Low molecular weight xanthan gum suppresses oxidative stress-induced apoptosis in rabbit chondrocytes

A novel coupled fermentation system for low-molecular-weight xanthan gum with diverse biological activities

Xanthan gum (XG) is a bacterial exopolysaccharide widely used in various industries due to its stability and rheological properties. Low-molecular-weight xanthan gum (LXG) exhibits enhanced properties and broader applications, but current degradation methods are limited. This study introduces an innovative coupled fermentation system for the efficient production of LXG. Endo-xanthanase from Microbacterium sp. XT11 was expressed in Pichia pastoris GS115, exhibiting optimal activity at pH 6.0 and 40 °C, with broad pH tolerance. The optimized coupled fermentation system used bean sprouts juice as nitrogen source, the inoculation quantity of X. campestris: P. pastoris was 1: 3, and the pH was controlled at 6.0. In the bioreactor, the total sugar concentration reached 12.12 g/L, the reducing sugar concentration reached 5.32 g/L, and the endo-xanthanase activity increased to 1150.26 U/L, which were 2.13, 2.3, and 3.71 times higher than those at the shake flask level, respectively. The prepared LXG had a molecular weight of 1093 Da and a monosaccharide ratio of 2.0:1.57:0.89 (glucose, mannose, and glucuronic acid). Bioactivity analysis revealed its antioxidant and prebiotic properties, promoting the growth of beneficial intestinal microbiota and metabolite production. This suggests the potential of LXG as a functional ingredient in intestinal health-focused foods and supplements.

Chloroxylenol at environmental concentrations can promote conjugative transfer of antibiotic resistance genes by multiple mechanisms

The intergeneric conjugative transfer of antibiotic resistance genes (ARGs) is recognized as an important way to the dissemination of antibiotic resistance. However, it is unknown whether the extensive use of chloroxylenol (para-chloro-meta-xylenol, PCMX) in many pharmaceutical personal care products will lead to the spread of ARGs. In this study, the abilities and mechanisms of PCMX to accelerate the intergeneric conjugative transfer were investigated. Results showed that exposure of bacteria to environmental concentrations of PCMX (0.20-1.00 mg/L) can significantly stimulate the increase of conjugative transfer by 8.45-9.51 fold. The phenotypic experiments and genome-wide RNA sequencing revealed that 0.02-5.00 mg/L PCMX exposure could increase the content of alkaline phosphatase and malondialdehyde, which are characteristic products of cell wall and membrane damage. In addition, PCMX could lead to excessive production of reactive oxygen species (ROS) by 1.26-2.00 times, the superoxide dismutase and catalase produced by bacteria in response to oxidative stress were not enough to neutralize the damage of ROS, thus promoting the conjugative transfer. Gene Ontology enrichment analysis indicated that cell membrane permeability, pili, some chemical compounds transport and energy metabolism affected conjugative transfer. This study deepened the understanding of PCMX in promoting propagation of ARGs, and provided new perspectives for use and treatment of personal care products.

Zwitterionic polymer modified xanthan gum with collagen II-binding capability for lubrication improvement and ROS scavenging

High friction of damaged cartilage requires long-acting lubricated additive, which can also effectively scavenge reactive oxidative species (ROS) produced by mechanically stimulated chondrocytes. In this study, xanthan gum (XG) was grafted by poly (sulfobetaine methacrylate) (PSBMA) (the [XG]/[SBMA] molar ratio is 1:5 or 1:10), forming nanoparticles and then conjugated with collagen II-binding peptide, finally obtaining CBPXGSB1/5 or CBPXGSB1/10. Therein, the CBPXGSB1/5 was chosen as optimal lubricated additive. The results show that hydrated effect of PSBMA side chains endows CBPXGSB1/5 with favorable lubrication property (COF is 0.063). Furthermore, the CBPXGSB1/5 combining lubrication property and specific binding capability together may achieve the long-acting lubrication for injured cartilage in medical field. The CBPXGSB1/5 also possesses antioxidation verified by DPPH assay and exhibits synergistically enhanced ROS (OH, O₂^- and H₂O₂) scavenging. Besides, cytotoxicity experiment demonstrates that CBPXGSB1/5 has good biocompatibility. Therefore, multifunctional CBPXGSB1/5 developed here may have promising application potential in osteoarthritis treatment.

