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Development of renal fibrosis is a hallmark of renal aging and chronic kidney disease of all etiologies and characterized by extensive renal cell injuries and subsequent myofibroblast transdifferentiations (MTDs), which are significantly influenced by aberrant histone deacetylase (HDAC) activities. However, the key HDAC isoforms and effectors that are causally involved in the processes remain poorly understood. Here, we report that aberrant HDAC3 induction and its inhibition of Klotho, a renal epithelium-enriched aging suppressor, contribute significantly to renal fibrogenesis. HDAC3 was preferentially elevated with concomitant Klotho suppression in fibrotic kidneys incurred by unilateral ureter obstruction (UUO) and aristolochic acid nephropathy (AAN), whereas Hdac3 knockout resisted the fibrotic pathologies. The HDAC3 elevation is substantially blocked by the inhibitors of TGFβ receptor and Smad3 phosphorylation, suggesting that TGFβ/Smad signal activates Hdac3 transcription. Consistently, an HDAC3-selective inhibitor RGFP966 derepressed Klotho and mitigated the renal fibrotic injuries in both UUO and AAN mice. Further, HDAC3 overexpression or inhibition in renal epithelia inversely affected Klotho abundances and HDAC3 was inducibly associated with transcription regulators NCoR and NF-kB and bound to Klotho promoter in fibrotic kidney, supporting that aberrant HDAC3 targets and transcriptionally inhibits Klotho under renal fibrotic conditions. More importantly, the antirenal fibrosis effects of RGFP966 were largely compromised in mice with siRNA-mediated Klotho knockdown. Hence, HDAC3 aberration and the subsequent Klotho suppression constitute an important regulatory loop that promotes MTD and renal fibrosis and uses of HDAC3-selective inhibitors are potentially effective in treating renal fibrotic disorders.

Background and purpose Development of pulmonary fibrosis is associated with altered DNA methylation modifications of fibrogenic gene expressions; however, their causal relationships and the underlying mechanisms remain unclear. This study investigates the critical role of DNA methylation aberration-associated suppression of PPARγ (peroxisome proliferator-activated receptor-gamma) in pulmonary fibrosis. Experimental approach Expressions of PPARγ and bioactive DNA methyltranferases, and PPARγ promoter methylation status were examined from fibrotic lungs of idiopathic pulmonary fibrosis (IPF) patients and bleomycin (Blm)-treated mice. DNA demethylating agent 5-Aza-2'-deoxycytidine (5aza) and glycyrrhizic acid (GA) derived from medicinal plant were assessed for their PPARγ derepression and anti-pulmonary fibrosis activities. PPARγ knockout mice were created to determine the critical role of PPARγ in the protections. Key results Lung PPARγ expressions were markedly suppressed in IPF patients and Blm mice, accompanied by increased methyltransferase (DNMT) 1/DNMT3a and PPARγ promoter hypermethylation. Administrations of 5aza and GA similarly demethylated PPARγ promoter, recovered the PPARγ loss and alleviated the fibrotic lung pathologies, including structural alterations and adverse expressions of fibrotic mediators and inflammatory cytokines. In cultured lung fibroblast and alveolar epithelial cells, GA alleviated the fibrotic PPARγ suppression in a gain of DNMT-sensitive manner, and in PPARγ knockout mice, the anti-fibrotic effects of 5aza and GA were significantly reduced, suggesting that PPARγ is a critical mediator of epigenetic pulmonary fibrogenesis. Conclusion and implications Aberrant DNMT1/3a elevations and the resultant PPARγ suppression contribute significantly to the development of pulmonary fibrosis, and strategies targeting DNMT/PPARγ axis by synthetic or natural small compounds might benefit patients with pulmonary fibrotic disorders.

