Mucosal gene signatures to predict response to infliximab in patients with ulcerative colitis.

BACKGROUND AND AIMS: Infliximab is an effective treatment for ulcerative colitis with over 60% of patients responding to treatment and up to 30% reaching remission. The mechanism of resistance to anti-tumour necrosis factor alpha (anti-TNFalpha) is unknown. This study used colonic mucosal gene expression to provide a predictive response signature for infliximab treatment in ulcerative colitis. METHODS: Two cohorts of patients who received their first treatment with infliximab for refractory ulcerative colitis were studied. Response to infliximab was defined as endoscopic and histological healing. Total RNA from pre-treatment colonic mucosal biopsies was analysed with Affymetrix Human Genome U133 Plus 2.0 Arrays. Quantitative RT-PCR was used to confirm microarray data. RESULTS: For predicting response to infliximab treatment, pre-treatment colonic mucosal expression profiles were compared for responders and non-responders. Comparative analysis identified 179 differentially expressed probe sets in cohort A and 361 in cohort B with an overlap of 74 probe sets, representing 53 known genes, between both analyses. Comparative analysis of both cohorts combined, yielded 212 differentially expressed probe sets. The top five differentially expressed genes in a combined analysis of both cohorts were osteoprotegerin, stanniocalcin-1, prostaglandin-endoperoxide synthase 2, interleukin 13 receptor alpha 2 and interleukin 11. All proteins encoded by these genes are involved in the adaptive immune response. These markers separated responders from non-responders with 95% sensitivity and 85% specificity. CONCLUSION: Gene array studies of ulcerative colitis mucosal biopsies identified predictive panels of genes for (non-)response to infliximab. Further study of the pathways involved should allow a better understanding of the mechanisms of resistance to infliximab therapy in ulcerative colitis. ClinicalTrials.gov number, NCT00639821.

Resistin is elevated following traumatic joint injury and causes matrix degradation and release of inflammatory cytokines from articular cartilage in vitro.

OBJECTIVE: Resistin is a secreted factor that is elevated in rheumatoid arthritis (RA) and believed to drive joint inflammation in vivo. This study was undertaken to determine if resistin is present in the joint following joint injury and to elucidate the role of resistin in cartilage degradation. METHODS: The level of resistin was measured in paired synovial fluid (SF) and serum samples from patients following joint injury (anterior cruciate ligament, ACL or meniscus tear). Localization of resistin was visualized by immunohistochemistry of synovial tissue and cartilage from healthy and OA donors. Mouse and human cartilage cultures were used to assess the effect of resistin on cartilage metabolism. RESULTS: In trauma patients, resistin levels declined with increasing time post injury. The resistin levels were highest in samples collected up to 1 week following traumatic injury (SF: 2980 pg/ml, serum: 7901 pg/ml) and lowest in samples collected 6-26 years post injury (SF: 686 pg/ml, serum: 5682 pg/ml). Resistin was shown to be expressed in macrophage-like cells in both healthy and OA synovial tissue. Treatment of mouse cartilage cultures with recombinant resistin led to a dose dependent loss of proteoglycan and induction of inflammatory cytokine and PGE(2) production. Recombinant resistin inhibited proteoglycan synthesis in human cartilage explants. CONCLUSION: Resistin is elevated both systemically and locally in the weeks immediately following joint injury and has a direct effect on cartilage matrix turnover and cytokine production. Resistin may play a role in the early stages of trauma-induced OA and may represent a new therapeutic target to slow joint destruction in OA.

Identification of interleukin-13 related biomarkers using peripheral blood mononuclear cells.

Asthma is a chronic disorder characterized by airway inflammation, reversible bronchial obstruction, hyper-responsiveness and remodelling. Data from human in vitro studies and experimental in vivo models of asthma has implicated interleukin (IL)-13 in the asthma phenotype suggesting that a therapeutic agent against it could be effective in treating asthma. The role of biomarkers is becoming increasingly important in the clinical development of therapeutics. Here we describe the use of the GeneChip((R)) DNA microarray technology platform to explore and identify potential response to therapy biomarkers that are associated with the biology of IL-13. Peripheral blood mononuclear cells (PBMCs) from eight healthy donors were cultured in the presence of IL-13, IL-4, an anti-IL-13 monoclonal antibody (mAb) or an isotype control mAb, and RNA from the treated cells was subjected to microarray analysis. The results revealed a number of genes, such as CCL17 (TARC), CCL22 (MDC), CCL23 (MPIF-1), CCL26 (eotaxin 3) and WNT5A (human wingless-type MMTV integration site family member 5A), that showed increased expression in the IL-13 and IL-4 treatment groups. Real-time polymerase chain reaction (PCR) subsequently confirmed these results. A follow-up study in PBMCs from five additional healthy donors showed that the neutralization of IL-13 completely blocked IL-13-induced TARC, MDC and eotaxin 3 production at the protein level. These data suggest that TARC, MDC, eotaxin 3, CCL23 and WNT5A if validated could serve as potential biomarkers for anti-IL-13 therapeutics.