Homeostatic regulation of T follicular helper and antibody response to particle antigens by IL-1Ra of medullary sinus macrophage origin.

Hepatitis B virus (HBV) vaccines are composed of surface antigen HBsAg that spontaneously assembles into subviral particles. Factors that impede its humoral immunity in 5% to 10% of vaccinees remain elusive. Here, we showed that the low-level interleukin-1 receptor antagonist (IL-1Ra) can predict antibody protection both in mice and humans. Mechanistically, murine IL-1Ra-inhibited T follicular helper (Tfh) cell expansion and subsequent germinal center (GC)-dependent humoral immunity, resulting in significantly weakened protection against the HBV challenge. Compared to soluble antigens, HBsAg particle antigen displayed a unique capture/uptake and innate immune activation, including IL-1Ra expression, preferably of medullary sinus macrophages. In humans, a unique polymorphism in the RelA/p65 binding site of IL-1Ra enhancer associated IL-1Ra levels with ethnicity-dependent vaccination outcome. Therefore, the differential IL-1Ra response to particle antigens probably creates a suppressive milieu for Tfh/GC development, and neutralization of IL-1Ra would resurrect antibody response in HBV vaccine nonresponders.

Humanized mice in cutaneous leishmaniasis-Suitability analysis of human PBMC transfer into immunodeficient mice.

Humanized mice represent a suitable preclinical test system for example therapeutic interventions in various disease settings, including infections. Here, we intended to establish such system for cutaneous leishmaniasis by infecting T, B and NK cell-deficient mice adoptively transferred with human peripheral blood mononuclear cells (PBMC). L major infection led to the establishment of parasite lesions harbouring viable parasites and human T cells, but parasite elimination was not seen due to a species-specific activity of T cell-derived human IFNγ. In addition, up to 50% of infected mice succumbed to severe graft-versus-host disease. In summary, even though long-term disease outcome assessments are impossible, this model of humanized mice can be used for studying lesion development and generation of oligoclonal anti-parasite human T cell responses in vivo.

NKG2A is a NK cell exhaustion checkpoint for HCV persistence.

Exhaustion of cytotoxic effector natural killer (NK) and CD8+ T cells have important functions in the establishment of persistent viral infections, but how exhaustion is induced during chronic hepatitis C virus (HCV) infection remains poorly defined. Here we show, using the humanized C/OTg mice permissive for persistent HCV infection, that NK and CD8+ T cells become sequentially exhausted shortly after their transient hepatic infiltration and activation in acute HCV infection. HCV infection upregulates Qa-1 expression in hepatocytes, which ligates NKG2A to induce NK cell exhaustion. Antibodies targeting NKG2A or Qa-1 prevents NK exhaustion and promotes NK-dependent HCV clearance. Moreover, reactivated NK cells provide sufficient IFN-γ that helps rejuvenate polyclonal HCV CD8+ T cell response and clearance of HCV. Our data thus show that NKG2A serves as a critical checkpoint for HCV-induced NK exhaustion, and that NKG2A blockade sequentially boosts interdependent NK and CD8+ T cell functions to prevent persistent HCV infection.

T cells mediate autoantibody-induced cutaneous inflammation and blistering in epidermolysis bullosa acquisita.

T cells are key players in autoimmune diseases by supporting the production of autoantibodies. However, their contribution to the effector phase of antibody-mediated autoimmune dermatoses, i.e., tissue injury and inflammation of the skin, has not been investigated. In this paper, we demonstrate that T cells amplify the development of autoantibody-induced tissue injury in a prototypical, organ-specific autoimmune disease, namely epidermolysis bullosa acquisita (EBA) - characterized and caused by autoantibodies targeting type VII collagen. Specifically, we show that immune complex (IC)-induced inflammation depends on the presence of T cells - a process facilitated by T cell receptor (TCR)γδ and NKT cells. Because tissue damage in IC-induced inflammation is neutrophil-dependent, we further analyze the interplay between T cells and neutrophils in an experimental model of EBA. We demonstrate that T cells not only enhance neutrophil recruitment into the site of inflammation but also interact with neutrophils in lymphatic organs. Collectively, this study shows that T cells amplify the effector phase of antibody-induced tissue inflammation.