Osteoarthritis (OA) is the most prevalent chronic degenerative joint disease with few treatment options. The pathogenesis of OA is characterized by sustained inflammation, oxidative stress and chondrocyte apoptosis that eventually lead to cartilage degradation and joint dysfunction. In the present study, we identified a synthetic triterpenoid CDDO-Im(1-[2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oyl] imidazole) as an activator of Nrf2 (nuclear factor erythroid 2-related factor 2) that displayed strong anti-OA effects. We showed that CDDO-Im (20 nM) significantly alleviated TNF-α-induced apoptosis of primary human chondrocytes and extracellular matrix degradation. In a mouse OA model incurred by DMM (destabilization of medial meniscus), administration of CDDO-Im (2.5 mg/kg, ip, every other day for 8 weeks) effectively reduced knee joint cartilage erosion and serum levels of inflammatory cytokines IL-1β and IL-6. We revealed that CDDO-Im (20 nM) significantly enhanced autophagy activities in chondrocytes, whereas the autophagy inhibition by chloroquine (CQ, 50 μM) or 3-methyladenine (3-MA, 5 mM) abrogated the anti-apoptosis and chondroprotective effects of CDDO-Im in TNF-α-treated chondrocytes. Moreover, we confirmed that CDDO-Im (1-20 nM) dose-dependently activated Nrf2 pathway in TNF-α-treated chondrocytes, and its chondroprotective and autophagy-enhancing effects were significantly diminished when Nrf2 signaling was blocked by Nrf2 inhibitor ML385 (20 μM) or siRNA-mediated Nrf2 knockdown. Together, our results demonstrate that CDDO-Im exhibits prominent chondroprotective and anti-OA activities owing to its Nrf2 activation and autophagy-enhancing properties, which might provide new insights into the strategies of OA clinical prevention and treatment.

Atherosclerosis (AS) is a risky cardiovascular disease with limited treatment options. Various pan or type-selective histone deacetylase (HDAC) inhibitors are reportedly atheroprotective against atherosclerosis (AS); however, the key effectors and the main cellular processes that mediate the protective effects remain poorly defined. Here, we report that PPARγ (Peroxisome proliferator-activated receptor gamma), a transcription factor actively involved in lipid metabolism with strong tissue protective and anti-inflammation properties, is a critical mediator of the anti-AS effects by HDAC inhibition. We showed that a well-known pan-HDAC inhibitor TSA (Trichostatin A) reduced foam cell formation of macrophages that is accompanied by a marked elevation of PPARγ and its downstream cholesterol efflux transporter ABCA1 (ATP-binding membrane cassette transport protein A1) and ABCG1. In an AS model of ApoE-/- mice fed on high-fat diet, TSA treatment alleviated AS lesions, similarly increased PPARγ and the downstream cholesterol transporters and mitigated the induction of inflammatory cytokine TNFα and IL-1β. Exploring the potential cause of PPARγ elevation revealed that TSA induced the acetylation of C/EBPα (CCAAT enhancer binding protein alpha), the upstream regulator of PPARγ, through which it increased PPARγ transactivation. More importantly, we generated a strain of PPARγ/ApoE double knockout mice and demonstrated that lack of PPARγ abrogated the protective effects of TSA on foam cell formation of peritoneal macrophages and the AS pathogenesis. Taken together, these results unravel that C/EBPα and PPARγ are the HDAC-sensitive components of an epigenetic signaling pathway mediating foam cell formation and AS development, and suggest that targeting C/EBPα/PPARγ axis by HDAC inhibitors possesses therapeutic potentials in retarding the progression of AS and the related cardiovascular diseases.

BACKGROUND: Osteomyelitis is a severe bone infection and typically leads to progressive bone resorption, destruction and dysfunction. Pyroptosis is a form of programmed cell death involved in various infectious diseases. However, the identification of pyroptosis and the role it plays in osteomyelitis remains to be clarified. In this study, we investigated the expression of pyroptosis-associated proteins in osteomyelitis and the effects of inhibiting pyroptosis on S. aureus-induced osteomyelitis both in vitro and in vivo. METHODS: The expression of pyroptosis-associated protein—NLRP3 (NLR Family Pyrin Domain Containing 3), Caspase1 and GSDMD (GasderminD) were examined in murine and human infectious bone fragments by western blot. Bone destruction was evaluated by microcomputed tomography (µCT). The concentration of inflammatory factors was tested by Enzyme linked Immunosorbent Assay (ELISA). The expression of pyroptosis-associated gene was detected by real-time quantitative polymerase chain reaction (RT-qPCR). RESULTS: The expression of pyroptosis-associated proteins in infectious bone fragments from patients with osteomyelitis was significantly higher than uninfected bone. Additionally, in S. aureus-induced murine osteomyelitis model, higher expression of pyroptosis-associated proteins was noticed. Furthermore, the inhibitors of pyroptosis-associated proteins alleviated S. aureus-induced pyroptosis both in vivo and in vitro. More importantly, the inhibition of pyroptosis restored the bone formative property, attenuated the aberrant activation of osteoclast in vitro and reversed bone injury in vivo. CONCLUSIONS: Our study identified pyroptosis as a key pathway in osteomyelitis and elaborated that the inhibition of pyroptosis could attenuate S. aureus-induced bone destruction in osteomyelitis, providing a potential treatment target to osteomyelitis.

