High-concentration homocysteine inhibits mitochondrial respiration function and production of reactive oxygen species in neuron cells.

OBJECTIVE: Homocysteine plays critical roles in cellular redox homeostasis, and hyperhomocysteinemia has been associated with multiple diseases, including neurological disorders involving reactive oxygen species-inducing and pro-inflammatory effects of homocysteine that are related to mitochondria. This study investigated the role of homocysteine in regulating mitochondria of neuron cell lines. METHODS: Neuron cells were pre-treated with homocysteine, and then flow cytometry was used to detect reactive oxygen species production and mitochondrial membrane potential, while Seahorse XFp Mito stress assay was used to comprehensively analyze mitochondrial function. RESULTS: The experimental results showed that high-concentration homocysteine diminished carbonyl cyanide-4 (trifluoromethoxy) phenylhydrazone-stimulated oxygen consumption rate and mitochondrial spare respiration capacity in a time- and concentration-dependent manner, and homocysteine also reduced reactive oxygen species in cultured neuron cell lines while no changes in mitochondrial membrane potential were observed. CONCLUSION: These results indicate that homocysteine diminished mitochondrial respiration function in neuron cell lines mediated by its reactive oxygen species-reducing effects, which may underlie the association between hyperhomocysteinemia and human diseases.

BNIP3 in hypoxia-induced mitophagy: Novel insights and promising target for non-alcoholic fatty liver disease.

BNIP3 localizes to the outer mitochondrial membrane, has been demonstrated to be extensively involved in abnormalities to mitochondrial metabolic function and dynamicsand in non-alcoholic fatty liver disease (NAFLD). However, its role in NAFLD under hypoxia remains unclear. This study aimed to investigate the expression and the role of BNIP3 in NAFLD under hypoxia, and explore its involvement in regulating NAFLD mitophagy, fatty acid ß-oxidation both in vivo and in vitro. BNIP3-mediated mitophagy level was analyzed using real-time quantitative polymerase chain reaction, Western blotting, immunofluorescence and electron microscopy. The role of BNIP3 in fatty acid ß-oxidation was evaluated using lipid droplet staining, triglyceride content determination, and cellular energy metabolism. The results showed that compared with the HFD-2200 m, the body weight, inflammatory liver injury, and lipid deposition were significantly reduced in the HFD-4500 m group (P < 0.05), but autophagy and mitophagy were increased, and the expression of the mitophagy receptor BNIP3 was increased (P < 0.05). Compared to the control group, BNIP3 knockdown in the hypoxia group resulted in decreased levels of CPT1, ATGL, and p-HSL in lipid-accumulating hepatocytes, lipid droplet accumulation and triglyceride content increased (P < 0.05). Moreover, the ability of lipid-accumulating hepatocytes to oxidize fatty acids was reduced by BNIP3 knockdown in the hypoxia group (P < 0.05). Therefore, it can be concluded that, in NAFLD mice under hypoxia, BNIP3-mediated mitophagy promotes fatty acid ß-oxidation. This study elucidated the role of BNIP3 in promoting fatty acid ß-oxidation in NAFLD under hypoxia, and suggests BNIP3 may serve as a novel potential therapeutic target for NAFLD.

Expression of protein phosphatase 4 in different tissues under hypoxia.

Relevant research data shows that there is a certain degree of energy metabolism imbalance in highland residents. Protein phosphatase 4 (PP4) has been found as a new factor in the regulation of sugar and lipid metabolism. Here, we investigate the differential expression of PP4 at a simulated altitude of 4,500 m in the heart, lung, and brain tissues of rats. A hypoxic plateau rat model was established using an animal decompression chamber. A blood routine test was performed by an animal blood cell analyzer on rats cultured for different hypoxia periods at 4,500 m above sea level. Quantitative polymerase chain reaction (qPCR) and western blot were used to detect the changes of protein phosphatase 4 catalytic subunit (PP4C) gene and protein in heart, lung, and brain tissues. The PP4C gene with the highest expression level found in rats slowly entering the high altitude area (20 m-2200 m-7 d-4500 m-3 d) was about twice as high as the low elevation group (20 m above sea level). The simulated high-altitude hypoxia induced an increase of PP4C expression level in all tissues, and the expression in the lung tissue was twice as expressed as heart and brain tissue at high altitude (P < 0.05). These results suggest that the PP4 phosphatase complex is ubiquitously expressed in rat tissues and likely involved in adaptation to or disease associated with high-altitude hypoxia.

