Modulation of the gut microbiota and short-chain fatty acid production by gac fruit juice and its fermentation in in vitro colonic fermentation

This study aimed to investigate the effects of gac fruit juice and its probiotic fermentation (FGJ) utilizing Lactobacillus paracasei on the modulation of the gut microbiota and the production of short-chain fatty acids (SCFAs). We conducted a comparison between FGJ, non-fermented gac juice (GJ), and control samples through in vitro digestion and colonic fermentation using the human gut microbiota derived from fecal inoculum. Our findings revealed that both GJ and FGJ led to an increase in the viability of Lactobacilli, with FGJ exhibiting even higher levels compared to the control. The results from the 16S rDNA amplicon sequencing technique showed that both GJ and FGJ exerted positive impact on the gut microbiota by promoting beneficial bacteria, notably Lactobacillus mucosae and Bacteroides vulgatus. Additionally, both GJ and FGJ significantly elevated the levels of SCFAs, particularly acetic, propionic, and n-butyric acids, as well as lactic acid, in comparison to the control. Notably, FGJ exhibited a more pronounced effect on the gut microbiota compared to GJ. This was evident in its ability to enhance species richness, reduce the Firmicutes to Bacteroidetes (F/B) ratio, promote Akkermansia, and inhibit pathogenic Escherichia coli. Moreover, FGJ displayed enhanced production of SCFAs, especially acetic and lactic acids, in contrast to GJ. Our findings suggest that the probiotic fermentation of gac fruit enhances its functional attributes in promoting a balanced gut microbiota. This beverage demonstrates potential as a functional food with potential advantages for sustaining intestinal health.

Effect of a Multispecies Synbiotic Supplementation on Body Composition, Antioxidant Status, and Gut Microbiomes in Overweight and Obese Subjects: A Randomized, Double-Blind, Placebo-Controlled Study

Studies investigating the effect of multispecies synbiotic supplementation in obesity management are limited. The current study was performed to evaluate the effects of multispecies probiotics mixed with fructooligosaccharides on body composition, antioxidant status, and gut microbiome composition in overweight and obese individuals. We employed a randomized, double-blind, placebo-controlled trial design, in which 63 individuals aged 18-45 years were assigned to receive either a synbiotic supplement or placebo for 12 weeks. The synbiotic group consumed a daily dose of 37 × 10⁹ colony-forming units (CFU) of a unique blend of seven different probiotics, along with 2 g of fructooligosaccharides, while the placebo group consumed 2 g of maltodextrin daily. Assessments were performed at baseline, week 6, and the end of the study. The results of the study indicated that synbiotic supplementation resulted in a significant reduction in waist circumference and body fat percentage compared to the baseline measurements, as observed at 12 weeks. At the end of the study, there were no significant differences observed in body weight, BMI, waist circumference, or percentage of body fat between the synbiotic group and the placebo group. An analysis of plasma antioxidant capacity revealed that synbiotic supplementation caused a significant increase in Trolox equivalent antioxidant capacity (TEAC) and a concomitant decrease in malondialdehyde (MDA) in the test group when compared to the placebo. For the gut microbiota analysis, synbiotic supplementation significantly decreased Firmicutes abundance and the Firmicutes/Bacteroidetes (F/B) ratio at week 12 as compared to the placebo group. Nevertheless, the synbiotic group did not exhibit any substantial alterations in other biochemical blood parameters compared to the placebo group. These findings suggest that multispecies synbiotic supplementation could be a beneficial strategy to improve body composition, antioxidant status, and gut microbiome composition in overweight and obese subjects.

