Pramipexole inhibits astrocytic NLRP3 inflammasome activation via Drd3-dependent autophagy in a mouse model of Parkinson's disease.

Inflammation is one of the pathogenic processes in Parkinson's disease (PD). Dopamine receptor agonist pramipexole (PPX) is extensively used for PD treatment in clinics. A number of studies show that PPX exerts neuroprotection on dopaminergic (DA) neurons, but the molecular mechanisms underlying the protective effects of PPX on DA neurons are not fully elucidated. In the present study, we investigated whether PPX modulated PD-related neuroinflammation and underlying mechanisms. PD model was established in mice by bilateral striatum injection of lipopolyssaccharide (LPS). The mice were administered PPX (0.5 mg·kg-1·d-1, i.p.) 3 days before LPS injection, and for 3 or 21 days after surgery, respectively, for biochemical and histological analyses. We showed that PPX administration significantly alleviated the loss of DA neurons, and suppressed the astrocyte activation and levels of proinflammatory cytokine IL-1ß in the substantia nigra of LPS-injected mice. Furthermore, PPX administration significantly decreased the expression of NLRP3 inflammasome-associated proteins, i.e., cleaved forms of caspase-1, IL-1ß, and apoptosis-associated speck-like protein containing a caspase recruit domain (ASC) in the striatum. These results were validated in LPS+ATP-stimulated primary mouse astrocytes in vitro. Remarkably, we showed that PPX (100-400 µM) dose-dependently enhanced the autophagy activity in the astrocytes evidenced by the elevations in LC3-II and BECN1 protein expression, as well as the increase of GFP-LC3 puncta formation. The opposite effects of PPX on astrocytic NLRP3 inflammasome and autophagy were eliminated by Drd3 depletion. Moreover, we demonstrated that both pretreatment of astrocytes with autophagy inhibitor chloroquine (40 µM) in vitro and astrocyte-specific Atg5 knockdown in vivo blocked PPX-caused inhibition on NLRP3 inflammasome and protection against DA neuron damage. Altogether, this study demonstrates an anti-neuroinflammatory activity of PPX via a Drd3-dependent enhancement of autophagy activity in astrocytes, and reveals a new mechanism for the beneficial effect of PPX in PD therapy.

BMAL1 regulation of microglia-mediated neuroinflammation in MPTP-induced Parkinson's disease mouse model.

Dysfunction of the circadian rhythm is one of most common nonmotor symptoms in Parkinson's disease (PD), but the molecular role of the circadian rhythm in PD is unclear. We here showed that inactivation of brain and muscle ARNT-like 1 (BMAL1) in 1-methyl-4-phenyl-1,2,4,5-tetrahydropyridine (MPTP)-treated mice resulted in obvious motor functional deficit, loss of dopaminergic neurons (DANs) in the substantia nigra pars compacta (SNpc), decrease of dopamine (DA) transmitter, and increased activation of microglia and astrocytes in the striatum. Time on the rotarod or calorie consumption, and food and water intake were reduced in the Bmal1-/- mice after MPTP treatment, suggesting that absence of Bmal1 may exacerbate circadian and PD motor function. We observed a significant reduction of DANs (~35%) in the SNpc, the tyrosine hydroxylase protein level in the striatum (~60%), the DA (~22%), and 3,4-dihydroxyphenylacetic acid content (~29%), respectively, in MPTP-treated Bmal1-/- mice. Loss of Bmal1 aggravated the inflammatory reaction both in vivo and in vitro. These findings suggest that BMAL1 may play an essential role in the survival of DANs and maintain normal function of the DA signaling pathway via regulating microglia-mediated neuroinflammation in the brain.

Insights into the Mechanism of Thiol-Triggered COS/H2S Release from N-Dithiasuccinoyl Amines.

The hydrolysis of carbonyl sulfide (COS) to form H2S by carbonic anhydrase has been demonstrated to be a viable strategy to deliver H2S in a biological system. Herein, we describe N-dithiasuccinoyl amines as thiol-triggered COS/H2S donors. Notably, thiol species especially GSH and homocysteine can trigger the release of both COS and H2S directly from several specific analogues via an unexpected mechanism. Importantly, two representative analogues Dts-1 and Dts-5 show intracellular H2S release, and Dts-1 imparts potent anti-inflammatory effects in LPS-challenged microglia cells. In conclusion, N-dithiasuccinoyl amine could serve as promising COS/H2S donors for either H2S biological studies or H2S-based therapeutics development.

