IL-18 receptor-α signalling pathway contributes to autoantibody-induced arthritis via neutrophil recruitment and mast cell activation

OBJECTIVES

The interleukin (IL)-18 signalling pathway is involved in animal models of collagen-induced arthritis, but the role of this pathway in autoantibody-induced arthritis is poorly understood. An autoantibody-induced arthritis model, K/BxN serum transfer arthritis, reflects the effector phase of arthritis and is important in innate immunity including neutrophils and mast cells. This study aimed to investigate the role of the IL-18 signalling pathway in autoantibody-induced arthritis using IL-18 receptor (IL-18R) α-deficient mice.

METHODS

K/BxN serum transfer arthritis was induced in IL-18Rα-/- and wild-type B6 (controls) mice. The severity of arthritis was graded, and histological and immunohistochemical examinations were performed on paraffin-embedded ankle sections. Total Ribonucleic acid (RNA) isolated from mouse ankle joints was analysed by real-time reverse transcriptase-polymerase chain reaction.

RESULTS

IL-18 Rα-/- mice had significantly lower arthritis clinical scores, neutrophil infiltration, and numbers of activated, degranulated mast cells in the arthritic synovium than in controls. IL-1β, which is indispensable for the progression of arthritis, was significantly downregulated in inflamed ankle tissue in IL-18 Rα-/- mice.

CONCLUSIONS

IL-18/IL-18Rα signalling contributes to the development of autoantibody-induced arthritis by enhancing synovial tissue expression of IL-1β and inducing neutrophil recruitment and mast cell activation. Therefore, inhibition of the IL-18Rα signalling pathway might be a new therapeutic strategy for rheumatoid arthritis.

Examination of Prognostic Factors in Anti-Melanoma Differentiation-Associated Gene 5 Antibody-Positive Dermatomyositis

OBJECTIVE

This study investigated the prognostic factors of anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis (MDA5-DM).

METHODS

This study analysed 34 MDA5-DM cases (20 and 14 in the survival and death groups, respectively) encountered at Kurume University between 2008 and 2021. The clinical, physiological, and computed tomography findings, pulmonary function, and serological results were retrospectively evaluated for each MDA5-DM case during the first visit and throughout the next 12 weeks.

RESULTS

In the death group, the mean age of patients was higher (47.6 vs. 61.8 years), while the duration from symptom onset to consultation was shorter (110 vs. 34.9 days). During the first visit, the death group demonstrated a significantly higher serum C-reactive protein (CRP) level (0.52 vs. 1.99) and a significantly lower albumin level (3.23 vs. 2.63) than the survival group; this persisted throughout the next 12 weeks. Poor prognosis was associated with CRP and albumin levels above 0.19 mg/dL and below 2.3 g/dL, respectively, 4 weeks after starting treatment.

CONCLUSION

Four weeks after beginning treatment, serum CRP and albumin levels of patients with MDA5-DM can be used to evaluate treatment response and predict prognosis.

Combination of Prednisolone and Calcineurin Inhibitors Prevents Lung Function Decline in Patients with Anti-aminoacyl-tRNA Synthetase Antibody-Positive Polymyositis/Dermatomyositis

OBJECTIVE

Anti-aminoacyl-tRNA synthetase antibody-positive polymyositis/dermatomyositis-associ ated interstitial lung disease (ARS-ILD) has a good prognosis, with few cases progressing to respiratory failure. This study aimed to determine factors predictive of lung function changes in patients with ARS-ILD.

METHODS

We retrospectively studied 49 patients with ARS-ILD treated at Kurume University Hospital Hospital between 2000 and 2018. We followed 30 patients for more than 2 years after prednisolone (PSL) therapy, with or without calcineurin inhibitors (CNIs), evaluating clinical, physiological, computed tomography, pulmonary func tion, and serological data.

RESULTS

After treatment for 24 months, no significant differences were noted between clinical parameters and improvement in forced vital capacity (FVC), %FVC, % carbon monoxide diffusing capacity/alveolar volume (%DLCO), and %DLCO/alveolar volume. Conversely, the annual change of %FVC significantly correlated with the Medical Research Council dyspnea scale grade and %FVC at the first visit and treatment. Furthermore, the annual change of %DLCO/VA significantly correlated with the duration from the first visit to treatment initiation.

CONCLUSION

Compared with PSL monotherapy, combining PSL and CNI showed greater mitigation of %FVC decline. The time from onset of ARS-ILD to the first visit is critical for preventing a decline in lung function, and as such, patients should be monitored carefully.

Periostin Is a Biomarker of Rheumatoid Arthritis-Associated Interstitial Lung Disease

Periostin was investigated as a biomarker for rheumatoid arthritis-associated interstitial lung disease (RA-ILD). This prospective study measured serum monomeric and total periostin, Klebs von den Lungen-6 (KL-6), surfactant protein D (SP-D), and lactate dehydrogenase (LDH) in 19 patients with RA-ILD, 20 RA without ILD, and 137 healthy controls (HC). All biomarkers were higher in RA-ILD than HC or RA without ILD. KL-6 accurately detected ILD in RA patients (area under curve [AUC] = 0.939) and moderately detected SP-D and monomeric and total periostin (AUC = 0.803, =0.767, =0.767, respectively). Monomeric and total periostin were negatively correlated with normal lung area and positively correlated with honeycombing, reticulation, fibrosis score, and the traction bronchiectasis grade but not inflammatory areas. Serum levels of SP-D, KL-6, and LDH did not correlate with the extent of those fibrotic areas on high-resolution CT. Serum monomeric and total periostin were higher in patients with RA-ILD with definite usual interstitial pneumonia pattern compared with other ILD patterns. Immunohistochemical analyses of biopsy or autopsy lung tissues from RA-ILD during the chronic phase and acute exacerbation showed that periostin was expressed in fibroblastic foci but not inflammatory or dense fibrosis lesions. Periostin is a potential biomarker for diagnosis, evaluating fibrosis, and deciding therapeutic strategies for patients with RA-ILD.

