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Appropriate regulation of IL-17 production in the host can mean the difference between effective control of pathogens and uncontrolled inflammation that causes tissue damage. Investigation of conventional CD4+ T cells (Th17 cells) has yielded invaluable insights into IL-17 function and its regulation. More recently, we and others reported production of IL-17 from innate αβ+ T cell populations, which was shown to occur primarily via IL-23R signaling through the transcription factor STAT-3. In our current study, we identify promyelocytic leukemia zinc finger (PLZF)–expressing iNKT, CD4−/CD8+, and CD4−/CD8− (DN) αβ+T cells, which produce IL-17 in response to TCR and IL-1 receptor ligation independently of STAT-3 signaling. Notably, this noncanonical pathway of IL-17 production may be important in mucosal defense and is by itself sufficient to control pathogenic Staphylococcus aureus infection at the ocular surface.

SMAP2 is an Arf GAP and modulates clathrin-coated vesicle formation. SMAP2-deficient male mice exhibited globozoospermia due to acrosome deformation. In SMAP2(−/−) spermatids, budding of proacrosomal vesicles from the TGN was distorted and clathrin traffic–related molecules such as CALM and syntaxin2 were mislocated.

IL-1 is a pro-inflammatory cytokine that plays an important role in inflammation and host responses to infection. We have previously shown that imbalances in the IL-1 and IL-1R antagonist (IL-1Ra) system cause the development of inflammatory diseases. To explore the role of the IL-1/IL-1Ra system in autoimmune disease, we analyzed myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) in mice bearing targeted disruptions of the IL-1α, IL-1β, IL-1α and IL-1β (IL-1) or IL-1Ra genes. IL-1α/β double-deficient (IL-1−/−) mice exhibited significant resistance to EAE induction with a significant reduction in disease severity, while IL-1α−/− or IL-1β−/− mice developed EAE in a manner similar to wild-type mice. IL-1Ra−/− mice also developed MOG-induced EAE normally with pertussis toxin (PTx) administration. In contrast to wild-type mice, however, these mice were highly susceptible to EAE induction in the absence of PTx administration. We found that both IFN-γ and IL-17 production and proliferation were reduced in IL-1−/− T cells upon stimulation with MOG, while IFN-γ, IL-17 and tumor necrosis factor-α production and proliferation were enhanced in IL-1Ra−/− T cells. These observations suggest that the IL-1/IL-1Ra system is crucial for auto-antigen-specific T cell induction and contributes to the development of EAE.

Endotoxin, a bacterial lipopolysaccharide (LPS), causes fatal septic shock via Toll-like receptor (TLR)4 on effector cells of innate immunity like macrophages, where it activates nuclear factor κB (NF-κB) and mitogen-activated protein (MAP) kinases to induce proinflammatory cytokines such as tumor necrosis factor (TNF)-α. Dok-1 and Dok-2 are adaptor proteins that negatively regulate Ras–Erk signaling downstream of protein tyrosine kinases (PTKs). Here, we demonstrate that LPS rapidly induced the tyrosine phosphorylation and adaptor function of these proteins. The stimulation with LPS of macrophages from mice lacking Dok-1 or Dok-2 induced elevated Erk activation, but not the other MAP kinases or NF-κB, resulting in hyperproduction of TNF-α and nitric oxide. Furthermore, the mutant mice showed hyperproduction of TNF-α and hypersensitivity to LPS. However, macrophages from these mutant mice reacted normally to other pathogenic molecules, CpG oligodeoxynucleotides, poly(I:C) ribonucleotides, or Pam3CSK4 lipopeptide, which activated cognate TLRs but induced no tyrosine phosphorylation of Dok-1 or Dok-2. Forced expression of either adaptor, but not a mutant having a Tyr/Phe substitution, in macrophages inhibited LPS-induced Erk activation and TNF-α production. Thus, Dok-1 and Dok-2 are essential negative regulators downstream of TLR4, implying a novel PTK-dependent pathway in innate immunity.