Cyanidin inhibits adipogenesis in 3T3-L1 preadipocytes by activating the PLC-IP3 pathway

Cyanidin is the most abundant anthocyanin found in red-purple plants and possesses anti-obesity properties. However, its mechanism of action in adipocytes remains unknown. The objective of this study was to elucidate how cyanidin inhibits adipocyte formation in 3T3-L1 preadipocytes. Cells were cultured in adipogenic differentiation medium supplemented with cyanidin and examined for adipogenesis, cell viability, and adipocyte gene expression using Oil Red O staining, MTT assay, and RT-qPCR. Real-time Ca²⁺ imaging analysis was performed in living cells to elucidate cyanidin's mechanism of action. The results demonstrated that cyanidin (1-50 μM) supplementation to the adipogenic medium inhibited adipogenesis by downregulating adipogenic marker gene expression (PPARγ, C/EBPα, adiponectin, and aP2) without affecting cell viability after 4 days of treatment. Stimulation of cells with cyanidin (30-100 μM) increased intracellular Ca²⁺ in a concentration dependent manner with peak calcium increases at 50 μM. Pretreatment of cells with the phospholipase C (PLC) inhibitor U73122, inositol triphosphate (IP₃) receptor blocker 2-APB, and depletion of endoplasmic reticulum Ca²⁺ stores by thapsigargin abolished the Ca²⁺ increases by cyanidin. These findings suggested that cyanidin inhibits adipocyte formation by activating the PLC-IP₃ pathway and intracellular Ca²⁺ signaling. Our study is the first report describing the mechanism underlying the anti-obesity effect of cyanidin.

Dietary anthocyanins inhibit insulin fibril formation and cytotoxicity in 3T3-L1 preadipocytes

Insulin fibril formation decreases the effectiveness of insulin therapy and causes amyloidosis in diabetes. Studies suggest that phytochemicals are capable of inhibiting fibril formation. Herein, we investigated the inhibitory effects of anthocyanins, including cyanidin, cyanidin-3-glucoside (C3G), cyanidin-3-rutinoside (C3R), malvidin, and malvidin-3-glucoside (M3G) on fibril formation. Our results revealed that anthocyanins (50-200 μM) significantly reduced the formation of insulin fibrils by increasing lag times and decreasing ThT fluorescence at the plateau phase. These findings were confirmed by TEM images, which showed reduced fibril length and number. Furthermore, FTIR analysis indicated that anthocyanins reduced the secondary structure transition of insulin from α-helix to β-sheet. Anthocyanins interacted with monomeric insulin (residues B8-B30) via H-bonds, van der Waals, and hydrophobic interactions, covering the fibril-prone segments of insulin (residues B12-B17). Based on the structure-activity analysis, the presence of glycosides and hydroxyl groups on phenyl rings increased intermolecular interaction, mediating the inhibitory effect of anthocyanins on fibril formation in the order of malvidin < cyanidin < M3G < C3G < C3R. Moreover, anthocyanins formed H-bonds with preformed insulin fibrils, except for malvidin. In preadipocytes, C3R, C3G, and cyanidin attenuated insulin fibril-induced cytotoxicity. In conclusion, anthocyanins are effective inhibitors of insulin fibril formation and cytotoxicity.

Cytokine Profiling and Intra-Articular Injection of Autologous Platelet-Rich Plasma in Knee Osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease leading to joint pain and stiffness. Due to lack of effective treatments, physical and psychological disabilities caused by OA have a detrimental impact on the patient’s quality of life. Emerging evidence suggests that intra-articular injection of platelet-rich plasma (PRP) may provide favorable results since PRP comprises not only a high level of platelets but also a huge amount of cytokines, chemokines, and growth factors. However, the precise mechanism and standardization method remain uncertain. This study aimed to examine cytokine profiling in both PRP and platelet-poor plasma (PPP) of knee OA patients and to determine the effects of PRP on OA chondrocytes and knee OA patients. PRP contained a wide variety of cytokines, chemokines, growth factors, and autologous intra-articular PRP injection resulted in favorable outcomes in knee OA patients. Significant increases in levels of IL-1, IL-2, IL-7, IL-8, IL-9, IL-12, TNF-α, IL-17, PDGF-BB, bFGF, and MIP-1β were detected in PRP compared to PPP (p < 0.001). An in vitro study showed a marked increase in proliferation in OA chondrocytes cultured with PRP, compared to PPP and fetal bovine serum (p < 0.001). In a clinical study, knee OA patients treated with PRP showed improvement of physical function and pain, assessed by physical performance, Western Ontario and McMaster Universities Arthritis Index and visual analog scale. Our findings from both in vitro and clinical studies suggest that intra-articular PRP injection in knee OA patients may be a potential therapeutic strategy for alleviating knee pain and delaying the need for surgery.