Positive Autoantibody Is Associated with Malignancies in Patients with Idiopathic Interstitial Pneumonias

Various autoantibodies are associated with clinical outcomes in patients with idiopathic interstitial pneumonias (IIPs). We retrospectively analyzed the association between autoantibodies and malignancies in IIP patients. Comprehensive analyses of autoantibodies were performed using immunoprecipitation and enzyme-linked immunosorbent assays in 193 consecutive IIP patients. Cancer-related factors were analyzed using logistic regression analysis. In total, 22 of 193 patients (11.4%) with IIP had malignant disease. In univariate analysis, positivity for any autoantibody (odds ratio (OR), 3.1; 95% confidence interval (CI), 1.2-7.7; p = 0.017) and antinuclear antibody titer ≥1:320 (OR, 3.4; CI, 1.2-9.8; p = 0.024) were significantly associated with malignancies. Positive anti-aminoacyl tRNA synthetase (ARS) (OR, 3.7; CI, 0.88-15.5; p = 0.074) and anti-Ro52 antibody (OR, 3.2; CI, 0.93-11.2; p = 0.065) tended to be associated with malignancies. In multivariate analysis, independent risk factors were male sex (OR, 3.7; CI, 1.0-13.5; p = 0.029) and positivity for any autoantibody (OR, 3.9; CI, 1.5-10.1; p = 0.004) in model 1, and male sex (OR, 3.9; CI, 1.0-15.3; p = 0.049), antinuclear antibody titer ≥1:320 (OR, 4.2; CI, 1.4-13.3; p = 0.013), and positivity for anti-ARS antibody (OR, 6.5; CI, 1.2-34.1; p = 0.026) in model 2. Positivity for any autoantibody, antinuclear and anti-ARS antibodies, and male sex were independent risk factors for malignancies in IIP patients. Testing autoantibodies in IIP patients might help the early diagnosis of malignancies.

Clinical Characteristics of Anti-TIF-1γ Antibody-Positive Dermatomyositis Associated with Malignancy

We retrospectively analyzed the clinical and laboratory data of patients diagnosed with anti-transcriptional intermediary factor 1 (TIF-1γ) antibody-positive polymyositis (PM)/dermatomyositis (DM) to clarify the characteristics of this disease. We identified 14 patients with TIF-1γ antibody-positive DM (TIF-1γ DM), 47 with anti-aminoacyl-tRNA synthetase antibody (ARS)-positive PM/DM, and 24 with anti-melanoma differentiation-associated gene 5 antibody (MDA-5)-positive PM/DM treated at the Kurume University Hospital between 2002 and 2020. Patients with TIF-1γ DM were significantly older than the other two groups. Nine patients with TIF-1γ DM were female, thirteen patients had DM, and one had clinically amyopathic DM. Primary malignant lesions were lung (3), uterus (2), colon (2), breast (2), ovary (1), lymphoma (1), and unknown (2). Cutaneous manifestation and dysphagia were the most common symptoms in TIF-1γ DM. Erythema (9/14), the V-neck sign (8/14), heliotrope (9/14), and nailfold telangiectasia (14/14) were significantly more common in TIF-1γ DM. Furthermore, no patients with TIF-1γ DM had interstitial lung abnormality on high-resolution CT. In patients with TIF-1γ DM, the frequency of dysphagia and unusual erythema, particularly that which spreads from the trunk, and nailfold telangiectasia, were characteristic findings. In most patients with TIF-1γ DM, it is necessary to administer other immunosuppressive drugs along with glucocorticoids.

Mast cells can produce transforming growth factor β1 and promote tissue fibrosis during the development of Sjögren's syndrome-related sialadenitis

OBJECTIVES

This study investigated the associations of mast cells with immune-mediated inflammation and fibrosis in patients with primary Sjögren's syndrome (pSS); it also explored the underlying pathophysiology of pSS-related sialadenitis.

METHODS

Twenty-two patients with pSS and 10 patients with sicca (control individuals) underwent labial salivary gland biopsies. Sections were subjected to staining and immunofluorescence analyses. HMC-1 human mast cells were cocultured with fibroblasts in vitro; fibroblasts were also grown in HMC-1 conditioned medium. mRNA levels of collagen Type I (Col1a) and transforming growth factor (TGF)β1 were analysed in cultured cells.

RESULTS

Mast cell numbers in labial salivary glands were significantly greater in patients with pSS than in control individuals. In salivary glands from patients with pSS, mast cell number was significantly correlated with fibrosis extent; moreover, mast cells were located near fibrous tissue and expressed TGFβ1. Col1a and TGFβ1 mRNAs were upregulated in cocultured fibroblasts and HMC-1 cells, respectively. Fibroblasts cultured in HMC-1 conditioned medium exhibited upregulation of Col1a mRNA; this was abrogated by TGFβ1 neutralizing antibodies.

CONCLUSIONS

Mast cell numbers were elevated in patients with pSS-related sialadenitis; these cells were located near fibroblasts and expressed TGFβ1. TGFβ1 could induce collagen synthesis in fibroblasts, which might contribute to fibrosis.

MEFV E148Q variant is more associated with familial Mediterranean fever when combined with other non-exon 10 MEFV variants in Japanese patients with recurrent fever

OBJECTIVE

To investigate the genetic characteristics of one of the MEFV gene variants, p.Glu148Gln (E148Q), in patients with familial Mediterranean fever (FMF) and examine its significance in Japanese patients with recurrent fever.

METHODS

The clinical phenotype and genomic variants of systemic autoinflammatory diseases (SAIDs), including MEFV, were analyzed in 211 Japanese patients with recurrent fever. Genetic analysis was performed via next-generation sequencing of exons, including exon-intron boundaries.

RESULTS

Twelve patients met the diagnostic criteria for SAIDs other than FMF. Considering 199 patients with recurrent fever, 137 cases (68.8%) were clinically diagnosed with FMF. Although Bonferroni-adjusted p-value did not reach significance level, the group containing heterozygous E148Q and other variants tended to be at higher risk of developing the FMF phenotype (nominal p = .036) than the group with heterozygous E148Q only. Comparison between the group with heterozygous E148Q and other variants and the heterozygous group containing non-E148Q showed no statistically significant difference in FMF phenotype expression (nominal p = 1.00).

CONCLUSION

Patients with heterozygous E148Q and other variants exhibited higher expression of FMF phenotype than those with heterozygous E148Q only, and suggested that other variants than E148Q as well as exon 10 variants might contribute to the FMF phenotype.

Risk Prediction Modeling Based on a Combination of Initial Serum Biomarker Levels in Polymyositis/Dermatomyositis-Associated Interstitial Lung Disease

OBJECTIVE

To establish predictive models for mortality in patients with polymyositis/dermatomyositis-associated interstitial lung disease (PM/DM-ILD) using a combination of initial serum biomarker levels.

