Th17 response to Dermatophagoides pteronyssinus is related to late-phase airway and systemic inflammation in allergic asthma

BackgroundTh17 cells may play a role in the development of late-phase allergen-induced airway and systemic inflammation in allergic asthma, although the mechanisms involved remain to be elucidated.MethodsA total of 36 subjects were enrolled into the study: 15 allergic asthma patients with early asthmatic reaction (n = 7) or dual asthmatic reaction (n = 8) developed to inhaled D. pteronyssinus, 13 patients with allergic rhinitis, and 8 healthy subjects. Peripheral blood and induced sputum were collected 24 h before as well as 7 h and 24 h after a bronchial challenge with D. pteronyssinus. Th17 cells were analyzed by FACS; IL-17 levels were determined by ELISA.ResultsAt baseline, the percentage of peripheral blood Th17 cells and serum and sputum IL-17 levels were significantly higher in all groups of studied patients compared with those of healthy subjects. After the bronchial challenge, there was a significant increase in the percentage of peripheral blood Th17 cells and in serum and sputum IL-17 levels in rhinitis and asthma patients compared with their baseline values, particularly in allergic asthma patients with the dual asthmatic reaction. Positive correlations were found between the percentage of Th17 cells and IL-17 levels in serum (Rs = 0.649; P = 0.009) as well in sputum (Rs = 0.583; P = 0.022) in allergic asthma patients 24 h after the bronchial challenge.ConclusionsThe Th17 response is associated with the development of late-phase airway and systemic inflammation after the inhalation of D. pteronyssinus in patients with allergic asthma.     

Interleukin-23 mediates the pathogenesis of LPS/GalN-induced liver injury in mice

BackgroundInterleukin-23 (IL-23) is required for T helper 17 (Th17) cell responses and IL-17 production in hepatitis B virus infection. A previous study showed that the IL-23/IL-17 axis aggravates immune injury in patients with chronic hepatitis B virus infection. However, the role of IL-23 in acute liver injury remains unclear.ObjectiveThe purpose of this study was to determine the role of the inflammatory cytokine IL-23 in lipopolysaccharide/d-galactosamine (LPS/GalN)-induced acute liver injury in mice.MethodsSerum IL-23 from patients with chronic hepatitis B virus (CHB), acute-on-chronic liver failure (ACLF) and healthy individuals who served as healthy controls (HCs) was measured by ELISA. An IL-23p19 neutralizing antibody or an IL-23p40 neutralizing antibody was administered intravenously at the time of challenge with LPS (10 μg/kg) and GalN (400 mg/kg) in C57BL/6 mice. Hepatic pathology and the expression of Th17-related cytokines, including IL-17 and TNF-α; neutrophil chemoattractants, including Cxcl1, Cxcl2, Cxcl9, and Cxcl10; and the stabilization factor Csf3 were assessed in liver tissue.ResultsSerum IL-23 was significantly upregulated in ACLF patients compared with CHB patients and HCs (P < 0.05 for both). Serum IL-23 was significantly upregulated in the non-survival group compared with the survival group of ACLF patients, which was consistent with LPS/GalN-induced acute hepatic injury in mice (P < 0.05 for both). Moreover, after treatment, serum IL-23 was downregulated in the survival group of ACLF patients (P < 0.001). Compared with LPS/GalN mice, mice treated with either an IL-23p19 neutralizing antibody or an IL-23p40 neutralizing antibody showed less severe liver tissue histopathology and significant reductions in the expression of Th17-related inflammatory cytokine, including IL-17 and TNF-α; neutrophil chemoattractants, including Cxcl1, Cxcl2, Cxcl9, and Cxcl10; and stabilization factors Csf3 within the liver tissue compared with LPS/GalN mice (P < 0.05 for all).ConclusionHigh serum IL-23 was associated with mortality in ACLF patients and LPS/GalN-induced acute liver injury in mice. IL-23 neutralizing antibodies attenuated liver injury by reducing the expression of Th17-related inflammatory cytokines, neutrophil chemoattractants and stabilization factors within the liver tissue, which indicated that IL-23 likely functions upstream of Th17-related cytokine and chemokine expression to recruit inflammatory cells into the liver.     