Background: Osteomyelitis is a severe bone infection and typically leads to progressive bone resorption, destruction and dysfunction. Pyroptosis is a form of programmed cell death involved in various infectious diseases. However, the identification of pyroptosis and the role it plays in osteomyelitis remains to be clarified. In this study, we investigated the expression of pyroptosis-associated proteins in osteomyelitis and the effects of inhibiting pyroptosis on S. aureus -induced osteomyelitis both in vitro and in vivo . Methods: The expression of pyroptosis-associated protein—NLRP3 (NLR Family Pyrin Domain Containing 3), Caspase1 and GSDMD (GasderminD) were examined in murine and human infectious bone fragments by western blot. Bone destruction was evaluated by microcomputed tomography (µCT). The concentration of inflammatory factors was tested by Enzyme linked Immunosorbent Assay (ELISA). The expression of pyroptosis-associated gene was detected by real-time quantitative polymerase chain reaction (RT-qPCR). Results: The expression of pyroptosis-associated proteins in infectious bone fragments from patients with osteomyelitis was significantly higher than uninfected bone. Additionally, in S. aureus -induced murine osteomyelitis model, higher expression of pyroptosis-associated proteins was noticed. Furthermore, the inhibitors of pyroptosis-associated proteins alleviated S. aureus -induced pyroptosis both in vivo and in vitro . More importantly, the inhibition of pyroptosis restored the bone formative property, attenuated the aberrant activation of osteoclast in vitro and reversed bone injury in vivo . Conclusions: Our study identified pyroptosis as a key pathway in osteomyelitis and elaborated that the inhibition of pyroptosis could attenuate S. aureus -induced bone destruction in osteomyelitis, providing a potential treatment target to osteomyelitis.

Cd anomalies are spreading along almost the whole of the Yangtze River Basin, discovered by the multi-purpose geochemical investigation being carried out in China, have been one of the major ecological environmental issues. By taking the Anhui section of the Yangtze River Basin as its object, a systematical study on the methodology of the source tracking and quantitative estimation of the Cd anomalies has been carried out in the article. By determining the contents of elements in suspended matters in the Anhui section of the trunk stream and main tributaries of Yangtze River, it is shown that the suspended matters are the main carriers of heavy metals for long distance migrations; the concentration of Cd in the suspended matters is considerably higher than those of other heavy metals, and this may be the main reason for forming the Cd anomalies spreading along the whole Yangtze River Basin. Also, the tributaries of Yangtze River have significant influences on the variations of heavy metal contents in the suspended matters in its trunk stream. The quantitative computation of output flow of heavy metals for the trunk stream and main tributaries for the Anhui section of Yangtze River shows that the largest output flow of heavy metals is from Qiupu River, with roughly 4.45 t of Cd deposited in soils along either bank of the Anhui section of Yangtze River. Results of source tracking of Cd anomalies along Shun'an River by detailed survey of suspended matters, soil survey on a scale of 1:50,000, and rock survey indicate that endogenetic mineral deposits, especially Pb-Zn deposits, are the largest suppliers of Cd in the suspended matters. With techniques of layer sampling of sediments on alluvial beds and isotopic age-determination, the geochemical history of the sedimentation of Cd and other heavy metals and thus resulting pollutions have been primarily reconstructed, with prediction and early warning of the evolution of anomalies of Cd and other heavy metals.