Interleukin (IL)-23 mediates Toxoplasma gondii–induced immunopathology in the gut via matrixmetalloproteinase-2 and IL-22 but independent of IL-17

Abstract

Peroral infection with Toxoplasma gondii leads to the development of small intestinal inflammation dependent on Th1 cytokines. The role of Th17 cells in ileitis is unknown. We report interleukin (IL)-23–mediated gelatinase A (matrixmetalloproteinase [MMP]-2) up-regulation in the ileum of infected mice. MMP-2 deficiency as well as therapeutic or prophylactic selective gelatinase blockage protected mice from the development of T. gondii–induced immunopathology. Moreover, IL-23–dependent up-regulation of IL-22 was essential for the development of ileitis, whereas IL-17 was down-regulated and dispensable. CD4+ T cells were the main source of IL-22 in the small intestinal lamina propria. Thus, IL-23 regulates small intestinal inflammation via IL-22 but independent of IL-17. Gelatinases may be useful targets for treatment of intestinal inflammation.

Regulation of the development of acute hepatitis by IL‐23 through IL‐22 and IL‐17 production

“…In infection with an attenuated strain of Salmonella enterica serovar Enteritidis, p19-deficient mice showed reduced survival and exacerbated liver necrosis only in the absence of IL-12 in an IL-17-independent manner [10]. In peroral infection with Toxoplasma gondii, which leads to the development of small intestine inflammation, the IL-23-dependent upregulation of IL-22 is essential for the development of ileitis; on the other hand, IL-17 is downregulated and dispensable [11].…”

“…IL-22 has both proinflammatory/pathological and protective properties, depending on the inflammatory context [21]. The proinflammatory/pathological nature is apparent in mouse models with diseases such as psoriasis [4] and rheumatoid arthritis [22], and T. gondii infection [11]. In contrast, IL-22 plays protective roles and has tissue-protective and antimicrobial properties in several mouse models with diseases such as inflammatory bowel disease (IBD) [23], hepatitis [24] and infection with invading pathogenic bacteria [10,25,26].…”

“…In infection with an attenuated strain of Salmonella enterica serovar Enteritidis, p19-deficient mice showed reduced survival and exacerbated liver necrosis only in the absence of IL-12 in an IL-17-independent manner [10]. In peroral infection with Toxoplasma gondii, which leads to the development of small intestine inflammation, the IL-23-dependent upregulation of IL-22 is essential for the development of ileitis; on the other hand, IL-17 is downregulated and dispensable [11].IL-22 is a member of the IL-10 cytokine family and plays important roles in inflammation, immune surveillance and tissue homeostasis [12][13][14][15] [10,25,26].Recently, we demonstrated that Notch, which is an evolutionally conserved molecule that controls cell fate decision in a variety of cells [27,28], drives IL-22 secretion by stimulating the AHR [29]. Mice that are deficient in RBP-J, a key mediator of Notch signaling, are highly susceptible to the detrimental immunopathology associated with Con A-induced hepatitis with little IL-22 production [29].…”

The distinct roles of MMP-2 and MMP-9 in acute DSS colitis

“…We have recently shown that treatment with the synthetic selective gelatinase blocker RO28-2653 prevented Toxoplasma gondii-infected mice from hyper-acute Th1-type-driven pan-ileitis, a model mimicking immunopathological key features of Crohn's disease [17]. Furthermore, MMP-2-, but not MMP-9-deficient mice were protected from ileitis development [17].…”

IL‐23 protection against Plasmodium berghei infection in mice is partially dependent on IL‐17 from macrophages

“…It is a heterodimeric molecule composed of p40 and p19 subunits [3]. The proinflammatory activities of IL-23 are responsible for the onset not only of autoimmune diseases such as rheumatoid arthritis and multiple sclerosis [4,5], but also infection-induced pathological consequences of infection with the pathogens causing Lyme disease and toxoplasma encephalitis, for example [6,7]. The known biological roles for IL-23 in inflammation include induction of Th17-induced secretion of IL-17 [8] and suppression of CD4 + CD25 + Treg [9].…”