The effects of corticosteroids on cytokine production from asthma lung lymphocytes

BackgroundLymphocytes play a central role in the pathophysiology of asthma. Corticosteroids have a limited effect in severe asthma and we hypothesise that lymphocytes play a central role in corticosteroid insensitivity. We investigated the effects of corticosteroids on cytokine production from lung lymphocytes obtained from patients with moderate severe asthma (MSA) compared to mild asthma (MA) and healthy non-smokers (HNS).MethodsBronchoalveolar lavage (BAL) cells obtained by bronchoscopy from patients with MSA and MA (n = 11 and n = 14 respectively) and HNS (n = 7) were stimulated with CD2/3/28 beads to activate the lymphocytes, in the presence or absence of dexamethasone (0.01–1 μM). Supernatants were assayed for IL-2, IFNγ, IL-17, IL-13 and IL-10 production.ResultsDexamethasone caused variable inhibition of cytokines; 1 μM inhibited IL-10 and IL-17 by 50% or lower, while inhibition > 50% was observed for IL-2, IL-13 and IFNγ. The effect of dexamethasone on IL-13 production was reduced in MSA.ConclusionThese findings suggest that the production of specific lymphocyte derived cytokines is poorly suppressed by corticosteroids in MSA, which may be responsible for persistent airway inflammation in these patients     

Human adipose tissue-derived mesenchymal stem cells in rheumatoid arthritis: Regulatory effects on peripheral blood mononuclear cells activation

Background and objectivesMesenchymal stem cells (MSCs) are multipotent adult stem cells with immunomodulatory properties. The mechanisms by which MSCs inhibit the proliferation of pro-inflammatory T cells have not been fully elucidated yet. It is assumed that pro-inflammatory T-cells play an important role in the development of autoimmune diseases. We investigated the potential therapeutic effects of human adipose tissue derived (Ad)-MSCs on the peripheral blood mononuclear cells (PBMCs) of rheumatoid arthritis (RA) patients and healthy individuals, with a particular focus on Th17-associated cytokines.Materials and methodsPBMCs from RA patients and healthy donors were co-cultured with Ad-MSCs and HeLa with or without Phytohemagglutinin (PHA). Finally, IL-6, IL-17, IL-21, IL-23 and TGF-β levels were determined by ELISA and quantitative real-time RT-PCR on co-culture supernatants and PBMCs, respectively.ResultsIn co-culture interaction, Ad-MSCs inhibited IL-17 secretion by PBMCs compared to unstimulated PBMCs cultured alone. In addition, IL-21 expressions in PBMCs of the patient group, and IL-17 and IL-21 in healthy group were inhibited by Ad-MSCs compared to PBMCs cultured alone. TGF-β expression in healthy individuals remarkably increased in both MSC-treated groups with and without PHA in comparison to PHA-stimulated and -unstimulated PBMCs.ConclusionsThis study demonstrates that human Ad-MSCs act as key regulators of immune tolerance by inhibiting the inflammation. Therefore, they can be attractive candidates for immunomodulatory cell-based therapy in RA.     

The role of regulatory B cells (Bregs) in the Tregs-amplifying effect of Sirolimus

