Immunobiology 219 (2014) 932–943 Contents lists available at ScienceDirect Immunobiology jo ur nal homep age: www.elsevier.com/locate/imbio Role of Fas/FasL signaling in regulation of anti-viral response during HSV-2 vaginal infection in mice Malgorzata Krzyzowska a,b,∗ , Piotr Orłowski a , Piotr B˛ aska b , Pawel Bodera a , Robert Zdanowski a , Wanda Stankiewicz a a Military Institute of Hygiene and Epidemiology, Warsaw, Poland b Department of Preclinical Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Warsaw, Poland a r t i c l e i n f o Article history: Received 18 February 2014 Received in revised form 29 June 2014 Accepted 29 July 2014 Available online 5 August 2014 Keywords: Fas/FasL HSV-2 Tregs Dendritic cells IL-10 a b s t r a c t Fas receptor–Fas ligand (FasL) signaling is involved in apoptosis of virus-infected cells but increasing evi- dence accumulates on Fas receptor as a mediator of apoptosis-independent processes such as induction of activating and pro-inflammatory signals. In this study, we examined the role of Fas/FasL pathway in reg- ulation of anti-viral response to genital HSV-2 infection using a murine model of HSV-2 infection applied to C57BL6/J, B6. MRL-Faslpr/J and B6Smn.C3-Faslgld/J mice. HSV-2 infection of Fas- and FasL-deficient mice led to decreased migration of IFN- expressing NK cells and CD4+ T cells, but not of  T cells, into the vaginal tissue. The vaginal tissues of HSV-2 infected Fas- and FasL-deficient mice showed increased production of IL-10, followed by low expression of the early CD69 activation marker on CD4+ and CD8+ T cells and increased numbers of regulatory T cells (Tregs). Experiments in co-cultures of CD4+ T cells and bone marrow derived dendritic cells showed that lack of bilateral Fas–FasL signaling led to expansion of Tregs and increased production of IL-10 and TGF-1. Our results demonstrate that Fas/FasL can regulate development of tolerogenic dendritic cells and expansion of Tregs early during HSV-2 infection, which further influences effective anti-viral response. © 2014 Elsevier GmbH. All rights reserved. Introduction Fas (CD95; tumor necrosis factor receptor superfamily member 6, TNFRSF6) is a member of the death receptor (DR) family, a subfamily of the tumor necrosis factor receptor superfamily. Crosslinking of Fas with its natural ligand – FasL (CD95L, CD178) or with agonistic antibodies induces apoptosis in sensitive cells. Fas-induced apoptosis is involved in the cytotoxic activity of T cells and NK cells (Davidson et al. 2002), peripheral B cell tolerance and elimination of self-reactive T cells (Ju et al. 1995; Stranges et al. 2007). Fas can also induce non-apoptotic signaling resulting in cell Abbreviations: BMDC, bone marrow derived dendritic cell; DC, dendritic cell; HSV-2, herpes simplex virus type 2; IFN, interferon; MHC, major histocompatibility complex; NK cells, natural killer cells; STD, sexually transmitted diseases; TCR, T- cell receptor; TGF, transforming growth factor; TNF, tumor necrosis factor; TNFRSF6, tumor necrosis factor receptor superfamily member 6; Tregs, regulatory T cells. ∗ Corresponding author. Present address: Department of Regenerative Medicine, Military Institute of Hygiene and Epidemiology, Kozielska 4, 01-163 Warsaw, Poland. Tel.: +48 501535456; fax: +48 226122718. E-mail addresses: krzyzowskam@yahoo.com, malloba@gmail.com (M. Krzyzowska). proliferation, angiogenesis, fibrosis and inflammation (Mocellin 2010; Ramaswamy et al. 2009). Herpes simplex virus type 2 (HSV-2) is a sexually transmitted virus that gives rise to genital herpes. Epithelial cells and kerati- nocytes are the primary target cells for HSV-2, but it also infects peripheral neuronal and immune cells (Gupta et al. 2007; Whitley 2001). In the majority of infected individuals, the virus estab- lishes latency in sacral ganglia, where it can be reactivated causing recurrent genital disease (Gupta et al. 2007; Whitley 2001). Mul- tiple cell types have been shown to contribute to the innate and adaptive immune response to HSV-2 infection. Natural killer (NK) cells are nonspecific innate cells, whose role in anti-HSV immu- nity involves cytokine production (IFN-), recognition, and killing of virally infected cells (Ashkar and Rosenthal 2003; Thapa et al. 2007). Another cell type – TCR + T cells have been shown to exert a protective role against HSV type 1 infection in a mouse model (Sciammas et al. 1997) and against intravaginal infection with HSV-2 (Nishimura et al. 2004). However, other studies strongly sug- gested that + T cells are not required for or involved in clearance of HSV-2 from the genital epithelium (Milligan et al. 2004; Rakasz et al. 1999). The adaptive cellular response is highly involved in the anti- HSV-2 defense, with CD8+ T cells producing IFN- and exerting http://dx.doi.org/10.1016/j.imbio.2014.07.021 0171-2985/© 2014 Elsevier GmbH. All rights reserved.