The inflammatory oral diseases are characterized by the persistent migration of polymorphonuclear leukocytes, monocytes, lymphocytes, plasma and mast cells, and osteoblasts and osteoclasts. In the last decade, there has been a great interest in the mediators responsible for the selective recruitment and activation of these cell types at inflammatory sites. Of these mediators, the chemokines have received particular attention in recent years. Chemokine messages are decoded by specific receptors that initiate signal transduction events, leading to a multitude of cellular responses, including chemotaxis and activation of inflammatory and bone cells. However, little is known about their role in the pathogenesis of inflammatory oral diseases. The purpose of this review is to summarize the findings regarding the role of chemokines in periapical and periodontal tissue inflammation, and the integration, into experimental models, of the information about the role of chemokines in human diseases.

Interleukin (IL)- [26] and is a proinflammatory cytokine in CIA [14,27]. Recent studies have also shown that the IL-33/ST2 pathway plays a significant role in the amplification of M2 polarization and chemokine production, which contribute to innate and antigen-induced airway inflammation [28] and protect against obesity-related metabolic events [29].Interestingly, the highest levels of IL-33 expression in naïve mice are found in the brain and spinal cord [15], indicating that IL-33 may have CNS-specific functions in addition to its role in immune modulation. Astrocytes express both and the expression of IL-33 in the CNS was increased in response to inflammatory stimuli [31]. Recently, it was also reported that IL-33 levels were elevated in the periphery and CNS of MS patients, implicating IL-33 in the pathogenesis of MS [32]. However, the precise role of IL-33 and its receptor in CNS under healthy and inflammatory conditions remain unclear.In the present study, we show that ST2 1C). Quantitative PCR analysis confirmed the upregulation of ST2 expression in Fig. 1B as it clearly shows the enhanced expression of ST2 mRNA in the CNS of mice with EAE compared with that of the naïve mice (Fig. 1D). ST2 −/− mice developed exacerbated EAETo identify an endogenous role of IL-33 in EAE, we next investigated the development of EAE in ST2 −/− mice. EAE was induced in C57BL/6 WT and ST2 −/− mice, Fig. 2A shows that the ST2 −/− mice developed more severe EAE than that in the WT mice. In agreement with many previous reports, BALB/c mice are resistant to the induction of EAE. However ST2 −/− BALB/c mice developed a mild but clearly detectable EAE while the WT BALB/c controls did not (Fig. 2B), the observation was further confirmed by histological analysis of the CNS tissues at day 19 after immunization ( Fig. 2C). Minimal leukocyte infiltration was found in the CNS of WT BALB/c mice whereas significant leukocyte infiltration was found in the submeningeal infiltration in the CNS tissues of ST2 −/− BALB/c mice ( Fig. 2C). IL-33 treatment attenuates EAE developmentWe next investigated the effect of exogenous IL-33 in the development of EAE. C57BL/6 mice were immunized as described in was injected intraperitoneally to each mouse daily from day 12 to day 20 after immunization. Both groups of mice developed similar degree of EAE from day 10 to day 15. However, from day 15, mice treated with IL-33 recovered significantly faster than the control mice treated with PBS ( Fig. 3A). In induced experimental autoimmune diseases, disease severity could vary between experiments even with the same protocol. Analysis using multiple comparisons suggests that the effect of IL-33 treatment on the outcome of EAE mice could be time revealed marked reduction of infiltrating cells in the spinal cord tissues of IL-33-treated mice (Fig. 3B). Importantly, IL-33 had no effect on the disease development in ST2 −/− C57BL/6 mice ( Fig. 3C) demonstrating the specificity of the IL-33 effect. IL-33 alters the cytokine production of EAE miceTo investigate the i...

