Immunomodulatory effects of chitosan oligosaccharides produced by chitosanase from Bacillus isolate

Chitosan oligosaccharides (COSs) are short-length oligomers produced by the action of chitosanase enzymes. These oligomers are characterized by high water solubility and bioavailability. COSs have demonstrated several biological activities in the medical field, including antitumor, antimicrobial, antioxidant, and immunomodulatory. This study aimed to assess and purify bio-produced COSs obtained from a culture containing a locally isolated Bacillus cereus strain from an Egyptian soil sample and investigate their biological activities, such as immunostimulatory and anti-inflammatory activities. The COSs were bio-produced by fermentation of a native B. cereus strain in media containing colloidal chitosan hydrolyzed by the action of chitosanase enzyme. COSs were then purified on a column packed with a Sephadex LH-20 column. The purified form of COSs were quantified and detected according to their molecular weights and degree of polymerization by UPLC-Mass spectroscopy. The purified COSs were detected as polymers of GlcN at different degrees of polymerization (DP1-DP6) and different molecular weight ranges (m z^-1). The purified COSs were administered orally to groups of mice to evaluate their immunostimulatory effects on cyclophosphamide-induced immunosuppression by measuring cytokine levels in their thymus glands and spleens. Cytokine analysis revealed that COSs enhanced the release of IL-6, TNF-α, and IFN-γ in both the thymus and spleen (p < 0.05). The activity of COSs as an anti-inflammatory was assessed by inducing edema in the paws using carrageenan. COSs' dose of 500 mg kg^-1 exhibited a potential anti-inflammatory effect when compared to dexamethasone (p < 0.05). This study concluded that the bio-produced COSs have considerable potential and are promising as a drug with immunostimulant activities. These observed activities resulted from the ability of COSs to stimulate the production of different cytokine markers in safe doses. Also, these COSs showed significant anti-inflammatory activity when administered orally.