Selective reconstitution of IFN-gamma gene function in Ncr1(+) NK cells is sufficient to control systemic vaccinia virus infection

Borst, Katharina; Flindt, Sven; Blank, Patrick; Larsen, Pia-Katharina; Chhatbar, Chintan; Skerra, Jennifer; Spanier, Julia; Hirche, Christoph; König, Martin; Alanentalo, Tomas; Hafner, Martin; Waibler, Zoe; Pfeffer, Klaus; Sexl, Veronika; Sutter, Gerd ; Mueller, Werner; Graalmann, Theresa und Kalinke, Ulrich (2020): Selective reconstitution of IFN-gamma gene function in Ncr1(+) NK cells is sufficient to control systemic vaccinia virus infection.
In: PLOS Pathogens 16(2), e1008279

Abstract

Viral infections induce interferon (IFN) responses that constitute a first line of defense. Type II IFN (IFN-gamma) is required for protection against lethal vaccinia virus (VACV) infection. To address the cellular origin of protective IFN-gamma responses during VACV infection, we generated IFN-gamma(OFF) mice, in which the endogenous IFN-gamma gene function can be reconstituted in a Cre-dependent manner. IFN-gamma(OFF) mice were intercrossed with Ncr1-Cre mice that express Cre selectively in Ncr1(+) innate cell subsests such as NK cells. Surprisingly, VACV infected IFN-gamma(Ncr1-ON) mice mounted two waves of IFN-gamma responses. Reconstitution of innate IFN-gamma was sufficient to restore cytokine responses that supported normal myeloid cell distribution and survival upon VACV infection. In conclusion, IFN-gamma derived from Ncr1(+) innate immune cells is sufficient to elicit fully effective immune responses upon VACV infection. Our new mouse model is suitable to further address the role of Ncr1(+) cell-derived IFN-gamma also in other models of infection, as well as of autoimmunity and cancer.

IFN-gamma is an enigmatic cytokine that shows direct anti-viral effects, confers upregulation of MHC-II and other components relevant for antigen presentation, and that adjusts the composition and balance of complex cytokine responses. It is produced during immune responses by innate as well as adaptive immune cells and can critically affect the course and outcome of infectious diseases, autoimmunity, and cancer. To selectively analyze the function of innate immune cell-derived IFN-gamma, we generated conditional IFN-gamma(OFF) mice, in which endogenous IFN-gamma expression is disrupted by a loxP flanked gene trap cassette inserted into the first intron of the IFN-gamma gene. IFN-gamma(OFF) mice were intercrossed with Ncr1-Cre or CD4-Cre mice that express Cre mainly in NK cells (IFN-gamma(Ncr1-ON) mice) or T cells (IFN-gamma(CD4-ON) mice), respectively. Rosa26RFP reporter mice intercrossed with Ncr1-Cre mice showed selective RFP expression in more than 80% of the NK cells, while upon intercrossing with CD4-Cre mice abundant RFP expression was detected in T cells, but also to a minor extent in other immune cell subsets. Previous studies showed that IFN-gamma expression is needed to promote survival of vaccinia virus (VACV) infection. Interestingly, during VACV infection of wild type and IFN-gamma(CD4-ON) mice two waves of serum IFN-gamma were induced that peaked on day 1 and day 3/4 after infection. Similarly, VACV infected IFN-gamma(Ncr1-ON) mice mounted two waves of IFN-gamma responses, of which the first one was moderately and the second one profoundly reduced when compared with WT mice. Furthermore, IFN-gamma(Ncr1-ON) as well as IFN-gamma(CD4-ON) mice survived VACV infection, whereas IFN-gamma(OFF) mice did not. As expected, ex vivo analysis of splenocytes derived from VACV infected IFN-gamma(Ncr1-ON) mice showed IFN-gamma expression in NK cells, but not T cells, whereas IFN-gamma(OFF) mice showed IFN-gamma expression neither in NK cells nor T cells. VACV infected IFN-gamma(Ncr1-ON) mice mounted normal cytokine responses, restored neutrophil accumulation, and showed normal myeloid cell distribution in blood and spleen. Additionally, in these mice normal MHC-II expression was detected on peripheral macrophages, whereas IFN-gamma(OFF) mice did not show MHC-II expression on such cells. In conclusion, upon VACV infection Ncr1 positive cells including NK cells mount two waves of early IFN-gamma responses that are sufficient to promote the induction of protective anti-viral immunity.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Tiermedizin ; Tiermedizin > Veterinärwissenschaftliches Department > Institut für Infektionsmedizin und Zoonosen
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• ISSN: 1932-6203
• Sprache: Englisch