METHODS

The Multicenter Retrospective Cohort of Japanese Patients with Myositis-Associated ILD (JAMI) database of 497 incident cases of PM/DM-ILD was used as a derivation cohort, and 111 cases were additionally collected as a validation cohort. Risk factors predictive of all-cause mortality were identified by univariate and multivariable Cox regression analyses using candidate serum biomarkers as explanatory variables. The predictive models for mortality were generated in patients with and those without anti-melanoma differentiation-associated gene 5 (MDA-5) antibody, using a combination of risk factors. Cumulative survival rates were assessed using Kaplan-Meier analysis, and were compared between subgroups using the Breslow test.

RESULTS

In the derivation cohort, C-reactive protein (CRP) and Krebs von den Lungen 6 (KL-6) levels were identified as independent risk factors for mortality in both anti-MDA-5-positive and anti-MDA-5-negative patients. We then developed a prediction model based on anti-MDA-5 antibody status, CRP level, and KL-6 level, termed the "MCK model," to identify patients at low (<15%), moderate (15-50%), or high (≥50%) risk of mortality, based on the number of risk factors. The MCK model successfully differentiated cumulative survival rates in anti-MDA-5-positive patients (P < 0.01 for low versus moderate risk and P = 0.03 for moderate versus high risk) and in anti-MDA-5-negative patients (P < 0.001 for low versus moderate risk). The utility of the MCK model was replicated in the validation cohort.

CONCLUSION

Our findings indicate that an evidence-based risk prediction model using CRP and KL-6 levels combined with anti-MDA-5 antibody status might be useful for predicting prognosis in patients with PM/DM-ILD.

Subcutaneous Cheek Nodule Associated with Granulomatosis with Polyangiitis

We herein report an unusual case of granulomatosis with polyangiitis (GPA) in a 65-year-old man in whom relapsed disease manifested as an anterior cheek nodule. Magnetic resonance imaging indicated the differential diagnoses of the subcutaneous nodule in the patient's anterior cheek to be inflammatory granulomatous lesions with GPA, malignancy, or infectious disease. A histopathological examination ruled out malignancy and infectious diseases, and necrotizing vasculitis was suspected. The subcutaneous nodule was successfully treated using rituximab, suggesting that it was associated with GPA, secondary to vasculitis. Clinicians should be aware of the possibility of such a rare manifestation of GPA.

CD163 deficiency facilitates lipopolysaccharide-induced inflammatory responses and endotoxin shock in mice

Objectives

Septic (or endotoxin) shock is a severe systemic inflammatory disease caused by bacteraemia or endotoxaemia. Although it is known that increased serum levels of CD163 are observed in septic/endotoxin shock patients, the exact function and significance of CD163 in macrophage activation remain unclear. Therefore, in the current study, we tested whether CD163 contributes to the pathogenesis of endotoxin shock in mice.

Methods and results

In samples obtained from autopsy, the number of CD163‐positive macrophages was increased in the kidney, liver, heart, bone marrow and spleen of patients who had died from septic/endotoxin shock when compared to patients who had died from other causes. The animal study revealed a significantly lower survival rate in CD163‐deficient mice after lipopolysaccharide (LPS) injection. Several cytokines and oxidative stress‐related molecules were significantly elevated in the sera of LPS‐induced endotoxin shock mice models. Higher concentrations of IL‐6, TNF‐α, IL‐1β, nitrite (NO2‐) and nitrate (NO3‐) and a lower concentration of IL‐10 were observed in CD163‐deficient mice treated with LPS. Similar results were observed in CD163‐deficient LPS‐stimulated macrophages. Furthermore, in an antitype II collagen antibody‐induced arthritis (CAIA), rheumatoid arthritis model, inflammation and bone erosion scores as well as the expression of IL‐6 and IL‐1β were significantly increased in CD163‐deficient mice.

Conclusions

CD163 was suggested to be involved in the regulation of inflammatory cytokine expression in septic/endotoxin shock and CAIA.

Clinical phenotypes and genetic analyses for diagnosis of systemic autoinflammatory diseases in adult patients with unexplained fever

OBJECTIVE

To make an accurate diagnosis of systemic autoinflammatory diseases (SAIDs), clinical and genetic analyses were performed in patients with unexplained fever.

METHODS

The clinical phenotype and genomic variants of 11 genes responsible for SAIDs were analyzed in 179 Japanese patients with unexplained fever. Genetic analysis was performed by next generation sequencing (NGS) on exons including exon-intron boundaries.

RESULTS

Three cases met the diagnostic criteria for SAIDs other than familial Mediterranean fever (FMF). Considering 176 patients with unexplained fever, 43 cases (24.0%) were clinically diagnosed as FMF. Gene variants were found in 53 cases (30.1%) when searching for variants in the 10 disease genes other than the MEFV gene. Among them, the most frequently-identified genes were NLRP3, NOD2, NLRP12, NLRC4, and PLCG2, which accounted for 14, 7, 17, 7, and 6 cases, respectively. These variants were less than 1% of healthy individuals or novel variants, but not regarded as pathogenic since the patients did not meet the diagnostic criteria of SAIDs caused by their identified variants clinically.

CONCLUSION

Twenty four percent of Japanese patients with unexplained fever were clinically diagnosed as FMF in this study. Low frequency but not pathogenic variants in genes other than MEFV were identified in 30.1% of the cases. It is not clear how much these gene variants contribute to the inflammatory phenotypes; therefore, further analysis would uncover their autoinflammatory phenotypes that cause fever.

Evaluation of usefulness in surfactant protein D as a predictor of mortality in myositis-associated interstitial lung disease

Objective

Surfactant protein D (SP-D) is considered a serum biomarker of various forms of interstitial lung disease (ILD). In this study, we examined the utility of SP-D as a predictive biomarker for mortality in patients with ILD associated with polymyositis/dermatomyositis (PM/DM) using large-scale multicentre cohort data.

Methods

We enrolled 381 patients with incident PM/DM-associated ILD in a multicentre retrospective cohort based on the availability of serum SP-D at the baseline. Demographic and clinical characteristics as well as the presence of autoantibodies to melanoma differentiation-associated gene 5 (MDA5) and aminoacyl tRNA synthetase were measured at the time of diagnosis, and follow-up survival data were collected prospectively.

