Mtb/HIV co-infection immune microenvironment subpopulations heterogeneity.

BACKGROUND: The co-infection of human immunodeficiency virus type 1 (HIV-1) and tuberculosis poses a lethal threat. Currently, our understanding of the altered immune responses and diverse immune cell subpopulations triggered by dual pathogen infections remains inadequate. METHODS: We utilized single-cell RNA sequencing data from the Gene Expression Omnibus database and the China National GeneBank Nucleotide Sequence Archive to study peripheral blood mononuclear cells from individuals infected with HIV-1 and those co-infected with Mycobacterium tuberculosis (Mtb)/HIV. We investigated cellular components, signaling pathways, biological functions, developmental trajectories, and gene regulatory networks among different cells to determine cellular heterogeneity in the progression of Mtb/HIV co-infection. RESULTS: We constructed a single-cell global transcriptional landscape of Mtb/HIV co-infection, revealing heterogeneity among various cell subpopulations. CD4+ T_RACK1_STAT1 subpopulation may participate in the JAK-STAT signaling pathway through RACK1-mediated transcriptional regulation of STAT1, potentially mediating the immune response in patients. Targeting CD8+ T_RACK1_TIGIT subpopulation via RACK1 may help restore the effector capacity of CD8+ T cells. Additionally, Mono_HSP90AA1 and Mono_APOBEC3A subpopulations were positioned at the endpoints of monocyte differentiation trajectories in different patients, suggesting their significant roles in distinct types of immune responses. CTL_GNLY and NK_HSPA1A subpopulations were specifically enriched in three distinct HIV-infected patient groups, indicating their crucial roles in the immune cytotoxicity associated with Mtb/HIV co-infection. CONCLUSION: The immune system disruptions caused by HIV-1 infection are further exacerbated by co-infection with Mtb. This compounded effect leads to significant heterogeneity in immune cell subpopulations among co-infected individuals, promoting immune system dysfunction.

Lactate dehydrogenase-1 may play a key role in the brain energy disturbance caused by cryptococcal meningitis.

BACKGROUND: Cryptococcal meningitis (CM) may affect the conversion of lactate to pyruvate in the brain, resulting in abnormal levels of adenosine triphosphate (ATP) throughout the brain. Lactate conversion to pyruvate is mainly caused by lactic dehydrogenase 1 (LDH1), which is composed of four LDHB subunits. However, the underlying mechanism of LDH1 in CM remains unclear. METHODS: Cerebrospinal fluid (CSF) from 17 patients was collected, including eight patients with non-infectious diseases of the central nervous system and nine patients with CM. Based on clinical data and laboratory reports, data regarding intracranial pressure, CSF white cell counts, lactate dehydrogenase (LDH), adenosine deaminase, glucose, protein, and chloridion were collected. Meanwhile, LDH1, LDH5, lactate, pyruvate, and ATP levels were detected in CSF. Whereafter, the levels of lactate, pyruvate, ATP, and the amplitude and frequency of action potentials in the neurons with low expression of LDHB were explored. RESULTS: Intracranial pressure and white cell count in CSF were significantly increased in patients with CM. In patients with CM, the LDH1, pyruvate, and ATP levels in the CSF were significantly decreased, and the levels of lactate were found to be increased. Furthermore, pyruvate and ATP levels were decreased, while lactate was increased in the neurons with low expression of LDHB. The amplitude and frequency of APs in the neurons with low expression of LDHB were significantly decreased. CONCLUSION: Reduced levels of LDH1 in the brain of patients with CM may lead to increased lactate levels, decreased pyruvate and ATP levels, and negatively affect neuronal activity.

TFEB/LAMP2 contributes to PM0.2-induced autophagy-lysosome dysfunction and alpha-synuclein dysregulation in astrocytes.

