Endogenous cytokine production protects T cells from spontaneous apoptosis during highly active antiretroviral therapy

Background

The availability of therapeutic regimens that effectively interfere with HIV‐1 replication provides novel opportunities to investigate mechanisms of T‐cell depletion as well as repopulation in infected individuals.

Methods

Nineteen HIV‐1‐infected individuals were investigated during one‐year follow‐up of highly active retroviral therapy (HAART). The frequencies of apoptotic T cells, as determined by propidium iodide, staining, TUNEL assay and analysis of annexin V, were assessed either in the absence or in the presence of anti‐interleukin (IL)2 and anti‐IL‐4 neutralizing Ab. Spontaneous and lectin‐induced cytokine production were assessed by ELISA.

Results

Increments of both naive and memory CD4 and CD8 T cells during HAART are accompanied by a decrease of T‐cell apoptosis that, after 12 months of HAART, reaches normal levels. This is associated with increments of both spontaneous and activation‐induced production of IL‐2 and IL‐4 by peripheral blood mononuclear cells (PBMCs), though only the latter was found defective at enrolment. During HAART, blocking of either IL‐2 or IL‐4 production by PBMCs using neutralizing Ab restores levels of T‐cell apoptosis consistent with those determined at enrolment. These data suggest that both IL‐2 and IL‐4 produced by PBMCs during HAART provide anti‐apoptotic signals that can contribute to an increased survival of T cells and may thus play a part in long‐term immune reconstitution.

Conclusions

An effective viral suppression and, possibly, effects of PI on molecular targets other than viral components, can support a progressive normalization of T‐cell survival that, at least in part, depends upon the restoration of proper soluble signals. These results provide evidence of a supporting role of endogenous cytokine production in peripheral T‐cell repopulation during an effective and prolonged viral suppression. This may be relevant for the definition of immune‐intervention targets aimed at immune reconstitution in HIV‐1‐infected patients.

     

Mitochondrial complex I inhibition is not required for dopaminergic neuron death induced by rotenone, MPP+, or paraquat

Inhibition of mitochondrial complex I is one of the leading hypotheses for dopaminergic neuron death associated with Parkinson's disease (PD). To test this hypothesis genetically, we used a mouse strain lacking functional Ndufs4, a gene encoding a subunit required for complete assembly and function of complex I. Deletion of the Ndufs4 gene abolished complex I activity in midbrain mesencephalic neurons cultured from embryonic day (E) 14 mice, but did not affect the survival of dopaminergic neurons in culture. Although dopaminergic neurons were more sensitive than other neurons in these cultures to cell death induced by rotenone, MPP⁺, or paraquat treatments, the absence of complex I activity did not protect the dopaminergic neurons, as would be expected if these compounds act by inhibiting complex 1. In fact, the dopaminergic neurons were more sensitive to rotenone. These data suggest that dopaminergic neuron death induced by treatment with rotenone, MPP⁺, or paraquat is independent of complex I inhibition.     

内皮素-1对缺氧/复氧所致心肌细胞凋亡的影响

目的探讨在缺氧/复氧过程中不同时期给予内皮素-1（ET-1）对缺氧/复氧所致心肌损伤与凋亡的影响。方法乳鼠心肌细胞缺氧/复氧模型,流式细胞仪检测心肌细胞凋亡,Hoechst 33258染色计算凋亡率,试剂盒检测乳酸脱氢酶（LDH）的活性。结果ET-1预处理组（EP）细胞生存率较缺氧复氧组（HR）提高,凋亡率下降,LDH活性下降;ET-1缺氧即刻处理组（EH）细胞生存率较HR组降低,凋亡率升高,LDH释放量增加;ET-1复氧处理组（ER）的细胞生存率、凋亡率及LDH活性与HR组均无统计学差异。结论ET-1预处理有心肌细胞保护作用,ET-1缺氧时有促进心肌细胞损伤和凋亡的作用。     

Cancer-protective effect of a synbiotic combination between Lactobacillus gasseri 505 and a Cudrania tricuspidata leaf extract on colitis-associated colorectal cancer

