Increased CD56(bright) NK cells in HIV-HCV co-infection and HCV mono-infection are associated with distinctive alterations of their phenotype.

BACKGROUND: HIV-HCV co-infection is associated with accelerated progression to hepatic fibrosis, cirrhosis and hepatocellular carcinoma than HCV mono-infection. The contribution of innate immunity during HIV-HCV co-infection has been a relatively under-investigated area. Natural killer (NK) cells are pivotal sentinels of innate immunity against viruses and tumour cells. In this study we evaluated the effect of HIV-HCV co-infection on peripheral blood NK cell subsets with emphasis on the phenotype of CD56(bright) NK cells. METHODS: Sixty patients were included in the study; HIV mono-infected (n = 12), HCV mono-infected (n = 15), HCV-HIV co-infected (n = 21) and healthy controls (n = 16). PBMCs were isolated and immunophenotyping of NK cells was performed by flowcytometry. RESULTS: We observed an expansion of CD56(bright) NK cell subset in HIV-HCV co-infection as compared to healthy controls and HIV mono-infected group. All the infected groups had an upregulated expression of the activating receptor NKG2D on CD56(bright) NK cells in comparison to healthy controls while not differing amongst themselves. The expression of NKp46 in HIV-HCV co-infected group was significantly upregulated as compared to both HIV as well as HCV mono-infections while NKp30 expression in the HIV-HCV co-infected group significantly differed as compared to HIV mono-infection. The CD56(bright) NK cell subset was activated in HIV-HCV co-infection as assessed by the expression of CD69 as compared to healthy controls but was significantly downregulated in comparison to HIV mono-infection. CD95 expression on CD56(bright) NK cells followed the same pattern where there was an increased expression of CD95 in HIV mono-infection and HIV-HCV co-infection as compared to healthy controls. In contrast to CD69 expression, CD95 expression in HCV mono-infection was decreased when compared to HIV mono-infection and HIV-HCV co-infection. Finally, expression of CXCR3 on CD56(bright) NK cells was increased in HIV-HCV co-infection in comparison to HIV mono-infection while remaining similar to HCV mono-infection. CONCLUSION: Thus, HIV-HCV co-infection is able to modulate the phenotype of CD56(bright) NK cell subset in a unique way such that NKp46 and CXCR3 expressions are distinct for co-infection while both mono-infections have an additive effect on CD56(bright), CD69 with CD95 expressions. HCV mono-infection has a dominant effect on NKp30 expression while NKG2D and CD127 expressions remained same in all the groups.

Analysis of Notch and TGF-ß Signaling Expression in Different Stages of Disease Progression During Hepatitis B Virus Infection.

OBJECTIVES: CD4+ regulatory T cells (Tregs) seem to have a key role in persistence of hepatitis B virus (HBV) infection. Notch and transforming growth factor (TGF-ß) signaling independently help in the differentiation and regulation of CD4+T cells, including T-helper (T(H)) 1, T(H)2, and Tregs. Whether, the two pathways have modulatory role on different stages of HBV infection and severity of liver disease is not clear. We investigated Notch and TGF-ß families' gene expression in peripheral blood and intrahepatic lymphocytes in patients with different stages of chronic HBV (CHB) infection. METHODS: Peripheral blood mononuclear cells (PBMCs), CD4(+), and CD8(+) T cells were isolated from patients with acute HBV (AVH-B, n=15), CHB (n=16), and controls (HC, n=10). In addition to PBMCs, intrahepatic lymphocytes were obtained from liver biopsies from CHB (n=12), cirrhosis (n=12), hepatocellular carcinoma (HCC, n=5), and healthy livers (n=5). Notch family (Notch1-4, Hes1, Jag1, and NF-kß) and TGF-ß family gene expressions were studied by real-time PCR, flow cytometry, and immunohistochemistry. RESULTS: Relative expression of Notch signaling target genes, Hes1 and NF-kß, was higher in the total PBMCs of AVH-B and CHB patients than that in HC patients (Log relative quantification (RQ); 1.1 AVH-B vs. 0.3 HC, 1.3 CHB vs. 0.3 HC; P=0.02). CD8(+) T cells showed upregulated expression of Hes1 and Notch1 (P=0.02 and 0.01, respectively) in AVH-B than in CHB patients. Also, in AVH-B patients, HBV-specific CD8(+) T-cell proliferation (5.74% vs. 2.7%) and TGF-ß signaling activity were higher. All Notch receptors and ligands were upregulated in the PBMCs in CHB infection (CHB vs. cirrhosis, P=0.001; CHB vs. HCC, P=0.023; and cirrhosis vs. HCC, P=NS). Intrahepatic expression of Notch1 and FoxP3 were significantly higher in cirrhotics and HCCs, and further blockage of Notch signaling reduced the FoxP3 expression. Array data of TGF-ß family showed increased TGF-ß3, TGF-α, SMAD3, SMAD4, SMAD6, and GDF9 expression on intrahepatic lymphocytes in cirrhotic and HCC patients compared with CHB. CONCLUSIONS: Our findings suggest that there is a complementary association between Notch1 and Hes1 in CD8(+)T cells during AVH-B infection. On development of CHB infection, repression of the Notch receptors mediates the regulation of immune response in patients, who progress to cirrhosis and HCC. Finally, HBV infection drives increased Notch1, TGF-ß, and FoxP3 expression on intrahepatic T cells in cirrhosis, resulting in fibrogenesis and disease progression.

