Cytokine Networks in the Pathophysiology of Inflammatory Bowel Disease

Chronic Stress, Inflammation, and Colon Cancer: A CRH System-Driven Molecular Crosstalk

Chronic stress is thought to be involved in the occurrence and progression of multiple diseases, via mechanisms that still remain largely unknown. Interestingly, key regulators of the stress response, such as members of the corticotropin-releasing-hormone (CRH) family of neuropeptides and receptors, are now known to be implicated in the regulation of chronic inflammation, one of the predisposing factors for oncogenesis and disease progression. However, an interrelationship between stress, inflammation, and malignancy, at least at the molecular level, still remains unclear. Here, we attempt to summarize the current knowledge that supports the inseparable link between chronic stress, inflammation, and colorectal cancer (CRC), by modulation of a cascade of molecular signaling pathways, which are under the regulation of CRH-family members expressed in the brain and periphery. The understanding of the molecular basis of the link among these processes may provide a step forward towards personalized medicine in terms of CRC diagnosis, prognosis and therapeutic targeting.

Phosphoinositide 3-Kinase P110δ-Signaling Is Critical for Microbiota-Activated IL-10 Production by B Cells that Regulate Intestinal Inflammation

The phosphoinositide 3-kinase catalytic subunit p110δ (PI3Kδ) gene maps to a human inflammatory bowel diseases (IBD) susceptibility locus, and genetic deletion of PI3Kδ signaling causes spontaneous colitis in mice. However, little is known regarding the role of PI3Kδ on IL-10-producing B cells that help regulate mucosal inflammation in IBD. We investigated the role of PI3Kδ signaling in B cell production of IL-10, following stimulation by resident bacteria and B cell regulatory function against colitis. In vitro, B cells from PI3KδD910A/D910A mice or wild-type B cells treated with PI3K specific inhibitors secreted significantly less IL-10 with greater IL-12p40 following bacterial stimulation. These B cells failed to suppress inflammatory cytokines by co-cultured microbiota-activated macrophages or CD4+ T cells. In vivo, co-transferred wild-type B cells ameliorated T cell-mediated colitis, while PI3KδD910A/D910A B cells did not confer protection from mucosal inflammation. These results indicate that PI3Kδ-signaling mediates regulatory B cell immune differentiation when stimulated with resident microbiota or their components, and is critical for induction and regulatory function of IL-10-producing B cells in intestinal homeostasis and inflammation.

Preventative delivery of IL-35 by Lactococcus lactis ameliorates DSS-induced colitis in mice

Ulcerative colitis (UC) is one of the two major forms of inflammatory bowel disease (IBD) characterized by superficial mucosal inflammation, rectal bleeding, diarrhea, and abdominal pain. Anti-inflammatory and immunosuppressive drugs have been used in the therapy of human UC. Interleukin (IL)-35, which functions as an anti-inflammatory cytokine, has been shown to play a potential therapeutic role in a UC-like mouse colitis induced by dextran sodium sulfate (DSS). However, the contribution of IL-35 via oral administration to colitis prevention has not been determined. In order to explore its preventative potentiality, a dairy Lactococcus lactis NZ9000 strain was engineered to express murine IL-35 (NZ9000/IL-35), and this recombinant bacteria was applied to prevent and limit the development of DSS-induced mouse colitis. We found that oral administration of NZ9000/IL-35 induced the accumulation of IL-35 in the gut lumen of normal mice. When administrated preventatively, NZ9000/IL-35-gavaged mice exhibited decreased weight loss, DAI score, colon shortening as well as colitis-associated histopathological changes in colon, indicating that the oral administration of NZ9000/35 contributed to the suppression of DSS-induced colitis progression. Moreover, much less Th17 cells and higher level of Treg cells in lamina propria, as well as increased colon and serum levels of IL-10 with a concomitant reduced pro-inflammatory cytokines, IL-6, IL-17A, IFN-γ, and TNF-α were apparently regulated by NZ9000/IL-35 in colitis mice. Together, we put forward direct evidence pinpointing the effectiveness of NZ9000/IL-35 in preventing UC-like mouse colitis, implying a potential candidate of this recombinant Lactococcus lactis that prevent the progression of IBD.