Results

Seventy-eight patients died during the median observation period of 18 months, and the majority of patients died of ILD. The SP-D levels at baseline were significantly lower (P = 0.02) in a non-survivor subset than in a survivor subset among the entire enrolled patients. However, the SP-D levels were higher in the non-survivor subset than in the survivor subset based on the stratification by anti-MDA5-positive, anti-ARS-positive and, double-negativity, although there was an only statistically significant difference (P = 0.01) in the double-negative group. Surprisingly, the SP-D levels were within the upper limit of normal, 110 ng/mL, in 54 (87%) of 62 anti-MDA5-positive patients who died. In the double-negative group, the mortality rates were significantly higher (P = 0.002) in a subset with SP-D ≥127.6 ng/mL, the cut-off value for mortality calculated by the receiver operating characteristic curve, than the other subset. All of patients with SP-D <127.6 ng/mL survived.

Conclusion

Serum SP-D levels behave differently among patients with stratified by anti-MDA5 antibody, anti-ARS antibody and both negativity in PM/DM-associated ILD. Its use in clinical practice should be applied with caution on the basis of the presence or absence of anti-MDA5 antibody or anti-ARS antibody.

Clinical and Genetic Analysis of 22 Japanese Patients with Familial Mediterranean Fever: An Examination of MEFV and 10 Other Genes Related to Autoinflammatory Syndromes

Objective Familial Mediterranean Fever (FMF) is the most frequent autoinflammatory syndrome, and its frequency is reported to be increasing in Japan. We studied the clinical features and genetic background of patients with FMF in our hospital. Methods We analyzed the clinical features and genomic variants of MEFV, as well as 10 genes related to other autoinflammatory syndromes, in 22 Japanese patients with FMF. A genetic analysis was performed with a next generation sequencer. Results The patients were classified into the typical FMF (n=16) and atypical FMF (n=6) groups. Fever, abdominal pain, thoracic pain, and arthralgia were observed in 22, 12, 8, and 10 patients, respectively. MEFV variants were found in 19 patients (86.4%). Two cases had no MEFV variants and one case only had a variant in the 3' untranslated region (3'-UTR) of MEFV. Genomic variants were found in genes other than MEFV in 7 patients (31.8%); however, none met the diagnostic criteria for autoinflammatory syndromes with disease-related gene variants, and all were classified as typical FMF. Moreover, none of the 6 patients with atypical FMF had any variants among the 10 disease-related genes. All cases in which the onset occurred before 20 years of age were classified as typical FMF. Conclusion The clinical features of FMF recorded in our hospital coincided with those from the Japanese national epidemiological survey of FMF in Japan. More than 30% of the patients with FMF had non-MEFV genes, related to other autoinflammatory syndromes, thereby suggesting that variants of these genes may act as a disease-modifier in FMF.

Elevation of pulmonary CD163+ and CD204+ macrophages is associated with the clinical course of idiopathic pulmonary fibrosis patients

Background

M2-like/repair macrophages are thought to contribute to fibrotic process of idiopathic pulmonary fibrosis (IPF). We analyzed the association between pulmonary accumulation of M2-like macrophages and survival in IPF patients.

Methods

Lung tissues were obtained by surgical lung biopsy from patients with IPF (n=16), nonspecific interstitial pneumonia (NSIP, n=8) and control subjects (n=14). Samples were also obtained at autopsy from 9 patients who died of acute exacerbation (AE) of IPF. Lung specimens and/or human peripheral blood mononuclear cells-derived macrophages were evaluated by immunohistochemistry for expression of CD68 (pan-macrophage marker), CD163, and CD204 (M2-like macrophage markers), and by in situ mRNA hybridization and ELISA for production of transforming growth factor-β1 (TGF-β1).

Results

CD68⁺, CD163⁺, and CD204⁺ cell counts and CD163⁺/CD68⁺ and CD204⁺/CD68⁺ cell ratios were comparable in IPF and NSIP lung tissues and significantly higher than in control tissues. IPF-AE lung samples contained significantly elevated CD68⁺ and CD163⁺ cell counts and CD163⁺/CD68⁺ cell ratio compared with IPF samples, whereas CD204⁺ cell counts and CD204⁺/CD68⁺ cells ratio did not differ. High CD163⁺/CD68⁺ and CD204⁺/CD68⁺ cell ratios were significantly associated with shorter overall survival and time-to-AE in IPF patients. In vitro-differentiated human CD163⁺ and CD204⁺ macrophages both secreted TGF-β1; however, the novel IPF drug pentraxin 2/serum amyloid protein could suppress secretion only by CD204⁺ macrophages.

Conclusions

Pulmonary accumulation of CD163⁺ and CD204⁺ macrophages is associated with worse clinical course in IPF patients. Suppression of macrophage activation and TGF-β1 secretion may be a potential therapeutic target for IPF.

Clinical characteristics of cancer-associated myositis complicated by interstitial lung disease: a large-scale multicentre cohort study

Objective

To clarify the incidence, risk factors, and impact of malignancy in patients with PM/DM-associated interstitial lung disease (ILD).

Methods

This study used data from 497 patients with PM/DM-associated ILD enrolled in a multicentre, retrospective and prospective cohort of incident cases. Cancer-associated myositis (CAM) was defined as malignancy diagnosed within 3 years before or after PM/DM diagnosis. Demographic and clinical information was recorded at the time of diagnosis, and data about the occurrence of mortality and malignancy was collected.

Results

CAM was identified in 32 patients with PM/DM-associated ILD (6.4%). Patients with CAM were older (64 vs 55 years, P &lt; 0.001), presented with arthritis less frequently (24% vs 49%, P = 0.01), and showed a lower level of serum Krebs von den Lungen-6 (687 vs 820 IU/l, P = 0.03) than those without CAM. The distribution of myositis-specific autoantibodies, including anti-melanoma differentiation–associated gene 5, anti-aminoacyl tRNA synthetase, and anti-transcriptional intermediary factor 1-γ antibodies, did not differ between the groups. Survival analysis demonstrated that CAM patients had a poorer survival than non-CAM patients (P = 0.006), primarily due to excess deaths by concomitant malignancy, while mortality due to ILD-related respiratory failure was similar between the groups (P = 0.51).

Conclusion

Concomitant malignancy can occur in patients with PM/DM-associated ILD, and has significant impact on mortality. Older age, lack of arthritis, and a lower level of serum Krebs von den Lungen-6 at diagnosis are predictors of concomitant malignancy.

A retrospective study of the tolerability of nintedanib for severe idiopathic pulmonary fibrosis in the real world

Background

Nintedanib is a tyrosine kinase inhibitor that has been shown to suppress progression of idiopathic pulmonary fibrosis (IPF). The efficacy and tolerability of nintedanib for IPF has been previously proven in the INPULSIS^® and INPULSIS-On^® trials. The aim of our study was to clarify the tolerability of nintedanib in the real world for severe IPF patients who were unable to enter the INPULSIS^® and INPULSIS-On^® trials.

