Reactivation of Intestinal Inflammation Is Suppressed by Catestatin in a Murine Model of Colitis via M1 Macrophages and Not the Gut Microbiota

Abstract

While there is growing awareness of a relationship between chromogranin-A (CHGA) and susceptibility to inflammatory conditions, the role of human catestatin [(hCTS); CHGA352-67] in the natural history of established inflammatory bowel disease is not known. Recently, using two different experimental models, we demonstrated that hCTStreated mice develop less severe acute colitis. We have also shown the implication of the macrophages in this effect. The aims of this study were to determine (1) whether hCTS treatment could attenuate the reactivation of inflammation in adult mice with previously established chronic colitis; (2) whether this effect is mediated through macrophages or the gut microbiota. Quiescent colitis was induced in 7-8-week-old C57BL6 mice using four cycles (2-4%) of dextran sulfate sodium. hCTS (1.5 mg/kg/day) treatment or vehicle started 2 days before the last induction of colitis and continuing for 7 days. At sacrifice, macro-and microscopic scores were determined. Colonic pro-inflammatory cytokines [interleukin (IL)-6, IL-1β, and TNF-α], anti-inflammatory cytokines (IL-10, TGF-β),classically activated (M1) (iNOS, Mcp1), and alternatively activated (M2) (Ym1, Arg1) macrophages markers were studied using ELISA and/or RT-qPCR. In vitro, peritoneal macrophages isolated from naïve mice and treated with hCTS (10 −5 M, 12 h) were exposed to either lipopolysaccharide (100 ng/ml, 12 h) to polarize M1 macrophages or to IL-4/IL-13 (20 ng/ml) to polarize M2 macrophages. M1/M2 macrophage markers along with cytokine gene expression were determined using RT-qPCR. Feces and mucosa-associated microbiota (MAM) samples were collected, and the V4 region of 16 s rRNA was sequenced. Micro-and macroscopic scores, colonic IL-6, IL-1β, TNF-α, and M1 macrophages markers were significantly decreased in the hCTS-treated group. Treatment did not have any effect on colonic IL-10, TGF-β, and M2 markers nor modified the bacterial richness, diversity, or the major phyla in colitic fecal and MAM samples. In vitro, pro-inflammatory cytokines levels, as well as their gene expression, were significantly reduced in hCTS-treated M1 macrophages. hCTS treatment did not affect M2 macrophage markers. These findings suggest that hCTS treatment attenuates the severity of inflammatory relapse through the modulation of the M1 macrophages and the release of pro-inflammatory cytokines.

Serum Catestatin Levels and Arterial Stiffness Parameters Are Increased in Patients with Inflammatory Bowel Disease

“…To the best of our knowledge, only one study thus far has measured serum CST levels in a small sample of IBD patients. However, serum CST concentrations were not their primary outcome and other relevant clinical information, as well as biochemical parameters are lacking in that study [31]. Therefore, we believe that this study is the first clinical study to investigate serum CST levels in the IBD population and control subjects with detailed relevance to disease characteristics.…”

“…Intestinal inflammation has been associated with dysfunctional ChgA production [28]. Consequently, several experimental studies on animal colitis model investigated the relationship of intestinal inflammation and CST secretion [29][30][31][32]. Rabbi et al evaluated the impact of CST on intestinal microbiota in mice and revealed significant changes that could potentially lead to development of new options in treating IBD patients [29].…”

“…Rabbi et al evaluated the impact of CST on intestinal microbiota in mice and revealed significant changes that could potentially lead to development of new options in treating IBD patients [29]. Furthermore, a few experimental studies have reported that an injection of human CST significantly attenuates intestinal inflammation and severity of inflammatory reactivation through down-regulation of macrophages, pro-inflammatory cytokines and pathways, including interleukin 6 (IL-6), interleukin 1β, tumor necrosis factor α (TNF-α) and signal transducer and activator of transcription 3 (STAT3) dependent pathway [30][31][32]. Muntjewerff et al even considered CST as an important potential therapeutic modality for various inflammatory and metabolic diseases [33].…”

“…Until this point, and to the best of our knowledge, only one study reported serum CST levels in small subset of IBD patients. However, they did not assess any interaction of CST and other clinically relevant factors and biochemical parameters, except C-reactive protein [31]. In addition, there are no published studies that explored the association of CST levels with arterial stiffness parameters, an important surrogate marker of increased cardiovascular risk, in IBD patients.…”

Semaphorin‐3E attenuates intestinal inflammation through the regulation of the communication between splenic CD11C+ and CD4+CD25− T‐cells

“…Murine models of colitis are key tools used to investigate the pathophysiology of intestinal inflammation (Auletta et al, ; Rabbi et al, ). Dextran sodium sulfate (DSS)‐induced colitis is the most common animal model of IBD used with over 4,000 entries in PubMed (Eissa et al, ); therefore, DSS‐induced colitis was used in this study (PubMed, RRID:SCR_004846).…”