Biodegradation and valorization of feather waste using the keratinase-producing bacteria and their application in environmentally hazardous industrial processes.

Poultry feathers are widely discarded as waste worldwide and are considered an environmental pollutant and a reservoir of pathogenic bacteria. Therefore, developing sustainable and environmentally friendly methods for managing feather waste is one of the important environmental protection requirements. In this study, we investigated a rapid and eco-friendly method for the degradation and valorization of feather waste using keratinase-producing Pseudomonas geniculata H10, and evaluated the applicability of keratinase in environmentally hazardous chemical processes. Strain H10 completely degraded chicken feathers within 48 h by producing keratinase using them as sources of carbon, nitrogen, and sulfur. The culture contained a total of 402.8 µM amino acids, including 8 essential amino acids, which was higher than the chemical treatment. Keratinase was a serine-type metalloprotease with optimal temperature and pH of 30 °C and 9, respectively, and showed relatively high stability at 10-40 °C and pH 3-10. Keratinase was also able to degrade various insoluble keratins such as duck feathers, wool, human hair, and nails. Furthermore, keratinase exhibited more efficient depilation and wool modification than chemical treatment, as well as novel functionalities such as nematicidal and exfoliating activities. This suggests that strain H10 is a promising candidate for the efficient degradation and valorization of feather waste, as well as the improvement of current industrial processes that use hazardous chemicals.

Dysbiosis of Fecal Microbiota in Tg2576 Mice for Alzheimer's Disease during Pathological Constipation.

Tg2576 transgenic mice for Alzheimer's disease (AD) exhibited significant phenotypes for neuropathological constipation, but no research has been conducted on the association of the fecal microbiota with dysbiosis. The correlation between fecal microbiota composition and neuropathological constipation in Tg2576 mice was investigated by examining the profile of fecal microbiota and fecal microbiota transplantation (FMT) in 9-10-month-old Tg2576 mice with the AD phenotypes and constipation. Several constipation phenotypes, including stool parameters, colon length, and histopathological structures, were observed prominently in Tg2576 mice compared to the wild-type (WT) mice. The fecal microbiota of Tg2576 mice showed decreases in Bacteroidetes and increases in the Firmicutes and Proteobacteria populations at the phylum level. The FMT study showed that stool parameters, including weight, water content, and morphology, decreased remarkably in the FMT group transplanted with a fecal suspension of Tg2576 mice (TgFMT) compared to the FMT group transplanted with a fecal suspension of WT mice (WFMT). The distribution of myenteric neurons and the interstitial cells of Cajal (ICC), as well as the enteric nervous system (ENS) function, remained lower in the TgFMT group. These results suggest that the neuropathological constipation phenotypes of Tg2576 mice may be tightly linked to the dysbiosis of the fecal microbiota.

Characterization and applicability of novel alkali-tolerant carbonatogenic bacteria as environment-friendly bioconsolidants for management of concrete structures and soil erosion.

Cracking and erosion are critical factors that reduce the mechanical properties and stability of concrete structures and soil, respectively. They are recognized worldwide as severe disasters causing the collapse of many structures including stone heritage and dams, and landslides. Therefore, it is essential to propose effective and environment-friendly management methods to prevent them. Carbonatogenesis has recently received considerable attention as a reliable biological process for remediating cracks in calcareous structures, stabilizing loose soils, and sequestering CO2 in the environment. Isolating and characterizing carbonatogenic bacteria with excellent performance is crucial for applying this process to the field of environmental and civil engineering. The aim of this study was to isolate new CaCO3-precipitating bacteria and investigate various properties for their use as bioconsolidants. Furthermore, the possibility of restoring damaged structures and stabilizing loose sandy soil using isolated strain was investigated. Strain LC13 with urease and CaCO3-precipitating activity was isolated from limestone cave soil in Korea and identified as Arthrobacter sulfureus by phenotypic characterization and 16S rRNA gene analysis. Although cell growth was observed after an adaptation period at pH 11, strain LC13 grew well at pH 7-11, indicating alkali tolerance. The optimal conditions for CaCO3 precipitation were 1.0% yeast extract, 2.5% urea, 0.35% NaHCO3, and 400 mM CaCl2, with an initial pH of 6.5 at 30 °C. Under optimized conditions, maximal CaCO3 (22.92 ± 0.14 g/l) precipitated after 3 days, which was 10.8-fold higher than the value in a urea-CaCl2 medium. CaCO3 precipitation by strain LC13 was associated with an increased pH due to ureolysis and protein deamination. Using an optimized medium as a cementation solution, strain LC13 completely remediated 340-760 µm wide cracks over 3 days, and also restored the spalling of concrete surfaces. Furthermore, the sand treated with LC13 solidified with a surface strength of 14.9 kPa. Instrumental analysis confirmed that the crystals precipitated were a mixture of CaCO3 polymorphs composed of rhombohedral calcite and spherical vaterite. These results suggest that A. sulfureus LC13 may be useful for implementing sustainable biorestoration and environmental management technologies such as the in situ remediation of structural cracks and in situ prevention of soil erosion.

