Biomarkers have been actively investigated to supplement functional and imaging modalities to predict the severity, therapeutic responsiveness, and progression of connective tissue disease-associated interstitial lung disease (CTD-ILD). This study aimed to evaluate Krebs von den Lungen 6 (KL-6) as a potential biomarker reflecting the severity of CTD-ILD as assessed through computed tomography (CT) and pulmonary function test (PFT) parameters. This retrospective study included 549 Korean patients with rheumatoid arthritis, systemic sclerosis, inflammatory myositis, and other CTDs with or without concurrent ILD. Serum KL-6 concentration (U/mL) was measured using the latex-enhanced immunoturbidimetric assay method. CT and PFT results were collected within 1 year of serum collection. A semiquantitative grade of ILD extent was evaluated through CT scan (grade 1, 0–25%; grade 2, 26–50%; grade 3, 51–75%; grade 4, 76–100%). CTD-ILD patients (n = 165) had elevated serum KL-6 levels compared to CTD patients without ILD (n = 384) (p < 0.001), and those findings were preserved after adjusting for age, sex, and CTD type. The semiquantitative grade of ILD on CT scan was significantly proportional to the KL-6 level, and the optimal cut-off KL-6 value effectively differentiated each ILD grade. The percent diffusing capacity of the lung for carbon monoxide (DLCO) (p < 0.001) and forced vital capacity (FVC) (p < 0.001) parameters had a moderate, negative correlation with the KL-6 level. Serum KL-6 levels were increased in CTD-ILD patients and had a positive correlation with CT grade and a negative correlation with FVC and DLCO. Serum KL-6 levels may reflect CTD-ILD severity.

Introduction: Adiponectin has been implicated in the pathogenesis of osteoarthritis (OA). We studied the effects of adiponectin on the OA cartilage homeostasis. Methods: Immunohistochemical analysis was performed to evaluate differential expression of adiponectin receptors (AdipoRs) in nonlesional and lesional areas of OA cartilage. Cartilage and chondrocytes from the knee joints of primary OA patients were cultured in the presence of adiponectin (0~30 μg/ml). The levels of total nitric oxide (NO), matrix metalloproteinase (MMP)-1, -3, and -13, and tissue inhibitor of metalloproteinase (TIMP)-1 were measured in the conditioned media. The levels of inducible NO synthase (iNOS) and MMPs were determined with the quantitative real-time reverse transcription-polymerase chain reaction. The concentrations of collagenase-cleaved type II collagen neoepitope (C1-2C) were determined in the supernatant of adiponectin-stimulated OA cartilage explants. The effects of kinase and NOS inhibitors were evaluated in the adiponectin-stimulated chondrocytes. Results: The expression levels of both AdipoR1 and AdipoR2 were significantly higher in lesional than in nonlesional areas of OA cartilage. The increased rate of AdipoR1-positive chondrocytes was twice that of AdipoR2-positive chondrocytes when compared between nonlesional and lesional areas. Adiponectin-stimulated OA chondrocytes showed increased total NO and MMP-1, -3, and -13 levels compared with nonstimulated cells. The TIMP-1 level was not affected. The C1-2C levels were increased by adiponectin in OA cartilage explant culture. AMP-activated protein kinase (AMPK) and c-Jun N-terminal kinase (JNK) inhibitors (compound C and SP600125) significantly suppressed adiponectin-induced production of total NO and MMP-1, -3, and -13. Inducible NOS inhibitors enhanced the expression of the adiponectin-induced MMPs. Conclusions: Adiponectin causes matrix degradation in OA cartilage and increases MMPs and iNOS expression via the AMPK and JNK pathways in human OA chondrocytes. The catabolic effects of adiponectin may be counteracted by NO.

Exosomes are involved in intercellular communication. The aim of this study was to investigate whether circulating exosomes effectively contribute to the inflammatory response in systemic lupus erythematosus (SLE). Exosomes were purified from SLE patients and healthy controls (HCs). Healthy peripheral blood mononuclear cells (PBMCs) were stimulated with exosomes isolated from SLE patients and HCs in the presence or absence of Toll-like receptor (TLR) inhibitors. Production of interferon (IFN)-α, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 were measured. Correlation between exosome levels and SLE disease activity was examined. The serum exosomes levels were significantly higher in SLE patients than in HCs. SLE exosomes induced a higher production of IFN-α, TNF-α, IL-1β, and IL-6 compared to healthy exosomes. SLE serum that was depleted of exosomes and SLE exosomes that were mechanically disrupted failed to induce any significant cytokine production. Exosome-mediated production of TNF-α, IL-1β, and IL-6 was decreased by the TLR4 antagonist, whereas that of IFN-α was suppressed by the TLR1/2, TLR7, and TLR9 antagonists. Exosome levels correlated with disease activity in SLE patients (rho = 0.846, p = 0.008). The circulating exosomes are immunologically active and their levels correlate with disease activity in SLE patients. The circulating exosomes might serve as novel biomarkers of SLE disease activity.

Yoon CH, et al. J Korean Med Sci. 2016 Jul;31(7):1127-1135. https://doi.org/10.3346/jkms.2016.31.7.1127

Histone deacetylase (HDAC) inhibitor has recently been reported to have a therapeutic effect as an anti-inflammatory agent in collagen-induced arthritis (CIA). We investigated the therapeutic effect of a new selective HDAC6 inhibitor, CKD-L, compared to ITF 2357 or Tubastatin A on CIA and regulatory T (Treg) cells in patients with rheumatoid arthritis (RA). CIA was induced by bovine type II collagen (CII) in DBA/1 J mice. Mice were treated with HDAC inhibitor for 18 days. Arthritis score was assessed and histological analysis was performed by hematoxylin and eosin (H&E) stain. Cytotoxic T-lymphocyte associated protein (CTLA)-4 expression in induced Treg cells was analyzed and suppression assay was analyzed using Treg cells and effector T (Teff) cells isolated from naive C57BL/6 mice by flow cytometry. Cytokines were analyzed in peripheral blood mononuclear cells (PBMC) of five patients with RA by enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (PCR). Tumor necrosis factor (TNF) was analyzed using PMA- activated THP-1 cells by ELISA. Suppression assay was analyzed using Treg cells and Teff cells isolated from RA patients by flow cytometry. In the CIA model, CKD-L and Tubastatin A significantly decreased the arthritis score. CKD-L increased CTLA-4 expression in Foxp3+ T cells and inhibited the proliferation of Teff cells in the suppression assay. In RA PBMC, CKD-L significantly inhibited TNF and interleukin (IL)-1β, and increased IL-10. CKD-L and Tubastatin A inhibited TNF secretion from PMA-activated THP-1 cells. CKD-L and ITF 2357 inhibited the proliferation of Teff cells in RA patients in the suppression assay. Tubastatin A had no effect on inhibition of proliferation. CKD-L decreased the arthritis score in CIA, reduced the expression of TNF and IL-1β, and increased the expression of IL-10 in PBMC from RA patients. CKD-L increased CTLA-4 expression and the suppressive function of Treg cells. These results suggest that CKD-L may have a beneficial effect in the treatment of RA.