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. Systemic cytokine profiles in Strongyloides infection: Strongyloides stercoralis, is a soil transmitted helminth infection, that infects 50 - 100 million people worldwide. Despite its widespread prevalence, very little is known about the immune response that characterizes human S. stercoralis infection. To study the systemic cytokine profile characteristic of Strongyloides infection, we measured the circulating levels of a large panel of pro - and anti - inflammatory cytokines in asymptomatic, infected individuals (n=32) and compared them to uninfected, endemic controls (n=24). Infected individuals exhibited significantly lower circulating levels of pro - inflammatory cytokines (IFN, TNF and IL-1b) and significantly higher levels of anti - inflammatory cytokines (IL-4, IL-5, IL-9, IL-10, IL-13, IL-27, IL-37 and TGFb). Moreover, treatment of Strongyloides infection resulted in a significant reversal of the cytokine profile with increased levels of pro - inflammatory (IFNg, TNFa, IL-2, IL-17A, IL-17F, IL-22, IL-23 and IL-1b) and decreased levels of anti - inflammatory (IL-4, IL-5, IL-9, IL-10, IL-13, IL-27, IL-37 and TGF) cytokines following treatment. Thus, S. stercoralis infection is characterized by alterations in the levels of systemic cytokines, reflecting major alterations in the underlying immune response to this chronic helminth infection. B. Modulation of T cell function in filarial infections by IL-19 and IL-24: IL-19 and IL-24 are cytokines highly expressed in filarial infections. To study the role of IL-19 and IL-24 in regulating T cell responses, we examined the frequency of Th1/Tc1, Th2/Tc2, Th9/Tc9, Th17/Tc17, Th22/Tc22 and Tr1 cells in 26 filarial-infected individuals stimulated with filarial antigen following IL-19 or IL-24 neutralization. IL-19 or IL-24 neutralization resulted in significantly enhanced frequencies of Th1/Tc1 and/or Th17/Tc17 cells and significantly reduced frequencies of Th2/Tc2, Tr1 and/or Th9/Tc9 cells. Thus, we demonstrate that IL-19 and IL-24 are associated with the modulation of T cell responses in filarial infections. Helminth and tuberculosis studies: A. Anthelmintic therapy modifies the systemic and mycobacterial-antigen-stimulated cytokine profile in helminth-latent Mycobacterium tuberculosis co-infection : Helminth infections are known to modulate cytokine responses in latent tuberculosis (LTB). However, whether this modulation is reversible upon anthelmintic therapy is not known. We measured the systemic and mycobacterial (TB) - antigen-stimulated levels of Type 1, Type 2, Type 17 and regulatory cytokines in individuals with LTB and with or without coexistent Strongyloides stercoralis (Ss) infection before and after anthelmintic therapy. Our data reveal that individuals with LTB and coexistent Ss infection have significantly lower levels of systemic and TB antigen-stimulated Type 1 (IFNg, TNFa and IL-2) and Type 17 (IL-17A and/or IL-17F) cytokines and significantly higher levels of systemic but not TB antigen-stimulated Type 2 (IL-4 and IL-5) and regulatory (TGFb) cytokines. Anthelmintic therapy resulted in significantly increased systemic levels of Type 1 and/or Type 17 cytokines and in significantly decreased systemic levels of Type 2 and regulatory (IL-10 and TGFb) cytokines. In addition, anthelmintic therapy resulted in significantly increased TB antigen-stimulated levels of Type 1 cytokines only. Our data therefore reveal that the modulation of systemic and TB antigen stimulated cytokine responses in Ss-LTB co-infection is reversible (for the most part) by anthelmintic treatment. Tuberculosis Studies: A. Circulating angiogenic factors as biomarkers of disease severity and bacterial burden in pulmonary tuberculosis: Angiogenesis and lymphangiogenesis are classical features of granuloma formation in pulmonary tuberculosis (PTB). In addition, the angiogenic factor - VEGF-A is a known biomarker for PTB. To examine the association of circulating angiogenic factors with PTB, we examined the systemic levels of VEGF-A, VEGF-C, VEGF-D, VEGF-R1, VEGF-R2, VEGF-R3, Angiopoietins (Ang) - 1 and 2 in individuals with PTB, latent TB (LTB) or no TB infection (NTB). Circulating levels of VEGF-A, VEGF-C, VEGF-R2, Ang-1 and Ang-2 were significantly higher in PTB compared to LTB or NTB individuals. Moreover, the levels of VEGF-A, VEGF-C and VEGF-R2 were significantly higher in PTB with bilateral and/or cavitary disease. The levels of these factors also exhibited a significant positive relationship with bacterial burdens in PTB. ROC analysis revealed VEGF-A, VEGF-R2 and Ang-2 as markers distinguishing PTB from LTB or NTB. Finally, the circulating levels of all the angiogenic factors examined were significantly reduced following successful chemotherapy. Therefore, our data demonstrate that PTB is associated with elevated levels of circulating angiogenic factors, possibly reflecting vascular and endothelial dysfunction. In addition, some of these circulating angiogenic factors could prove useful as biomarkers to monitor disease severity, bacterial burden and therapeutic responses. B. Enhanced plasma levels of angiopoietins as biomarkers of disease severity and bacterial burden in pulmonary tuberculosis: To examine the association of circulating angiopoietins with TB disease or infection, we examined the systemic levels of Angiopoietin (Ang) 1, Angiopoietin (Ang) 2 and Tie-2 receptor in individuals with PTB, latent TB (LTB) or no TB infection (NTB). Circulating levels of Ang 1, Ang 2 and Tie 2 were significantly higher in PTB compared to LTB or NTB individuals. Moreover, the levels of were Ang 1, Ang 2 and Tie 2 significantly higher in PTB with bilateral disease. The levels of these factors also exhibited a significant positive relationship with bacterial burdens in PTB. ROC analysis revealed Ang - 2 as a marker distinguishing PTB from LTB or NTB. Finally, the circulating levels of Ang-1, Ang-2 and Tie-2 were significantly reduced following anti-tuberculous chemotherapy. Therefore, our data demonstrate that PTB is associated with elevated levels of circulating angiopoietins, possibly reflecting endothelial dysfunction. In addition, Ang-2 could prove useful as a biomarker to monitor disease severity, bacterial burden and therapeutic responses. Tuberculosis and diabetes: A.Impaired cytokine but enhanced cytotoxic marker expression in Mycobacterium tuberculosis - induced CD8+ T cells in Type 2 diabetic individuals with latent tuberculosis: Type 2 diabetes mellitus (DM) is a risk factor for active tuberculosis (TB) in latent TB (LTB) individuals. To explore the influence of DM on CD8+ T cell responses in LTB, we estimated the cytokine and cytotoxic marker expression pattern in individuals with LTB-DM and LTB without DM. LTB-DM is characterized by diminished frequencies of CD8+ Th1, Th2 and Th17 cells following TB - antigen stimulation. In contrast, LTB-DM is characterized by enhanced frequencies of CD8+ T cells expressing cytotoxic markers. Thus, our results suggest that coincident DM modulates CD8+ T cell function in latent tuberculosis.
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