Comprehensive metabolomic, proteomic and physiological analyses of grain yield reduction in rice under abrupt drought-flood alternation stress.

Abrupt drought-flood alternation (T1) is a meteorological disaster that frequently occurs during summer in southern China and the Yangtze river basin, often causing a significant loss of rice production. In this study, the response mechanism of yield decline under abrupt drought-flood alternation stress at the panicle differentiation stage was analyzed by looking at the metabolome, proteome as well as yield and physiological and biochemical indexes. The results showed that drought and flood stress caused a decrease in the yield of rice at the panicle differentiation stage, and abrupt drought-flood alternation stress created a synergistic effect for the reduction of yield. The main reason for the decrease of yield per plant under abrupt drought-flood alternation was the decrease of seed setting rate. Compared with CK0 (no drought and no flood), the net photosynthetic rate and soluble sugar content of T1 decreased significantly and its hydrogen peroxidase, superoxide dismutase, peroxidase activity increased significantly. The identified differential metabolites and differentially expressed proteins indicated that photosynthesis metabolism, energy metabolism pathway and reactive oxygen species response have changed strongly under abrupt drought-flood alteration stress, which are factors that leads to the rice grain yield reduction.

Epigenetic Regulation of Autophagy.

Epigenetics refers to reversible and hereditary changes in gene expression without alterations in DNA sequences, such as DNA methylation, histone modification and chromatin remodelling. It was first proposed by Waddington in the book Introduction to Modern Genetics in 1939. Autophagy includes at least four processes: autophagy induction, autophagosome formation, autophagosome fusion with lysosomes and lysosomal degradation of cytoplasmic components. The whole process is complex and dynamic, and involves at least 30 autophagy-related proteins. This degradative machinery is regulated by multiple signal molecules. Autophagy was once considered to be a cytoplasmic event; however, in recent years, emerging evidence suggests that nuclear components (transcription factors, histone modification, microRNAs, etc.) also play an important role in autophagy regulation (Baek and Kim 2017). Among them, epigenetic regulation of autophagy has gained much attention. The epigenetic machinery can not only modify autophagy-related genes but also affect some signal molecule genes that regulate autophagy, thus impacting their transcription and subsequent autophagy. This chapter focuses on the role and recent progress in autophagy regulation by DNA methylation and histone modifications. The role of non-coding RNAs such as microRNA in autophagy regulation will be covered in other chapters.

Impaired CBS-H2S signaling axis contributes to MPTP-induced neurodegeneration in a mouse model of Parkinson's disease.

Hydrogen sulfide (H2S), a novel neuromodulator, is linked to the pathogenesis of several neurodegenerative disorders. Exogenous application of H2S exerts neuroprotection via anti-inflammation and anti-oxidative stress in animal and cellular models of Parkinson's disease (PD). However, the role of endogenous H2S and the contribution of its various synthases in PD remain unclear. In the present study, we found a decline of plasma and striatal sulfide level in 1-methy-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced PD mouse model. Interestingly, among the three H2S generating enzymes, only cystathionine ß-synthase (CBS) expression was largely reduced in the striatum of MPTP-treated mice. The in vitro study confirmed a significant decrease of CBS expression in 1-methyl-4-phenylpyridinium (MPP+)-stimulated astrocytes and microglia, but not in neurons or SH-SY5Y dopaminergic cells. Striatal CBS overexpression, elicited by stereotaxic delivery with Cbs gene using recombinant adeno-associated-virus (rAAV-Cbs), successfully enhanced the sulfide level in the striatum and partially rescued the MPTP-induced dopaminergic neurotoxicity in the midbrain. Specifically, striatal CBS overexpression alleviated the motor deficits and dopaminergic neuron losses in the nigro-striatal pathway, with a concomitant inhibition of glial activation in MPTP-treated mice. Furthermore, compared to rAAV-Vector, rAAV-Cbs injection reduced the aberrant accumulation of nitric oxide and 3-nitrotyrosine (an indicator of protein nitration) in the striatum of MPTP-treated mice. Notably, it also attenuated the increase of nitrated α-synuclein level in MPTP mice. The in vitro study demonstrated that lentivirus-mediated CBS overexpression elevated the sulfide generation in glial cells. Moreover, glial CBS overexpression offered protection to midbrain dopaminergic neurons through repressing nitric oxide overproduction in both glial and neuronal cells induced by MPP+. Taken together, our data suggest that impaired CBS-H2S axis may contribute to the pathogenesis of PD, and that modulation of this axis may become a novel therapeutic approach for PD.