Cyanidin-3-rutinoside stimulated insulin secretion through activation of L-type voltage-dependent Ca2+ channels and the PLC-IP3 pathway in pancreatic β-cells

Cyanidin-3-rutinoside (C3R) is an anthocyanin with anti-diabetic properties found in red-purple fruits. However, the molecular mechanisms of C3R on Ca²⁺-dependent insulin secretion remains unknown. This study aimed to identify C3R's mechanisms of action in pancreatic β-cells. Rat INS-1 cells were used to elucidate the effects of C3R on insulin secretion, intracellular Ca²⁺ signaling, and gene expression. The results showed that C3R at 60, 100, and 300 µM concentrations significantly increased insulin secretion via intracellular Ca²⁺ signaling. The exposure of cells with C3R concentrations up to 100 μM did not affect cell viability. Pretreatment of cells with nimodipine (voltage-dependent Ca²⁺ channel (VDCC) blocker), U73122 (PLC inhibitor), and 2-APB (IP₃ receptor blocker) inhibited the intracellular Ca²⁺ signals by C3R. Interestingly, C3R increased intracellular Ca²⁺ signals and insulin secretion after depletion of endoplasmic reticulum Ca²⁺ stores by thapsigargin. However, insulin secretion was abolished under extracellular Ca²⁺-free conditions. Moreover, C3R upregulated mRNA expression for Glut2 and Kir_6.2 genes. These findings indicate that C3R stimulated insulin secretion by promoting Ca²⁺ influx via VDCCs and activating the PLC-IP₃ pathway. C3R also upregulates the expression of genes necessary for glucose-induced insulin secretion. This is the first study describing the molecular mechanisms by which C3R stimulates Ca²⁺-dependent insulin secretion from pancreatic β-cells. These findings contribute to our understanding on how anthocyanins improve hyperglycemia in diabetic patients.

Cyanidin Attenuates Methylglyoxal-Induced Oxidative Stress and Apoptosis in INS-1 Pancreatic β-Cells by Increasing Glyoxalase-1 Activity

Recently, the mechanisms responsible for anti-glycation activity of cyanidin and its derivatives on the inhibition of methylglyoxal (MG)-induced protein glycation and advanced glycation-end products (AGEs) as well as oxidative DNA damage were reported. In this study, we investigated the protective effect of cyanidin against MG-induced oxidative stress and apoptosis in rat INS-1 pancreatic β-cells. Exposure of cells to cytotoxic levels of MG (500 µM) for 12 h caused a significant reduction in cell viability. However, the pretreatment of cells with cyanidin alone (6.25–100 μM) for 12 h, or cotreatment of cells with cyanidin (3.13–100 μM) and MG, protected against cell cytotoxicity. In the cotreatment condition, cyanidin (33.3 and 100 μM) also decreased MG-induced apoptosis as determined by caspase-3 activity. Furthermore, INS-1 cells treated with MG increased the generation of reactive oxygen species (ROS) during a 6 h exposure. The MG-induced increase in ROS production was inhibited by cyanidin (33.3 and 100 μM) after 3 h stimulation. Furthermore, MG diminished the activity of glyoxalase 1 (Glo-1) and its gene expression as well as the level of total glutathione. In contrast, cyanidin reversed the inhibitory effect of MG on Glo-1 activity and glutathione levels. Interestingly, cyanidin alone was capable of increasing Glo-1 activity and glutathione levels without affecting Glo-1 mRNA expression. These findings suggest that cyanidin exerts a protective effect against MG-induced oxidative stress and apoptosis in pancreatic β-cells by increasing the activity of Glo-1.

