Fibromodulin Ablation Exacerbates the Severity of Acute DSS Colitis

Epidemiological studies have linked pigment production to protection against certain human diseases. In contrast to African Americans, European descendants are more likely to suffer from angiogenesis-dependent diseases, and inflammatory diseases such as wet age-related macular degeneration (ARMD) and ulcerative colitis (UC), respectively. Here, we found that albino mice producing high levels of fibromodulin (FMOD) developed less severe acute colitis than mice lacking FMOD as assessed by the clinical symptoms and the histopathological changes. In a dextran sodium sulfate (DSS)-induced acute colitis mouse model, depletion of FMOD affected the expression and localization of tight junction proteins contributing to destruction of the epithelial barrier. Furthermore, this study demonstrates the development of a stronger inflammatory response after DSS treatment in the absence of FMOD. FMOD depletion led to an increase in activated T cells, plasmacytoid dendritic cells (pDCs), and type I IFN production. These findings strongly suggest that FMOD may serve as a potential biomarker in determining disease severity of UC in the population of light-skinned individuals with European descent.

Retroviral Glycoprotein-Mediated Immune Suppression via the potassium Channel KCa3.1- A new strategy for treatment of Inflammatory Bowel Diseases.

Background and Purpose: Peptides derived from retroviral envelope proteins have been shown to possess a wide range of immunosuppressive and anti-inflammatory activities. We have previously reported identification of such a peptide derived from the envelope protein coded by a human endogenous retrovirus (HERV). In this study we assessed effects of this peptide treatment on inhibition of immune response in the DSS-induced mice model of colitis. Furthermore, we identified that in vitro the peptide inhibits the KCa3.1 potassium channel, a potential target for therapy of immune diseases. Experimental Approach: We characterized an immunosuppressive peptide ENV59, from a specific HERV envelope protein, in vivo effects on inflammation control in acute colitis mice model and in vitro on the production of pro-inflammatory cytokines. Furthermore, we described in vitro ENV59-GP3 effects with respect to potency of inhibition on KCa3.1 channels and calcium influx. Key Results: ENV59-GP3 peptide treatment showed reduction of the disease score in the DSS-induced acute colitis mice model, which was comparable to effects of the KCa3.1 channel blocker NS6180. Analysis of cytokine production from DSS-mice model treated animals revealed equipotent inhibitory effects of the ENV59-GP3 and NS6180 compounds on the production of IL-6, TNF-α, IL-1β. Patch clamp studies show that the peptide ENV59-GP3 is a blocker of the potassium channel KCa3.1. Conclusion and Implications: Env59-GP3 represents KCa3.1 channel inhibitor underlining the implications of using virus derived channel blockers for treatment of autoimmune diseases. There are no drugs with a similar mechanism of action currently on the market.

Pineapple Leaf Phenols Attenuate DSS-Induced Colitis in Mice and Inhibit Inflammatory Damage by Targeting the NF-κB Pathway

Colitis is not fully curable, although currently, some treatment options are being adopted. In this study, we investigated the effects of pineapple leaf phenols (PLPs), natural phenol products from pineapple leaves, on DSS-induced colitis in mice. The results showed that PLPs dramatically decreased the inflammatory response by inhibiting NF-κB activation and the secretion of pro-inflammatory factors. Moreover, PLPs provided protection against DSS-induced acute colitis by maintaining epithelial integrity. Caffeic and P-coumaric acids had similar effects and could be the active components responsible for PLPs’ effect on colitis. These results indicate that the oral administration of PLPs might be considered as a therapeutic strategy in the treatment of patients with colitis. However, further research on clinical applications and the exact effect of PLPs on colitis is required.