ABSTRACT

Previously, a synbiotic combination of probiotic Lactobacillus gasseri 505 (LG) and a new prebiotic, Cudrania tricuspidata leaf extract (CT) in fermented milk, designated FCT, showed an in vitro immunomodulatory effect and antioxidant activity. Although synbiotic combination might have cancer-protective effects, these activities have not been fully validated in vivo. Ten-week treatment of LG, CT, or FCT to azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colitis-associated colorectal cancer (CAC) mouse model reduced both the incidence of colonic tumors and damage to the colonic mucosa effectively, suggesting a cancer-protective effect. To understand these, biomarkers associated with inflammation, colon barrier, apoptosis, and cancer cell proliferation were monitored in AOM/DSS group versus LG/CT/FCT groups. A synbiotic combination (FCT) down-regulated pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1β, and IL-6) and inflammation-associated enzymes (iNOS and COX-2), and up-regulated anti-inflammatory cytokines (IL-4 and IL-10). In addition, colon barrier experiment revealed that biomarkers of mucus layer (MUC-2 and TFF3) and tight junction (occludin and ZO-1) were up-regulated. Subsequent apoptosis experiment showed that pro-apoptotic factors (p53, p21, and Bax) were up-regulated and anti-apoptotic factors (Bcl-2 and Bcl-xL) were down-regulated. Furthermore, comparative metagenome analysis of gut microbiota revealed that Staphylococcus decreased but Lactobacillus, Bifidobacterium, and Akkermansia increased, supporting their protective effects, accompanied by increased short-chain fatty acids (SCFAs). Taken together, the FCT administration showed cancer-protective effects by reducing the risk of colitis-associated colon cancer via regulation of inflammation, carcinogenesis, and compositional change of gut microbiota. Consequently, the synbiotic combination (FCT) could be a novel potential health-protective natural agent against CAC.     

Neutrophil and platelet antibodies in autoimmune lymphoproliferative syndrome

BACKGROUND AND OBJECTIVES: Autoimmune lymphoproliferative syndrome (ALPS), is an inherited disorder characterized by defective lymphocyte apoptosis, lymphadenopathy, splenomegaly, accumulation of T-cell receptor (TCR)-alphabeta+ CD4- CD8- T cells (double-negative T cells) and autoimmunity. We investigated the incidence and nature of neutrophil and platelet antibodies in patients with ALPS. MATERIALS AND METHODS: Sera from 26 patients with ALPS were tested for neutrophil antibodies by granulocyte immunofluorescence, granulocyte agglutination and monoclonal antibody immobilization assays of granulocyte antigens, and for platelet antibodies using a solid-phase antibody-detection system. RESULTS: Neutrophil antibodies were detected in 46% of patients with ALPS. Antibody specificity could be defined in eight of the 12 patients with neutrophil antibodies. Among these eight patients, four had antibodies directed against more than one antigen. Overall, 14 antibodies directed to specific antigens were identified: three were directed to the HNA-1a antigen of FcgammaRIIIb; two to the HNA-1b antigen of Fcgamma-RIIIb; two to epitopes common to all FcgammaRIIIb molecules; four to the HNA-2a antigen of the NB1 glycoprotein; and three to neutrophil beta2 integrins. Platelet antibodies were detected in 35% of patients with ALPS. No antibody specificities were identified among the platelet antibodies. There was no association between the detection of neutrophil antibodies and a history of clinical neutropenia, or between the detection of platelet antibodies and a history of clinical thromobocytopenia. CONCLUSIONS: Neutrophil and platelet antibodies are important markers of ALPS, but do not always cause clinical cytopenias. The specificities of neutrophil antibody were similar to those found in children with autoimmune neutropenia but without ALPS.     

