Role of the tumor necrosis factor antagonists in the treatment of inflammatory bowel disease: an update

Microfibrillar-associated protein 4 as a predictive biomarker of treatment response in patients with chronic inflammatory diseases initiating biologics: secondary analyses based on the prospective BELIEVE cohort study

BACKGROUND

Currently, there are no reliable biomarkers for predicting treatment response in chronic inflammatory diseases (CIDs).

OBJECTIVE

To determine whether serum microfibrillar-associated protein 4 (MFAP4) levels can predict the treatment response to biological therapy in patients with CIDs.

METHODS

The BELIEVE study was originally designed as a prospective, multi-center cohort study of 233 patients with either rheumatoid arthritis, psoriatic arthritis, psoriasis, axial spondyloarthritis, Crohn's disease, or ulcerative colitis, initiating treatment with a biologic agent (or switching to another). Clinical assessment and blood sample collection were performed at baseline and 14-16 weeks after treatment initiation. The primary analyses included participants with available blood samples at baseline; missing data were handled as non-responders. The patients were stratified into the upper tertile of serum MFAP4 (High MFAP4) versus a combined category of middle and lower tertiles (Other MFAP4). The primary outcome was the proportion of patients with clinical response to biologic therapy after 14-16 weeks.

RESULTS

211 patients were included in the primary analysis population. The mean age was 43.7 (SD: 14.8) years, and 120 (59%) were female. Positive treatment response was observed in 41 (59%) and 69 (49%) for High MFAP4 and Other MFAP4, respectively. When adjusting for pre-specified variables (CID, age, sex, smoking status, and BMI), the adjusted OR was 2.28 (95% CI: 1.07 to 4.85) for a positive treatment outcome in the High MFAP4 group.

CONCLUSION

A high MFAP4 status before initiating biological treatment is associated with a positive clinical response, when adjusting for confounding factors.

The Combined Administration of Eicosapentaenoic Acid (EPA) and Gamma-Linolenic Acid (GLA) in Experimentally Induced Colitis: An Experimental Study in Rats

Background/Objectives: Ulcerative colitis (UC) is a chronic inflammatory bowel disease with limited effective treatments, prompting the need for investigation of novel therapeutic approaches. Eicosapentaenoic acid (EPA) and gamma-linolenic acid (GLA) have demonstrated potential anti-inflammatory properties, but their combined effects on UC have not been thoroughly investigated. This study aimed to evaluate the effect of the combined administration of EPA and GLA on clinical and histopathologic features of experimental UC models. Methods: Thirty-six male Wistar rats were randomized in three groups (DSS group, Ensure Plus group, and Oxepa group), with twelve rats in each group. Experimental colitis was induced by administrating dextran sulfate sodium (DSS) 8%. The DSS group received tap water, the Ensure Plus group was given a high caloric diet, and the Oxepa group received a special diet containing high levels of EPA and GLA. Disease activity index (DAI) and microscopic activity index (MAI) were measured. Inflammatory markers were calculated both in blood and large intestine, liver, spleen, and lung tissue samples. Neutrophil and macrophage populations were assessed with immunohistochemistry. Results: No significant differences in the DAI index were found between the groups, but the MAI revealed statistically significant differences (p < 0.001). While no significant differences were observed in tumor necrosis factor-alpha (TNF-α) levels, interleukin-17 (IL-17) levels in the large intestine showed statistically significant differences (p = 0.05), with the Ensure Plus and Oxepa groups displaying lower levels compared to the DSS group (p = 0.021 and p = 0.043, respectively). Significant differences in neutrophil infiltration were found in both the large intestine (p < 0.001) and lungs (p = 0.002), with the Oxepa group showing fewer cells. Similarly, significant differences in macrophage infiltration were observed in the large intestine (p = 0.038) and spleen (p < 0.001), with the Oxepa group having lower macrophage counts. Conclusions: In conclusion, the combination of EPA and GLA demonstrates local anti-inflammatory effects and improves the histopathological outcomes in UC.

The RhoGAP activity of myosin IXB is critical for osteoclast podosome patterning, motility, and resorptive capacity

Osteoclasts are large, multinucleated cells of the monocyte-macrophage lineage that generate specialized substrate adhesion complexes to facilitate their function as bone-degrading cells. The patterning and function of these actin-based complexes, podosomes and sealing zones, are regulated by the small GTPase Rho. Myosin IXB (Myo9b) is a unique actin-based motor protein that contains a RhoGAP domain, which, like other RhoGAPs, is inhibitory to Rho signaling. In this study, Myo9b is shown to be expressed in osteoclasts and act as a critical regulator of podosome patterning and osteoclast function. SiRNA-mediated knockdown of Myo9b results in increased activity of Rho but not Rac in osteoclasts. Knockdown in osteoclasts on glass results in altered podosome patterning and decreased motility, and this effect is reversed by addition of a Rho inhibitor. SiRNA-mediated suppression of Myo9b expression in osteoclasts on bone results in a dramatic loss of resorptive capacity even though sealing zones appear normal. This loss of resorption is also reversible with addition of a Rho inhibitor. Cells with diminished Myo9b levels display mislocalization and suppressed activation of Src, a tyrosine kinase with critical effects on osteoclast actin cytoskeletal rearrangement and function. In addition, siRNA-treated cells display poorly formed microtubule networks and a lack of tubulin acetylation, a marker of microtubule stability. However, short-term addition of TNFα to cells with suppressed Myo9b levels overcomes or circumvents these defects and causes increased sealing zone size and resorptive capacity. These results indicate that the RhoGAP activity of Myo9b plays a key role in regulating the actin-based structures necessary for osteoclast motility and resorption, and confirms that Myo9b can act as a motorized signaling molecule that links Rho signaling to the dynamic actin cytoskeleton.