Methods

We retrospectively investigated medical records of 8 patients with severe IPF and 14 patients with non-severe IPF who had been treated with nintedanib. The criteria to define severe IPF were forced vital capacity (FVC) of <50% predicted and/or diffusing capacity of the lung for carbon monoxide/alveolar volume (D_LCO/VA) of <30% predicted or unmeasurable. Severity of adverse event was evaluated using the Common terminology criteria for each adverse event version 4.0. We compared changes in FVC and serum KL-6 level, incidence and severity of adverse events, and incidence of permanent or temporary discontinuation of nintedanib in between severe and non-severe IPF groups.

Results

The median treatment period was 578.5 days. The most frequent adverse event was diarrhea (73%). Only 2 patients required permanent discontinuation of nintedanib due to adverse events. There was no difference in incidence or severity of adverse events or incidence of permanent or temporary discontinuation of nintedanib in between severe and non-severe IPF groups. Among subjects, decline in FVC during 6 months post-nintedanib treatment were significantly lower than prior to treatment, but change in serum KL-6 level showed no significant difference between these 2 timepoints.

Conclusions

Our study showed that nintedanib was tolerable for IPF patients who would not have been eligible for entry into previous clinical trials due to low pulmonary function. Although therapeutic strategy for severe IPF should be planned carefully, initiation of nintedanib treatment should not be dismissed solely for reasons of low pulmonary function.

Attenuated Airway Eosinophilic Inflammations in IL-38 Knockout Mouse Model

BACKGROUND

The role of IL-38, a new member of the IL-1 family, in airway eosinophilic inflammatory conditions such as asthma is unclear. To investigate the role of IL-38 in airway eosinophilic inflammation, an IL-38-gene deficient (KO) murine asthma model was analyzed.

METHODS

The numbers of eosinophils and neutrophils, and levels of IL-5, IL-13 and IL-17A protein and mRNA in bronchoalveolar lavage fluid (BALF) and lung tissue were compared between wild-type (WT) and IL-38-KO mice after OVA sensitization and challenge. The effects of additional purified recombinant mouse (rm) IL-38 protein were investigated in the IL-38-KO murine asthma model.

RESULTS

The IL-38 and IL-5 mRNA in WT mice was significantly higher after OVA challenge than after saline challenge (p<0.05). The number of airway eosinophils in IL-38-KO mice was significantly lower than in WT mice after OVA challenge (p<0.01). BALF analysis confirmed the lower number of airway eosinophils in IL-38-KO mice and showed that this was significantly associated with lower IL-5 protein levels (r=0.92, p<0.0001). However, the additional rm IL-38 protein did not neutralize airway eosinophilia in IL-38-KO mice.

CONCLUSION

IL-38 may enhance airway eosinophilic inflammation in asthma through IL-5 induction.

Clinical Characteristics of Relapsing Polychondritis: A Report of 8 Cases in Japan

OBJECTIVES

Relapsing polychondritis (RP) is a very rare autoimmune disorder characterized by recurrent episodes of inflammation and destruction of cartilaginous tissues. We examined the clinical characteristics, management, and outcomes of Japanese RP patients.

METHODS

We identified 8 RP cases in our department between 2003 and 2017. Detailed clinical features, testing, treatment, and outcomes were recorded.

RESULTS

The mean time from symptom onset to diagnosis was 9 months. Four cases presented with auricular chondritis and laryngotracheal involvement and 3 cases presented with a saddle nose deformity. Anti-type II collagen antibody was positive in 5 of 6 cases. Of 3 cases with associated diseases (rheumatoid arthritis, ulcerative colitis, and Sjögren's syndrome), 2 died of respiratory failure.

CONCLUSIONS

When RP is diagnosed, early computed tomography or pulmonary function testing is essential to enable early treatment. Undiagnosed airway involvement can cause tracheobronchial wall fibrosis, leading to fixed stenosis.

Low positive titer of anti-melanoma differentiation-associated gene 5 antibody is not associated with a poor long-term outcome of interstitial lung disease in patients with dermatomyositis

BACKGROUND

Anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5-Ab) is associated with fatal rapidly progressive interstitial lung disease (RP-ILD) in patients with dermatomyositis (DM). We attempted to clarify whether anti-MDA5-Ab is associated with long-term outcomes in patients with DM-ILD.

METHODS

Thirty-six patients with DM-ILD were retrospectively analyzed for their serum anti-MDA5-Ab by using an enzyme-linked immunosorbent assay. We analyzed the association between clinical parameters, including the serum levels of anti-MDA5-Ab and ferritin.

RESULTS

Fourteen patients (39%) were positive for anti-MDA5-Ab. The serum levels of anti-MDA5-Ab and ferritin in 7 patients with acute death were higher than those in the surviving patients. An "unclassifiable pattern" on chest computed tomography and the development of RP-ILD were also prognostic markers. The serum levels of anti-MDA5-Ab and ferritin (cut-off levels, 100 IU/mL and 899 ng/mL, respectively) were markers predictive of acute death, showing good sensitivity (86% and 83%) and specificity (97% and 100%). All 7 patients with acute death developed RP-ILD and were positive for anti-MDA5-Ab, including 6 patients with a high titer (≥100 IU/mL), whereas only 2 patients (29%) developed RP-ILD among the 7 survivors with a low titer of anti-MDA5-Ab ( < 100 IU/mL). In contrast, a low positive titer of anti-MDA5-Ab was not associated with changes in pulmonary function for 2 years.

CONCLUSIONS

Although a high serum titer of anti-MDA5-Ab (≥100 IU/mL) is associated with acute death via the development of RP-ILD, outcomes in the chronic phase for patients with a low titer of anti-MDA5-Ab ( < 100 IU/mL) were similar to those of patients without anti-MDA5-Ab.

The co-existence of Lemierre's syndrome and Bezold's abscesses due to Streptococcus constellatus: A case report

RATIONALE

The ancient infectious diseases, Lemierre's Syndrome and Bezold's Abscesses are rare.

PATIENT CONCERNS

A 70-year-old Japanese woman with a 15-year history of Parkinson's disease was referred to our hospital due to fever, occipital headache and bilateral shoulder pain that had continued for three months. She had been prescribed prednisolone due to a diagnosis of polymyalgia rheumatica.

DIAGNOSES

A blood culture revealed bacteremia of Streptococcus constellatus. In addition, computed tomography revealed Bezold's abscesses and Lemierre's syndrome.

