Human Genetics And Molecular Medicine - Research Publications

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Author: search.filters.author.Garg, Nisha Jain

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    P47 phox2/2 Mice Are Compromised in Expansion and Activation of CD8 + T Cells and Susceptible to Trypanosoma cruzi Infection
    (Public Library of Science (PLOS), 2014) Dhiman, Monisha; Garg, Nisha Jain
    Macrophage activation of NAD(P)H oxidase (NOX2) and reactive oxygen species (ROS) is suggested to kill Trypanosoma cruzi that causes Chagas disease. However, the role of NOX2 in generation of protective immunity and whether these mechanisms are deregulated in the event of NOX2 deficiency are not known, and examined in this study. Our data showed that C57BL/6 p47phox−/− mice (lack NOX2 activity), as compared to wild-type (WT) mice, succumbed within 30 days post-infection (pi) to low doses of T. cruzi and exhibited inability to control tissue parasites. P47phox−/− bone-marrow and splenic monocytes were not compromised in maturation, phagocytosis and parasite uptake capacity. The deficiency of NOX2 mediated ROS was compensated by higher level of inducible nitric oxide synthase (iNOS) expression, and nitric oxide and inflammatory cytokine (TNF-α, IFN-γ, IL-1β) release by p47phox−/− macrophages as compared to that noted in WT controls infected by T. cruzi. Splenic activation of Th1 CD4+T cells and tissue infiltration of immune cells in T. cruzi infected p47phox−/− mice were comparable to that noted in infected control mice. However, generation and activation of type 1 CD8+T cells was severely compromised in p47phox−/− mice. In comparison, WT mice exhibited a robust T. cruzi-specific CD8+T cell response with type 1 (IFN-γ+TNF-α>IL-4+IL-10), cytolytic effector (CD8+CD107a+IFN-γ+) phenotype. We conclude that NOX2/ROS activity in macrophages signals the development of antigen-specific CD8+T cell response. In the event of NOX2 deficiency, a compromised CD8+T cell response is generated, leading to increased parasite burden, tissue pathogenesis and mortality in chagasic mice.
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    Innate Immune Responses and Antioxidant/Oxidant Imbalance Are Major Determinants of Human Chagas Disease
    (Public Library of Science, 2013) Dhiman, Monisha; Coronado, Yun A.; Vallejo, Cecillia K.; Peterson, John R.; Ejilemele, Adetoun; Nunez, Sonia; Zago, Maria Paola; Spratt, Hiedi; Garg, Nisha Jain
    Background:We investigated the pathological and diagnostic role of selected markers of inflammation, oxidant/antioxidant status, and cellular injury in human Chagas disease.Methods:Seropositive/chagasic subjects characterized as clinically-symptomatic or clinically-asymptomatic (n = 116), seronegative/cardiac subjects (n = 102), and seronegative/healthy subjects (n = 45) were analyzed for peripheral blood biomarkers.Results:Seropositive/chagasic subjects exhibited an increase in sera or plasma levels of myeloperoxidase (MPO, 2.8-fold), advanced oxidation protein products (AOPP, 56%), nitrite (5.7-fold), lipid peroxides (LPO, 12-17-fold) and malondialdehyde (MDA, 4-6-fold); and a decline in superoxide dismutase (SOD, 52%) and glutathione (GSH, 75%) contents. Correlation analysis identified a significant (p<0.001) linear relationship between inflammatory markers (AOPP/nitrite: r = 0.877), inflammation and antioxidant/oxidant status (AOPP/glutathione peroxidase (GPX): r = 0.902, AOPP/GSH: r = 0.806, Nitrite/GPX: 0.773, Nitrite/LPO: 0.805, MDA/MPO: 0.718), and antioxidant/oxidant levels (GPX/MDA: r = 0.768) in chagasic subjects. Of these, MPO, LPO and nitrite biomarkers were highly specific and sensitive for distinguishing seropositive/chagasic subjects from seronegative/healthy controls (p<0.001, training and fitting AUC/ROC >0.95). The MPO (r = 0.664) and LPO (r = 0.841) levels were also correlated with clinical disease state in chagasic subjects (p<0.001). Seronegative/cardiac subjects exhibited up to 77% decline in SOD, 3-5-fold increase in LPO and glutamate pyruvate transaminase (GPT) levels, and statistically insignificant change in MPO, AOPP, MDA, GPX, GSH, and creatine kinase (CK) levels.Conclusions:The interlinked effects of innate immune responses and antioxidant/oxidant imbalance are major determinants of human Chagas disease. The MPO, LPO and nitrite are excellent biomarkers for diagnosing seropositive/chagasic subjects, and MPO and LPO levels have potential utility in identifying clinical severity of Chagas disease. ? 2013 Dhiman et al.