FOXP3⁺ T regulatory cell modifications in inflammatory bowel disease patients treated with anti-TNFα agents

Treg modulation has been hypothesized as one of the mechanisms by which antitumor necrosis factor α (TNFα) agents exert their action in rheumatoid arthritis (RA) and inflammatory bowel disease (IBD). However, data in IBD are still conflicting. We evaluated CD4⁺CD25⁺FOXP3⁺ (Tregs) by flow cytometry in peripheral blood from 32 adult IBD patient before (T0) and after the induction of anti-TNFα therapy (T1). Eight healthy controls (HCs) were included. We also evaluated the number of FOXP3⁺ cells in the lamina propria (LP) in biopsies taken in a subset of patients and controls. Treg frequencies were significantly increased in peripheral blood from our patients after anti-TNFα therapy compared to T0. T1 but not T0 levels were higher than HC. The increase was detectable only in clinical responders to the treatment. A negative correlation was found among delta Treg levels and the age of patients or disease duration and with the activity score of Crohn's disease (CD). No significant differences were found in LP FOXP3⁺ cells. Our data suggest the possibility that in IBD patients the treatment with anti-TNFα may affect Treg percentages and that Treg modifications may correlate with clinical response, but differently in early versus late disease.

Experimental human endotoxemia: a model of the systemic inflammatory response syndrome?

BACKGROUND

The normal human intravenous endotoxin model has been used for more than 50 years. It was once considered a possible model of sepsis, but, because no infection is present, it is better described as a model of systemic inflammation. We demonstrate herein that at least three of four systemic inflammatory response syndrome (SIRS) criteria are achieved with the model.

METHODS

Otherwise healthy human volunteers were given Escherichia coli endotoxin 2 ng/kg intravenously. Vital signs were monitored, and blood samples were collected over time for assessment of white blood cells (WBCs), cytokines, counter-regulatory hormones, and monocyte receptors.

RESULTS

The means of three variables (core temperature, heart rate, WBC) met the SIRS criteria. Compared with baseline, cytokines were elevated acutely, with tumor necrosis factor-alpha (TNFα) exhibiting temporal primacy over the other cytokines. Counter-regulatory hormones (cortisol, epinephrine) also were elevated acutely. Finally, the monocyte cell-surface receptors cluster of differentiation molecule (CD) 11b and TNF receptor-II were elevated and decreased, respectively.

CONCLUSIONS

The experimental human endotoxin model satisfies SIRS criteria and probably is best described as a model of Toll-like receptor 4 agonist-induced systemic inflammation.

Tumor necrosis factor α inhibits expression of the iron regulating hormone hepcidin in murine models of innate colitis

Background

Abnormal expression of the liver peptide hormone hepcidin, a key regulator of iron homeostasis, contributes to the pathogenesis of anemia in conditions such as inflammatory bowel disease (IBD). Since little is known about the mechanisms that control hepcidin expression during states of intestinal inflammation, we sought to shed light on this issue using mouse models.

Methodology/Principal Findings

Hepcidin expression was evaluated in two types of intestinal inflammation caused by innate immune activation—dextran sulfate sodium (DSS)-induced colitis in wild-type mice and the spontaneous colitis occurring in T-bet/Rag2-deficient (TRUC) mice. The role of tumor necrosis factor (TNF) α was investigated by in vivo neutralization, and by treatment of a hepatocyte cell line, as well as mice, with the recombinant cytokine. Expression and activation of Smad1, a positive regulator of hepcidin transcription, were assessed during colitis and following administration or neutralization of TNFα. Hepcidin expression progressively decreased with time during DSS colitis, correlating with changes in systemic iron distribution. TNFα inhibited hepcidin expression in cultured hepatocytes and non-colitic mice, while TNFα neutralization during DSS colitis increased it. Similar results were obtained in TRUC mice. These effects involved a TNFα-dependent decrease in Smad1 protein but not mRNA.

Conclusions/Significance

TNFα inhibits hepcidin expression in two distinct types of innate colitis, with down-regulation of Smad1 protein playing an important role in this process. This inhibitory effect of TNFα may be superseded by other factors in the context of T cell-mediated colitis given that in the latter form of intestinal inflammation hepcidin is usually up-regulated.