cytokines ͉ inflammation ͉ pain ͉ rheumatoid arthritis ͉ hyperalgesia I L-33 is a recently described member of the IL-1 family that includes IL-1␤ and IL-18. Like IL-1␤ and IL-18, IL-33 was found to have strong immunomodulatory functions (1). However, unlike IL-1␤ and IL-18, which mainly promote T-helper 1 (Th1)-associated responses, IL-33 predominantly induces the production of Th2 cytokines (IL-5 and IL-13) and increases the levels of serum Ig. IL-33 was recently found to be the ligand for the orphan receptor ST2 (1), which also is known as T1, DER4, or Fit (2-5). The interaction between IL-33 and ST2 was sufficient to trigger the activation of NF-B and all three MAPKs (p38, ERK1/2, and JNK1/2) in a mast cell line. In vitro, IL-33 enhanced IL-5 and IL-13 production by polarized Th2, but not Th1, cell lines. In addition, the administration of human IL-33 into naïve mice provoked innate type 2 cytokine, IgE production, and eosinophilia (1).The ST2 gene encodes two isoforms of ST2 protein: ST2L, a transmembrane form, and soluble ST2 (sST2) (6), a secreted form that can serve as a decoy receptor of IL-33 (1). ST2L is preferentially expressed on Th2, but not Th1, cells (7,8) and can profoundly suppress innate and adaptive immunity (9, 10). ST2 also is expressed on mast cells, macrophages, and fibroblasts. We have previously shown that sST2 is a potent inhibitor of collagen-induced arthritis in mice (11), suggesting that the IL-33-ST2 signaling pathway is a key mediator of rheumatoid arthritis (RA). Arthritic lesions are accompanied by movement limitation secondary to articular hyperalgesia, and there is consistent evidence that cytokines induce hypernociception (hyperalgesia and/or allodynia in experimental animals) (12-15). Therefore, we have investigated the role of IL-33 in immune inflammatory hypernociception in mice.We report here that IL-33 is a key mediator of methylated BSA (mBSA)-induced cutaneous and articular mechanical hypernociception. IL-33 mediates hypernociception via the sequential TNF␣ 3 IL-1␤ 3 IFN␥ 3 endothelin 1 (ET-1) 3 prostaglandin (PG) E 2 signaling cascade. These results therefore reveal a hitherto uncharacterized important pathway of antigen-induced hypernociception normally associated with Th1 response. Furthermore, our results suggest that IL-33 may be a potential therapeutic target for immune inflammatory hypernociception. Results IL-33Mediates Cutaneous Mechanical Hypernociception. IL-33 intraplantar (i.pl.) injection induced mechanical hypernociception in mice in a dose-and time-dependent manner (Fig. 1A). The response was significant from 0.5 h, reaching maximal response between 3 and 5 h, decreasing thereafter to a control level at 48 h. The IL-33-induced hypernociception was restricted to the ipsilateral paw at the doses used (data not shown), indicating a local effect. A 70 ng per paw dose and readout at 3 h were chosen for subsequent experiments. IL-33-induced cutaneous hypernociception was significantly inhibited by the treatment with sST2-Fc, but not by the Fc control (Fig. 1B...

These results suggest that suppression of IL-33R expression in neutrophils, preventing IL-33-induced neutrophil migration, may be an important mechanism of anti-TNFalpha therapy of inflammation.

Our results showed a predominance of osteoclast activity in granulomas that was correlated with the Th1 response. The concomitant expression of Treg cell markers suggests a possible suppression of the Th1 response in granulomas. On the other hand, in cysts the Th2 activity is augmented. The mechanisms of periradicular lesion development are still not fully understood but the imbalance of immune and osteoclastic cell activity in cysts and granulomas seems to be critically regulated by Treg cells.

These findings suggest that regulatory T cells play an important role in the progression and establishment of immune dysfunction observed in experimental sepsis.

Type 17 helper T (Th17) cells are implicated in the pathogenesis many of human autoimmune diseases. Development of Th17 can be enhanced by the activation of aryl hydrocarbon receptor (AHR) whose ligands include the environmental pollutant dioxin, potentially linking environmental factors to the increased prevalence of autoimmune disease. We report here that nitric oxide (NO) can suppress the proliferation and function of polarized murine and human Th17 cells. NO also inhibits AHR expression in Th17 cells and the downstream events of AHR activation, including IL-22, IL-23 receptor, and Cyp1a1. Conversely, NO did not affect the polarization of Th17 cells from mice deficient in AHR. Furthermore, mice lacking inducible nitric oxide synthase ( Nos2 −/− ) developed more severe experimental autoimmune encephalomyelitis than WT mice, with elevated AHR expression, increased IL-17A, and IL-22 synthesis. NO may therefore represent an important endogenous regulator to prevent overexpansion of Th17 cells and control of autoimmune diseases caused by environmental pollutants.

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