Clinical Characteristics of HIV-Infected Patients with Venous Thromboembolism and Different CD4+ T Lymphocyte Levels.

OBJECTIVE: This study aims to analyze the clinical characteristics of HIV-infected patients complicated with venous thromboembolism (VTE). METHODS: Seventy HIV-infected patients complicated with VTE were enrolled from Beijing Ditan Hospital Capital Medical University from October 2009 to December 2020 and divided into two groups according to CD4+. The clinical data of 70 patients were observed, including general conditions, laboratory indexes, viral load, antiretroviral therapy (ART) before the diagnosis of VTE, and thrombus treatment. RESULTS: The patients were divided into two groups according to the CD4+ T lymphocyte count. There were 27 patients with a CD4+ T lymphocyte count ≥200 cells/ul, classified as group A (27/70, 38.6%), and there were 43 patients with a CD4+ T lymphocyte count <200 cells/ul, classified as group B (43/70, 61.4%). In group B, these patients included 37 males and 6 females. The average age was 47.1±12.1 years old. The average levels of the following indexes were: D-dimer, 3.5 mg/L (0.7, 6.9); total cholesterol, 4.4 mmol/L (3.3, 5.5); triglycerides, 1.4 mmol/L (0.9, 2.0); low density lipoprotein, 1.9 mmol/L (1.5,2.5); albumin, 31.8±6.4 g/L; CD4+, 66 cells/ul (18, 127); viral load, 12347 copies/mL (27, 203936). Sixty-three patients (63/70, 90%) had started highly active ART (HAART) before VTE was diagnosed, 37 patients (37/70, 52.9%) were complicated with bacterial pneumonia, 16 patients had Mycobacterium tuberculosis (16/70, 22.9%), 13 patients had Pneumocystis carinii pneumonia (PCP) (13/70, 18.6%), and eight patients were complicated with cytomegalovirus (CMV) infection (8/70, 11.4%). Twenty-four patients had tumors, and 15 patients had HIV-related tumors (15/70, 21.4%). There were significant differences between the two groups in the time from the diagnosis of HIV to the discovery of thrombosis, the time from ART to the discovery of thrombosis and bacterial pneumonia, and the differences in WBC, PLT, Hb, CRP, PTA, INR, TCHO, LDL-C, ALB, and viral load were statistically significant. CONCLUSION: The prevalence of VTE in HIV-infected people in the last 11 years was 1.4%. In patients with a high viral load, CRP, D-dimer levels, and low CD4+ and albumin levels, 11.4-22.9% were complicated with an opportunistic infection, and 21.4% had HIV-related tumors. There were significant differences between the two groups in high viral load, CRP, D-dimer, and low albumin.

Role of paraoxonase-1 in the protection of hydrogen sulfide-donating sildenafil (ACS6) against homocysteine-induced neurotoxicity.

ACS6, a novel hydrogen sulfide (H2S)-releasing sildenafil, has been demonstrated to inhibit superoxide formation through donating H2S. We have previously found that ACS6 antagonizes homocysteine-induced apoptosis and cytotoxicity. The aim of the present study is to explore the molecular mechanisms underlying ACS6-exerted protective action against the neurotoxicity of homocysteine. In the present work, we used PC12 cells to explore whether paraoxonase-1 (PON-1) is implicated in ACS6-induced neuroprotection against homocysteine neurotoxicity. We show that ACS6 treatment results in prevention of homocysteine-caused neurotoxicity and overproduction of reactive oxygen species (ROS). Homocysteine downregulates the expression and activity of PON-1; however, this effect is significantly blocked by co-treatment with ACS6. The specific inhibitor of PON-1 2-hydroxyquinoline reverses the inhibitory effect of ACS6 on homocysteine-induced neurotoxicity and intracellular ROS accumulation. These results indicate that ACS6 protects PC12 cells against homocysteine-induced neurotoxicity by upregulating PON-1 and suggest a promising role of PON-1 as a novel therapeutic strategy for homocysteine-induced toxicity.

Hydrogen sulfide prevents formaldehyde-induced neurotoxicity to PC12 cells by attenuation of mitochondrial dysfunction and pro-apoptotic potential.

Hydrogen sulfide (H(2)S) has been shown to act as a neuroprotectant and antioxidant. Numerous studies have demonstrated that exposure to formaldehyde (FA) causes neuronal damage and that oxidative stress is one of the most critical effects of FA exposure. Accumulation of FA is involved in the pathogenesis of Alzheimer's disease (AD). The aim of present study is to explore the inhibitory effects of H(2)S on FA-induced cytotoxicity and apoptosis and the molecular mechanisms underlying in PC12 cells. We show that sodium hydrosulfide (NaHS), a H(2)S donor, protects PC12 cells against FA-mediated cytotoxicity and apoptosis and that NaHS preserves the function of mitochondria by preventing FA-induced loss of mitochondrial membrane potential and release of cytochrome c in PC12 cells. Furthermore, NaHS blocks FA-exerted accumulation of intracellular reactive oxygen species (ROS), down-regulation of Bcl-2 expression, and up-regulation of Bax expression. These results indicate that H(2)S protects neuronal cells against neurotoxicity of FA by preserving mitochondrial function through attenuation of ROS accumulation, up-regulation of Bcl-2 level, and down-regulation of Bax expression. Our study suggests a promising future of H(2)S-based preventions and therapies for neuronal damage after FA exposure.

Endogenous hydrogen sulfide is involved in asymmetric dimethylarginine-induced protection against neurotoxicity of 1-methyl-4-phenyl-pyridinium ion.

Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase (NOS) inhibitor, is profoundly protective against 1-methy-4-phenylpyridinium ion (MPP+)-induced neurotoxicity. Reactive oxygen species (ROS) overproduction contributes to the neurotoxicity of MPP+; while hydrogen sulfide (H2S) is a pivotal endogenous antioxidant. This study is to assess the potential role of endogenous H2S in the neuroprotection of ADMA against MPP+-induced toxicity in PC12 cells. We showed that ADMA prevented MPP+-induced inhibition of endogenous H2S generation through inhibiting the down-regulation of cystathionine-ß-synthetase (CBS, the major enzyme responsible for endogenous H2S generation in PC12 cells) expression and activity elicited by MPP+. ADMA obviously attenuated MPP+-triggered accumulation of intracellular ROS, dissipation of mitochondrial membrane potential (MMP), release of cytochrome c (Cyt-c), and downregulation of Bcl-2 protein expression in PC12 cells. Inhibition of CBS activity by amino-oxyacetate and CBS silencing with a short hairpin RNA vector targeting rat CBS gene reversed the protective action of ADMA against MPP+-caused cytotoxicity, ROS overproduction, and MMP loss in PC12 cells. These results indicate that the protection of ADMA against MPP+-mediated neurotoxicity involves the melioration of MPP+-induced inhibition of endogenous H2S generation. Our findings suggest that modulation of H2S production provide new therapeutic targets for the treatment of neurodegenerative disease, such as Parkinson's disease.

Formaldehyde induces neurotoxicity to PC12 cells involving inhibition of paraoxonase-1 expression and activity.

1. Formaldehyde (FA) has been found to cause toxicity to neurons. However, its neurotoxic mechanisms have not yet been clarified. Increasing evidence has shown that oxidative damage is one of the most critical effects of formaldehyde exposure. Paraoxonase-1 (PON-1) is a pivotal endogenous anti-oxidant. Thus, we hypothesized that FA-mediated downregulation of PON1 is associated with its neurotoxicity. 2. In the present work, we used PC12 cells to study the neurotoxicity of FA and explore whether PON-1 is implicated in FA-induced neurotoxicity. 3. We found that FA has potent cytotoxic and apoptotic effects on PC12 cells. FA induces an accumulation of intracellular reactive oxygen species along with downregulation of Bcl-2 expression, as well as increased cytochrome c release. FA significantly suppressed the expression and activity of PON-1 in PC12 cells. Furthermore, H(2)S, an endogenous anti-oxidant gas, antagonizes FA-induced cytotoxicity as well as 2-hydroxyquinoline, a specific inhibitor of PON-1, which also induces cytotoxicity to PC12 cells. 4. The results of the present study provide, for the first time, evidence that the inhibitory effect on PON-1 expression and activity is involved in the neurotoxicity of FA, and suggest a promising role of PON-1 as a novel therapeutic strategy for FA-mediated toxicity.

Inhibition of endogenous hydrogen sulfide generation is associated with homocysteine-induced neurotoxicity: role of ERK1/2 activation.

Both elevated homocysteine and decreased hydrogen sulfide (H(2)S) are observed in the brains of Alzheimer's disease (AD) patients. Reactive oxygen species (ROS) overproduction contributes to the neurotoxicity of homocysteine; however, H(2)S is an endogenous antioxidant gas. Therefore, the aim of this study was to investigate whether the imbalance of proportion to this endogenous protective antioxidant gas is involved in homocysteine-caused neurotoxicity. We show that homocysteine inhibits the generation of endogenous H(2)S and the expression and activity of cystathionine-ß-synthetase (CBS), the main enzyme responsible for the generation of H(2)S in PC12 cells. S-Adenosylmethionine, an activator of CBS, not only prevents homocysteine-induced inhibition of endogenous H(2)S production but also attenuates homocysteine-triggered cytotoxicity and accumulation of ROS. We find that activation of ERK1/2 occurs in homocysteine-treated PC12 cells and blockade of ERK1/2 with U0126 abolished the homocysteine-induced cytotoxicity and inhibitory effect on endogenous H(2)S generation. These results indicate that homocysteine neurotoxicity involves reduction of H(2)S production, which is caused by inhibition of CBS and mediated by activation of ERK1/2. Our study suggests a promising future of H(2)S-based therapies for neurodegenerative diseases such as AD.

Hydrogen sulfide antagonizes homocysteine-induced neurotoxicity in PC12 cells.

Hydrogen sulfide (H2S) has been shown to protect neurons against oxidative stress. Lower levels of H(2)S as well as accumulation of homocysteine (Hcy), a strong risk of Alzheimer's disease (AD), are reported in the brains of AD patients. The aim of present study is to explore the protection of H2S against Hcy-induced cytotoxicity and apoptosis and the molecular mechanisms underlying in PC12 cells. We show that sodium hydrosulfide (NaHS), a H2S donor, protects PC12 cells against Hcy-mediated cytotoxicity and apoptosis by preventing both the loss of mitochondrial membrane potential (MMP) and the increase in intracellular reactive oxygen species (ROS) induced by Hcy. NaHS not only promotes the expression of bcl-2, but also blocks the down-regulation of bcl-2 by Hcy. These results indicate that H2S protects neuronal cells against neurotoxicity of Hcy by preserving MMP and attenuating ROS accumulation through up-regulation of bcl-2 level. Our study suggests a promising future of H2S-based therapies for neurodegenerative diseases such as AD.