Sirolimus can significantly amplify regulatory T cells (Tregs) in vivo and in vitro, but the specific mechanism of this has not been well documented. The role of regulatory B cells (Bregs) in the Tregs-amplifying effect of Sirolimus was investigated in peripheral blood mononuclear cells (PBMCs) in vitro in this study. The results showed that the percentages of both CD19 + CD24 + CD38 + TGF-β1 + Bregs and CD19 + CD24 + CD38 + IL-10 + Bregs to B cells were elevated by Sirolimus in PBMCs including B cells. Sirolimus significantly enhances the cytokine production of transforming growth factor-β1 (TGF-β1) and interleukin-10 (IL-10) in PBMCs with B cells, and the enhancement significantly decreased in PBMCs without B cells. The percentage of CD4 + CD25 + Foxp3 + Tregs to T cells was also elevated by Sirolimus in PBMCs including B cells. The elevation of Tregs percentage decreased in PBMCs without B cells and recovered when additional TGF-β1 and IL-10 were added. The amplification of Tregs by Sirolimus was partially inhibited when either TGF-β1 or IL-10 was neutralized, and it even disappeared when these two cytokines were both neutralized. These results indicate that Sirolimus can amplify Bregs and Tregs in PBMCs in vitro, and Bregs may be the why Sirolimus amplifies Tregs.     

Astilbin inhibits Th17 cell differentiation and ameliorates imiquimod-induced psoriasis-like skin lesions in BALB/c mice via Jak3/Stat3 signaling pathway

The flavonoid astilbin is the major active component extracted from the rhizome of Smilax glabra, which has been widely used in China to treat inflammatory and autoimmune diseases, Psoriasis is a common chronic inflammatory disease in which T helper 17 (Th17) cells play an important role, provoking inflammation. We employed an imiquimod (IMQ)-induced psoriasis-like mouse model to investigate the effect of astilbin in inflammation. Mice were administered 25 to 50 mg/kg astilbin. Inflammation of psoriasis-like lesions was assessed by histology, circulating levels of T cells were assessed by flow cytometry and cytokines by bead-based immunoassay. Jak/Stat3 in isolated T cells was assessed by Western blotting and RORγt expression was assessed by RT-PCR. Administration of astilbin ameliorated IMQ-induced keratinocyte proliferation, infiltration of CD3 + cells to psoriatic lesions and ameliorated elevations in circulating CD4 + and CD8 + T cells and inflammatory cytokines (IL-17A, TNF-α, IL-6, IFN-γ and IL-2). In vitro, astilbin inhibited Th17 cell differentiation and IL-17 secretion of isolated T cells, and inhibited Jak/Stat3 signaling in Th17 cells, while up-regulating Stat3 inhibitor SCOSE3 expression in psoriatic lesions. Thus, astilbin likely alleviates psoriasis-like skin lesions by inhibiting Th17 related inflammation. Astilbin represents as an interesting candidate drug for immunoregulation of psoriasis.     

Paeoniflorin suppresses IL-6/Stat3 pathway via upregulation of Socs3 in dendritic cells in response to 1-chloro-2,4-dinitrobenze

Mounting evidence has suggested that inflammation is associated with IL-6/Stat3 pathway in dendritic cells (DCs) and Th17 cells, which are critical for development of allergic contact dermatitis (ACD). Paeoniflorin (PF) has been clinically proved to be effective in the treatment of inflammatory skin diseases such as ACD. We have previously demonstrated the effect of PF on DCs stimulated with 1-chloro-2,4-dinitrobenze (DNCB) and naïve CD4⁺ CD45RA⁺ T cells for Th17 cell differentiation. However, whether PF down-regulates IL-6/Stat3 in DCs and Th17 cells remains to be explored. In this study, we show clearly that PF markedly decreases IL-6/Stat3 in DCs stimulated with DNCB at both gene and protein levels compared with control DCs in vitro. Meanwhile, PF up-regulates suppressor of cytokine signaling 3 (Socs3). Such decreased expression of IL-6/Stat3 is abolished in DCs that were transfected with Socs3 short interfering RNA (siRNA). When mice CD4⁺ CD45 RA⁺ T cells were co-cultured with PF-treated DCs stimulated with/without DNCB, the gene expression of the Th17 cell markers such as retinoic acid-related orphan nuclear hormone receptor γt (RORγt), IL-17A, and IL-23R decreased, in accordance with the less secretions of IL-17 and IL-23 in vitro and in vivo. Finally, the suppressed Th17 differentiation induced by PF can be abolished by additional recombinant mouse IL-6. Our results suggest that the anti-inflammatory mechanisms introduced by depletion of Socs3 expression or inactivation of the negative regulator such as Socs3 may represent a promising strategy for the prevention of ACD.     