Mitochondria: Potential Targets for Osteoarthritis

Osteoarthritis (OA) is a common and disabling joint disorder that is mainly characterized by cartilage degeneration and narrow joint spaces. The role of mitochondrial dysfunction in promoting the development of OA has gained much attention. Targeting endogenous molecules to improve mitochondrial function is a potential treatment for OA. Moreover, research on exogenous drugs to improve mitochondrial function in OA based on endogenous molecular targets has been accomplished. In addition, stem cells and exosomes have been deeply researched in the context of cartilage regeneration, and these factors both reverse mitochondrial dysfunctions. Thus, we hypothesize that biomedical approaches will be applied to the treatment of OA. Furthermore, we have summarized the global status of mitochondria and osteoarthritis research in the past two decades, which will contribute to the research field and the development of novel treatment strategies for OA.

Xanthan gum and locust bean gum substrate improves bovine embryo development

One of the major difference between the in vivo and in vitro embryonic environments is the stiffness of the culture substrate. Xanthan gum (XG) and locust bean gum (LBG) are natural materials that are safe, inexpensive and easy to handle. In this study, we investigated the effects of using a polysaccharide culture substrate made from 1% XG and 1% LBG (XG-LBG gel) on bovine embryonic development. Oocytes collected from bovine ovaries were subjected to maturation, and fertilization to generate embryos at an early developmental stage (>4 cell stage). Cleaved embryos were further cultured in a well of 96-well cell culture plate coated with or without XG-LBG gel for 5 days. While the developmental rate up to the blastocyst stage did not differ between the two culture systems (control, 38.0 vs. gel, 38.6%), blastocysts developed on the XG-LBG gel produced significantly high cell numbers and ATP content. Embryos cultured on XG-LBG gels for 24 hr had high expression levels of F-actin and a highly even distribution of E-cadherin. In addition, embryos developed on XG-LBG gel demonstrated increased translocation of YAP to the nucleus and increased connective tissue growth factor (CTGF) protein levels (downstream of Hippo signalling). These findings suggest that soft culture substrates improve embryonic development by enhancing mechanotransduction, including YAP-CTGF signalling.

Characterization and Antioxidant Activity of a Low-Molecular-Weight Xanthan Gum

In the present work, a low-molecular-weight xanthan gum (LW-XG) was successfully obtained via biodegradation of commercial xanthan by the endophytic fungus Chaetomium globosum CGMCC 6882. The monosaccharide composition of LW-XG was glucose, mannose, and glucuronic acid in a molar ratio of 1.63:1.5:1.0. The molecular weight of LW-XG was 4.07 × 10⁴ Da and much smaller than that of commercial xanthan (2.95 × 10⁶ Da). Antioxidant assays showed that LW-XG had a good scavenging ability on DPPH radicals, superoxide anions, and hydroxyl radicals and good ferric reducing power. Moreover, LW-XG exhibited excellent protective effect on H₂O₂-injured Caco-2 cells. Results of this work suggested that LW-XG could be used in foods or pharmaceuticals to alleviate and resist the oxidative damage induced by the overproduction of reactive oxygen species.

Xanthan gum and Locust bean gum gel supports in vitro development of porcine oocytes derived from early antral follicles

Early antral follicle (EAF)-derived porcine oocytes develop more readily on polyacrylamide-gel (PAG) than on plastic plates. Xanthan gum (XG) and locust bean gum (LBG) are edible polysaccharides. We investigated XG-LBG gel supports in the development of EAF-derived porcine oocytes. XG and LBG were mixed in a 1:1 ratio to form a substrate. We cultured oocyte granulosa cell complexes (OGCs) from the EAFs on XG-LBG gels of various concentrations. The oocyte diameters were comparable among the 0.3, 0.5, and 1.0% gels; granulosa cell proliferation was greater on the 1.0% gel. The proliferation and survival rates of the granulosa cells, and the histone H4 at lysine 12 acetylation levels were higher in OGCs cultured on 1.0% XG-LBG than those grown on 0.3% PAG. Development to the blastocyst stage was 13.8% for the XG-LBG gels and 9.4% for PAG. In conclusion, XG-LBG are safe and efficient substrates for in vitro culture of oocytes.