Characterization of the Synergistic Effect between Ligands of Opioid and Free Fatty Acid Receptors in the Mouse Model of Colitis

Background: Recent studies suggest that lipids, including free fatty acids (FFAs), are necessary for proper μ opioid receptor (MOR) binding and that activation of opioid receptors (ORs) improves intestinal inflammation. The objective of the study was to investigate a possible interaction between the ORs and FFA receptors (FFARs) ligands in the colitis. Methods: The potential synergistic effect of ORs and FFARs ligands was evaluated using mouse model of acute colitis induced by dextran sulfate sodium (DSS, 4%). Compounds were injected intraperitoneally (i.p.) once or twice daily at the doses of 0.01 or 0.02 mg/kg body weight (BW) (DAMGO—an MOR agonist), 0.3 mg/kg BW (DPDPE—a δ OR (DOR) agonist) and 1 mg/kg BW (naloxone—a non-selective OR antagonist, GLPG 0974—a FFAR2 antagonist, GSK 137647—a FFAR4 agonist and AH 7614—a FFAR4 antagonist) for 4 days. Results: Myeloperoxidase (MPO) activity was significantly decreased after DAMGO (0.02 mg/kg BW) and GSK 137647 (1 mg/kg BW) administration and co-administration as compared to DSS group. Conclusions: Treatment with ligands of ORs and FFARs may affect the immune cells in the inflammation; however, no significant influence on the severity of colitis and no synergistic effect were observed.

Amelioration of DSS-induced Acute Colitis in Mice by Recombinant Monomeric Human Interleukin-22

Interleukin-22 (IL-22), a pleiotropic cytokine, is known to have a profound effect on the regeneration of damaged intestinal barriers. The potential therapeutic benefit of IL-22 is expected to be exploited in the attenuation and treatment of colitis. However, because of the disease-promoting role of IL-22 in chronic inflammation, a comprehensive evaluation is required to translate IL-22 into the clinical domain. Here, we present the effective production of soluble human IL-22 in bacteria to prove whether recombinant IL-22 has the ability to ameliorate colitis and inflammation. IL-22 was expressed in the form of a biologically active monomer and a non-functional dimer. Monomeric IL-22 (mIL-22) was highly purified through a series of three separate chromatographic methods and an enzymatic reaction. We reveal that the resulting mIL-22 is correctly folded and is able to phosphorylate signal transducer and activator of transcription 3 in HT-29 cells. Subsequently, we demonstrate that mIL-22 enables the attenuation of dextran sodium sulfate-induced acute colitis in mice, as well as the suppression of pro-inflammatory cytokine production. Collectively, our results suggest that the recombinant mIL-22 is suitable to study the biological roles of endogenous IL-22 in immune responses and can be developed as a biological agent associated with inflammatory disorders.

Adipose tissue-derived mesenchymal stem cells ameliorate experimental acute colitis in rats

Complete treatment of ulcerative colitis (UC) is still difficult, while conventional therapies have various adverse effects. Mesenchymal stem cells (MSCs) have anti-inflammatory and immunomodulatory properties to be a therapeutic candidate for UC. We evaluated therapeutic potential of adipose tissue-derived mesenchymal stem cells (AdSCs) in treatment of an acute colitis rat model using histological and molecular assessments. Thirty male Sprague Dawley acetic acid-induced (2 mL of 3%) acute colitis rat models were randomly divided into three equal groups of control receiving 0.5 mL/kg of normal saline, sulfasalazine group receiving 500 mg/kg sulfasalazine and AdSCs group transplanted transrectally with 2×106 MSCs. They were evaluated histologically and by real time PCR for expression of apoptotic genes until 21 days. MSCs were spindle shape and positive for osteogenic and adipogenic differentiation. They displayed mesenchymal and lacked hematopoietic markers. In control group, severe inflammation, edema, ulcer, necrosis and infiltration of leukocytes were noticed. In sulfasalazine group, a moderate inflammation, edema, ulcer, necrosis and infiltration of leukocytes were visible; and in AdSCs group, mild inflammation, congestion, and infiltration of leukocytes were observed with a mild edema, but necrosis was absent in colonic tissue. A stronger decrease in expression of Bax, together with a higher increase in Bcl-2 was noted in AdSCs group. Based on histological and molecular findings, AdSCs were effective to ameliorate colitis lesions through their anti-inflammatory and anti-apoptotic activities showing that transplantation of AdSCS can be a potentially useful strategy in treatment of colitis.