Atmospheric particulate matter (PM) exacerbates the risk factor for Alzheimer's and Parkinson's diseases (PD) by promoting the alpha-synuclein (α-syn) pathology in the brain. However, the molecular mechanisms of astrocytes involvement in α-syn pathology underlying the process remain unclear. This study investigated PM with particle size <200 nm (PM0.2) exposure-induced α-syn pathology in ICR mice and primary astrocytes, then assessed the effects of mammalian target of rapamycin inhibitor (PP242) in vitro studies. We observed the α-syn pathology in the brains of exposed mice. Meanwhile, PM0.2-exposed mice also exhibited the activation of glial cell and the inhibition of autophagy. In vitro study, PM0.2 (3, 10 and 30 µg/mL) induced inflammatory response and the disorders of α-syn degradation in primary astrocytes, and lysosomal-associated membrane protein 2 (LAMP2)-mediated autophagy underlies α-syn pathology. The abnormal function of autophagy-lysosome was specifically manifested as the expression of microtubule-associated protein light chain 3 (LC3II), cathepsin B (CTSB) and lysosomal abundance increased first and then decreased, which might both be a compensatory mechanism to toxic α-syn accumulation induced by PM0.2. Moreover, with the transcription factor EB (TFEB) subcellular localization and the increase in LC3II, LAMP2, CTSB, and cathepsin D proteins were identified, leading to the restoration of the degradation of α-syn after the intervention of PP242. Our results identified that PM0.2 exposure could promote the α-syn pathological dysregulation in astrocytes, providing mechanistic insights into how PM0.2 increases the risk of developing PD and highlighting TFEB/LAMP2 as a promising therapeutic target for antagonizing PM0.2 toxicity.

Single-cell RNA sequencing revealed potential targets for immunotherapy studies in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a solid tumor prone to chemotherapy resistance, and combined immunotherapy is expected to bring a breakthrough in HCC treatment. However, the tumor and tumor microenvironment (TME) of HCC is highly complex and heterogeneous, and there are still many unknowns regarding tumor cell stemness and metabolic reprogramming in HCC. In this study, we combined single-cell RNA sequencing data from 27 HCC tumor tissues and 4 adjacent non-tumor tissues, and bulk RNA sequencing data from 374 of the Cancer Genome Atlas (TCGA)-liver hepatocellular carcinoma (LIHC) samples to construct a global single-cell landscape atlas of HCC. We analyzed the enrichment of signaling pathways of different cells in HCC, and identified the developmental trajectories of cell subpopulations in the TME using pseudotime analysis. Subsequently, we performed transcription factors regulating different subpopulations and gene regulatory network analysis, respectively. In addition, we estimated the stemness index of tumor cells and analyzed the intercellular communication between tumors and key TME cell clusters. We identified novel HCC cell clusters that specifically express HP (HCC_HP), which may lead to higher tumor differentiation and tumor heterogeneity. In addition, we found that the HP gene expression-positive neutrophil cluster (Neu_AIF1) had extensive and strong intercellular communication with HCC cells, tumor endothelial cells (TEC) and cancer-associated fibroblasts (CAF), suggesting that clearance of this new cluster may inhibit HCC progression. Furthermore, ErbB signaling pathway and GnRH signaling pathway were found to be upregulated in almost all HCC tumor-associated stromal cells and immune cells, except NKT cells. Moreover, the high intercellular communication between HCC and HSPA1-positive TME cells suggests that the immune microenvironment may be reprogrammed. In summary, our present study depicted the single-cell landscape heterogeneity of human HCC, identified new cell clusters in tumor cells and neutrophils with potential implications for immunotherapy research, discovered complex intercellular communication between tumor cells and TME cells.

GE11 peptide-decorated acidity-responsive micelles for improved drug delivery and enhanced combination therapy of metastatic breast cancer.

Nanotechnology-mediated drug delivery systems suffer from insufficient retention in tumor tissues and unreliable drug release at specific target sites. Herein, we developed an epidermal growth factor receptor-targeted multifunctional micellar nanoplatform (GE11-DOX+CEL-M) by encapsulating celecoxib into polymeric micelles based on the conjugate of GE11-poly(ethylene glycol)-b-poly(trimethylene carbonate) with doxorubicin to suppress tumor growth and metastasis. The polymeric micelles maintained stable nanostructures under physiological conditions but quickly disintegrated in a weakly acidic environment, which is conducive to controlled drug release. Importantly, GE11-DOX+CEL-M micelles effectively delivered the drug combination to tumor sites and enhanced tumor cell uptake through GE11-mediated active tumor targeting. Subsequently, GE11-DOX+CEL-M micelles dissociated in response to intracellular slightly acidic microenvironmental stimuli, resulting in rapid release of celecoxib and doxorubicin to synergistically inhibit the proliferation and migration of tumor cells. Systemic administration of GE11-DOX+CEL-M micelles into mice bearing subcutaneous 4T1 tumor models resulted in higher tumor growth suppression and decreased lung metastasis of tumor cells compared with micelles without GE11 decoration or delivering only doxorubicin. Furthermore, the micelles effectively reduced the systemic toxicity of the chemotherapy drugs. This nanotherapeutic system provides a promising strategy for safe and effective cancer therapy.