Xanthan Gum Ameliorates Osteoarthritis and Mitigates Cartilage Degradation via Regulation of the Wnt3a/β-Catenin Signaling Pathway

Background

Osteoarthritis (OA) is a joint disease characterized by articular cartilage degeneration and inflammation. We have previously clarified that a xanthan gum (XG) preparation exerts ameliorating effect on a rabbit OA model by regulating matrix metalloproteinase (MMP)-1 and MMP-3, which are critical proteins in the Wnt3a/β-catenin pathway. Thus, it is reasonable to predict that the Wnt3a/β-catenin pathway is involved in the treatment of OA with XG.

Material/Methods

The effect of XG in OA model animals were observed by hematoxylin and eosin staining (HE), Safranin O staining, and Fast Green staining. Articular cartilage degradation on the medial plateau sides was quantified using the modified Pritzker OARSI score. The levels of IL-6, TNF-α, and IL-1β in synovial fluid were determined with ELISA. The protective effect of XG in rat chondrocytes was assessed by CCK8 assay. Moreover, activation of the Wnt3a/β-catenin pathway and the expression of MMP13, ADAMTS5, aggrecan, and collagen II under the influence of XG was measured by Western blot and qRT-PCR.

Results

Our results showed that XG reduced the OARSI score and the concentration of inflammatory cytokines in OA after intra-articular injection. XG acted on Wnt3a/β-catenin in ATDC5 cells in a dose-dependent manner and exhibited a protective effect. XG also decreased the expression of MMP13 and ADAMTS5 and rescued the inhibition of aggrecan and collagen II expression in SNP-stimulated chondrocytes.

Conclusions

These results indicate that the effects of XG are related to the Wnt3a/β-catenin pathway and XG suppresses matrix degradation by inhibiting the expression of MMPs and ADAMTS and promotes aggrecan and collagen II content in the ECM, indicating its favorable potential for use in OA therapy.

HP-1 inhibits the progression of ccRCC and enhances sunitinib therapeutic effects by suppressing EMT

Trametes robiniophila Murr (Huaier) has been used for many years as an adjuvant treatment for tumors. Sunitinib is the first-line therapy for end-stage renal cancer, but its side effects and drug resistance limit its clinical application. Cell counting kit- 8 (CCK-8), colony formation, scratch, and Transwell assays showed that Huaier polysaccharide (HP-1) reduced tumor progression. Its combination with sunitinib elicited stronger antitumor effects, including induction of apoptosis and cycle arrest. HP-1-induced effects depended on CIP2A downregulation and suppression of the EMT process. Moreover, qPCR and western blotting experiments showed that CIP2A downregulation was particularly pronounced after treatment with the combination therapy and was associated with EMT suppression. In addition, the HP-1/sunitinib combination inhibited the PI3K/Akt/VEGFR pathway, reducing the expression of pathway-related proteins. The HP-1-induced enhancement of sunitinib effects on tumor growth were also observed in vivo in a xenograft mouse model. Overall, these results indicated that HP-1 exerted antitumor effects against clear cell renal cell carcinoma (ccRCC) and enhanced the therapeutic efficacy of sunitinib.

Simultaneous production of polyhydroxyalkanoate and xanthan gum: From axenic to mixed cultivation

In the present study, mixed and axenic submerged cultures of Cupriavidus necator and Xanthomonas campestris were performed for simultaneous and individual PHA and XG productions using palm oil (Elaeis guineensis) as substrate. Rotational Central Compound Design (RCCD) was successfully used in the optimization of individual productions of PHA (3.39 g L^-1, Mw = 692.6 kDa) and XG (1.77 g L^-1, Mw = 36.6 × 10⁵ kDa). Novel simultaneous production of PHA (6.43 g L^-1, Mw = 629.2 kDa) and XG (1.98 g L^-1, Mw = 25.0 × 10⁵ kDa), executed in bacterial co-cultivation, revealed to be a successful strategy to increment polymer synthesis, especially PHA. XG bioconversions followed a general trend of lower production in co-culture. Culture configurations also altered polymers properties and characteristics.

Changes in conjunctival epithelial cells after treatment with 0.2% xanthan gum eye drops in mild-moderate dry eye

PURPOSE

To study the effects of xanthan gum eye drops on the ocular surface and conjunctival cytology of patients with mild-moderate dry eye.