Chrysanthemum boreale Makino Inhibits Oxidative Stress-Induced Neuronal Damage in Human Neuroblastoma SH-SY5Y Cells by Suppressing MAPK-Regulated Apoptosis.

Oxidative stress has been demonstrated to play a pivotal role in the pathological processes of many neurodegenerative diseases. In the present study, we demonstrated that Chrysanthemum boreale Makino extract (CBME) suppresses oxidative stress-induced neurotoxicity in human neuroblastoma SH-SY5Y cells and elucidated the underlying molecular mechanism. Our observations revealed that CBME effectively protected neuronal cells against H2O2-induced cell death by preventing caspase-3 activation, Bax upregulation, Bcl-2 downregulation, activation of three mitogen-activated protein kinases (MAPKs), cAMP response element-binding protein (CREB) and NF-κB phosphorylation, and iNOS induction. These results provide evidence that CBME has remarkable neuroprotective properties in SH-SY5Y cells against oxidative damage, suggesting that the complementary or even alternative role of CBME in preventing and treating neurodegenerative diseases is worth further studies.

Characterization of a Novel CaCO3-Forming Alkali-Tolerant Rhodococcus erythreus S26 as a Filling Agent for Repairing Concrete Cracks.

Biomineralization, a well-known natural phenomenon associated with various microbial species, is being studied to protect and strengthen building materials such as concrete. We characterized Rhodococcus erythreus S26, a novel urease-producing bacterium exhibiting CaCO3-forming activity, and investigated its ability in repairing concrete cracks for the development of environment-friendly sealants. Strain S26 grown in solid medium formed spherical and polygonal CaCO3 crystals. The S26 cells grown in a urea-containing liquid medium caused culture fluid alkalinization and increased CaCO3 levels, indicating that ureolysis was responsible for CaCO3 formation. Urease activity and CaCO3 formation increased with incubation time, reaching a maximum of 2054 U/min/mL and 3.83 g/L, respectively, at day four. The maximum CaCO3 formation was achieved when calcium lactate was used as the calcium source, followed by calcium gluconate. Although cell growth was observed after the induction period at pH 10.5, strain S26 could grow at a wide range of pH 4-10.5, showing its high alkali tolerance. FESEM showed rhombohedral crystals of 20-60 µm in size. EDX analysis indicated the presence of calcium, carbon, and oxygen in the crystals. XRD confirmed these crystals as CaCO3 containing calcite and vaterite. Furthermore, R. erythreus S26 successfully repaired the artificially induced large cracks of 0.4-0.6 mm width.

Bacterial indoleacetic acid-induced synthesis of colloidal Ag2O nanocrystals and their biological activities.

The biosynthesis and biological activity of colloidal Ag2O nanocrystals have not been well studied, although they have potential applications in many fields. For the first time, we developed a reducing agent free, cost-effective technique for Ag2O biosynthesis using Xanthomonas sp. P5. The optimal conditions for Ag2O synthesis were 50 °C, pH 8, and 2.5 mM AgNO3. Using these conditions the yield of Ag2O obtained at 10 h was about five times higher than that obtained at 12 h under unoptimized conditions. Ag2O was characterized by FESEM-EDS, TEM, dynamic light scattering, XRD, and UV-Visible spectroscopy. Indoleacetic acid produced by the strain P2 was involved in the synthesis of Ag2O. Ag2O exhibited a broad antimicrobial spectrum against several human pathogens. Furthermore, Ag2O exhibited 1,1-diphenyl-2-picrylhydrazyl (IC50 = 25.1 µg/ml) and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonate (IC50 = 16.8 µg/ml) radical scavenging activities, and inhibited collagenase (IC50 = 27.9 mg/ml). Cytotoxicity of Ag2O was tested in fibroblast cells and found to be non-toxic, demonstrating biocompatibility.

