Serum miRNA Signature in Rheumatoid Arthritis and "At-Risk Individuals".

Background: MicroRNAs (miRNAs) are small non-coding RNAs which have been implicated as potential biomarkers or therapeutic targets in autoimmune diseases. This study examines circulatory miRNAs in RA patients and further investigates if a serum miRNA signature precedes clinical manifestations of disease in arthralgia or "at-risk individuals". Methods: Serum was collected from HC subjects (N = 20), RA patients (N = 50), and arthralgia subjects (N = 10), in addition to a subgroup of the RA patients post-methotrexate (MTX) (N = 18). The FirePlex miRNA Immunology-V2 panel was selected for multiplex analysis of 68 miRNAs in each sample. DNA intelligent analysis (DIANA)-mirPath and Ingenuity Pathway Analysis (IPA) software were used to predict pathways targeted by the dysregulated miRNAs. Results: 8 miRNA (miR-126-3p, let-7d-5p, miR-431-3p, miR-221-3p, miR-24-3p, miR-130a-3p, miR-339-5p, let-7i-5p) were significantly elevated in RA serum compared to HC (all p < 0.01) and 1 miRNA (miR-17-5p) was significantly lower in RA (p < 0.01). High specificity and sensitivity were determined by receiver operating characteristic (ROC) curve analysis. Both miR-339-5p and let-7i-5p were significantly reduced post-MTX (both p < 0.01). MiR-126-3p, let-7d-5p, miR-431-3p, miR-221-3p, miR-24-3p, miR-130a-3p were also significantly elevated in subjects "at risk" of developing RA (all p < 0.05) compared to HC. IPA analysis of this miRNA signature identified downstream targets including key transcription factors NF-κB, STAT-1, STAT-3, cytokines IL-1ß, TNF-α, and matrix-metalloproteases all importantly associated with RA pathogenesis. Conclusion: This study identified six miRNAs that are altered in both RA and "at-risk individuals," which potentially regulate key downstream pathways involved in regulating inflammation. These may have potential as predictive signature for disease onset and early progression.

Insulin-Resistant Pathways Are Associated With Disease Activity in Rheumatoid Arthritis and Are Subject to Disease Modification Through Metabolic Reprogramming: A Potential Novel Therapeutic Approach.

OBJECTIVE: To investigate a role for insulin-resistant pathways in inflammation and therapeutic targeting for disease modification in rheumatoid arthritis (RA). METHODS: RA disease activity and cardiovascular risk factors, including insulin resistance and body mass index (BMI), were assessed in an Irish RA cohort. Glucose transporter 1 (GLUT-1) and GLUT-4 activity in RA and osteoarthritis (OA) synovial tissue was examined using immunohistochemistry. Spontaneous release of proinflammatory mediators from ex vivo RA synovial explants and primary synovial fibroblast (SF) cell culture supernatants was quantified by enzyme-linked immunosorbent assay. Phosphorylated AMP-activated protein kinase (p-AMPK) and GLUT-1 protein expression was analyzed by Western blotting. Cellular glycolytic and oxidative phosphorylation was assessed using extracellular flux analysis. RESULTS: Insulin resistance was independently associated with both BMI (unstandardized coefficient B 0.113 [95% confidence interval (95% CI) 0.059-0.167]; P < 0.001) (n = 61) and swollen joint count in 28 joints (SJC28) (B 0.114 [95% CI 0.032-0.197]; P = 0.008) (n = 61). Increased GLUT-1 expression in RA synovium (n = 26) versus OA synovium (n = 16) was demonstrated (P = 0.0003), with increased expression in the lining, sublining, and vascular regions. In contrast, decreased GLUT-4 expression in the RA lining layer (n = 21) versus the OA lining layer (n = 8) was observed (P = 0.0358). Decreased GLUT-1 protein expression was observed in parallel with increased p-AMPK protein expression in SFs in the presence of metformin (n = 4). Metformin increased glycolytic activity and decreased oxidative phosphorylation in RASFs (n = 7) (P < 0.05 for both). Metformin or aminoimidazole carboxamide ribonucleotide presence decreased spontaneous production of interleukin-6 (IL-6), IL-8, and monocyte chemotactic protein 1 in RA synovial explants and SFs (n = 5-7). CONCLUSION: Insulin resistance is significantly associated with BMI and synovitis in RA, suggesting distinct interplay between glucose availability and inflammation in RA. Furthermore, the effect of metformin on proinflammatory mechanisms suggests a role for AMPK-modifying compounds in the treatment of RA.

Kdm6a and Kdm6b: Altered expression in malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is a rare aggressive cancer of the pleura primarily associated with prior exposure to asbestos. The current standard of care for patients suffering from MPM is a combination of cisplatin and pemetrexed (or alternatively cisplatin and raltitrexed). Most patients, however, die within 24 months of diagnosis. New therapies are therefore urgently required for this disease. Inflammation is thought to be a key element in the pathogenesis of MPM, and recently Kdm6 family members (Kdm6a and Kdm6b) have been identified as playing important roles in inflammatory processes. As such these genes could potentially represent novel candidate targets for intervention in MPM. Using RT-PCR we examined the expression of Kdm6aA and Kdm6b in a panel of MPM cell lines and in a cohort of snap-frozen patient samples isolated at surgery comprising benign, epithelial, biphasic and sarcomatoid histologies. Both Kdm6a and Kdm6b were found to be significantly overexpressed in MPM at the mRNA level. However, tests examining if targeting therapeutically Kdm6a/b using a specific small molecule inhibitor (GSK-J4) was potentially useful for treating MPM, revealed that anti-proliferative activity was higher at lower drug concentrations in cell lines derived from normal mesothelial cells compared to those derived from malignant cells. Treatments with GSK-J4 were found to be associated with the induction of apoptosis and increased expression of pro-inflammatory cytokines. As such our results demonstrate that whilst members of the Kdm6 family are overexpressed in MPM they may not be suitable candidates for therapy and may elicit a cytokine storm.

KAT5 (Tip60) is a potential therapeutic target in malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is a rare aggressive cancer of the pleura. Asbestos exposure (through inhalation) is the most well established risk factor for mesothelioma. The current standard of care for patients suffering from MPM is a combination of cisplatin and pemetrexed (or alternatively cisplatin and raltitrexed). Most patients, however, die within 24 months of diagnosis. New therapies are therefore urgently required for this disease. Lysine acetyltransferases (KATs) including KAT5 have been linked with the development of cisplatin resistance. This gene may therefore be altered in MPM and could represent a novel candidate target for intervention. Using RT-PCR screening the expression of all known KAT5 variants was found to be markedly increased in malignant tumors compared to benign pleura. When separated according to histological subtype, KAT5 was significantly overexpressed in both the sarcomatoid and biphasic subgroups for all transcript variants. A panel of MPM cell lines including the normal pleural cells LP9 and Met5A was screened for expression of KAT5 variants. Treatment of cells with a small molecule inhibitor of KAT5 (MG-149) caused significant inhibition of cellular proliferation (p<0.0001), induction of apoptosis and was accompanied by significant induction of pro-inflammatory cytokines/chemokines.