METHODS

This prospective, double-masked, controlled trial included 30 patients (age > 60 and Ocular Surface Disease Index score >12 and <33), divided into two groups of 15 subjects and treated with 0.2% xanthan gum eye drops (group 1) or 0.5% carboxymethylcellulose (group 2) qid. After a run-in period with saline qid, patients were evaluated by Ocular Surface Disease Index questionnaire, clinical assessment, and impression cytology at baseline (T0) and after 1 month (T1). For impression cytology, cellularity, cell-to-cell contacts, nucleus/cytoplasm ratio, chromatin aspect, goblet cells distribution, keratinization, and the presence of inflammatory cells were considered. Parameters were scored from 0 (no alterations) to 3 (evident alterations). For statistical analysis, Student's t-test, Wilcoxon rank-sum test, and Mann-Whitney U-test were used.

RESULTS

Clinically, after 1 month of treatment, group 1 showed an improvement of corneal stain (T0 = 1.1 ± 1.4; T1 = 0.5 ± 0.7; p = 0.03) and a reduction of Schirmer I test (T0 = 9.8 ± 6.1; T1 = 5.9 ± 4.1; p = 0.001). In group 2, no differences were found between T0 and T1 for all the clinical tests. For impression cytology, in group 1 cellularity (T0 = 0.6 ± 0.5; T1 = 0.3 ± 0.5; p = 0.05), chromatin aspect (T0 = 1.2 ± 0.4; T1 = 0.8 ± 0.5; p = 0.01), keratinization (T0 = 1 ± 0.7; T1 = 0.5 ± 0.5; p = 0.03), and total score (T0 = 5.8 ± 1.3; T1 = 3.6 ± 1.7; p = 0.003) were significantly ameliorated, while in group 2 only total score improved significantly (T0 = 5 ± 1.4; T1 = 4.3 ± 1.5; p = 0.01). The comparison between groups showed significant amelioration for keratinization in group 1 at T1 (p = 0.02).

CONCLUSION

The treatment with xanthan gum, a molecule with anti-oxidant and mucoadhesive properties, ameliorated conjunctival epithelium of mild-moderate dry eye patients better than carboxymethylcellulose.

Lower range of molecular weight of xanthan gum inhibits apoptosis of chondrocytes through MAPK signaling pathways

LRWXG has previously been reported to have a protective effect on chondrocytes, preventing apoptosis induced by oxidative stress. In this study, we were aimed at determining whether LRWXG exerts its anti-apoptotic activity through the MAPK signaling pathways in chondrocytes. Our results show that, at the cellular level, apoptosis of chondrocytes in the groups treated by LRWXG decreases compared with groups treated by inhibitors alone and model group under conditions of oxidative stress in a dose-dependent manner. Mechanistically at the molecular level, LRWXG regulates the MAPK pathway induced by oxidative stress: The levels of phosphorylation of JNK and p38 proteins in the groups treated by LRWXG are lower than model group, while compared with corresponding groups of inhibitors, there are no significant difference; For other related proteins, LRWXG reduces the levels of the apoptosis-related proteins BAX and cleaved caspase-3, and increases the level of anti-apoptotic protein BCL2. In addition, LRWXG can significantly reduce the levels of inflammatory-related factors such as COX2, PEG2, TNFα and IL1β, and inhibits the expression of MMPs, increasing the content of type II collagen. The results of this research strongly suggest that LRWXG exerts its anti-apoptotic activity via regulating the MAPK signaling pathways in vitro.

Synthesis and In Vitro Antitumor Activity of Novel Bivalent β-Carboline-3-carboxylic Acid Derivatives with DNA as a Potential Target

A series of novel bivalent β-carboline derivatives were designed and synthesized, and in vitro cytotoxicity, cell apoptosis, and DNA-binding affinity were evaluated. The cytotoxic results demonstrated that most bivalent β-carboline derivatives exhibited stronger cytotoxicity than the corresponding monomer against the five selected tumor cell lines (A549, SGC-7901, Hela, SMMC-7721, and MCF-7), indicating that the dimerization at the C³ position could enhance the antitumor activity of β-carbolines. Among the derivatives tested, 4B, 6i, 4D, and 6u displayed considerable cytotoxicity against A549 cell line. Furthermore, 4B, 6i, 4D, and 6u induced cell apoptosis in a dose-dependent manner, and caused cell cycle arrest at the S and G2/M phases. Moreover, the levels of cytochrome C in mitochondria, and the expressions of bcl-2 protein, decreased after treatment with β-carbolines, which indicated that 6i and 6u could induce mitochondria-mediated apoptosis. In addition, the results of UV-visible spectral, thermal denaturation, and molecular docking studies revealed that 4B, 6i, 4D, and 6u could bind to DNA mainly by intercalation.

