Suppressive activity and altered conventional phenotype markers/mediators of regulatory T cells in patients with self‐limiting hepatitis E

Abstract

Hepatitis E virus (HEV) is a major cause of self-limiting acute viral hepatitis in several developing countries. Elevated levels of peripheral CD4(+) CD25(+) Foxp3(+) , CD4(+) CD25(-) Foxp3(+) and rise in IL-10 in hepatitis E have been associated with the involvement of regulatory T cells (Treg). The functional role of the same is yet elusive. In the current study, we have assessed (i) Foxp3 expression by real-time PCR and by flow cytometry, (ii) the levels of antigen-specific IL-10 and TGF-β by ELISA, (iii) functional analysis of Treg cells and (iv) expression of Treg-associated conventional phenotypes by flow cytometry in 54 acute patients, 44 recovered individuals from hepatitis E and in 33 healthy controls. Foxp3 mRNA elevation in the acute compared with recovered group and elevation in Foxp3(+) cells in both patient groups were significantly elevated. The levels of IL-10 and TGF-β in the acute patients and TGF-β in the recovered individuals were elevated. Significantly higher expression of CTLA-4, PD1, GITR, CD95, CD103 and CD73 on Treg and T effector (Teff) cells was detected in the patient groups. Treg cells of acute patients and recovered individuals exhibited suppressive activity indicating that the Treg cells of hepatitis E patients are functional. The suppressive capacity of Treg cells in acute hepatitis E patients was significantly higher compared with the recovered individuals. Based on our findings, the suppressive functionality of these key markers associated with hepatitis E Treg function need further exploration to get a better understanding of the mechanisms of Treg-mediated suppression.

Hepatitis E rORF2p Stimulated and Unstimulated Peripheral Expression Profiling in Patients with Self-Limiting Hepatitis E Infection

“…Hence, we might be capturing the molecules present on the CD4 + T cells only. This theory supports our previous report of higher expression of CTLA-4, PD1, GITR, CD95, CD103, and CD73 on the CD4 + T regulatory and T effector cells of HEV patients [9]. …”

“…Complying this, there are reports indicating the involvement of cytokines, chemokines, and soluble factors in self-limiting HEV infection [5–9]. However, up/downregulation of cytokines and soluble receptors is an indirect measurement of immune activation not revealing which immune cells are activated.…”

“…We have recently reported peripheral CD11c, CD80, and CD83 expressions to be high in hepatitis E patients, CD11c expression to be positively associated with HEV replication [14], and association of T regulatory (Treg) cells in acute HEV infection [8]. Higher expressions of CTLA-4, PD1, GITR, CD95, CD103, and CD73 on T regulatory and T effector cells of HEV patients have indicated probable involvement of these molecules in Treg-mediated suppression [9]. …”

Identification and characterization of cellular proteins interacting with Hepatitis E virus untranslated regions

“…The immunosuppressive effect of exosomes that can decrease the proliferation of T-lymphocytes (Taylor et al, 2003;Huber et al, 2005;Clayton et al, 2007) and natural killer cells (Clayton et al, 2008) or promote the differentiation of immunosuppressive cells, such as regulatory T-cells (Szajnik et al, 2010) or myeloid cells (Valenti et al, 2006) has been reported. It has been demonstrated that HEV infection causes suppressive activity and altered conventional phenotype markers of T regulatory cells (Rathod et al, 2014). It has been also demonstrated that exosomes may have a role in innate defence against respiratory pathogens and HCV (Kesimer et al, 2009;Dreux et al, 2012).…”

“…The gene expression analysis of selected interacting partners was performed in PBMCs isolated from HEV infected, recovered and healthy individuals using SYBR green based qPCR. Peripheral blood mononuclear cells (PBMCs) were isolated from fresh blood collected in K3 EDTA tube by Ficoll-Hypaque density gradient centrifugation (Rathod et al, 2014). Cells were re-suspended in RPMI 1640 medium (Invitrogen, USA) supplemented with 2 mmol/l l-Glutamine, 1 mmol/l sodium pyruvate and 20 g/ml of gentamycin.…”