Mechanism of subchronic vinyl chloride exposure combined with a high-fat diet on hepatic steatosis.

Vinyl chloride (VC) is a common industrial organic chlorine and environmental pollutant. In recent years, the dietary structure of residents especially Chinese has gradually shifted to western dietary patterns. VC aggravates dietary fatty acid-induced hepatic steatosis, but its mechanism is still unclear. And if the risk factors for steatosis persist, more severe diseases such as fibrosis and cirrhosis will occur. Therefore, we studied the effects and mechanisms of VC (160 and 800 mg/m3 ) and its metabolite (chloroacetaldehyde, 2.25, 4.5, and 9 µM) on hepatic steatosis of high-fat diet (HFD)-fed mice and palmitic acid (PA, 100 µM) treated HepG2 cells. Liver and serum biochemical indicators and pathological staining of the liver showed that the hepatic steatosis of VC combined with HFD groups was more severe than that of single-exposure groups (HFD group, low-dose VC group, and high-dose VC group). Moreover, VC enhanced HFD-induced oxidative stress (OS) and endoplasmic reticulum stress (ERS) and further upregulated the expression of sterol regulatory element-binding protein 1 (SREBP-1) and FAS. Besides, antioxidants and ERS inhibitors reduced the steatosis of HepG2 cells induced by VC metabolites and PA. These results suggest that VC exposure can enhance the degree of hepatic steatosis in HFD-fed mice. VC combined with HFD led to OS and ERS and upregulated the expression of de novo lipogenesis-related proteins, which may be related to the occurrence of hepatic steatosis. And the increased expression of CYP2E1 induced by VC combined with HFD may be the cause of OS.

Arsenic-fluoride co-exposure induced endoplasmic reticulum stress resulting in apoptosis in rat heart and H9c2 cells.

Exposure to arsenic (As) or fluoride (F) has been shown to cause cardiovascular disease (CVDs). However, evidence about the effects of co-exposure to As and F on myocardium and their mechanisms remain scarce. Our aim was to fill the gap by establishing rat and H9c2 cell exposure models. We determined the effects of As and/or F exposure on the survival rate, apoptosis rate, morphology and ultrastructure of H9c2 cells; in addition, we tested the related genes and proteins of endoplasmic reticulum stress (ERS) and apoptosis in H9c2 cells and rat heart tissues. The results showed that As and/or F exposure induced early apoptosis of H9c2 cells and caused endoplasmic reticulum expansion. Additionally, the mRNA and protein expression levels of GRP78, PERK and CHOP in H9c2 cells were higher in the exposure groups than in the control group, and could be inhibited by 4-PBA. Furthermore, we found that As and/or F exposure increased the expression level of GRP78 in rat heart tissues, but interestingly, the expression level of CHOP protein was increased in the F and As groups, while significantly decreased in the co-exposure group. Overall, our results suggested that ERS-induced apoptosis was involved in the damage of myocardium by As and/or F exposure. In addition, factorial analysis results showed that As and F mainly play antagonistic roles in inducing myocardial injury, initiating ERS and apoptosis after exposure.

Suppressive Monocytes Impair MAIT Cells Response via IL-10 in Patients with Severe COVID-19.

Immune cell responses are strikingly altered in patients with severe coronavirus disease 2019 (COVID-19), but the immunoregulatory process in these individuals is not fully understood. In this study, 23 patients with mild and 22 patients with severe COVID-19 and 6 asymptomatic carriers of COVID-19 were enrolled, along with 44 healthy controls (HC). Peripheral immune cells in HC and patients with COVID-19 were comprehensively profiled using mass cytometry. We found that in patients with severe COVID-19, the number of HLA-DRlow/- monocytes was significantly increased, but that of mucosal-associated invariant T (MAIT) cells was greatly reduced. MAIT cells were highly activated but functionally impaired in response to Escherichia coli and IL-12/IL-18 stimulation in patients with severe COVID-19, especially those with microbial coinfection. Single-cell transcriptome analysis revealed that IFN-stimulated genes were significantly upregulated in peripheral MAIT cells and monocytes from patients with severe COVID-19. IFN-α pretreatment suppressed MAIT cells' response to E. coli by triggering high levels of IL-10 production by HLA-DRlow/--suppressive monocytes. Blocking IFN-α or IL-10 receptors rescued MAIT cell function in patients with severe COVID-19. Moreover, plasma from patients with severe COVID-19 inhibited HLA-DR expression by monocytes through IL-10. These data indicate a unique pattern of immune dysregulation in severe COVID-19, which is characterized by enrichment of suppressive HLA-DRlow/- monocytes associated with functional impairment of MAIT cells through the IFN/IL-10 pathway.