Leishmania interferes with host cell signaling to devise a survival strategy.

The protozoan parasite Leishmania spp. exists as extracellular promastigotes in its vector whereas it resides and replicates as amastigotes within the macrophages of its mammalian host. As a survival strategy, Leishmania modulates macrophage functions directly or indirectly. The direct interference includes prevention of oxidative burst and the effector functions that lead to its elimination. The indirect effects include the antigen presentation and modulation of T cell functions in such a way that the effector T cells help the parasite survive by macrophage deactivation. Most of these direct and indirect effects are regulated by host cell receptor signaling that occurs through cycles of phosphorylation and dephosphorylation in cascades of kinases and phosphatases. This review highlights how Leishmania selectively manipulates the different signaling pathways to ensure its survival.

Vaccination with a novel recombinant Leishmania antigen plus MPL provides partial protection against L. donovani challenge in experimental model of visceral leishmaniasis.

The acquisition of immunity following subclinical or resolved infection with the intracellular parasite Leishmania donovani suggests that vaccination could prevent visceral leishmaniasis. The characteristics and in vitro stimulating capability of the recombinant proteins expressed by previously identified clones on the basis of their capacity to stimulate an indigenously established Leishmania-specific cell line leading to high level of IFN-gamma suggested these to be potential candidates for immunoprophylaxis against leishmaniasis. In this study, we investigated the protective efficacy of purified recombinant proteins from two of the identified cDNA clones along with the adjuvant MPL, in a hamster model of experimental leishmaniasis. We demonstrate here that the immunization of animals with one of the recombinant proteins (rF14) having 97% similarity to C1 clone of L. chagasi ribosomal protein gene P0 (rLiP0) along with MPL provided partial protection against the virulent challenge of L. donovani. The absence of antigen-specific lymphoproliferative responses in these immunized animals may be responsible for the lack of complete and long-lasting protection.

An epitope-specific PCR test for diagnosis of Leishmania donovani infections.

The carboxy-terminal region of recombinant heat shock protein 70 of Leishmania donovani has been shown to have an immunodominant epitope. We designed a PCR assay using a new set of primers encompassing the gene sequence from 457bp to 927bp, which amplified a segment of the L. donovani genome in a species-specific manner. The assay was sensitive enough to detect 0.5pg of parasite DNA, which increased 10-fold (0.05pg) when an internal probe (583-609bp) was used in the Southern blot. The assay was able to detect parasite DNA from the liver and spleen of L. donovani-infected hamsters as well as lesion aspirates from parasitologically confirmed post-kala-azar dermal leishmaniasis (PKDL) and bone marrow aspirates from visceral leishmaniasis (VL) patients. No amplification was seen with axenically cultured promastigotes of L. infantum, L. tropica, L. major, L. mexicana, L. aethiopica or other intracellular organisms such as Entamoeba histolytica, Mycobacterium tuberculosis, Plasmodium vivax or human peripheral blood mononuclear cells. This PCR provides a specific tool for the diagnosis of VL and PKDL with simultaneous species identification.