Echinococcus multilocularis protoscoleces enhance glycolysis to promote M2 Macrophages through PI3K/Akt/mTOR Signaling Pathway.

Alveolar Echinococcosis (AE) is a zoonotic parasitic disease caused by Echinococcus multilocularis, but its pathogenesis remains unclear. The primary objective of this study is to explore whether Echinococcus multilocularis protoscoleces (PSCs) regulate macrophage polarization and glucose metabolism by PI3K/Akt/mTOR signaling pathway. We found that large numbers of CD68+ macrophages gathered in close liver issue from the lesion in AE patients. PSCs preferentially differentiated into M2 macrophages and the expressions of HK1, PFKL, PKM2, PI3K, Akt, p-Akt, mTOR and p-mTOR increased. The above results show that Echinococcus multilocularis protoscoleces enhance glycolysis to promote M2 macrophages through PI3K/Akt/mTOR signaling pathway.

Lactate Modulates Cellular Metabolism Through Histone Lactylation-Mediated Gene Expression in Non-Small Cell Lung Cancer.

Lactate has been observed to fuel TCA cycle and is associated with cancer progression in human lung cancer, the leading cause of cancer deaths worldwide, but the effect of lactate on lung cancer metabolism is rarely reported. In this study, disordered metabolism in non-small cell lung cancer was demonstrated by increased G6PD and SDHA protein levels via immunofluorescence, and up-regulated lactate dehydrogenase was found to be associated with poor prognosis. Then flow cytometry and Seahorse XFe analyzer were utilized to detect the effect of lactate on glycolysis and mitochondrial function in non-small cell lung cancer cells. The results show that in non-small cell lung cancer cells lactate attenuates glucose uptake and glycolysis while maintaining mitochondrial homeostasis as indicated by improved mitochondrial membrane potential. Further exploration found that mRNA levels of glycolytic enzymes (HK-1, PKM) and TCA cycle enzymes (SDHA, IDH3G) are respectively down-regulated and up-regulated by lactate, and increased histone lactylation was observed in promoters of HK-1 and IDH3G via chromatin immunoprecipitation assay. Taken together, the above results indicate that lactate modulates cellular metabolism at least in part through histone lactylation-mediated gene expression in non-small cell lung cancer.

The effects of hypoxia on mitochondrial function and metabolism in gastric cancer cells.

BACKGROUND: A number of studies have found that metabolic disorders are the characteristic manifestations of tumor cells. However, the effects of hypoxic environment on mitochondrial function and glucose metabolism of tumor cells were still unclear. The study wanted to explore the regulatory mechanism of hypoxic environment on mitochondrial function and metabolism in gastric cancer cells. METHODS: The animal model of gastric cancer and MKN45 were treated in a hypoxic environment. Mitochondrial membrane potential and reactive oxygen species (ROS) levels were analyzed by flow cytometry, qPCR was used to detect the expression levels of glycose metabolism key enzymes, damage repair genes and mitochondrial DNA (mtDNA) copy numbers in gastric cancer. RESULTS: Compared with 2,000 m normal gastric cancer tissue, the decreased of mitochondrial membrane potential and the production of ROS reduced, the expressions of glucose metabolism genes [the M1 isoform of Hexokinase (HK1), pyruvate kinase (PKM), Succinate dehydrogenase (SDHA), Glucose-6-phosphate dehydrogenase (G6PD)], homologous recombination repair gene (RAD51) and repair DNA double-stranded broken gene (ASTCT2) increased, and aerobic respiration reduced in gastric cancer cells. In the hypoxic environment, the decreased of mitochondrial membrane potential reduced, the production of ROS and mtDNA copies increased, HK1 expression increased, the expressions of SDHA, G6PD, RAD51 and ASCT-2 decreased, and the aerobic respiration decreased. CONCLUSIONS: Hypoxia plays an important role in maintaining mitochondrial functions in gastric cancer cells by promoting glycolysis and inhibiting mitochondrial aerobic respiration capacity.

The association between homocysteine and ischemic stroke subtypes in Chinese: A meta-analysis.

