Single Long-lasting Pharmacodynamic Study Of Low Molecular Weight Xanthan Gum In Osteoarthritis

Osteoarthritis(OA)is a degenerative joint disease mainly affecting the elderly.It characterizes articular cartilage destruction,subchondral bone damage,and synovial inflammation.Several therapeutic drugs are available for injection into the joint cavity,such as hyaluronic acid(HA),which is already on the market.However,the presence of hyaluronidase in the human body causes HA to degrade quickly in the joint cavity.It requires repeated injections causing pain to patients and increasing the risk of infection.Xanthan gum(XG)is a microbial extracellular heteropolysaccharide prepared by the fermentation of Xanthomonas campestris(X58).It has been used widely in medical and pharmaceutical fields because of its good biocompatibility,high viscosity,and pseudoplasticity at low concentrations.Our previous studies indicated that intra-articular(IA)injection of low molecular weight xanthan gum(LWXG)inhibited the processes of various OA animal models.LWXG administered twice in five weeks had similar effectiveness to HA administered five times in five weeks.It is necessary to reduce the number of injections and study the longer-lasting pharmacodynamics of LWXG.Therefore,in this experiment,long-lasting single-injection pharmacodynamics evaluated LWXG by extending the dosing interval.To investigate the mechanism of action of LWXG in OA by studying the central metabolic pathways and targets of action after intra-articular injection of LWXG through serum metabolomics and articular cartilage transcriptomics.This paper focuses on the above contents,and the main results include the followings.1.Preparation of xanthan gum APIIn this project,Xanthomonas campestris strains preserved in the laboratory were activated.The XG boutique was obtained through fermentation,isolation,degradation,and purification,followed by anhydrous ethanol precipitation.The multi-angle laser light scattering instrument determined LWXG API with a molecular weight of 8.446×105 Da.It could be used for the subsequent study of this experiment.2.Low molecular weight xanthan gum pharmacodynamic studyIn this experiment,H2O2 stimulation of ATDC5 cells was used to induce the OA injury model.CCK8 investigated the effect of the OA model,western blot,fluorescence staining,and structured illumination microscopy(SIM)after adding LWXG treatment.The results showed that LWXG could inhibit the reduction of cell viability induced by H2O2 stimulation and promote Aggrecan and COL2A1 protein expression in OA cell models.Meanwhile,LWXG could reduce the elevated intracellular ROS level caused by H2O2 stimulation,which has antioxidants and protects mitochondria in cells from damage,thus inhibiting cellular inflammation production and apoptosis.The OA animal model was established by excising the medial meniscus of the left knee in rats.Macroscopic evaluation,histopathological staining score,knee joint differential measurement,rat hindfoot support assay,and Micro-CT scan joint images were used to evaluate the pharmacodynamics of LWXG for seven weeks after a single injection.Compared with the NS group,both LWXG and HA injections improved articular cartilage lesions.LWXG still had therapeutic effects after seven weeks of a single administration,which could be further extended for pharmacodynamic studies at longer dosing intervals.3.Serum metabolomics and articular cartilage transcriptomics in ratsThis study examined serum samples from rats in Sham,NS,and LWXG groups by LC-MS non-targeted metabolomics technique.The results showed that three metabolic pathways,glutathione metabolism,arginine,proline metabolism,and D-glutamine and D-glutamate metabolism,were significantly altered after LWXG injection.The rat articular cartilage samples from Sham,NS,and LWXG groups were sequenced by transcriptome sequencing technology.The differentially expressed genes obtained were analyzed,and the TRPS1 gene was predicted by cis-targeting of LncRNA MSTRG.118244.38.It was screened as a candidate causative gene for LWXG treatment of OA.The next step will be to investigate its pathogenic mechanism in OA,which will help screen drug targets for the therapeutic effects of LWXG.