, chemokines play a vital role in the protective immune responses in LTB, we postulated that coexistent helminth infection could modulate chemokine production in helminth-LTB co-infection. To test this, we measured the levels of a panel of CC and CXC chemokines at baseline and following mycobacterial-antigen or mitogen stimulation in individuals with latent tuberculosis with (Ss+LTB+) or without Strongyloides stercoralis (Ss) (Ss-LTB+) infection and in individuals without both infections (HC). At baseline, Ss +LTB+ individuals exhibited significantly diminished production of CCL1, CCL2, CCL4, CCL11, CXCL9, CXCL10 and CXCL11 in comparison to Ss-LTB+ and/or HC individuals. Upon mycobacterial stimulation, Ss+LTB+ individuals exhibited significantly diminished production of CCL1, CCL2, CCL4, CCL11, CXCL2, CXCL9 and CXCL10 in comparison to Ss-LTB+ and/or HC individuals. Upon mitogen stimulation, Ss+LTB+ did not exhibit any significant differences in chemokine production in comparison to the other groups. Finally, after anthelmintic treatment, the baseline levels of CCL1, CCL2, CCL4, CCL11 and CXCL11 and mycobacterial-antigen stimulated levels of CCL1, CCL2, CCL11, CXCL2 and CXCL10 were significantly increased in Ss+LTB+ individuals. Thus, our data demonstrate that Ss+LTB+ individuals are associated with a compromised ability to express both CC and CXC chemokines and that this defect is at least partially reversible upon treatment. Hence, coexistent helminth infection induces down modulation of chemokine responses in LTB individuals, with likely potential effects on TB pathogenesis. B. Tuberculous lymphadenitis is associated with altered levels of circulating angiogenic factors Angiogenic factors like vascular endothelial growth factor (VEGF) and angiopoietin (Ang) are important in granuloma formation and serve as biomarkers in pulmonary tuberculosis. The association of these angiogenic factors in tuberculous lymphadenitis (TBL) has not been explored. Hence, our study examined the association of VEGF and Ang family molecules in TBL. We measured the systemic levels of VEGF-A, VEGF-C, VEGF-D, VEGF-R1, VEGF-R2, VEGF-R3, Ang-1, Ang-2 and TIE2 levels in TBL and latent TB individuals (LTB). Similarly, we also examined VEGF-A, VEGF-C and Ang-2 levels in the lymph node (LN) culture supernatants of the same TBL individuals. The circulating levels of VEGF-A and VEGF-C were significantly diminished, whereas VEGF-R2, R3, Ang-2 and TIE2 levels were significantly elevated in TBL. Likewise, VEGF-A, VEGF-C and Ang-2 levels were significantly elevated in LN supernatants when compared to plasma levels in TBL individuals. ROC analysis revealed VEGF-C and VEGF-R2 markers clearly distinguished TBL from LTB. Following chemotherapy, VEGF-C and Ang-1 levels were significantly altered. No association was observed for angiogenic factors compared with culture grade and lymph node (LN) size, except for VEGF-A. Also, TBL VEGF-A levels were significantly decreased in multiple LN when compared with single LN. Our data reveals that altered levels of circulating angiogenic factors in TBL might reflect underlying vasculo-endothelial dysfunction. Reversal of angiogenic markers after anti-TB treatment reveals that these angiogenic markers may serve as biomarkers of disease severity or response to chemotherapy in TBL.