Role of interleukin-23 as a biomarker in rheumatoid arthritis patients and its correlation with disease activity

BackgroundIL-23 is a pro-inflammatory cytokine belonging to the IL-12 cytokine family. IL-23 is essential for the differentiation of Th17 lymphocytes, a subtype of T lymphocyte implicated in chronic inflammatory/autoimmune mediated diseases. Experimental models of arthritis and clinical indications have highlighted an important role for Th17 lymphocytes in the pathogenesis of RA. However the role and mechanism of action of IL-23 in the pathogenesis of RA are still not fully understood.ObjectiveThis study was conducted to assess the level of IL-23 in patients with RA as well as the relationship between the IL-23 level and disease activity.MethodsThe study includes 77 patients with RA fulfilling the American College of Rheumatology (ACR) revised criteria for diagnosis of RA as well as 25 age and sex matched healthy subjects as controls. Patients were divided according to disease activity into four groups: DAS 28 score (˂ 2.6), 10 patients in remission, DAS 28 score between 2.6–3.2, 10 patients with low disease activity, DAS 28 score ranges between (3.2–5.1), 30 patients with moderate disease activity and DAS 28 score (˂ 5.1), 27 patients with High disease activity. Disease activity were determined by the 28-joint disease activity score (DAS 28). Anti-citrullinated protein antibodies (ACPA) was done. The levels of IL-23 were determined by enzyme-linked immunosorbent assay (ELISA).ResultsSerum level of IL-23 was significantly elevated in RA patients (78.92 ± 52.47) compared to control group (33.34 ± 3.99) (P < 0.001). However, no correlations were found between IL-23 and DAS 28 score, and other patients characteristics.ConclusionOur results imply that IL-23 may potentially play a role in the pathogenesis of RA and may be a useful biomarker for the diagnosis of this disease. Targeting the IL-23 cytokine may provide a new therapeutic approach in the treatment of RA.     

Exogenous C3 protein enhances the adaptive immune response to polymicrobial sepsis through down-regulation of regulatory T cells

BackgroundThe role of complement system in bridging innate and adaptive immunity has been confirmed in various invasive pathogens. It is still obscure how complement proteins promote T cell-mediated immune response during sepsis. The aim of this study is to investigate the role of exogenous C3 protein in the T-cell responses to sepsis.MethodsSepsis was induced by colon ascendens stent peritonitis (CASP) in wild-type C57BL/6 mice, sham-operated mice for control. Human purified C3 protein (HuC3, 1 mg) was intraperitoneally injected at 6 h post-surgery, with 200 μl phosphate-buffered saline as control. The levels of C3 and cytokines, the expression of FOXP3 and NF-κB, and the percentages of CD4⁺ T-cell subsets were compared among the groups at given time points.ResultsThe polymicrobial sepsis produced considerable release of TNF-α and IL-10, and caused complement C3 exhaustion. Exogenous C3 administration markedly improved the 48 h survival rate, as compared with nontreatment (40% vs. 5%, P < 0.01). The expression of FOXP3 protein was increased during sepsis, but can be suppressed by HuC3 administration. A single injection of HuC3 postponed the decline of differentiated Th1 cells, and depressed the activation of Th2/Th17 cells. Besides, the Th1–Th2 shift in late stage of sepsis can be controlled under C3 supplementation. The suppression of NF-κB pathway might be related to the appearance of immunocompromise.ConclusionsThe study confirmed the important role of exogenous C3 in up-regulation of adaptive immune response to sepsis. The complement pathway would be a pivotal target for severe sepsis management.     