Co-exposure to fluoride and arsenic disrupts intestinal flora balance and induces testicular autophagy in offspring rats.

While numerous studies have shown that fluoride or arsenic exposure may damage the reproductive system, there are few reports of co-exposure to fluoride and arsenic. In addition, the literature on autophagy and intestinal flora composition in reproductive toxicity studies of co-exposure to fluoride and arsenic is insufficient. In this study, we developed a rat model of fluoride and arsenic exposure via drinking water from pre-pregnancy to 90 days postnatal. Sprague-Dawley rats were randomly divided into sterile water control group, fluoride group (100 mg/L NaF), arsenic group (50 mg/L NaAsO2) and combined exposure group (100 mg/L NaF+50 mg/L NaAsO2). Our results showed that fluoride and arsenic exposure caused a reduction in testicular weight and significant pathological damage to tissue. We found that the levels of follicle-stimulating hormone, luteinizing hormone, and testosterone were reduced to varying degrees. Meanwhile experiments showed that fluoride and arsenic exposure can modulate autophagic flux, causing increased levels of Beclin1 and LC3 expression and decreased p62 expression. Analogously, by performing 16S sequencing of rat feces, we found 24 enterobacterial genera that differed significantly among the groups. Furthermore, the flora associated with testicular injury were identified by correlation analysis of hormonal indices and autophagy alterations with intestinal flora composition at the genus level, respectively. In summary, our study shows that fluoride and arsenic co-exposure alters autophagic flux in the testis, causes testicular injury, and reveals an association between altered intestinal flora composition and testicular injury.

ITRAQ-based proteomics reveals the potential mechanism of fluoride-induced myocardial contraction function damage.

Fluorosis is a worldwide public health problem, and its adverse effects on the heart have been confirmed by many studies. Abnormal myocardial contractions are often associated with impairment of cardiac function as a cause or consequence. We designed two-part experiments to search for biomarkers and clarify the underlying molecular mechanism of fluoride on myocardial contraction. First, we used Pressure-volume Loop analysis to evaluate changes in myocardial function indexes with multiple fluoride exposure levels in mice (0, 30, 70, and 150 mg/L) exposed for 4 weeks. The results showed that fluoride exposure affects the heart pump function and reduces cardiac contractility. Then, we established a rat model of fluoride exposure (0, 30, 60, and 90 mg/L) for 6 months to carry out proteomic analysis of fluoride-induced myocardial contractile injury. Hematoxylin-eosin (H&E) staining was used to determine the severity of myocardial injury, and myocardial tissue samples were submitted for isobaric tags for relative and absolute quantitation (ITRAQ) analysis. A total of 1607 proteins were successfully identified with 294 differentially expressed proteins (DEPs) in fluoride treated groups. According to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, 12 DEPs were confirmed to be involved in pathways related to myocardial contraction. Furthermore, we constructed a protein-protein interaction (PPI) network for these 12 core DEPs to illustrate the role and location of each DEP in the myocardial contraction pathway. The results of this study are helpful for identify a potential mechanism and biomarkers of fluoride-induced myocardial contraction function damage, moreover, which can provide a new insight into the heart toxicity of fluoride in animals at the proteomics level.

Single-cell transcriptomics of blood reveals a natural killer cell subset depletion in tuberculosis.