INTERVENTIONS

We administered ceftriaxone for 31 days, followed by oral amoxicillin.

OUTCOMES

The patient recovered and the abscesses improved.

LESSONS

This case underscores the importance of blood culture tests and cross-referencing with radiological imagings in the diagnoses of these rare critical infectious diseases that mimic polymyalgia rheumatica.

Successful Treatment of Rapidly Progressive Unclassifiable Idiopathic Interstitial Pneumonia with Anti-melanoma Differentiation-associated Gene-5 Antibody by Intensive Immunosuppressive Therapy

We describe a case of a woman who presented with a persistent cough, general fatigue, and a fever. Interstitial lung disease was rapidly progressive and resistant to high-dose steroid therapy. She tested positive for the presence of anti-melanoma differentiation-associated gene 5 (MDA-5) antibody, although she had no skin manifestations of dermatomyositis. She was eventually diagnosed with unclassifiable idiopathic interstitial pneumonia and was successfully treated with intensive immunosuppressive therapy including intravenous cyclophosphamide. To our knowledge, this is the first report of anti-MDA-5 antibody in a patient with idiopathic interstitial pneumonia.

The Successful Treatment of Myeloperoxidase Antineutrophil Cytoplasmic Antibody-positive Hypertrophic Pachymeningitis in Patients with the Limited Form of Granulomatosis with Polyangiitis Using Methotrexate: Two Case Reports

Recent findings have indicated a close relationship between myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-positive hypertrophic pachymeningitis and the limited form of granulomatosis with polyangiitis (GPA). In Japan, MPO-ANCA-positive hypertrophic pachymeningitis predominantly occurs in elderly individuals. We herein describe the cases of two patients with MPO-ANCA-positive hypertrophic pachymeningitis associated with the limited form of GPA who were successfully treated with a combination of corticosteroids and methotrexate. Although methotrexate has been shown to be less effective than cyclophosphamide for inducing the remission of GPA in patients with organ-threatening diseases, its safety and efficacy may make it a useful alternative treatment modality for patients with the limited form of GPA who show meningeal involvement.

Association of anti-aminoacyl-transfer RNA synthetase antibody and anti-melanoma differentiation-associated gene 5 antibody with the therapeutic response of polymyositis/dermatomyositis-associated interstitial lung disease

BACKGROUND

We attempted to clarify whether the presence of anti-aminoacyl-transfer RNA synthetase antibody (anti-ARS Ab) or anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5 Ab) is associated with the therapeutic response of polymyositis/dermatomyositis-associated interstitial lung disease (PM/DM-ILD).

METHODS

We retrospectively investigated 22 patients with PM/DM-ILD (10 positive for anti-ARS Ab and nine positive for anti-MDA5 Ab) for whom antibody analysis of conserved serum was possible. We assessed mortality in the first three months as the therapeutic response in the acute phase and compared changes in clinical data for up to one year considered as the chronic phase. We classified the clinical changes over the year into three groups: Improvement (increased % vital capacity [%VC] or diffusing capacity of the lung for carbon monoxide [%D_LCO]≥10 or 15%), deterioration (decreased %VC or %D_LCO≥10 or 15%), and no change (remainder of the changes). The extent of abnormality demonstrated by high-resolution computed tomography (HRCT) was scored.

RESULTS

Positivity for anti-MDA5 Ab, but not for anti-ARS Ab, was associated with mortality in the first 3 months. Evaluation of the therapeutic response in the first year showed that positivity for the anti-ARS Ab, but not for the anti-MDA5 Ab, was associated with an improvement in %D_LCO and a decline in the serum KL-6 levels. Positivity for the anti-ARS Ab or negativity for anti-MDA5 Ab was associated with a greater decrease in bronchial dilatation as seen by HRCT.

CONCLUSIONS

Anti-ARS and anti-MDA5 Abs are associated with the therapeutic response of PM/DM-ILD.

A retrospective cohort study of outcome in systemic sclerosis-associated interstitial lung disease

BACKGROUND

The relationship between the histological pattern and survival in systemic sclerosis-associated interstitial lung disease (SSc-ILD) is unclear. In patients with SSc-ILD, we investigated whether the clinical data obtained by non-invasive examinations could be used for prognostic evaluation, and attempted to clarify whether complicating acute exacerbation (AE) and the selection of pharmacological therapy were associated with survival.

METHODS

Thirty-five patients with SSc-ILD, who had not been diagnosed by surgical lung biopsy were analyzed, retrospectively. The HRCT findings were evaluated by 2 radiologists and classified into "CT-UIP" or "CT-inconsistent with UIP" patterns based on whole lung interpretations. HRCT scores were calculated based on the extent of abnormality evidenced by HRCT. The log-rank test was used to determine variables, including clinical parameters and histories.

RESULTS

Twelve (34%) of the 35 patients died during a median follow-up period of approximately 7.9 years. The log-rank test showed that a higher mortality was associated with higher age, a CT-UIP pattern, a higher score for ground-glass attenuation with traction bronchiectasis on HRCT, and complicating AE, whereas a lower mortality was significantly associated with the use of immunosuppressants. A CT-UIP pattern was significantly associated with a higher incidence of later AE.

CONCLUSION

Treatment with immunosuppressants was associated with a longer survival, and complicating AE is a predictor of shortened survival in SSc-ILD patients. Among the clinical parameters determined by non-invasive examinations, a CT-UIP pattern and the extent of fibrotic lesions on HRCT, but not a histological pattern of UIP, may be predictors of shortened survival.

An Autopsy Case of Anti-melanoma Differentiation-associated Gene-5 Antibody-positive Clinical Amyopathic Dermatomyositis Complicated by Rapidly Progressive Interstitial Lung Disease

A 62-year-old man presented with heliotrope rash, Gottron's sign, and mild muscle weakness. Both of his lung fields showed interstitial changes that worsened rapidly. He was diagnosed with clinical amyopathic dermatomyositis with rapidly progressive interstitial lung disease. The patient died of respiratory failure, despite the administration of immunosuppressive therapy. Autopsy revealed diffuse alveolar damage. An antibody analysis, which was performed postmortem, detected the presence of anti-melanoma differentiation-associated gene (MDA)-5 antibodies. Clinicians should note the clinical, radiologic, and serologic findings to predict anti-MDA-5 antibody-associated rapidly progressive interstitial lung disease.

