###### Abstract  
The bioactive peptides hydrolyzed from bone collagen have been found to possess health-promoting effects by regulating chronic diseases such as arthritis and hypertension. In the current study, the anti-inflammatory effect of bovine bone gelatin peptides (GP) was evaluated in 264.7 macrophages cells and followed by animal trials to investigate their interference on inflammatory cytokines and gut microbiota compositions in dextran sodium sulfate (DSS)-induced C57 BL/6 mice. The GP was demonstrated to alleviate the extra secretion of interleukin-6 (IL-6), nitric oxide (NO) and tumor necrosis factor-\(\alpha\)(TNF-\(\alpha\)) in lipopolysaccharide-saccharide (LPS)-induced RAW264.7 cells. In DSS-induced colitis mice, the gavage of GP was demonstrated to ameliorate the IBD symptoms of weight loss, hematochezia and inflammatory infiltration in intestinal tissues. In serum, the proinflammatory-matory cytokines (TNF-\(\alpha\),IL-6, MCP-1, IL-1\(\beta\)) were suppressed along with the decreasing effect on toll-like receptor 4 and cyclooxygenase-2 by GP treatment. In the analysis of gut microbiota, the GP was checked to modulate the abundance of _Akkermansia_, _Parasutterella_, _Peptococcus_, _Bifidobacterium_ and _Saccharibacteria_. The above results imply that GP could attenuate DSS-induced colitis by suppressing the inflammatory cytokines and regulating the gut microbiota. bovine bone gelatin; peptides; inflammatory cytokines; colon; gut microbiota +
Footnote †: journal: _Anticle_  
0000-0001-999-4000-0001-9999-4000-0001-9999-4000-0001-9999-40001-9999-40001-99999-40001-99999-40001-99999-40001-9  
where [7], oyster soft tissue [8], and sturgeon muscle [9] were all demonstrated to have the anti-inflammatory effect on suppressing the expression of the inflammatory cytokines in RAW264.7 macrophages cells. Thus, the RAW264.7 macrophages were generally used as a cell model to evaluate the anti-inflammatory effect of bioactive compounds as its sensitivity to immune stimulation. Isolated from egg white proteins, MLGATSL, DEDTQAMPFR, DEDTQAMPF, and MSYSAGF significantly inhibited the IL-8 and TNF-\(\alpha\) secretion and also down-regulated the mRNA expression of TNF-\(\alpha\), IL-17, IL-6, MCP-1, IL-1\(\beta\), and IFN-\(\gamma\) in colitis mice [10]. Besides, the gut microbiota plays an important role in the homeostasis of intestinal health, meanwhile, diet nutrition could induce the changes of microbiota composition as well as their biological functions, which finally posed the bidirectional communications among the intestinal microbiota and the host [11]. Similar to a previous report, the intake of proteins or bioactive peptides would regulate the composition of gut microbiota, which in turn could participate in the immune responses as well as mucosal transport system [12]. These studies all implied that dietary protein hydrolysate or bioactive peptides could get involved in regulating the composition of the microbiota, which then subsequently affect the immune system and gut homeostasis in promoting gut health. In the meat livestock slaughtering industry, bone is regarded as a by-product with further processing needed for use in feed and fertilizer. Besides water, protein is the major composition, accounting for 11-15% of bone among which collagen accounts for 40-50% of total proteins [13]. Collagen could be further produced to protein hydrolysate as well as bioactive peptides with beneficial effects, such as antihypertension, antioxidant, immune-regulating effect, and prevention of osteearicular diseases [14; 15]. Chicken bone-collagen-derived peptides significantly suppressed the secretion of IL-1\(\beta\) and TNF-\(\alpha\) in cartilage cells, where the small molecule weight fractions showed stronger free radicals scavenging and anti-inflammatory effect [16]. In addition, the collagen-derived peptides were also demonstrated to relieve arthritis and rheumatoid arthritis symptoms [17].