Combustible and non-combustible tobacco product preparations differentially regulate human peripheral blood mononuclear cell functions

Natural killer (NK) cells and T cells play essential roles in innate and adaptive immune responses in protecting against microbial infections and in tumor surveillance. Although evidence suggests that smoking causes immunosuppression, there is limited information whether the use of smokeless tobacco (ST) products affects immune responses. In this study, we assessed the effects of two preparations of cigarette smoke, ST extract and nicotine on T cell and NK cell responses using Toll-like receptor-ligand stimulated human peripheral blood mononuclear cells (PBMCs). The tobacco product preparations (TPPs) tested included whole smoke conditioned media (WS-CM), total particulate matter (TPM) and a ST product preparation in complete artificial saliva (ST/CAS). The PBMCs were stimulated with polyinosinic:polycytidylic acid (poly I:C) and lipopolysaccharide (LPS). A marked reduction of the expression of intracellular IFN-γ and TNF-α was evident in NK cells and T cells treated with WS-CM and TPM. Consistently, attenuation of ligand-induced secretion of cytokines (IL-1β, IL-10, IL-12 and TNF-α) from PBMCs treated with WS-CM and TPM were observed. While the treatment with TPPs did not alter the expression of the maturation marker CD69, WS-CM and TPM inhibited the cytolytic activity of human PBMCs. Suppression of perforin by WS-CM was also detected. Although interference from the vehicle confounded the interpretation of effects of ST/CAS, some effects were evident only at high concentrations. Nicotine treatment minimally impacted expression of cytokines and cytolytic activity. Data presented herein suggests that the function of NK cells and T cells is influenced by exposure to TPPs (based on equi-nicotine units) in the following order: WS-CM > TPM > ST/CAS. These findings are consistent with the hypothesis put forward by others that chronic smoking leads to immunosuppression, an effect that may contribute to increased microbial infections and cancer incidence among smokers.     

Immunomodulatory effects induced by intramuscular administration of autologous total immunoglobulin G in patients with atopic dermatitis

BackgroundPolyvalent human immunoglobulin G (IgG) preparations produced from the plasma pools of healthy blood donors have been used for the treatment of various autoimmune diseases and allergic diseases because of their anti-inflammatory and immunomodulatory effects. We hypothesized that intramuscular administration of autologous total IgG would induce immunomodulatory effects in patients with allergic diseases, based on the clinical efficacy of autologous blood therapy in patients with atopic dermatitis (AD).MethodsSixteen adult AD patients with IgE-mediated sensitization to the house dust mite (Dermatophagoides farinae) received intramuscular injections of 50 mg autologous total IgG twice a week for 4 weeks. The serum levels of IgE, IgG, and IgG4 antibodies to the recombinant group 2 major allergen of Dermatophagoides farinae (Der f 2) and serum levels of interleukin (IL)-10, IL-4, IL-12, and interferon gamma (IFN-γ) were measured by enzyme-linked immunosorbent assay at baseline and at weeks 4, 8, and 12.ResultsThe serum level of IgE antibodies to Der f 2 was significantly decreased at 12 weeks compared with baseline (p < 0.005). The serum levels of IgG and IgG4 antibodies to Der f 2 were significantly increased at 4, 8, and 12 weeks compared with baseline (p < 0.05). The serum levels of IL-10 and IFN-γ were significantly increased at 4, 8, and 12 weeks compared with baseline (p < 0.05). There were no significant differences in the serum levels of IL-4 or IL-12 before and after intramuscular administrations of autologous total IgG (p > 0.05).ConclusionIntramuscular administration of autologous total IgG induced anti-allergic immunomodulatory effects in AD patients. Further studies are required to evaluate the detailed immunological mechanism underlying these effects.     