IL-38: A new factor in rheumatoid arthritis

The newly characterized cytokine IL-38 (IL-1F10) belongs to the IL-1 family of cytokines. Previous work has demonstrated that IL-38 inhibited Candida albicans-induced IL-17 production from peripheral blood mononuclear cells. However, it is still unclear whether IL-38 is an inflammatory or an anti-inflammatory cytokine. We generated anti-human IL-38 monoclonal antibodies in order to perform immunohistochemical staining and an enzyme-linked immunosorbent assay. While human recombinant IL-38 protein was not cleaved by recombinant caspase-1, chymase, or PR3 in vitro, overexpression of IL-38 cDNA produced a soluble form of IL-38 protein. Furthermore, immunohistochemical analysis showed that synovial tissues obtained from RA patients strongly expressed IL-38 protein. To investigate the biological role of IL-38, C57BL/6 IL-38 gene-deficient (^−/−) mice were used in an autoantibody-induced rheumatoid arthritis (RA) mouse model. As compared with control mice, IL-38 ^(−/−) mice showed greater disease severity, accompanied by higher IL-1β and IL-6 gene expression in the joints. Therefore, IL-38 acts as an inhibitor of the pathogenesis of autoantibody-induced arthritis in mice and may have a role in the development or progression of RA in humans.

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The soluble form of IL-38 is detected in the sera obtained from of RA patients.

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IL-38 protein was highly expressed in the synovial lining of RA synovium.

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IL-38 expression was up-regulated during arthritis in mice at the mRNA level.

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IL-38 may attenuate joint inflammation by inhibiting the IL-1 induced inflammation.

Successful treatment of rectal ulcers in a patient with systemic lupus erythematosus using corticosteroids and tacrolimus

Systemic lupus erythematosus (SLE) is frequently accompanied by gastrointestinal symptoms. Although all parts of the gastrointestinal tract may be affected, colonic involvement is quite rare. Colonic ulceration, particularly in the rectum, is associated with a high mortality rate in patients with SLE, despite immunosuppressive therapy. While a standard regimen for treating rectal ulcers as a complication of SLE has not been established, combination therapy with steroids and immunosuppressive agents is necessary because of the associated high mortality rate. In this report, we describe a patient with SLE whose condition was complicated with ulcerative lesions in the rectum and sigmoid colon; the lesions were successfully treated with a combination of corticosteroids and tacrolimus therapy. Tacrolimus could be a useful additional or alternative modality for treating rectal involvement in SLE.

IL-33/ST2 promotes tissue mastocytosis under conditions of inflammation (CCR3P.219)

Mast cells (MC) are potent innate immune cells that accumulate in chronically inflamed tissues, where they have been implicated in multiple allergic and inflammatory diseases. MC express the IL-33 receptor ST2, and this new member of the IL-1 cytokine family is recognized as an important pathway both for direct MC activation and for priming MC to respond to other pro-inflammatory signals. However, IL-33 has no known role in tissue mastocytosis. Using primary MC cultured from human skin, we found that IL-33 did not alter MC proliferation but instead protected MC from apoptosis, principally through upregulation of the anti-apoptotic molecule BCLXL. Murine bone marrow-derived MC demonstrated a similar response to IL-33, dependent entirely upon ST2, allowing us to test the role of this biology in vivo. Mice lacking ST2 exhibited fewer peritoneal MC as well as reduced accumulation of MC in inflamed arthritic joints and helminth-infected intestine. Upon engraftment into the peritoneum, WT MC exhibited a clear, IL-33-mediated survival advantage over ST2-deficient MC, in particular after thioglycollate-induced peritonitis. Together, these data reveal a novel, cell-intrinsic role for the IL-33/ST2 axis in tissue mastocytosis, especially under conditions of local inflammation.

Successful treatment of macrophage activation syndrome in a patient with dermatomyositis by combination with immunosuppressive therapy and plasmapheresis

Macrophage activation syndrome (MAS), also known as secondary hemophagocytic lymphohistiocytosis, is mediated by cytokine overproduction from excessive activation of T lymphocytes and macrophages. We present a dermatomyositis patient with MAS, caused by hypercytokinemia. The combination of tacrolimus and plasma exchange therapy was effective in this case for treating MAS. This combination therapy is especially useful for MAS refractory to steroids.

A case of late-onset systemic lupus erythematosus with severe anemia

A 59-year-old woman was referred to our hospital because of severe anemia and leucopenia. Although she developed mild arthralgia without the typical symptoms of systemic lupus erythematosus (SLE), positivity for anti-Sm antibodies led us to a diagnosis of late-onset SLE. Autoimmune hemolytic anemia (AIHA) and suppression of reticulocyte production were considered to have been involved in the etiology of severe anemia. Administration of oral prednisolone (PSL) resulted in a marked improvement of the hematological abnormalities. As late-onset SLE is rare and patients tend to show the typical symptoms less frequently, close attention should be focused on latent symptoms and immunological findings.

Interleukin-33 primes mast cells for activation by IgG immune complexes

Mast cells (MCs) are heterogeneous cells whose phenotype is modulated by signals received from the local microenvironment. Recent studies have identified the mesenchymal-derived cytokine IL-33 as a potent direct activator of MCs, as well as regulator of their effector phenotype, and have implicated this activity in the ability of mast cells to contribute to murine experimental arthritis. We explored the hypothesis that IL-33 enables participation of synovial MCs in murine K/BxN arthritis by promoting their activation by IgG immune complexes. Compared to wild-type (WT) control mice, transgenic animals lacking the IL-33 receptor ST2 exhibited impaired MC-dependent immune complex-induced vascular permeability (flare) and attenuated K/BxN arthritis. Whereas participation of MCs in this model is mediated by the activating IgG receptor FcγRIII, we pre-incubated bone marrow-derived MCs with IL-33 and found not only direct induction of cytokine release but also a marked increase in FcγRIII-driven production of critical arthritogenic mediators including IL-1β and CXCL2. This "priming" effect was associated with mRNA accumulation rather than altered expression of Fcγ receptors, could be mimicked by co-culture of WT but not ST2(-/-) MCs with synovial fibroblasts, and was blocked by antibodies against IL-33. In turn, WT but not ST2(-/-) MCs augmented fibroblast expression of IL-33, forming a positive feedback circuit. Together, these findings confirm a novel role for IL-33 as an amplifier of IgG immune complex-mediated inflammation and identify a potential MC-fibroblast amplification loop dependent on IL-33 and ST2.