BACKGROUND: The findings on the association between elevated plasma homocysteine levels and the risk of the trial of org 10172 in acute stroke treatment (TOAST) of ischemic stroke have been inconsistent in Chinese. So far, there is no meta-analysis about the association between Hcy and the TOAST subtypes of ischemic stroke in Chinese. This study; therefore, aimed to evaluate whether elevated homocysteine levels are associated with the TOAST subtypes of ischemic stroke using a meta-analysis. MATERIALS AND METHODS: A systematic search of electronic databases were conducted for studies reporting homocysteine levels in ischemic stroke and the TOAST of ischemic stroke to April 18, 2018. The data were extracted after the application of inclusion and exclusion criteria. All the data were analyzed using Stata software version 9.0 (Stata Corp LP, College Station, TX). The standardized mean difference (SMD) and 95% confidence interval (CI) were used to compare continuous variables. RESULTS: Thirteen studies comprising 3114 participants (2243 patients and 871controls) met the eligibility criteria and were included in the meta-analysis. The meta-analysis revealed that the ischemic stroke group had significantly higher levels of homocysteine than controls (SMD = 1.15, 95% CI = 0.85-1.45, P < .05). The subgroup analyses suggested that the groups of patients with large-artery atherosclerosis, small-vessel occlusion, cardioembolism, stroke of other determined etiology and stroke of undetermined etiology had significantly higher levels of homocysteine compared to those in the control group (large-artery atherosclerosis: SMD = 2.12, 95% CI = 1.40-2.84, P < .05; small-vessel occlusion: SMD = 1.10, 95% CI = 0.72-1.48, P < .05; CE: SMD = 1.17, 95% CI = 0.64-1.71, P < .05; stroke of other determined etiology: SMD = 0.88, 95% CI = 0.53-1.24, P < .05; stroke of undetermined etiology: SMD = 1.50, 95% CI = 0.66-2.33, P < .05, respectively). CONCLUSION: This meta-analysis found that ischemic stroke patients and the TOAST of ischemic stroke patients in Chinese had significantly higher homocysteine levels than the controls, suggesting that serum homocysteine levels may be a risk factor for ischemic stroke and the TOAST subtypes of ischemic stroke in Chinese.

Identification of the tropomyosin (HL-Tm) in Haemaphysalis longicornis.

Haemaphysalis longicornis tropomyosin (HL-Tm) was amplified by RT-PCR. The cDNA contained a 825 bp open reading frame coding for 274 amino acids with a predicted theoretical isoelectric point (pI) of 4.55 and molecular weight of 31.7 kDa. Real-time RT-PCR analysis showed that the expression levels of the HL-Tm in the unfed-females were significantly higher than in other tested developmental stages (eggs, unfed-larvae and unfed-nymphs). Western blot analysis showed that rabbit anti-serum against H. longicornis unfed-adult ticks recognized the recombinant HL-Tm protein (rHL-Tm). Immunization of rabbits with the rHL-Tm resulted in a statistically significant reduction of female engorgement and oviposition. Silencing of HL-Tm by RNAi showed a decrease in tick engorgement and oviposition, which is consistent with the effect of recombinant protein vaccine on the adults. These results showed that tick HL-Tm might be involved in the regulation of ticks blood-feeding, growth and oviposition.

Phylogenetic analysis of Babesia species in China based on Cytochrome b (COB) gene.

In this study, a mitochondrial marker consisting of an approximately 550-bp region of the Cytochrome b genes (COB) was amplified by polymerase chain reaction (PCR) and sequenced from individual Babesia species. Sequence variation between Babesia species from China was 1.6-30.8%. The constructed phylogenetic tree based on the three unlinked gene sequences (partial COB gene, 18S rDNA and ITS) that evolve at different rates by the method of Neighbor-joining revealed the phylogenetic relationship of Babesia species in China compared with other published corresponding sequences from Babesia species. These data indicate that the 18S rDNA more reliably distinguish the deeper branches among some Babesia species than the partial COB gene and ITS, however, the partial COB gene sequence is better for recognizing close lineages among some Babesia species than the 18S rDNA and ITS sequences. So the combined phylogenetic analysis based on the multiple unlinked loci with different evolving rates can facilitate to establish the more reliable phylogenetic relationship of the Babesia genus. The data could be applicable for the survey of parasite dynamics, epidemiological studies as well as prevention and control of the disease.

Cytochrome c oxidase subunit III (COX3) gene, an informative marker for phylogenetic analysis and differentiation of Babesia species in China.