IL-1 is a proinflammatory cytokine that plays important roles in inflammation. However, the role of this cytokine under physiological conditions is not known completely. In this paper, we analyzed the role of IL-1 in maintaining body weight because IL-1 receptor antagonist–deficient (IL-1Ra−/−) mice, in which excess IL-1 signaling may be induced, show a lean phenotype. Body fat accumulation was impaired in IL-1Ra−/− mice, but feeding behavior, expression of hypothalamic factors involved in feeding control, energy expenditure, and heat production were normal. When IL-1Ra−/− mice were treated with monosodium glutamate (MSG), which causes obesity in wild-type mice by ablating cells in the hypothalamic arcuate nucleus, they were resistant to obesity, indicating that excess IL-1 signaling antagonizes the effect of MSG-sensitive neuron deficiency. IL-1Ra−/− mice showed decreased weight gain when they were fed the same amount of food as wild-type mice, and lipid accumulation remained impaired even when they were fed a high-fat diet. Interestingly, serum insulin levels and lipase activity were low in IL-1Ra−/− mice, and the insulin levels were low in contrast to wild-type mice after MSG treatment. These observations suggest that IL-1 plays an important role in lipid metabolism by regulating insulin levels and lipase activity under physiological conditions.

IL-1 is a pro-inflammatory cytokine consisted of two molecular species, IL-1alpha and IL-1beta, and the IL-1 receptor antagonist (IL-1Ra) is a natural inhibitor of both molecules. Although it is suggested that IL-1 potentiates immune responses mediated by T(h)2 cells, the role of IL-1 in asthma still remains unclear. In this study, we demonstrate that the ovalbumin (OVA)-induced airway hypersensitivity response (AHR) in IL-1alpha/beta-deficient (IL-1alpha/beta(-/-)) mice was significantly reduced from the levels seen in wild-type mice, whereas the responses seen in IL-1Ra(-/-) mice were profoundly exacerbated, suggesting that IL-1 is required for T(h)2 cell activation during AHR. OVA-specific T cell proliferation, IL-4 and IL-5 production by T cells, and IgG1 and IgE production by B cells in IL-1alpha/beta(-/-) mice were markedly reduced compared with these responses in wild-type mice; such responses were enhanced in IL-1Ra(-/-) mice. Using IL-1alpha(-/-) and IL-1beta(-/-) mice, we determined that both IL-1alpha and IL-1beta are involved in this reaction. Both IgG1 and IgE levels were reduced in IL-1beta(-/-) mice, while only IgE levels were affected in IL-1alpha(-/-) mice, indicating a functional difference between IL-1alpha and IL-1beta. These observations indicate that IL-1 plays important roles in the development of AHR.

Contact hypersensitivity (CHS) is a typical inflammatory response against contact allergens. Inflammatory cytokines, including IL-1 and tumor necrosis factor (TNF)-alpha, are implicated in the reaction, although the precise roles of each cytokine have not been completely elucidated. In this report, we dissected the functional roles of IL-1 and TNF-alpha during CHS. CHS induced by 2,4,6-trinitorochlorobenzene as well as oxazolone was suppressed in both IL-1alpha/beta(-/-) and TNF-alpha(-/-) mice. Hapten-specific T cell activation, as examined by T cell proliferation, OX40 expression and IL-17 production, was reduced in IL-1alpha/beta(-/-) mice, but not in TNF-alpha(-/-) mice, suggesting that IL-1 but not TNF-alpha is required for hapten-specific T cell priming in the sensitization phase. On the other hand, TNF-alpha, induced by IL-1, was necessary for the induction of local inflammation during the elicitation phase. We also found that the expression of IFN-gamma-inducible protein 10 (IP-10) was augmented at the inflammatory site. Although IP-10 mRNA expression was abrogated in TNF-alpha(-/-) mice, both CHS development and TNF-alpha mRNA expression occurred normally in IFN-gamma(-/-) mice, indicating that the induction of IP-10 during CHS was primarily controlled by TNF-alpha. Interestingly, CHS was suppressed by treatment with anti-IP-10 mAb, suggesting a critical role for IP-10 in CHS. Reduced CHS in TNF-alpha(-/-) mice was reversed by IP-10 injection during the elicitation phase. Thus, it was shown that the roles for IL-1 and TNF-alpha are different, although both cytokines are crucial for the development of CHS.