Hydrogen sulfide inhibits ATP-induced neuroinflammation and Aß1-42 synthesis by suppressing the activation of STAT3 and cathepsin S.

Neuroinflammation and excessive ß-amyloid1-42 (Aß1-42) generation contribute to the pathogenesis of Alzheimer's disease (AD). Emerging evidence has demonstrated that hydrogen sulfide (H2S), an endogenous gasotransmitter, produces therapeutic effects in AD; however, the underlying mechanisms remain largely elusive. In the present study, we investigated the effects of H2S on exogenous ATP-induced inflammation and Aß1-42 production in both BV-2 and primary cultured microglial cells and analyzed the potential mechanism(s) mediating these effects. Our results showed that NaHS, an H2S donor, inhibited exogenous ATP-stimulated inflammatory responses as manifested by the reduction of pro-inflammatory cytokines, ROS and activation of nuclear factor-κB (NF-κB) pathway. Furthermore, NaHS also suppressed the enhanced production of Aß1-42 induced by exogenous ATP, which is probably due to its inhibitory effect on exogenous ATP-boosted expression of amyloid precursor protein (APP) and activation of ß- and γ-secretase enzymes. Thereafter, we found that exogenous ATP-induced inflammation and Aß1-42 production requires the activation of signal transducer and activator of transcription 3 (STAT3) and cathepsin S (Cat S) as inhibition of the activity of either proteins attenuated the effect of exogenous ATP. Intriguingly, NaHS suppressed exogenous ATP-induced phosphorylation of STAT3 and the activation of Cat S. In addition, we observed that NaHS led to the persulfidation of Cat S at cysteine-25. Importantly, mutation of cysteine-25 into serine attenuated the activity of Cat S stimulated by exogenous ATP and subsequent inflammation and Aß1-42 production, indicating its involvement in H2S-mediated effect. Taken together, our data provide a novel understanding of H2S-mediated effect on neuroinflammation and Aß1-42 production by suppressing the activation of STAT3 and Cat S.

Attenuation of hyperalgesia responses via the modulation of 5-hydroxytryptamine signalings in the rostral ventromedial medulla and spinal cord in a 6-hydroxydopamine-induced rat model of Parkinson's disease.

Background Although pain is one of the most distressing non-motor symptoms among patients with Parkinson's disease, the underlying mechanisms of pain in Parkinson's disease remain elusive. The aim of the present study was to investigate the role of serotonin (5-hydroxytryptamine) in the rostral ventromedial medulla (RVM) and spinal cord in pain sensory abnormalities in a 6-hydroxydopamine-treated rat model of Parkinson's disease. Methods The rotarod test was used to evaluate motor function. The radiant heat test and von Frey test were conducted to evaluate thermal and mechanical pain thresholds, respectively. Immunofluorescence was used to examine 5-hydroxytryptamine neurons and fibers in the rostral ventromedial medulla and spinal cord. High-performance liquid chromatography was used to determine 5-hydroxytryptamine and 5-hydroxyindoleacetic acid levels. Results The duration of running time on the rotarod test was significantly reduced in 6-hydroxydopamine-treated rats. Nociceptive thresholds of both mechanical and heat pain were reduced compared to sham-treated rats. In addition to the degeneration of cell bodies and fibers in the substantia nigra pars compacta, the number of rostral ventromedial medulla 5-hydroxytryptamine neurons and 5-hydroxytryptamine fibers in the spinal dorsal horn was dramatically decreased. 5-Hydroxytryptamine concentrations in both the rostral ventromedial medulla and spinal cord were reduced. Furthermore, the administration of citalopram significantly attenuated pain hypersensitivity. Interestingly, Intra-rostral ventromedial medulla (intra-RVM) microinjection of 5,7-dihydroxytryptamine partially reversed pain hypersensitivity of 6-hydroxydopamine-treated rats. Conclusions These results suggest that the decreased 5-hydroxytryptamine contents in the rostral ventromedial medulla and spinal dorsal horn may be involved in hyperalgesia in the 6-hydroxydopamine-induced rat model of Parkinson's disease.

