IFN-γ-Inducible Protein 10 (IP-10; CXCL10)-Deficient Mice Reveal a Role for IP-10 in Effector T Cell Generation and Trafficking

TLDR

IP‑10 is a chemokine released by IFN‑stimulated cells that attracts activated T cells and is up‑regulated in Th1‑driven inflammatory diseases, where it is thought to recruit T cells to sites of tissue inflammation. The authors generated IP‑10‑deficient mice by targeted gene disruption to investigate the chemokine’s in vivo function. IP‑10‑deficient mice exhibited profoundly impaired T‑cell proliferation, IFN‑γ secretion, contact hypersensitivity, and antiviral immunity, with reduced recruitment of CD4⁺ and CD8⁺ lymphocytes and lower levels of IFN‑γ‑induced chemokines in the brain, underscoring IP‑10’s essential role in effector T‑cell generation and trafficking.

Abstract

Abstract IFN-γ-inducible protein 10 (IP-10, CXCL10), a chemokine secreted from cells stimulated with type I and II IFNs and LPS, is a chemoattractant for activated T cells. Expression of IP-10 is seen in many Th1-type inflammatory diseases, where it is thought to play an important role in recruiting activated T cells into sites of tissue inflammation. To determine the in vivo function of IP-10, we constructed an IP-10-deficient mouse (IP-10−/−) by targeted gene disruption. Immunological analysis revealed that IP-10−/− mice had impaired T cell responses. T cell proliferation to allogeneic and antigenic stimulation and IFN-γ secretion in response to antigenic challenge were impaired in IP-10−/− mice. In addition, IP-10−/− mice exhibited an impaired contact hypersensitivity response, characterized by decreased ear swelling and reduced inflammatory cell infiltrates. T cells recovered from draining lymph nodes also had a decreased proliferative response to Ag restimulation. Furthermore, IP-10−/− mice infected with a neurotropic mouse hepatitis virus had an impaired ability to control viral replication in the brain. This was associated with decreased recruitment of CD4+ and CD8+ lymphocytes into the brain, reduced levels of IFN-γ and the IFN-γ-induced chemokines monokine induced by IFN-γ (Mig, CXCL9) and IFN-inducible T cell α chemoattractant (I-TAC, CXCL11) in the brain, decreased numbers of virus-specific IFN-γ-secreting CD8+ cells in the spleen, and reduced levels of demyelination in the CNS. Taken together, our data suggest a role for IP-10 in both effector T cell generation and trafficking in vivo.