Adenosine triphosphate enhances osteoblast differentiation of rat dental pulp stem cells via the PLC-IP3 pathway and intracellular Ca 2+ signaling

Intracellular Ca²⁺ signals are essential for stem cell function and play a significant role in the differentiation process. Dental pulp stem cells (DPSCs) are a potential source of stem cells; however, the mechanisms controlling cell differentiation remain largely unknown. Utilizing rat DPSCs, we examined the effect of adenosine triphosphate (ATP) on osteoblast differentiation and characterized its mechanism of action using real-time Ca ²⁺ imaging analysis. Our results revealed that ATP enhanced osteogenesis as indicated by Ca ²⁺ deposition in the extracellular matrix via Alizarin Red S staining. This was consistent with upregulation of osteoblast genes BMP2, Mmp13, Col3a1, Ctsk, Flt1, and Bgn. Stimulation of DPSCs with ATP (1-300 µM) increased intracellular Ca ²⁺ signals in a concentration-dependent manner, whereas histamine, acetylcholine, arginine vasopressin, carbachol, and stromal-cell-derived factor-1α failed to do so. Depletion of intracellular Ca ²⁺ stores in the endoplasmic reticulum by thapsigargin abolished the ATP responses which, nevertheless, remained detectable under extracellular Ca ²⁺ free condition. Furthermore, the phospholipase C (PLC) inhibitor U73122 and the inositol triphosphate (IP ₃ ) receptor inhibitor 2-aminoethoxydiphenyl borate inhibited the Ca ²⁺ signals. Our findings provide a better understanding of how ATP controls osteogenesis in DPSCs, which involves a Ca ²⁺ -dependent mechanism via the PLC-IP ₃ pathway. This knowledge could help improve osteogenic differentiation protocols for tissue regeneration of bone structures.

Transient receptor potential melastatin 4 channel is required for rat dental pulp stem cell proliferation and survival

OBJECTIVES

Investigate the role of the transient receptor potential melastatin 4 (TRPM4) channel in rat dental pulp stem cell (DPSC) proliferation and survival.

MATERIALS AND METHODS

Immunofluorescence and FACS analysis were used to detect the stem cell marker CD90. Alizarin Red S and Oil Red O staining were used to identify osteoblast and adipocyte differentiation, respectively. To characterize TRPM4, patch-clamp recordings were obtained from single cells in the whole-cell configuration mode. The significance of TRPM4 for proliferation and survival was examined with 9-phenanthrol, a TRPM4 inhibitor during a 96-hour period of culture. Real-time Ca²⁺ imaging analysis with Fura-2AM was used to investigate the impact of TRPM4 on intracellular Ca²⁺ signals.

RESULTS

DPSCs were CD90-positive and differentiated into osteoblasts. Patch-clamp recordings revealed currents typical of TRPM4 that were Ca²⁺ -activated, voltage-dependent and Na⁺ -conducting. Inhibition of TRPM4 resulted in a significant reduction in the cell population after a 96-hr period of culture and transformed the biphasic pattern of intracellular Ca²⁺ signalling into sustained oscillations.

CONCLUSIONS

Rat DPSCs have stem cell characteristics and functional TRPM4 channels that are required for proliferation and survival. These data suggest that the shape and frequency of intracellular Ca²⁺ signals may mediate stem cell proliferation and survival.

Effect of vitamin E on oxidative stress level in blood, synovial fluid, and synovial tissue in severe knee osteoarthritis: a randomized controlled study

Background

This study was performed to evaluate the antioxidative and anti-inflammatory effects of vitamin E on oxidative stress in the plasma, synovial fluid, and synovial tissue of patients with knee osteoarthritis.

Methods

Seventy-two patients with late-stage knee osteoarthritis scheduled for total knee arthroplasty were randomized to take oral placebo (Group A) or 400 IU of vitamin E (Group B) once a day for 2 months before undergoing surgery. The blood levels of endpoints indicating oxidative stress or antioxidant capacity, Knee Society Score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index score (WOMAC), and adverse effects were compared before and after the intervention between the two groups. At surgery, these redox endpoints and histological findings were compared between the synovial fluid and synovial tissue.