BACKGROUND: Tuberculosis (TB) continues to be a critical global health problem, which killed millions of lives each year. Certain circulating cell subsets are thought to differentially modulate the host immune response towards Mycobacterium tuberculosis (Mtb) infection, but the nature and function of these subsets is unclear. METHODS: Peripheral blood mononuclear cells (PBMC) were isolated from healthy controls (HC), latent tuberculosis infection (LTBI) and active tuberculosis (TB) and then subjected to single-cell RNA sequencing (scRNA-seq) using 10 × Genomics platform. Unsupervised clustering of the cells based on the gene expression profiles using the Seurat package and passed to tSNE for clustering visualization. Flow cytometry was used to validate the subsets identified by scRNA-Seq. FINDINGS: Cluster analysis based on differential gene expression revealed both known and novel markers for all main PBMC cell types and delineated 29 cell subsets. By comparing the scRNA-seq datasets from HC, LTBI and TB, we found that infection changes the frequency of immune-cell subsets in TB. Specifically, we observed gradual depletion of a natural killer (NK) cell subset (CD3-CD7+GZMB+) from HC, to LTBI and TB. We further verified that the depletion of CD3-CD7+GZMB+ subset in TB and found an increase in this subset frequency after anti-TB treatment. Finally, we confirmed that changes in this subset frequency can distinguish patients with TB from LTBI and HC. INTERPRETATION: We propose that the frequency of CD3-CD7+GZMB+ in peripheral blood could be used as a novel biomarker for distinguishing TB from LTBI and HC. FUND: The study was supported by Natural Science Foundation of China (81770013, 81525016, 81772145, 81871255 and 91942315), National Science and Technology Major Project (2017ZX10201301), Science and Technology Project of Shenzhen (JCYJ20170412101048337) and Guangdong Provincial Key Laboratory of Regional Immunity and Diseases (2019B030301009). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Co-exposure to Arsenic-Fluoride Results in Endoplasmic Reticulum Stress-Induced Apoptosis Through the PERK Signaling Pathway in the Liver of Offspring Rats.

Arsenic and fluoride are two of the major groundwater pollutants. To better understand the liver damage induced during development, 24 male rats exposed to fluoride (F), arsenic (As), and their combination (As + F) from the prenatal stage to 90 days after birth were selected for analysis. Histopathological results showed vacuolar degeneration in the As and As + F groups. Compared to those in the control group, aspartate aminotransferase and alanine aminotransferase levels were significantly increased in the combined group. Catalase activity significantly decreased in the treatment groups compared to that in the controls, and the malondialdehyde content in the As and As + F groups was significantly higher than those in the control group. We further evaluated whether this damage is linked to endoplasmic reticulum stress and its related pathways. The mRNA expression levels of PERK, GRP78, EIF2α, ATF4, and CHOP as well as the protein levels of CHOP was significantly increased in the As + F group compared with the control group. These results demonstrate that As, F, and their combination could lead to liver function damage and reduce the antioxidant capacity of the liver to cause oxidative damage to tissues. Moreover, the combination of As and F triggers endoplasmic reticulum stress-induced apoptosis in liver cells by activating the PERK pathway in the unfolded protein response. As and F seem to have different independent effects, whereas their combination resulted in more severe effects overall.

Subchronic exposure to arsenite and fluoride from gestation to puberty induces oxidative stress and disrupts ultrastructure in the kidneys of rat offspring.

Underground drinking water is commonly contaminated with arsenite (As) and fluoride (F) associated with chronic kidney diseases in humans; however, the combined renal toxicity of these pollutants and the underlying mechanisms are still unclear. The aim of the present study was to investigate the interaction between As and F regarding toxic effects on the kidney of rat offspring exposed to pollutants during prenatal and postnatal development. Pregnant rats were randomly divided into four groups that received NaAsO2 (50 mg/L), NaF (100 mg/L), NaAsO2 (50 mg/L) and NaF (100 mg/L) in drinking water, or clean water, respectively, during gestation and lactation. After weaning, six male pups were randomly selected from each group and continued on the same treatment as their mothers for up to three months. The results revealed that subchronic exposure to high-dose As and/or F decreased the organ coefficient of the kidneys and disrupted kidney ultrastructure, moreover inhibited the activity of antioxidant enzymes and increased the generation of malondialdehyde in the kidney. As exposure alone or combined with F led to an upregulation of nuclear factor erythroid 2-related factor-2 (Nrf2) and its regulatory targets (Ho-1, Gclc, and Nqo1), whereas the effect of F alone was not significant. These results suggest that the renal toxicity of As and F is associated with the induction of mitochondrial damage and oxidative stress, and alters the expression of Nrf2 and its regulatory targets. Furthermore, variance analysis results showed that an interaction between As and F in the toxicity process.