In this study a 552-bp region of the cytochrome c oxidase subunit III (COX3) was amplified by polymerase chain reaction (PCR) and sequenced from individual Babesia species. Sequence variation between Babesia species from China ranged between 0 and 32.4%. We analyzed the phylogenetic performance of the partial sequence of the COX3 gene to resolve Babesia relationships as compared to the nuclear 18S rRNA and the mitochondrial cytochrome b (COB) gene, These data indicate that the COX3 gene seems to be superior to the COB gene and the 18S rRNA in recognizing close lineages among some Babesia species. Our work indicates that the COX3 gene does complement and corroborate the phylogenetic inferences observed with the nuclear 18S rRNA and the COB gene previously reported. The combined phylogenetic analysis based on the nuclear 18S rRNA and the COX3 gene significantly improved (bootstrap) intraspecies support of the phylogenetic relationship. The presence of additional variable sites in the COX3 gene allowed an improved interspecies differentiation of Babesia species in this study. The data could be applicable for the survey of parasite dynamics, epidemiological studies as well as prevention and control of the disease.

Discrimination between ovine Babesia and Theileria species in China based on the ribosomal protein S8 (RPS8) gene.

Ovine babesiosis and theileriosis are important hemoprotozoal diseases of sheep and goats in tropical and subtropical regions that lead to economic losses in these animals. PCR-restriction fragment length polymorphism (PCR-RFLP) is a reliable molecular diagnostic tool for discriminating Theileria or Babesia species in the same host. In this study, the DNA sequences of a ribosomal protein S8 (RPS8) gene from four species of piroplasms in China were used to develop a species-specific PCR-RFLP diagnostic tool. The sensitivity of the PCR assays was 0.1 pg DNA for B. motasi and 1 pg DNA for T. uilenbergi and 10 pg DNA for Babesia sp. Xinjiang-2005 and T. luwenshuni. The clear size difference of the PCR products allowed for a direct discrimination for B. motasi, Babesia sp. Xinjiang-2005 and ovine Theileria species (T. uilenbergi and T. luwenshuni), except that the mixed infection between T. uilenbergi and T. luwenshuni may be difficult to distinguish, simply after the electrophoretic separation of the amplification products. Further T. uilenbergi and T. luwenshuni diagnoses were made by digesting the PCR product with SacI. The established method could be applicable for the survey of parasite dynamics, and epidemiological studies as well as prevention and control of the disease.

RPS8--a new informative DNA marker for phylogeny of Babesia and Theileria parasites in China.

Piroplasmosis is a serious debilitating and sometimes fatal disease. Phylogenetic relationships within piroplasmida are complex and remain unclear. We compared the intron-exon structure and DNA sequences of the RPS8 gene from Babesia and Theileria spp. isolates in China. Similar to 18S rDNA, the 40S ribosomal protein S8 gene, RPS8, including both coding and non-coding regions is a useful and novel genetic marker for defining species boundaries and for inferring phylogenies because it tends to have little intra-specific variation but considerable inter-specific difference. However, more samples are needed to verify the usefulness of the RPS8 (coding and non-coding regions) gene as a marker for the phylogenetic position and detection of most Babesia and Theileria species, particularly for some closely related species.

First report on the occurrence of Rickettsia slovaca and Rickettsia raoultii in Dermacentor silvarum in China.

BACKGROUND: Rickettsioses are among both the longest known and most recently recognized infectious diseases. Although new spotted fever group rickettsiae have been isolated in many parts of the world including China, Little is known about the epidemiology of Rickettsia pathogens in ticks from Xinjiang Autonomous Region of China. METHODS: In an attempt to assess the potential risk of rickettsial infection after exposure to ticks in Xinjiang Uygur Autonomous Region of China, a total of 200 Dermacentor silvarum ticks collected in Xinyuan district were screened by polymerase chain reaction based on the outer membrane protein A gene. RESULTS: 22 of the 200 specimens (11%) were found to be positive by PCR. Phylogenetic analysis of OmpA sequences identified two rickettsial species, Rickettsia raoultii (4.5%) and Rickettsia slovaca (6.5%). CONCLUSIONS: This study has reported the occurrence of Rickettsia raoultii and Rickettsia slovaca in Xinjiang Autonomous Region of China and suggests that Dermacentor silvarum could be involved in the transmission of rickettsial agents in China. Further studies on the characterization and culture of rickettsial species found in Dermacentor silvarum should be performed to further clarify this. Additionally, the screening of human specimens for rickettsial disease in this region will define the incidence of infection.