Synovial fibroblasts promote the expression and granule accumulation of tryptase via interleukin-33 and its receptor ST-2 (IL1RL1)

A characteristic feature of tissue resident human mast cells (MCs) is their hTryptase-beta-rich cytoplasmic granules. Mouse MC protease-6 (mMCP-6) is the ortholog of hTryptase-beta, and we have shown that this tetramer-forming tryptase has beneficial roles in innate immunity but adverse roles in inflammatory disorders like experimental arthritis. Because the key tissue factors that control tryptase expression in MCs have not been identified, we investigated the mechanisms by which fibroblasts mediate the expression and granule accumulation of mMCP-6. Immature mouse bone marrow-derived MCs (mBMMCs) co-cultured with fibroblast-like synoviocytes (FLS) or mouse 3T3 fibroblasts markedly increased their levels of mMCP-6. This effect was caused by an undefined soluble factor whose levels could be increased by exposing FLS to tumor necrosis factor-alpha or interleukin (IL)-1beta. Gene expression profiling of mBMMCs and FLS for receptor.ligand pairs of potential relevance raised the possibility that IL-33 was a sought after fibroblast-derived factor that promotes tryptase expression and granule maturation via its receptor IL1RL1/ST2. MCs lacking IL1RL1 exhibited defective fibroblast-driven tryptase accumulation, whereas recombinant IL-33 induced mMCP-6 mRNA and protein accumulation in wild-type mBMMCs. In agreement with these data, synovial MCs from IL1RL1-null mice exhibited a marked reduction in mMCP-6 expression. IL-33 is the first factor shown to modulate tryptase expression in MCs at the mRNA and protein levels. We therefore have identified a novel pathway by which mesenchymal cells exposed to inflammatory cytokines modulate the phenotype of local MCs to shape their immune responses.

Arabidopsis Tic62 and ferredoxin-NADP(H) oxidoreductase form light-regulated complexes that are integrated into the chloroplast redox poise

Translocation of nuclear-encoded preproteins across the inner envelope of chloroplasts is catalyzed by the Tic translocon, consisting of Tic110, Tic40, Tic62, Tic55, Tic32, Tic20, and Tic22. Tic62 was proposed to act as a redox sensor of the complex because of its redox-dependent shuttling between envelope and stroma and its specific interaction with the photosynthetic protein ferredoxin-NADP(H) oxidoreductase (FNR). However, the nature of this close relationship so far remained enigmatic. A putative additional localization of Tic62 at the thylakoids mandated further studies examining how this feature might be involved in the respective redox sensing pathway and the interaction with its partner protein. Therefore, both the association with FNR and the physiological role of the third, thylakoid-bound pool of Tic62 were investigated in detail. Coexpression analysis indicates that Tic62 has similar expression patterns as genes involved in photosynthetic functions and protein turnover. At the thylakoids, Tic62 and FNR form high molecular weight complexes that are not involved in photosynthetic electron transfer but are dynamically regulated by light signals and the stromal pH. Structural analyses reveal that Tic62 binds to FNR in a novel binding mode for flavoproteins, with a major contribution from hydrophobic interactions. Moreover, in absence of Tic62, membrane binding and stability of FNR are drastically reduced. We conclude that Tic62 represents a major FNR interaction partner not only at the envelope and in the stroma, but also at the thylakoids of Arabidopsis thaliana and perhaps all flowering plants. Association with Tic62 stabilizes FNR and is involved in its dynamic and light-dependent membrane tethering.

Activation of invariant natural killer T cells by synthetic glycolipid ligands suppresses autoantibody-induced arthritis

OBJECTIVE

Stimulation of invariant natural killer T (iNKT) cells with SGL-S23, a novel synthetic glycolipid analog of alpha-galactosylceramide with an elongated sphingosine chain, has been shown to strongly suppress K/BxN serum transfer arthritis. This study was designed to evaluate the protective effects of SGL-S23 in an effector phase of arthritis.

METHODS

To induce arthritis, C57BL/6 mice were injected with 150 mul of serum from K/BxN mice (KRN TCR-transgenic mice crossed with nonobese diabetic mice). Subsequently, synthetic glycolipid ligands were administered intraperitoneally twice, either 3 times starting on day 0 (the day of K/BxN serum injection) or twice starting on day 3. Neutralizing antibody against interferon-gamma (IFNgamma) interleukin-4 (IL-4), IL-10, or transforming growth factor beta was administered 4 hours before injection of SGL-S23. Recombinant IFNgamma was administered subcutaneously every day. The severity of arthritis was monitored using a macroscopic scoring system. Cytokine production and plasma histamine levels were measured by enzyme-linked immunosorbent assay.

RESULTS

SGL-S23 strongly suppressed K/BxN serum transfer arthritis by inhibiting inflammatory cell infiltration and subsequent destruction of cartilage and bone. The inhibitory effect mediated by SGL-S23 was abolished by neutralization of IFNgamma. Systemic administration of IFNgamma prevented the development of inflammatory arthritis. Histamine release was suppressed by administration of SGL-S23 or IFNgamma. Degranulated mast cells in the synovium were significantly reduced in SGL-S23-treated mice, suggesting that suppression of mast cell activation contributed to the inhibition of arthritis.

CONCLUSION

These findings suggest that activation of iNKT cells with glycolipid ligands holds promise with regard to the treatment of autoimmune diseases such as rheumatoid arthritis. SGL-S23 has clinical benefit over alpha-galactosylceramide since it induces a weaker cytokine production response in iNKT cells, therefore reducing potential side effects caused by excessive cytokine release.

IFN-gamma inhibits inflammatory arthritis via suppression of mast cell activation. (129.23)

KBxN mice spontaneously develop arthritis similar to RA in humans, and transfer of serum from arthritic K/BxN mice into healthy animals provokes arthritis within days independently on T and B cells. K/BxN serum-induced arthritis is mediated by anti-glucose-6-phsophate-isomerase IgGs. Here we demonstrate that synthetic glycolipid ligand, a-galactocylceramide (alpha-GalCer) or its analogue with an elongated sphingosine chain strongly suppressed K/BxN serum transfer arthritis by inhibiting inflammatory cellular infiltration and subsequent destruction of cartilage and bone. The inhibitory effect mediated by these glycolipd ligands was abolished by neutralization of IFN-gamma and systemic administration of IFN-gamma prevented the development of inflammatory arthritis. Furthermore, we demonstrate that histamine release involved in the induction of arthritis was suppressed by administration of glycolipid ligands or IFN-gamma. In addition, degranulation of mast cells in synomium was significantly suppressed in glycolipid ligands-treated mice, suggesting that the suppression of mast cell activation contributes to the inhibition of arthritis.