Results

In blood samples, the pre-intervention of oxidative stress and antioxidative capacity were not different between Group A and Group B. In post-intervention blood samples, the Malondialdehyde (Group A 1.34 ± 0.10, Group B 1.00 ± 0.09, p < 0.02), Alpha tocopherol (Group A 15.92 ± 1.08, Group B 24.65 ± 1.47, p < 0.01) and Trolox equivalent antioxidant capacity (Group A 4.22 ± 0.10, Group B 5.04 ± 0.10, 0 < 0.01) were significantly different between Group A and Group B. In synovial fluid samples, the Malondialdehyde (Group A 1.42 ± 0.12, Group B 1.06 ± 1.08, p 0.01), Alphatocopherol (Group A 4.51, Group B 7.03, p < 0.01), Trolox equivalent antioxidant capacity (Group A, 1.89 ± 0.06, Group B 2.19 ± 0.10) were significantly different between Group A and Group B. The pre-intervention WOMAC score and KSS score were not different between Group A and Group B. The post-intervention WOMAC score was significantly improved in all categories in Group B (Pain: Group A 27.26 ± 0.89, Group B 19.19 ± 1.43, p < 0.01; Stiffness: Group A 8.23 ± 0.79, Group B 5.45 ± 0.73, p 0.01; Function: Group A 94.77 ± 4.22, Group B 72.74 ± 6.55, p < 0.01). The post-intervention KSS score was significantly improved in all categories in Group B (Clinical: Group A 25.31 ± 14.33, Group B 33.52 ± 16.96, p < 0.01; Functional: Group A 41.43 ± 16.11, Group B 51.61 ± 19.60, p 0.02). Significantly fewer synovial tissue cells were stained with nitrotyrosine and hematoxylin–eosin in Group B than in Group A. There were no differences in adverse effects or surgical complications between the groups.

Conclusion

Vitamin E is an effective antioxidant that can improve clinical symptoms and reduce oxidative stress conditions in patients with late-stage knee osteoarthritis.

Trial registration

This research project had been approved for registration at Thai Clinical Trials Registry (TCTR) since 2016–08-28 11:26:32 (Retrospective registered). The TCTR identification number is TCTR20160828001.

The inhibitory activity of herbal medicines on the keys enzymes and steps related to carbohydrate and lipid digestion

BACKGROUND

Obesity and overweight are consistently associated with metabolic disorders including hyperglycemia and hyperlipidemia. Herbal medicines have been currently suggested as an alternative source of potentially useful antihyperglycemic, antihyperlipidemic, antioxidant activities. The objective of this study was to assess the in vitro inhibitory effects of eleven herbal medicines on carbohydrate and lipid digestive enzymes and the key steps of lipid digestion including the inhibition of micelle formation and the ability to bind bile acid. In addition, antioxidant activity of herbal medicines was also investigated.

METHODS

α-Glucosidase, pancreatic α-amylase, pancreatic lipase, and pancreatic cholesterol esterase inhibitory activities of aqueous extract of herbal medicines were measured using the enzymatic colorimetric assay. The formation of cholesterol micelles was determined using the cholesterol assay kit. The bile acid binding was measured using the colorimetric assay. Antioxidant activities were assessed by using four methods including Trolox equivalent antioxidant capacity (TEAC), oxygen radical absorbance capacity ORAC), superoxide radical scavenging activity (SRSA), and hydroxyl radical scavenging activity (HRSA).