The cytokine interleukin‐1 (IL‐1) has been implicated in ischemic brain damage, because the IL‐1 receptor antagonist markedly inhibits experimentally induced neuronal loss. However, to date, no studies have demonstrated the involvement of endogenous IL‐1α and IL‐ 1β in neurodegeneration. We report here, for the first time, that mice lacking IL‐1α/β (double knockout) exhibit markedly reduced neuronal loss and apoptotic cell death when exposed to transient cardiac arrest. Furthermore, we show that, despite the reduced neuronal loss, phosphorylation of JNK/SAPK (c‐Jun NH2‐ terminal protein kinase/stress activated protein kinase) and p38 enzymes remain elevated in IL‐1 knockout mice. In contrast, the inducible nitric oxide (iNOS) immunoreactivity after global ischemia was reduced in IL‐1 knockout mice as compared with wild‐type mice. The levels of nitrite (NO2−) and nitrate (NO3−) in the hippocampus of wild‐type mice were increased with time after ischemia‐reperfusion, whereas the increase was significantly inhibited in IL‐1 knockout mice. These observations strongly suggest that endogenous IL‐1 contributes to ischemic brain damage, and this influence may act through the release of nitric oxide by iNOS. J. Comp. Neurol. 448:203–216, 2002. © 2002 Wiley‐Liss, Inc.

To elucidate the roles of interleukin-1 (IL-1) in the development of 2 etiologically different rheumatoid arthritis (RA) models: the type II collagen (CII)–induced arthritis (CIA) model and the human T cell leukemia virus type I transgenic (HTLV-I Tg) mouse model. For the CIA model, DBA/1J-background IL-1α^−/−, IL-1β^−/−, IL-1α/β^−/−, and wild-type littermate mice were immunized with CII. For the HTLV-I Tg model, BALB/c IL-1β^−/− or IL-1α/β^−/− mice were crossed with HTLV-I Tg mice. The effects of IL-1 deficiency were assessed as follows: Development of arthritis was assessed both macroscopically and microscopically. Serum antibody titer was measured by enzyme-linked immunosorbent assay. Proliferative response of lymph node cells was assayed by measurement of ³H-thymidine incorporation. Expression of T cell surface molecule CD40 ligand (CD40L) and OX40 was determined by multicolor flow cytometric analysis. The development of arthritis was markedly suppressed in IL-1α/β^−/− mice in both models, although the effect was less prominent in HTLV-I Tg mice. Deficiency of only IL-1α or only IL-1β was also associated with disease suppression. Antibody production after immunization with CII was normal in IL-1α/β^−/− mice, while autoantibody production was suppressed in IL-1α/β^−/− HTLV-I Tg mice. In IL-1α/β^−/− mice, the T cell proliferative response against CII was greatly reduced in both the CIA and the HTLV-I Tg models, suggesting inefficiency of T cell activation. Furthermore, expression of CD40L and OX40 on T cells was greatly reduced in IL-1α/β^−/− mice. These observations suggest that T cell activation by IL-1 is important for the development of autoimmunity and arthritis in these mice.