Vesicular monoamine transporter 2 (Vmat2) knockdown elicits anxiety-like behavior in zebrafish.

Vesicular monoamine transporter 2 (Vmat2) is widely distributed in the central nervous system, and responsible for uptaking transmitters into the vesicles. However, whether Vmat2-deficiency is related to the anxiety is rarely investigated, especially in zebrafish. Here, we reported Vmat2 heterzygous mutant zebrafish displayed anxiety-like behavior. The mutants spent less time in the top area and took longer latency to the top in the novel tank test. Consistently, they showed dark avoidance in the light/dark box test, with longer duration in the light zone and increased number of crossing between the two zones. Monoamine concentration analysis showed that the levels of monoamine neurotransmitters including dopamine (DA), 5-hydroxy tryptamine (5-HT) and norepinephrine (NE), as well as their metabolites were decreased in VMAT mutants. Taken together, these findings suggest that Vmat2 heterzygous mutant zebrafish may serve as a new model of anxiety, which may be related with the low level of DA, 5-HT and NE.

DNA methylation in cystathionine-γ-lyase (CSE) gene promoter induced by ox-LDL in macrophages and in apoE knockout mice.

Recent studies suggest that epigenetic alterations such as DNA methylation control many aspects of monocytes/macrophages and participate in the pathogenesis of atherosclerosis, a lipid-driven inflammatory disorder. Our and other groups demonstrated that dysregulation of cystathionine γ-lyase (CSE) -hydrogen sulfide (H2S) pathway was involved in monocyte/macrophages-mediated inflammation and atherosclerosis. However, it remains unknown whether altered cse methylation in macrophages may play a role in linking CSE-H2S dysregulation and atherosclerosis. In the present study, we showed that plasma H2S and H2S production in the peritoneal macrophages of apolipoprotein knockout (apoE(-/-)) mice gradually decreased with ages, and were also lower than that in control mice at 12 weeks older. Moreover, CSE mRNA expressions decreased while DNA methyltransferase (DNMT) expressions increased in the peritoneal macrophages isolated from apoE(-/-) mice, compared to age-matched wildtype mice. Similar observations were obtained in an in vitro study. In oxidized low-density lipoprotein (ox-LDL)-treated raw264.7 macrophages, cse transcription was down-regulated while the expression and activity of DNMT was up-regulated, associated with enhanced DNA methylation in cse promoter. Suppression of DNMT with its inhibitor or siRNA reversed the decrease of CSE mRNA. Therefore, our data suggest that DNA hypermethylation of CpG rich region in cse promoter might contribute to the decrease of cse transcription and H2S production in macrophages, and thus contribute to atherosclerosis development.

Neuroprotective Effects of Paeoniflorin on 6-OHDA-Lesioned Rat Model of Parkinson's Disease.

Paeoniflorin (PF) is the main active component extracted from the roots of Paeonialactiflora, a traditional Chinese medicine used for the treatment of neurodegenerative disorders, especially Parkinson's disease (PD). The degeneration of dopaminergic (DA-) neurons in PD may be caused by pathological activation of acid-sensing ion channels (ASICs). Thus, we designed a series of experiments to evaluate the therapeutic effects of PF and to test whether its effects are related to its inhibitory effect on ASIC1a. We found that systemic administration of PF or ASICs blockers (psalmotoxin-1 and amiloride) improved behavioral symptoms, delayed DA-neuronal loss and attenuated the reduction of dopamine (DA) and its metabolites in a rat model of 6-hydroxydopamine (6-OHDA)-induced PD. In addition, our data showed that PF, like ASICs blockers, regulated the expression of ASIC1a, decreased the level of α-synuclein (α-SYN), and improved autophagic dysfunction. Further experiments showed that ASIC1a knockdown down-regulated the α-SYN level and alleviated the autophagic injury in the 6-OHDA-treated ASIC1a-silenced PC12 cells. In summary, these findings indicate that PF enhanced the autophagic degradation of α-SYN and, thus, protected DA-neurons against the neurotoxicity caused by 6-OHDA. These findings also provide experimental evidence that PF may be a neuroprotectant for PD by acting on ASIC1a and that ASIC1a may be involved in the pathogenesis of PD.

Mineralization initiation of MC3T3-E1 preosteoblast is suppressed under simulated microgravity condition.