Association between methylation of DNA damage response-related genes and DNA damage in hepatocytes of rats following subchronic exposure to vinyl chloride.

In the present study, we investigated the association between methylation of DNA damage response-related genes such as cyclin-dependent kinase inhibitor (CDKN)2A, Ras association (RalGDS/AF-6) domain family member (RASSF)1A, O6-methylguanine DNA methyltransferase (MGMT), Kirsten rat sarcoma viral oncogene homolog (KRAS), and spleen-associated tyrosine kinase (SYK) and DNA damage in hepatocytes of rats following subchronic exposure to vinyl chloride (VC). Sixty-four healthy rats were randomly divided into three VC exposure groups (5, 25, and 125 mg/kg) and an untreated negative control group (n = 16 each). VC was administered by intraperitoneal injection every other day for a total of three times a week. Eight randomly selected rats from each group were sacrificed at the end of 6 and 12 weeks, and liver tissue was harvested for the comet assay and for assessment of DNA methylation level and mRNA expression of related genes by PCR. Overall methylation levels in the genome of hepatocytes in VC-exposed rats were higher than those in the control group at 6 and 12 weeks (P < 0.05), although no differences were observed with regarding to dose (P > 0.05). After 12 weeks of exposure, differences in the methylation of RASSF1A and MGMT promoter regions were observed between the high-dose group and other groups (P < 0.05), whereas no differences were observed for the KRAS, SYK, and CDKN2A promoters (P > 0.05). These results suggest that DNA damage and increased genome-wide methylation are biomarkers for VC exposure and that RASSF1A and MGMT promoter methylation is related to the carcinogenic mechanism of VC.

Comparative Transcriptomics Reveals the Role of the Toll-Like Receptor Signaling Pathway in Fluoride-Induced Cardiotoxicity.

Many studies have shown that fluorosis due to long-term fluoride intake has damaging effects on the heart. However, the mechanisms underlying cardiac fluorosis have not been illuminated in detail. We performed high-throughput transcriptome sequencing (RNA-Seq) on rat cardiac tissue to explore the molecular effects of NaF exposure. In total, 372 and 254 differentially expressed genes (DEGs) were identified between a group given 30 mg/L NaF and control and between a group given 90 mg/L NaF and control, respectively. The transcript levels of most of these genes were significantly down-regulated and many were distributed in the Toll-like receptor signaling pathway. Transcriptome analysis revealed that herpes simplex infection, ECM-receptor interaction, influenza A, cytokine-cytokine receptor interaction, apoptosis, and Toll-like receptor signaling pathway were significantly affected. IL-6 and IL-10 may play a crucial role in the cardiac damage caused by NaF as external stimuli according to protein-protein interaction (PPI) network analysis. The results of qRT-PCR and Western blotting showed a marked decreased mRNA and protein levels of IL-1, IL-6, and IL-10 in the low concentration fluoride (LF) and high concentration fluoride (HF) groups, which was in agreement with RNA-Seq results. This is the first study to investigate NaF-induced cardiotoxicity at a transcriptome level.

Sodium metabisulfite modulation of potassium channels in pain-sensing dorsal root ganglion neurons.

The effects of sodium metabisulfite (SMB), a general food preservative, on potassium currents in rat dorsal root ganglion (DRG) neurons were investigated using the whole-cell patch-clamp technique. SMB increased the amplitudes of both transient outward potassium currents and delayed rectifier potassium current in concentration- and voltage-dependent manner. The transient outward potassium currents (TOCs) include a fast inactivating (A-current or IA) current and a slow inactivating (D-current or ID) current. SMB majorly increased IA, and ID was little affected. SMB did not affect the activation process of transient outward currents (TOCs), but the inactivation curve of TOCs was shifted to more positive potentials. The inactivation time constants of TOCs were also increased by SMB. For delayed rectifier potassium current (IK), SMB shifted the activation curve to hyperpolarizing direction. SMB differently affected TOCs and IK, its effects major on A-type K+ channels, which play a role in adjusting pain sensitivity in response to peripheral redox conditions. SMB did not increase TOCs and IK when adding DTT in pipette solution. These results suggested that SMB might oxidize potassium channels, which relate to adjusting pain sensitivity in pain-sensing DRG neurons.