Improved biosynthesis of silver nanoparticles using keratinase from Stenotrophomonas maltophilia R13: reaction optimization, structural characterization, and biomedical activity.

In the present study, keratinase from Stenotrophomonas maltophilia R13 was used for the first time as a reducing agent for the eco-friendly synthesis of AgNPs. The keratinase produced by strain R13 was responsible for the reduction of silver ions and the subsequent formation of AgNPs. Maximum AgNP synthesis was achieved using 2 mM AgNO3 at pH 9 and 40 °C. Electron microscopy and dynamic light scattering analysis showed AgNPs were spherical and of average diameter ~ 8.4 nm. X-ray diffraction revealed that AgNPs were crystalline. FTIR indicated AgNPs were stabilized by proteins present in the crude enzyme solution of strain R13. AgNPs exhibited a broad antimicrobial spectrum against several pathogenic microorganisms, and the antimicrobial mechanism appeared to involve structural deformation of cells resulting in membrane leakage and subsequent lysis. AgNPs also displayed 1,1-diphenyl-2-picrylhydrazyl (IC50 = 0.0112 mg/ml), 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonate radical scavenging (IC50 = 0.0243 mg/ml), and anti-collagenase (IC50 = 23.5 mg/ml) activities.

Quercetin promotes gastrointestinal motility and mucin secretion in loperamide-induced constipation of SD rats through regulation of the mAChRs downstream signal.

CONTEXT: Quercetin (QCT) has been known as a potential therapeutic strategy for gastrointestinal diseases because it contributes to the stabilization of mast cells, the prevention of histamine release and modulation of CaCC chloride channel. OBJECTIVE: We investigated the laxative effect and action mechanism of QCT in Lop-induced constipation model. MATERIALS AND METHODS: Constipation of SD rats was induced by subcutaneous injection of loperamide (Lop) (4 mg/kg weight) in 0.5% Tween 20 twice a day for three days. After 24 h, the constipation group was further treated with 1× PBS (Lop + Vehicle treated group), 10 mg/kg of QCT (Lop + LQCT treated group), 20 mg/kg of QCT (Lop + MQCT treated group) or 40 mg/kg QCT (Lop + HQCT treated group) at once. At 24 h after QCT treatment, the constipation phenotypes were measured and the transverse colon was collected from SD rats. RESULTS: The gastrointestinal motility, the number of stools and histological structures were significantly recovered in Lop + QCT treated group compared with the Lop + Vehicle treated group. Also, above activity of epithelial cells and smooth muscle cells were regulated by the mRNA expression of the muscarinic acetylcholine receptors M2 and M3 (mAChR M2 and M3) and some mediators of their downstream signalling pathway. Finally, laxative effects of QCT on mAChR signalling pathway were significantly inhibited by the treatment of mAChR antagonist in primary smooth muscle of rat intestine cells (pRISMCs). CONCLUSIONS: This study provides the first strong evidence that QCT can be considered an important candidate for improving chronic constipation induced by Lop treatment in animal models.

Diosgenin effectively suppresses skin inflammation induced by phthalic anhydride in IL-4/Luc/CNS-1 transgenic mice.

To quantitatively evaluate the therapeutic effects of diosgenin (DG) and investigate the role of IL-4 on skin inflammation, alterations in luciferase-derived signal and general phenotype biomarkers were measured in IL-4/Luc/CNS-1 transgenic mice with phthalic anhydride (PA)-induced skin inflammation after treatment with DG for 4 weeks. High levels of luciferase-derived signal detected in the abdominal region and submandibular lymph node (SL) of the PA treated group was significantly decreased by 67-88% in the PA + DG cotreated group. Furthermore, the weight of the lymph node and spleen, IgE concentration, epidermis thickness, and number of infiltrated mast cells were lower in the PA + DG treated group than the PA + Vehicle treated group. Moreover, expression of IL-6 and vascular endothelial growth factor (VEGF) also decreased in the PA + DG cotreated group. These results suggest that PA-induced skin inflammation could be successfully suppressed by DG treatment in IL-4/Luc/CNS-1 Tg mice through attenuation of IL-4 and IL-6 expression, as well as decreased IgE concentration and mast cells infiltration.