Contact hypersensitivity (CHS) is a T cell-mediated cellular immune response caused by epicutaneous exposure to contact allergens. In this reaction, after the first epicutaneous allergen sensitization, Langerhans cells (LC) catch allergens and migrate from the skin to draining lymph nodes (LN) and activate naive T cells. Although IL-1 is suggested to be involved in these processes, the mechanisms have not been elucidated completely. In this report, to elucidate roles of IL-1α and IL-1β in CHS, we analyzed ear swelling in 2,4,6-trinitrochlorobenzene (TNCB)-induced CHS using gene-targeted mice. We found that ear swelling was suppressed in IL-1α-deficient (IL-1α–/–) mice but not in IL-1β–/– mice. LC migration from the skin into LN was delayed in both IL-1α–/– and IL-1β–/– mice, suggesting that this defect was not the direct cause for the reduced CHS in these mice. However, we found that the proliferative response of trinitrophenyl (TNP)-specific T cells after sensitization with TNCB was specifically reduced in IL-1α–/– mice. Furthermore, adoptive transfer of TNP-conjugated IL-1-deficient epidermal cells (EC) into wild-type mice indicated that only IL-1α, but not IL-1β, produced by antigen-presenting cells in EC could prime allergen-specific T cells. These observations indicate that IL-1α, but not IL-1β, plays a crucial role in TNCB-induced CHS by sensitizing TNP-specific T cells.

Interleukin (IL)-1 is a proinflammatory cytokine that plays important roles in inflammation, host defense, and the neuro-immuno-endocrine network. IL-1 receptor antagonist (ra) is an endogenous inhibitor of IL-1 and is supposed to regulate IL-1 activity. However, its pathophysiological roles in a body remain largely unknown. To elucidate the roles of IL-1ra, IL-1ra–deficient mice were produced by gene targeting, and pathology was analyzed on different genetic backgrounds. We found that all of the mice on a BALB/cA background, but not those on a C57BL/6J background, spontaneously developed chronic inflammatory polyarthropathy. Histopathology showed marked synovial and periarticular inflammation, with articular erosion caused by invasion of granulation tissues closely resembling that of rheumatoid arthritis in humans. Moreover, elevated levels of antibodies against immunoglobulins, type II collagen, and double-stranded DNA were detected in these mice, suggesting development of autoimmunity. Proinflammatory cytokines such as IL-1β, IL-6, and tumor necrosis factor α were overexpressed in the joints, indicating regulatory roles of IL-1ra in the cytokine network. We thus show that IL-1ra gene deficiency causes autoimmunity and joint-specific inflammation and suggest that IL-1ra is important in maintaining homeostasis of the immune system. Possible involvement of IL-1ra gene deficiency in RA will be discussed.

Interleukin (IL)-1 is a major mediator of inflammation and exerts pleiotropic effects on the neuro-immuno-endocrine system. To elucidate pathophysiological roles of IL-1, we have first produced IL-1α/β doubly deficient (KO) mice together with mice deficient in either the IL-1α, IL-1β, or IL-1 receptor antagonist (IL-1ra) genes. These mice were born healthy, and their growth was normal except for IL-1ra KO mice, which showed growth retardation after weaning. Fever development upon injection with turpentine was suppressed in IL-1β as well as IL-1α/β KO mice, but not in IL-1α KO mice, whereas IL-1ra KO mice showed an elevated response. At this time, expression of IL-1β mRNA in the diencephalon decreased 1.5-fold in IL-1α KO mice, whereas expression of IL-1α mRNA decreased >30-fold in IL-1β KO mice, suggesting mutual induction between IL-1α and IL-1β. This mutual induction was also suggested in peritoneal macrophages stimulated with lipopolysaccharide in vitro. In IL-1β KO mice treated with turpentine, the induction of cyclooxygenase-2 (EC 1.14.99.1) in the diencephalon was suppressed, whereas it was enhanced in IL-1ra KO mice. We also found that glucocorticoid induction 8 h after turpentine treatment was suppressed in IL-1β but not IL-1α KO mice. These observations suggest that IL-1β but not IL-1α is crucial in febrile and neuro-immuno-endocrine responses, and that this is because IL-1α expression in the brain is dependent on IL-1β. The importance of IL-1ra both in normal physiology and under stress is also suggested.