Ethyl pyruvate ameliorates inflammatory arthritis in mice

ObjectivesEthyl pyruvate (EP) is the ethyl ester of pyruvate and has antioxidative and anti-inflammatory effects. This study aimed to evaluate the therapeutic effect of EP in inflammatory arthritis and to identify the underlying mechanisms.MethodsMice with collagen-induced arthritis (CIA) were treated with the vehicle control or EP at 20 mg/kg, and clinical and histological analyses were performed on the animals. The differentiation of murine CD4 + T cells into T helper 17 (Th17) cells in the presence of EP was investigated in vitro. The effects of EP on osteoclastogenesis were determined by staining for tartrate-resistant acid phosphatase, and measuring the mRNA levels of osteoclastogenesis-related genes. The expression of high-mobility group box 1 (HMGB1) was evaluated after EP therapy using immunohistochemical staining and Western blotting.ResultsEP significantly improved the clinical and histological features of arthritis in CIA mice. EP suppressed the differentiation of CD4 + T cells into Th17 cells, and inhibited the expression of RORγt. The generation of osteoclasts and osteoclastogenic markers from murine and human monocytes was significantly reduced in the presence of EP. The expression of HMGB1 in the synovium was significantly lower in CIA mice treated with EP, compared to control CIA mice. During osteoclastogenesis, HMGB1 release from monocytes was inhibited in the presence of EP.ConclusionsEP attenuated synovial inflammation and bone destruction in the experimental arthritis model through suppression of IL-17 and HMGB-1. The data suggests that EP could be a novel therapeutic agent for the treatment of inflammatory arthritis, such as rheumatoid arthritis.     

Dextran sulfate sodium-induced acute experimental colitis in C57BL/6 mice is mitigated by selenium

BackgroundSodium selenite has been shown to have a protective role in experimental colitis. Th1 and Th17 responses are involved in the pathogenesis of dextran sulfate sodium (DSS)-induced colitis and inflammatory bowel disease. This study investigated whether sodium selenite can suppress Th1/Th17-mediated experimental colitis.MethodsMice were administered sodium selenite (2 μg/g body weight) by gavage daily for 30 days. Beginning on day 21, mice were administered 2.5% oral DSS for 9 days. The mice were sacrificed on day 31. Survival rates, clinical symptoms, colon lengths, and histological changes were determined.ResultsPretreatment with sodium selenite (2 μg/g body weight) improved survival rates, colon shortening, body weight loss, disease activity index, and histopathological score in mice with DSS-induced colitis. Pretreatment with sodium selenite restored interleukin-10 and Foxp3 excretion, as well as reducing the levels of interferon-γ and interleukin-17A.ConclusionsPretreatment with sodium selenite showed therapeutic potential for preventing colitis in mice. This effect may be mediated by the immunomodulation of regulatory T cells, expressing anti-inflammatory genes that suppress Th1 and Th17 responses.     

TLR4-HMGB1 signaling pathway affects the inflammatory reaction of autoimmune myositis by regulating MHC-I

ObjectivesTo analyze the effects of TLR4 on the expression of the HMGB1, MHC-I and downstream cytokines IL-6 and TNF-α, and to investigate the biological role of the TLR4-HMGB1 signaling pathway in the development of the autoimmune myositis.MethodsWe built mice models with experimental autoimmune myositis (EAM) and used the inverted screen experiment to measure their muscle endurance; we also examined inflammatory infiltration of muscle tissues after HE staining; and we assessed the expression of MHC-I using immunohistochemistry. In addition, peripheral blood mononuclear cells (PBMC) were extracted and flow cytometry was utilized to detect the effect of IFN-γ on the expression of MHC-I. Furthermore, PBMCs were treated with IFN-γ, anti-TLR4, anti-HMGB1 and anti-MHC-I. Real-time PCR and western blotting were employed to examine the expressions of TLR4, HMGB1 and MHC-I in different groups. The ELISA method was also utilized to detect the expression of the downstream cytokines TNF-α and IL-6.ResultsThe expressions of TLR4, HMGB1 and MHC-I in muscle tissues from mice with EAM were significantly higher than those in the control group (all P < 0.05). After IFN-γ treatment, the expressions of TLR4, HMGB1, MHC-I, TNF-α and IL-6 in PBMCs significantly increased (all P < 0.05). The treatment of anti-TLR4, anti-HMGB1 and anti-MHC-I could significantly downregulate the expression of MHC-I (all P < 0.05). In addition, anti-TLR4 and anti-HMGB1 significantly reduced the expression of TNF-α and IL-6 (all P < 0.05).ConclusionsThe TLR4-HMGB1 signaling pathway affects the process of autoimmune myositis inflammation by regulating the expression of MHC-I and other pro-inflammatory cytokines.     