Microgravity decreases the differentiation of osteoblast. However, as this process is multistage and complex, the mechanism by which microgravity inhibits osteoblast differentiation is still unclear. We have previously found that 24 h acute treatment of simulated microgravity (SM) with a random positioning machine (RPM) significantly inhibited the differentiation of preosteoblasts and have explored whether osteoblasts show different response to microgravity condition at other stages, such as the mineralizing-stage. Murine MC3T3-E1 preosteoblasts induced for osteogenic differentiation for seven days were cultured either under normal gravity or SM conditions for 24 h. SM treatment significantly suppressed mineralized nodule formation. Alkaline phosphatase (ALP) activity was dramatically decreased, and the expression of ALP gene was downregulated. Expression of well-known markers and regulators for osteoblasts differentiation, including osteocalcin (OC), type I collagen α1 (Col Iα1), dentin matrix protein 1 (DMP1) and runt-related transcription factor 2 (Runx2), were downregulated. Western blot analysis showed that the phosphorylated extracellular signal-regulated kinase (p-ERK) level was lower under SM condition. Thus, the initiation of osteoblast mineralization is suppressed by SM condition, and the suppression may be through the regulation of ALP activity and the osteogenic gene expression. ERK signaling might be involved in this process. These results are relevant to the decrease of osteoblast maturation and bone formation under microgravity condition.

Sulfide oxidation and nitrate reduction for potential mitigation of H2S in landfills.

Because H2S emitted by landfill sites has seriously endangered human health, its removal is urgent. H2S removal by use of an autotrophic denitrification landfill biocover has been reported. In this process, nitrate-reducing and sulfide-oxidizing bacteria use a reduced sulfur source as electron donor when reducing nitrate to nitrogen gas and oxidizing sulfur compounds to sulfate. The research presented here was performed to investigate the possibility of endogenous mitigation of H2S by autotrophic denitrification of landfill waste. The sulfide oxidation bioprocess accompanied by nitrate reduction was observed in batch tests inoculated with mineralized refuse from a landfill site. Repeated supply of nitrate resulted in rapid oxidation of the sulfide, indicating that, to a substantial extent, the bioprocess may be driven by functional microbes. This bioprocess can be realized under conditions suitable for the autotrophic metabolic process, because the process occurred without addition of acetate. H2S emissions from landfill sites would be substantially reduced if this bioprocess was introduced.

Homocysteine Triggers Inflammatory Responses in Macrophages through Inhibiting CSE-H2S Signaling via DNA Hypermethylation of CSE Promoter.

Hyperhomocysteinemia (HHcy) is an independent risk factor of atherosclerosis and other cardiovascular diseases. Unfortunately, Hcy-lowering strategies were found to have limited effects in reducing cardiovascular events. The underlying mechanisms remain unclear. Increasing evidence reveals a role of inflammation in the pathogenesis of HHcy. Homocysteine (Hcy) is a precursor of hydrogen sulfide (H2S), which is formed via the transsulfuration pathway catalyzed by cystathionine ß-synthase and cystathionine γ-lyase (CSE) and serves as a novel modulator of inflammation. In the present study, we showed that methionine supplementation induced mild HHcy in mice, associated with the elevations of TNF-α and IL-1ß in the plasma and reductions of plasma H2S level and CSE expression in the peritoneal macrophages. H2S-releasing compound GYY4137 attenuated the increases of TNF-α and IL-1ß in the plasma of HHcy mice and Hcy-treated raw264.7 cells while CSE inhibitor PAG exacerbated it. Moreover, the in vitro study showed that Hcy inhibited CSE expression and H2S production in macrophages, accompanied by the increases of DNA methyltransferase (DNMT) expression and DNA hypermethylation in cse promoter region. DNMT inhibition or knockdown reversed the decrease of CSE transcription induced by Hcy in macrophages. In sum, our findings demonstrate that Hcy may trigger inflammation through inhibiting CSE-H2S signaling, associated with increased promoter DNA methylation and transcriptional repression of cse in macrophages.

Characteristics of H2S emission from aged refuse after excavation exposure.