RESULTS

The extracts (1 mg/mL) markedly inhibited intestinal maltase (5.16 - 44.33 %), sucrase (1.25-45.86 %), pancreatic α-amylase (1.75-12.53 %), pancreatic lipase (21.42-85.93 %), and pancreatic cholesterol esterase (2.92-53.35 %). The results showed that all extracts exhibited the inhibitory activity against pancreatic lipase with the IC₅₀ values ranging from 0.015 to 4.259 mg/mL. In addition, the incorporation of cholesterol into micelles was inhibited by the extracts (6.64-33.74 %). The extracts also bound glycodeoxycholic acid (9.9-15.08 %), taurodeoxycholic acid (12.55-18.18 %), and taurocholic acid (11.91 - 18.4 %). Furthermore, the extracts possessed various antioxidant activities including the TEAC values (0.50 - 4.70 μmol trolox/mg dried extract), the ORAC values (9.14-44.41 μmol trolox/mg dried extract), the SRSA (0.31 - 18.82 mg trolox/mg dried extract), and the HRSA (0.05-2.29 mg trolox/mg dried extract). The findings indicated that Syzygium aromaticum, Phyllanthus amarus, Thunbergia laurifolia were the effective promising antihyperglycemic and antihyperlipidemic agents. Statistical analysis demonstrated strong positive significant correlations between the contents of phenolic compounds and % inhibition of pancreatic lipase (r = 0.885, p < 0.001), % inhibition of pancreatic cholesterol esterase (r = 0.761, p < 0.001), and the TEAC value (r = 0.840, p < 0.001). Furthermore, there was a strongly positive correlation between the TEAC value and % inhibition of pancreatic cholesterol esterase (r = 0.851, p < 0.001) and % inhibition of pancreatic lipase (r = 0.755, p < 0.001).

CONCLUSIONS

Three herbal medicines including Syzygium aromaticum, Thunbergia laurifolia, and Phyllanthus amarus markedly inhibited the intestinal α-glucosidase, pancreatic α-amylase, pancreatic lipase, and pancreatic cholesterol esterase. They also reduced formation of cholesterol micelle and bound bile acid. The findings indicate that these herbal medicines might be a promising agent for antihyperglycemic, antihyperlipidemic, and antioxidant activities.

Protective effect of cyanidin against glucose- and methylglyoxal-induced protein glycation and oxidative DNA damage

Cyanidin, a natural anthocyanin abundant in fruits and vegetables, has shown the health benefits due to its pharmacological properties. However, there was no evidence regarding anti-glycation activity of cyanidin. The aim of the study was to investigate the inhibitory effect of cyanidin on methylglyoxal (MG)- and glucose-induced protein glycation in bovine serum albumin (BSA) as well as oxidative DNA damage. Free radical scavenging activity and the MG-trapping ability of cyanidin were also investigated. The results demonstrated that cyanidin (0.125-1mM) significantly inhibited the formation of fluorescent and non-fluorescent AGEs in BSA/MG and BSA/glucose systems. There was a significantly improved protein thiol in BSA/MG and BSA/glucose when incubated with cyanidin. Correspondingly, cyanidin decreased the level of protein carbonyl content in BSA/glucose system. Moreover, cyanidin (0.5-1mM) prevented lysine/MG-mediated oxidative DNA damage in the absence or presence of copper ion. The results demonstrated that cyanidin showed the MG-trapping ability in a concentration-dependent manner. Cyanidin also reduced superoxide anion and hydroxyl radical generation in lysine/MG system. The mechanism by which cyanidin inhibited protein glycation was the MG-trapping ability and the free radical scavenging activity. The present study suggests that cyanidin might be a promising antiglycation agent for preventing or ameliorating AGEs-mediated diabetic complications.

Isoferulic acid prevents methylglyoxal-induced protein glycation and DNA damage by free radical scavenging activity

BACKGROUND

Isoferulic acid (IFA), a naturally occurring cinnamic acid derivative, is a main active ingredient of the rhizoma of Cimicifuga dahurica. It has been shown various pharmacological activities. The aim of the study was to investigate the effect of IFA against MG-induced protein glycation and oxidative DNA damage. Free radical scavenging activity and the MGO-trapping abilities of IFA were also investigated.