Selective adipogenic differentiation of human periodontal ligament stem cells stimulated with high doses of glucose

Periodontal tissue damage, accompanied by the degradation and destruction of periodontal tissue collagen, is one of the most clinically common complications and difficulty self-repair in patients with diabetes. Human periodontal ligament stem cells (PDLSC) are the undifferentiated mesenchymal cells that persist in the periodontal ligament after development of periodontal tissue and the ability of PDLSC osteogenic differentiation is responsible for repairing periodontal tissue defects. However, the reasons of high glucose environment in diabetic patients inhibiting PDLSC to repair periodontal tissues are unclear. To address these issues, we propose exposing PDLSC to high-sugar mimics the diabetic environment and investigating the activity of osteogenic differentiation and adipogenic differentiation of PDLSC. At the cellular level, high glucose can promote the adipogenic differentiation and inhibit osteogenic differentiation to decrease the self-repair ability of PDLSC in periodontal tissues. Mechanistically at the molecular level, these effects are elicited via regulating the mRNA and protein expression of C/EBPβ, PPAR-γ.

Construction of injectable, pH sensitive, antibacterial, mineralized amino acid yolk-shell microspheres for potential minimally invasive treatment of bone infection

INTRODUCTION

Treatment of infection within bone is difficult, and conventional surgical treatment brings intense pain to the patients physically and mentally. There is an urgent need to develop injectable nano- and/or micro-medicine for minimally invasive treatment of osteomyelitis.

METHODS

In this paper, amino acid (L-lysine [Lys]) was mineralized into yolk-shell structured CaCO3 microspheres (MSs). The morphologies of the obtained MSs were investigated by scanning electron microscopy and transmission electron microscopy. The composition of CaCO3 MSs was identified by using Fourier transform infrared spectroscopy. The as-prepared CaCO3 MSs were examined with power X-ray diffraction analysis to obtain the crystallographic structure of the MSs.

RESULTS

The as prepared Lys encapsulated CaCO3 MSs (Lys@CaCO3 MSs) were used as micro-drug to improve acidic environment of osteomyelitis caused by bacterial infection and promote osteoblast proliferation under oxidative stress. These pH responsive Lys@CaCO3 MSs have a drug loading efficiency of 89.8 wt % and drug loading content (DLC) of 22.3 wt %.

CONCLUSION

Our results demonstrated that Lys@CaCO3 MSs can effectively kill Staphylococcus aureus and promote proliferation and differentiation of osteoblasts under stimulation of H2O2 at pH = 5.5.

Could Oxidative Stress Regulate the Expression of MicroRNA-146a and MicroRNA-34a in Human Osteoarthritic Chondrocyte Cultures?

Oxidative stress and the overproduction of reactive oxygen species (ROS) play an important role in the pathogenesis of osteoarthritis (OA). Accumulating evidence has demonstrated the involvement of microRNAs (miRNAs) dysregulation in disease development and progression. In this study, we evaluated the effect of oxidative stress on miR-146a and miR-34a expression levels in human OA chondrocytes cultures stimulated by H₂O₂. Mitochondrial ROS production and cell apoptosis were detected by flow cytometry. The antioxidant enzymes SOD-2, CAT, GPx, the transcriptional factor NRF2 and the selected miRNAs were analyzed by qRT-PCR. The H₂O₂-induced oxidative stress was confirmed by a significant increase in superoxide anion production and of the apoptotic ratio. Furthermore, H₂O₂ significantly up-regulated the expression levels of SOD-2, CAT, GPx and NRF2, and modulated miR-146a and miR-34a gene expression. The same analyses were carried out after pre-treatment with taurine, a known antioxidant substance, which, in our experience, counteracted the H₂O₂-induced effect. In conclusion, the induction of oxidative stress affected cell apoptosis and the expression of the enzymes involved in the oxidant/antioxidant balance. Moreover, we demonstrated for the first time the modification of miR-146a and miR-34a in OA chondrocytes subjected to H₂O₂ stimulus and we confirmed the antioxidant effect of taurine.