Cucurbitacin B inhibits immunomodulatory function and the inflammatory response in macrophages.

Cucurbitacin B (CuB) is a triterpenoid that is widely distributed in the plant kingdom and has a variety of biological activities. However, the immunomodulatory and anti-inflammatory effects of CuB have not been well characterized. Therefore, in this study, we investigated the effects of CuB on parameters related to antigen presentation and T-cell activation. Specifically, we examined the effects of CuB on basal and lipopolysaccharide (LPS)-induced expression of class I and II MHC molecules, CD40, CD54, CD80, and CD86 in peritoneal macrophages. The LPS-a expression of MHC II, CD40, CD54, and CD80 was significantly attenuated by CuB. However, expression levels of MHC I and CD86 were not changed by CuB. CuB inhibited the production of intracellular reactive oxygen species induced by LPS and blocked the LPS-activated release of pro-inflammatory mediators, such as nitric oxide (NO), prostaglandin E2, tumor necrosis factor-α, interleukin (IL)-6, IL-12, and IL-1ß, without any cytotoxicity. Consistent with this, CuB also reduced the expression levels of inducible NO synthase and cyclooxygenase-2 induced by LPS. Furthermore, we demonstrated that the anti-inflammatory effects of CuB were dependent on the induction of heme oxygenase-1 expression via Nrf2 activation. Taken together, these data indicate that CuB possesses immunomodulatory and anti-inflammatory effects, and it may be used as an effective herbal remedy for the treatment and prevention of inflammation.

Effect of Phosphate Addition on Cadmium Precipitation and Adsorption in Contaminated Arable Soil with a Low Concentration of Cadmium.

The objectives of this study were to determine (1) the phosphorus (P) level required to induce cadmium (Cd) precipitation in a contaminated arable soil with low concentrations of Cd and (2) the primary mechanism of Cd immobilization at different P levels. Phosphorus was added at levels of 0 800, 1600, and 16,000 mg P kg(-1) to a soil containing 5.57 mg Cd kg(-1). The concentration of 1 M NH4OAc extractable Cd decreased significantly with P levels up to 1600 mg kg(-1) due to an increase in soil pH and negative charge of soil (p<0.001). A further decrease in 1 M NH4OAc extractable Cd concentration was noted when P was increased to 16,000 mg P kg(-1) and may have been the result of Cd precipitation. This study suggest that adding P at high levels may help in the formation of geochemically stable Cd minerals in soil containing low levels of this heavy metal.

Cellulose film regenerated from Styela clava tunics have biodegradability, toxicity and biocompatibility in the skin of SD rats.

Cellulose is one of the most widespread biomolecules in nature and has been exploited in various applications including scaffolding, tissue engineering, and tissue formation. To evaluate the biocompatibility of cellulose film manufactured from Styela clava tunics (SCT-CF), these films were implanted in Sprague-Dawley (SD) rats for various lengths of time, after which they were subjected to mechanical and biological analyses. The cellulose powders (12-268 m) obtained from SCT was converted into films via casting methods without adding any additives. SCT-CF contained about 98 % α-cellulose and very low concentrations of ßß-cellulose. Additionally, the crystallinity index (CrI) of SCT-CF was lower (10.71 %) than that of wood pulp-cellulose films (WP-CF) (33.78 %). After implantation for 90 days, the weight loss and formation of surface corrugations were greater in SCT-CF than that of WP-CF, while the surface roughness was significantly higher in WP-CF than SCT-CF. However, there were no differences in the number of white blood cells between SCT-CF implanted rats and vehicle implanted rats. The level of metabolic enzymes representing liver and kidney toxicity in the serum of SCT-CF implanted rats was maintained at levels consistent with vehicle implanted rats. Moreover, no significant alteration of the epidermal hyperplasia, inflammatory cell infiltration, redness, and edema were observed in SD rats implanted with SCT-CF. Taken together, these results indicate that SCT-CF showed good degradability and non-toxicity without inducing an immune response in SD rats. Further, the data presented here constitute strong evidence that SCT-CF has the potential for use as a powerful biomaterial for medical applications including stitching fiber, wound dressing, scaffolding, absorbable hemostats and hemodialysis membrane.