METHODS

The fluorescent MG-derived AGEs and non-fluorescent N(ε)-(carboxymethyl) lysine (N(ε)-CML) was measured using a spectrofluorometer and an enzyme linked immunosorbant assay (ELISA). Protein carbonyl content was used to detect protein oxidation. Gel electrophoresis was used to determine DNA damage. Superoxide anion radicals and hydroxyl radicals were determined using cytochrome c reduction assay and thiobarbituric acid reactive 2-deoxy-D-ribose oxidation products, respectively. The MG-trapping capacity was performed by HPLC.

RESULTS

IFA (1.25-5 mM) inhibited the formation of fluorescent MG-derived AGEs, and N(ε)-CML, and protein carbonyl in bovine serum albumin. In addition, IFA (0.1-1 mM) also prevented MG/lysine-mediated oxidative DNA damage in the presence and absence of copper ion. The protective ability of IFA was directly correlated to inhibition of hydroxyl and superoxide anion radical generation during the reaction of MG and lysine. Most notably, IFA had no the directly trapping ability to MG.

CONCLUSIONS

The present results highlighted that free radical scavenging activity, but not the MG-trapping ability, is the mechanism of IFA for preventing MG-induced protein glycation and DNA damage.

Upregulation of inducible nitric oxide synthase and nitrotyrosine expression in primary knee osteoarthritis

BACKGROUND

To investigate nitrite and inducible nitric oxide synthase (iNOS) levels in the plasma and synovial fluid of patients with primary knee osteoarthritis (OA) and to determine protein nitrotyrosine in synovial tissue of OA patients.

MATERIAL AND METHOD

Thirty patients and 30 healthy controls were recruited into the present study. Plasma and synovial fluid nitrite levels were measured using Griess reaction. Plasma and synovial fluid iNOS concentrations were analyzed by enzyme-linked immunosorbent assay. Nitrotyrosine was detected immunohistochemically in synovial tissue of OA patients.

RESULTS

Plasma and synovial fluid nitrite concentration in the OA group were significantly higher than those in the healthy control group were (p = 0.007 and p = 0.012). Furthermore, plasma iNOS levels were significantly higher in the OA group than those in healthy control group were (p = 0.04). Moreover, nitrotyrosine was detected immunohistochemically in macrophages, synovial lining layer and synoviocytes of synovial tissue in the OA group.

CONCLUSION

These findings indicate that reactive nitrogen species and nitrotyrosine-containing proteins may be involved in the joint destruction process, and play a potential role in the pathogenesis of knee osteoarthritis.

Oxidative stress, vitamin e, and antioxidant capacity in knee osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a chronic progressive degenerative joint disorder which is characterised by strongly age-related regressive changes in articular cartilage. The objective of this study was to evaluate oxidative stress and antioxidant parameters in plasma and synovial fluid of patients with primary knee osteoarthritis.

MATERIAL AND METHODS

Thirty-five OA patients and 35 healthy controls were recruited for this study. Nitrite, malondialdehyde (MDA), vitamin E, Trolox Equivalent Antioxidant Capacity (TEAC), and Ferric Reducing Antioxidant Power (FRAP) levels in plasma and synovial fluid were determined.

RESULTS

Plasma nitrite levels in OA patients were significantly higher than those in healthy controls (p = 0.037). Furthermore, plasma MDA levels were significantly higher in OA patients than those in healthy controls (p < 0.001). Moreover, plasma vitamin E levels in OA patients were significantly lower than those in healthy controls (p < 0.001). Synovial fluid vitamin E levels of OA patients were significantly lower than paired plasma samples (p < 0.001). The total antioxidant capacities, as were measured by TEAC and FRAP assays in plasma of OA patients, were significantly lower than those in healthy controls (p < 0.01). MDA concentrations were positively correlated with nitrite concentrations but they were negatively associated with vitamin E and TEAC levels in synovial fluid of OA patients.

CONCLUSION

The increased plasma levels of nitrite and MDA and the decreased plasma levels of vitamin E, TEAC, and FRAP indicated that oxidative stress was present in OA patients. These findings suggest that oxidative stress plays a potential role in pathophysiology of knee osteoarthritis.