5-Lipoxygenase-derived lipid mediators are not required for the development of NSAID-induced inflammatory bowel disease in IL-10-/- mice

Blockade of the renin-angiotensin system prevents acute and immunologically relevant colitis in murine models

BACKGROUND

Blockade of the renin-angiotensin system (RAS) has been shown to alleviate inflammatory processes in the gastrointestinal tract. The aim of this study was to determine if blockade of the RAS would be effective in an immunologically relevant colitis model, and to compare outcome with an acute colitis model.

METHODS

A losartan analog, CCG-203025 (C₂₃H₂₆ClN₃O₅S) containing a highly polar sulfonic acid moiety that we expected would allow localized mucosal antagonism with minimal systemic absorption was selected as an angiotensin II type 1a receptor antagonist (AT1aR-A). Two colitis models were studied: (1) Acute colitis was induced in 8- to 10-week-old C57BL/6J mice by 2.5 % dextran sodium sulfate (DSS, in drinking water) for 7 days. (2) IL10-/-colitis Piroxicam (200 ppm) was administered orally in feed to 5-week-old IL-10-/-mice (C57BL/6J background) for 14 days followed by enalaprilat (ACE-I), CCG-203025 or PBS administered transanally for 14 days.

RESULTS

In the DSS model, weight loss and histologic score for CCG-203025 were better than with placebo. In the IL10-/-model, ACE-I suppressed histologic damage better than CCG-203025. Both ACE-I and CCG-203025 reduced pro-inflammatory cytokines and chemokines.

CONCLUSIONS

This study demonstrated the therapeutic efficacy of both ACE-I and AT1aR-A for preventing the development of both acute and immunologically relevant colitis.

Selective Targeting of a Disease-Related Conformational Isoform of Macrophage Migration Inhibitory Factor Ameliorates Inflammatory Conditions

Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine and counterregulator of glucocorticoids, is a potential therapeutic target. MIF is markedly different from other cytokines because it is constitutively expressed, stored in the cytoplasm, and present in the circulation of healthy subjects. Thus, the concept of targeting MIF for therapeutic intervention is challenging because of the need to neutralize a ubiquitous protein. In this article, we report that MIF occurs in two redox-dependent conformational isoforms. We show that one of the two isoforms of MIF, that is, oxidized MIF (oxMIF), is specifically recognized by three mAbs directed against MIF. Surprisingly, oxMIF is selectively expressed in the plasma and on the cell surface of immune cells of patients with different inflammatory diseases. In patients with acute infections or chronic inflammation, oxMIF expression correlated with inflammatory flare-ups. In addition, anti-oxMIF mAbs alleviated disease severity in mouse models of acute and chronic enterocolitis and improved, in synergy with glucocorticoids, renal function in a rat model of crescentic glomerulonephritis. We conclude that oxMIF represents the disease-related isoform of MIF; oxMIF is therefore a new diagnostic marker for inflammation and a relevant target for anti-inflammatory therapy.

Fatty acids, lipid mediators, and T-cell function

Research toward the mechanisms underlying obesity-linked complications has intensified during the last years. As a consequence, it has become clear that metabolism and immunity are intimately linked. Free fatty acids and other lipids acquired in excess by current feeding patterns have been proposed to mediate this link due to their immune modulatory capacity. The functional differences between saturated and unsaturated fatty acids, in combination with their dietary intake are believed to modulate the outcome of immune responses. Moreover, unsaturated fatty acids can be oxidized in a tightly regulated and specific manner to generate either potent pro-inflammatory or pro-resolving lipid mediators. These oxidative derivatives of fatty acids have received detailed attention during the last years, as they have proven to have strong immune modulatory capacity, even in pM ranges. Both fatty acids and oxidized fatty acids have been studied especially in relation to macrophage and T-cells functions. In this review, we propose to focus on the effect of fatty acids and their oxidative derivatives on T-cells, as it is an active area of research during the past 5 years. The effect of fatty acids and their derivatives on activation and proliferation of T-cells, as well as the delicate balance between stimulation and lipotoxicity will be discussed. Moreover, the receptors involved in the interaction between free fatty acids and their derivatives with T-cells will be summarized. Finally, the mechanisms involved in modulation of T-cells by fatty acids will be addressed, including cellular signaling and metabolism of T-cells. The in vitro results will be placed in context of in vivo studies both in humans and mice. In this review, we summarize the latest findings on the immune modulatory function of lipids on T-cells and will point out novel directions for future research.

NSAIDs and the colon

PURPOSE OF REVIEW

To better understand the effects of NSAIDs on the colon.

RECENT FINDINGS

An epidemiological study has confirmed that NSAIDs increase the risk of hospitalizations for lower gastrointestinal complications, though the estimated rate of hospitalization was lower than that for upper gastrointestinal complications. Proton-pump inhibitors were associated with reduction in hospitalizations for upper but not lower gastrointestinal complications. Current research on cyclooxygenase (COX) inhibition in patient and animal models suggests that COX-1 and COX-2 may have different roles in the exacerbation of inflammatory bowel disease. Epidemiological research on the chemoprevention of colorectal cancer with aspirin suggests that the positive effect of risk reduction is only observed after long-term treatment. The search for targets of chemopreventive drugs is ongoing. COX-2 inhibition still seems preferred option, as the effects observed with aspirin (the only chemopreventive agent with some apparent future) are more profound only in tumors and cells expressing COX-2. Other molecules such as nitric oxide NSAIDs, especially nitric oxide aspirin, are under intensive experimental research.

SUMMARY

NSAID use increases the risk of hospitalizations due to complications in the lower gastrointestinal tract. By inhibiting COX-2 or other tumorigenic targets, NSAIDs, especially aspirin or new aspirin derivates, may prevent colon cancer in selected populations.