Hydrogen sulfide (H2S(g)) emission from landfills is a widespread problem, especially when aged refuse is excavated. H2S(g) emission from aged refuse exposed to air was investigated and the results showed that large amounts of H2S(g) can be released, especially in the first few hours after excavation, when H2S(g) concentrations in air near refuse could reach 2.00 mg m(-3). Initial exposure to air did not inhibit the emission of H2S(g), as is generally assumed, but actually promoted it. The amounts of H2S(g) emitted in the first 2 d after excavation can be very dangerous, and the risks associated with the emission of H2S(g) could decrease significantly with time. Unlike a large number of sulfide existed under anaerobic conditions, the sulfide in aged municipal solid waste can be oxidized chemically to elemental sulfur (but not sulfate) under aerobic conditions, and its conversion rate was higher than 80%. Only microorganisms can oxidize the reduced sulfur species to sulfate, and the conversion rate could reach about 50%. Using appropriate techniques to enhance these chemical and biological transformations could allow the potential health risks caused by H2S(g) after refuse excavation to be largely avoided.

Hydrogen sulfide inhibits the renal fibrosis of obstructive nephropathy.

Hydrogen sulfide has recently been found decreased in chronic kidney disease. Here we determined the effect and underlying mechanisms of hydrogen sulfide on a rat model of unilateral ureteral obstruction. Compared with normal rats, obstructive injury decreased the plasma hydrogen sulfide level. Cystathionine-ß-synthase, a hydrogen sulfide-producing enzyme, was dramatically reduced in the ureteral obstructed kidney, but another enzyme cystathionine-γ-lyase was increased. A hydrogen sulfide donor (sodium hydrogen sulfide) inhibited renal fibrosis by attenuating the production of collagen, extracellular matrix, and the expression of α-smooth muscle actin. Meanwhile, the infiltration of macrophages and the expression of inflammatory cytokines including interleukin-1ß, tumor necrosis factor-α, and monocyte chemoattractant protein-1 in the kidney were also decreased. In cultured kidney fibroblasts, a hydrogen sulfide donor inhibited the cell proliferation by reducing DNA synthesis and downregulating the expressions of proliferation-related proteins including proliferating cell nuclear antigen and c-Myc. Further, the hydrogen sulfide donor blocked the differentiation of quiescent renal fibroblasts to myofibroblasts by inhibiting the transforming growth factor-ß1-Smad and mitogen-activated protein kinase signaling pathways. Thus, low doses of hydrogen sulfide or its releasing compounds may have therapeutic potentials in treating chronic kidney disease.

Downregulation of cystathionine ß-synthase/hydrogen sulfide contributes to rotenone-induced microglia polarization toward M1 type.

Microglia-mediated neuroinflammation is implicated in the pathogenesis of several neurodegenerative disorders. Microglia can be activated and polarized to exert pro- or anti-inflammatory roles in response to specific stimulus. Rotenone is an environmental toxin that has been shown to activate microglia and neuroinflammation. However, the effects and mechanisms of rotenone on microglia polarization are poorly studied. In the present study, we demonstrated that rotenone enhanced the levels of M1 phenotypic genes including TNF-α, iNOS and COX-2/PGE2 but reduced that of M2 markers such as Ym1/2 and IL-10 in mouse primary and immortalized microglia. Moreover, the transcription and protein expression of cystathionine-ß-synthase (CBS), as well as hydrogen sulfide (H2S) production were decreased in rotenone-treated primary microglia. Elevating endogenous H2S via CBS over-expression in immortalized microglia not only reduced the expression of pro-inflammatory M1 genes, but also enhanced the anti-inflammatory M2 marker IL-10 production in response to rotenone stimulation as compared to vector-transfected cells. Similarly, pretreatment with H2S donor NaHS (50, 100 and 500µmol/L) attenuated the increases of M1 gene expression triggered by rotenone treatment, and enhanced the M2 gene Ym1/2 expression in mouse primary microglia. In addition, we observed reactive oxygen species (ROS) scavenger N-acetyl-l-cysteine reversed the down-regulation of CBS and H2S generation caused by rotenone in microglia. NaHS pretreatment also decreased the ROS formation in rotenone-stimulated microglia. Taken together, these results reveal that probably via triggering ROS formation, rotenone suppressed the CBS-H2S pathway and thus promoted microglia polarization toward M1 pro-inflammatory phenotype.

Expression and functions of ASIC1 in the zebrafish retina.