Modulation of Th1/Th2 cytokine production by selective and nonselective phosphodiesterase inhibitors administered to mice

Phosphodiesterase (PDE) inhibitors can modulate the functions of immune cells, including T lymphocytes, due to increased intracellular levels of cyclic nucleotides. The drugs (aminophylline, milrinone and sildenafil) were administered once or five times at 24 h intervals at the following doses: 20 mg/kg, im, 1 mg/kg, im and 1 mg/kg, po, respectively.Th1 and Th2 cytokine levels (IL-2, IFN-γ, IL-4, IL-5, TNF) were determined 12, 24 or 72 h after the last administration of the drugs. A commercial BD^TM Cytometric Bead Array Mouse Th1/Th2 Cytokine Kit (CBA) was used to determine the levels of Th1/Th2 cytokines in the serum.Neither of the PDE inhibitors under investigation administered once changed IFN-γ, TNF and IL-4 production. A single dose of aminophyl-line decreased the production of IL-2 (after 12 h). A single dose of milrinone did not affect Th1/Th2 cytokine secretion. Sildenafil administered once decreased the production of IL-2 (after 72 h). A temporary enhancement in the level of IL-5 was observed 12 h after a single dose of sildenafil. No changes in Th1 and Th2 cytokine production were observed after five doses of PDE inhibitors under investigation. These results indicate that nonstimulated lymphocytes Th1 and Th2 exhibited a slight sensitivity to aminophylline and sildenafil. The drugs under investigation were ineffective inhibitors of Th1/Th2 cytokine production.     

Betahistine attenuates murine collagen-induced arthritis by suppressing both inflammatory and Th17 cell responses

The objective of this study was to evaluate the potential therapeutic effects of betahistine dihydrochloride (betahistine) in a collagen-induced arthritis (CIA) mouse model. CIA was induced in DBA/1 male mice by primary immunization with 100 μl of emulsion containing 2 mg/ml chicken type II collagen (CII) mixed with complete Freund's adjuvant (CFA) in an 1:1 ratio, and booster immunization with 100 μl of emulsion containing 2 mg/ml CII mixed with incomplete Freund's adjuvant (IFA) in an 1:1 ratio. Immunization was performed subcutaneously at the base of the tail. After being boosted on day 21, betahistine (1 and 5 mg/kg) was orally administered daily for 2 weeks. The severity of CIA was determined by arthritic scores and assessment of histopathological joint destruction. Expression of cytokines in the paw and anti-CII antibodies in the serum was evaluated by ELISA. The proliferative response against CII in the lymph node cells was measured by ³H-thymidine incorporation assay. The frequencies of different CII specific CD4⁺ T cell subsets in the lymph node were determined by flow-cytometric analysis. Betahistine treatment attenuated the severity of arthritis and reduced the levels of pro-inflammatory cytokines, including TNF-α, IL-6, IL-23 and IL-17A, in the paw tissues of CIA mice. Lymph node cells from betahistine-treated mice showed a decrease in proliferation, as well as a lower frequency of Th17 cells. In vitro, betahistine suppressed CD4⁺ T cell differentiation into Th17 cells. These results indicate that betahistine is effective in suppressing both inflammatory and Th17 responses in mouse CIA and that it may have therapeutic value as an adjunct treatment for rheumatoid arthritis.