Soil pH effect on phosphate induced cadmium precipitation in Arable soil.

The objective of this study was to determine soil pH conditions that allow cadmium (Cd) to precipitate as Cd minerals in phosphate (P) amended soil. Cadmium immobilization could be attributed primarily to Cd adsorption due to increase in pH and negative charge. Soil pH might not affect Cd precipitation as Cd3(PO4)2 by direct reaction of Cd and P in the studied soil, even when soil pH increased up to 9.0. However, Cd might precipitate as CdCO3 with increasing pH up to 9.0 in P untreated soil and up to 8.0 in P treated soil depending on CO2 level.

WITHDRAWN: Dietary supplementation of Artemisia capillaris on immunity in Paralichthys olivaceus against Edwardsiella tarda.

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

WITHDRAWN: Effects of saponin supplementation diet on hematological, biochemical, and immunological responses in Epinephelus bruneus against Vibrio alginolyticus.

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Enzyme-mediated biocalcification by a novel alkaliphilic Bacillus psychrodurans LC40 and its eco-friendly application as a biosealant for crack healing.

Biocalcification is a natural biochemical process, which has been regarded as a promising method for sequestering heavy metals or carbon dioxide in the environment, healing cracks in concrete structures, and stabilizing soil. One of the key factors in this process is calcium carbonate-producing bacteria. The purpose of this study was to maximize the production of calcium carbonate by alkaliphilic Bacillus psychrodurans LC40 isolated from a limestone cave, by manipulating the medium composition for fast and non-detrimental crack healing, and to investigate the mechanism of its production. Strain LC40 could grow well in the strongly alkaline region (pH 9.5-11), indicating its alkaliphilic nature. The optimal medium for calcium carbonate production contained 2% tryptone, 1.5% urea, 0.15% NaHCO3, and 150 mM calcium formate (pH 6). Using this medium, the yield of calcium carbonate at 72 h was approximately 8.6-fold higher than that obtained through Urea-CaCl2 medium. In this culture, the urease and carbonic anhydrase activities were observed simultaneously, and the pH of the medium was found to have increased to 9.4, leading to maximum calcium carbonate production. This suggests that this pH value is achieved by the synergistic action of the two enzymes, resulting in a high calcium carbonate yield. The crystals were characterized by FESEM, EDS and XRD, which confirmed the production of rhombohedral and spherical calcium carbonate crystals containing vaterite and calcite. Strain LC40 completely healed a 0.75 mm wide crack in a very short time of 3 days using the optimized medium as a cementation solution. Our findings indicate that B. psychrodurans LC40 could be a promising candidate for the development of eco-friendly biosealant applicable to environmentally stressed concrete structures.

Overexpression of the PanaxginsengCYP703 Alters Cutin Composition of Reproductive Tissues in Arabidopsis.

Cytochrome P450 (CYP) catalyzes a wide variety of monooxygenation reactions in plant primary and secondary metabolisms. Land plants contain CYP703, belonging to the CYP71 clan, which catalyzes the biochemical pathway of fatty acid hydroxylation, especially in male reproductive tissues. Korean/Asian ginseng (Panax ginseng Meyer) has been regarded as one of important medicinal plant for a long time, however the molecular mechanism is less known on its development. In this study, we identified and characterized a CYP703A gene in P. ginseng (PgCYP703A4), regarding reproductive development. PgCYP703A4 shared a high-sequence identity (81-83%) with predicted amino acid as CYP703 in Dancus carota, Pistacia vera, and Camellia sinensis as well as 76% of amino acid sequence identity with reported CYP703 in Arabidopsis thaliana and 75% with Oryza sativa. Amino acid alignment and phylogenetic comparison of P. ginseng with higher plants and known A. thaliana members clearly distinguish the CYP703 members, each containing the AATDTS oxygen binding motif and PERH as a clade signature. The expression of PgCYP704B1 was only detected in P. ginseng flower buds, particularly in meiotic cells and the tapetum layer of developing anther, indicating the conserved role on male reproduction with At- and Os- CYP703. To acquire the clue of function, we transformed the PgCYP703A4 in A. thaliana. Independent overexpressing lines (PgCYP703A4ox) increased silique size and seed number, and altered the contents of fatty acids composition of cutin monomer in the siliques. Our results indicate that PgCYP703A4 is involved in fatty acid hydroxylation which affects cutin production and fruit size.