It has been demonstrated that acid sensing ionic channels (ASICs) are present in the central and peripheral nervous system of mammals, including the retina. However, it remains unclear whether the zebrafish retina also expresses ASICs. In the present study, the expression and distribution of zasic1 were examined in the retina of zebrafish. Both zasic1 mRNA and protein expressions were detected in the adult zebrafish retina. A wide distribution of ASIC1 in zebrafish retina was confirmed using whole mount in situ hybridization and immunohistochemistry study. Acidosis-induced currents in the isolated retinal ganglion cells (RGCs) were also recorded using whole cell patch clamping. Moreover, blockade of ASICs channel significantly reduced the locomotion of larval zebrafish in response to light exposure. In sum, our data demonstrate the presence of ASIC1 and its possible functional relevance in the retina of zebrafish.

Statins upregulate cystathionine γ-lyase transcription and H2S generation via activating Akt signaling in macrophage.

Hydrogen sulfide (H2S), the third gaseous transmitter, is implicated in various pathophysiologic processes. In the cardiovascular system, H2S exerts effects of cardioprotection, vascular tone regulation, and atherogenesis inhibition. Recent studies demonstrated that atorvastatin, the inhibitor of 3-hydroxyl-3-methyl coenzyme A reductase, affected H2S formation in kidney and other organs. However, the underlying mechanisms are not fully understood. In this study, we examined the effects of three different statins (fluvastatin, atorvastatin and pravastatin) on H2S formation in raw264.7 macrophages. There was a remarkable rise in H2S level in fluvastatin- and atorvastatin-stimulated macrophages, while pravastatin failed to show any significant effect on it. Moreover, fluvastatin and atorvastatin enhanced the mRNA and protein expression of cystathionine γ-lyase (CSE) in dose- and time-dependent manners. Fluvastatin also markedly enhanced the CSE activity. However, fluvastatin did not alter the mRNA or protein expression of another H2S-producing enzyme 3-mercaptopyruvate sulfurtransferase. Blockade of CSE with its inhibitor dl-propargylglycine (PAG) or siRNA markedly reduced the H2S level in fluvastatin-stimulated macrophages. In addition, fluvastatin elevated Akt phosphorylation, which occurred as early as 15 min after treatment, peaked at 1h, and lasted at least 3h. Both PI3K inhibitor LY294002 (10 µM) and Akt inhibitor perifosine (10µM) were able to reverse the increases of CSE mRNA and H2S production in fluvastatin-stimulated macrophages. Last, we showed that fluvastatin reduced the mRNA levels of pro-inflammatory molecules such as IL-1ß and MCP-1 in LPS-treated macrophages, which were completely reversed by CSE inhibitor PAG. Taken together, the findings demonstrate that statins may up-regulate CSE expression/activity and subsequently elevate H2S generation by activating Akt signaling pathway and also imply that CSE-H2S pathway plays a critical role in the anti-inflammation elicited by statins.

Safety and effectiveness of remdesivir in hospitalized patients with COVID-19 and severe renal impairment: experience at a large medical center.

BACKGROUND: Literature on the safety of remdesivir in hospitalized COVID-19 patients with severe renal impairment is limited. We aimed to investigate the safety and effectiveness of remdesivir in this population. METHODS: We conducted a retrospective cohort study of adult hospitalized COVID-19 patients who received remdesivir between April 2022 and October 2022. Outcomes were compared between estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m2 and ≥30 mL/min/1.73 m2 groups. The primary safety outcomes were acute kidney injury (AKI) and bradycardia, while the primary effectiveness outcomes included mortality in COVID-19-dedicated wards and hospital mortality. Secondary outcomes included laboratory changes, disease progression, and recovery time. RESULTS: A total of 1,343 patients were recruited, with 307 (22.9%) in the eGFR <30 group and 1,036 (77.1%) in the eGFR ≥30 group. Patients with an eGFR <30 had higher risks of AKI (adjusted hazard ratio [aHR] 2.92, 95% CI 1.93-4.44) and hospital mortality (aHR 1.47, 95% CI 1.06-2.05) but had comparable risks of bradycardia (aHR 1.15, 95% CI 0.85-1.56) and mortality in dedicated wards (aHR 1.43, 95% CI 0.90-2.28) than patients with an eGFR ≥30. Risk of disease progression was higher in the eGFR <30 group (adjusted odds ratio 1.62, 95% CI 1.16-2.26). No difference between the two groups in laboratory changes and recovery time. CONCLUSIONS: Hospitalized COVID-19 patients receiving remdesivir with severe renal impairment had an increased risk of AKI, hospital mortality, and COVID-19 disease progression compared to patients without severe renal impairment.