Effects of mycosubtilin homolog algicides from a marine bacterium, Bacillus sp. SY-1, against the harmful algal bloom species Cochlodinium polykrikoides.

The marine bacterium, Bacillus sp. SY-1, produced algicidal compounds that are notably active against the bloom-forming alga Cochlodinium polykrikoides. We isolated three algicidal compounds and identified these as mycosubtilins with molecular weights of 1056, 1070, and 1084 (designated MS 1056, 1070, and 1084, respectively), based on amino acid analyses and 1H, 13C, and two-dimensional nuclear magnetic resonance spectroscopy, including 1H-15N heteronuclear multiple bond correlation analysis. MS 1056 contains a ß-amino acid residue with an alkyl side chain of C15, which has not previously been seen in known mycosubtilin families. MS 1056, 1070, and 1084 showed algicidal activities against C. polykrikoides with 6-h LC50 values of 2.3 ± 0.4, 0.8 ± 0.2, and 0.6 ± 0.1 µg/ml, respectively. These compounds also showed significant algicidal activities against other harmful algal bloom species. In contrast, MS 1084 showed no significant growth inhibitory effects against other organisms, including bacteria and microalgae, although does inhibit the growth of some fungi and yeasts. These observations imply that the algicidal bacterium Bacillus sp. SY-1 and its algicidal compounds could play an important role in regulating the onset and development of harmful algal blooms in natural environments.

Dysbiosis of Fecal Microbiota From Complement 3 Knockout Mice With Constipation Phenotypes Contributes to Development of Defecation Delay.

Significant phenotypes for constipation were detected in complement 3 (C3) knockout (KO) mice, although no research has been conducted on an association with alteration of gut microbiota. To investigate the effects of dysbiosis on fecal microbiota from C3 KO mice with constipation, the composition of fecal microbiota was characterized in mid-colons of 16-week-old C3 KO mice, and their function for defecation delay development was examined after fecal microbiota transplantation (FMT) of C3 KO mice. Some significant alterations in constipation phenotypes, including stool parameters and histopathological structure, were detected in 16-week-old C3 KO mice compared to those of wild-type (WT) mice. Fecal microbiota of C3 KO mice exhibited decreases in Anaerocolumna, Caecibacterium, Christensenella, Kineothrix, and Oscillibacter populations and increases in Prevotellamassilia, Reuthenibacterium, Prevotella, Eubacterium, Culturomica, Bacteroides, and Muribaculum populations. In FMT study, key stool parameters, including weight and water content, were remarkably declined in a transplanted KO (KFMT) group of antibiotics-induced depletion of microbiota (AiDM)-WT and AiDM-KO mice, and a similar change was observed in fecal morphology. However, intestine length decreased in only the KFMT group of AiDM-WT mice compared with that of AiDM-KO mice. The mucosal layer and muscle thickness were commonly decreased in the KFMT group of AiDM-WT and AiDM-KO mice, and significant alterations in the crypt structure of Lieberkuhn and molecular regulators, including AQP8, C-kit, and 5-HT, were observed in the same group. Taken together, results of the present study indicate that dysbiosis of fecal microbiota from C3 KO mice with constipation phenotypes has a key role in the induction and regulation of defecation delay.

Therapeutic Applications of Type 2 Diabetes Mellitus Drug Metformin in Patients with Osteoarthritis.

Type 2 diabetes mellitus (T2DM) and osteoarthritis (OA) are common chronic diseases that frequently co-exist. The link between OA and T2DM is attributed to common risk factors, including age and obesity. Several reports suggest that hyperglycemia and accumulated advanced glycosylation end-products might regulate cartilage homeostasis and contribute to the development and progression of OA. Metformin is used widely as the first-line treatment for T2DM. The drug acts by regulating glucose levels and improving insulin sensitivity. The anti-diabetic effects of metformin are mediated mainly via activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK), which is an energy sensing enzyme activated directly by an increase in the AMP/ATP ratio under conditions of metabolic stress. Dysregulation of AMPK is strongly associated with development of T2DM and metabolic syndrome. In this review, we discuss common risk factors, the association between OA and T2DM, and the role of AMPK. We also address the adaptive use of metformin, a known AMPK activator, as a new drug for treatment of patients with OA and T2DM.