Early induction of apoptosis in B-chronic lymphocytic leukaemia cells by hydroxychloroquine: activation of caspase-3 and no protection by survival factors

We have investigated the effect of hydroxychloroquine (HCQ), an anti-rheumatic drug, on malignant B cells from 20 patients with B-chronic lymphocytic leukaemia (B-CLL). HCQ induced a decrease in cell viability in a dose- and time-dependent manner. The mean IC50 was 32 +/- 7 microg/ml (range, 10-75 microg/ml) for 24 h of exposure. This cytotoxic effect was owing to apoptosis, as demonstrated by morphological changes, annexin V binding capacity and DNA fragmentation (28 +/- 4% of apoptotic cells as early as 5 h post incubation, increasing to 82 +/- 4% at 18 h post treatment). The apoptosis was associated with caspase-3 activation because the cleavage and activity of caspase-3 were increased by HCQ. The amount of bcl-2 protein was reduced during apoptosis, evidenced using quantitative flow cytometry. As early as 1 h post-HCQ treatment, a reduction of the mitochondrial transmembrane potential was measured by 3,3'-dihexyloxacarbocyanine iodide. Interestingly, the HCQ effect was not affected by exposure to interleukin-4 or co-culture with bone marrow stromal cells. Our observations suggest that HCQ may offer a new therapeutic tool in the treatment of B-CLL patients.     

β-咔啉类生物碱对人胃癌SGC-7901细胞增殖、凋亡的影响及机制探讨

目的观察β-咔啉类生物碱对体外培养的人胃癌SGC-7901细胞增殖及凋亡的影响,并探讨其作用机制。方法不同浓度β-咔啉类生物碱处理人胃癌SGC-7901细胞48 h后,检测细胞增殖、凋亡情况,并以荧光定量聚合酶链反应(RTPCR)和蛋白印迹法(Western blot)分别测定细胞中抑癌基因PTEN、蛋白激酶B(AKT)基因mRNA及其蛋白表达。结果不同浓度的β-咔啉类生物碱均能抑制人胃癌SGC-7901细胞的增殖,其中40μg/m L浓度的抑制效果较其他浓度及5-Fu干预组更显著(P0.01),并可诱导细胞凋亡。不同浓度β-咔啉类生物均可引起PTEN mRNA和蛋白表达增加,AKT mRNA和蛋白表达减少,其中40μg/m L浓度的调节效果较其他浓度及5-Fu干预组更显著(P0.01)。结论β-咔啉类生物碱可抑制人胃癌SGC-7901细胞增殖,诱导凋亡,其作用机制可能是通过上调PTEN及下调AKT蛋白的表达实现。     

番茄红素对人精子冷冻损伤的保护作用及机制研究

目的:通过在人精子冷冻保护液中添加不同浓度的番茄红素,研究番茄红素对精子冷冻损伤的可能保护作用及机制。方法:选择吉林省人类精子库捐精者的精液标本25份,每份精液一式4份,3∶1加入冷冻保护液后混匀,不含番茄红素者设为对照组(Ly0),而Ly2、Ly5、Ly10实验组混合液中分别含有2、5、10μmol/L的番茄红素,冷冻复苏精液进行常规分析,采用流式细胞术分析冻融后各组精子的凋亡率;采用硫代巴比妥酸(TBA)比色法检测精子中脂质过氧化产物丙二醛(MDA)浓度。利用JC-1标记法检测线粒体膜电位。结果:冻融后各组精子运动参数较新鲜精液参数均明显下降(P<0.01),Ly5组冻融后精子凋亡率[(25.68±4.36)%]较对照组[(33.26±4.78)%]显著下降(P<0.05);Ly5组线粒体膜电位水平[(66.18±14.23)%]显著高于对照组[(55.24±12.31)%],P<0.05;Ly2、Ly5、Ly10组的MDA水平与对照组比较,无统计学差异(P>0.05)。结论:在精液冷冻保护液中添加一定浓度的番茄红素可以减少线粒体氧化损伤,减轻活性氧对精子质膜的氧化应激损伤,从而提高精子的抗凋亡能力。     

EGF Receptor Deletion in Podocytes Attenuates Diabetic Nephropathy

The generation of reactive oxygen species (ROS), particularly superoxide, by damaged or dysfunctional mitochondria has been postulated to be an initiating event in the development of diabetes complications. The glomerulus is a primary site of diabetic injury, and podocyte injury is a classic hallmark of diabetic glomerular lesions. In streptozotocin-induced type 1 diabetes, podocyte-specific EGF receptor (EGFR) knockout mice (EGFR^podKO) and their wild-type (WT) littermates had similar levels of hyperglycemia and polyuria, but EGFR^podKO mice had significantly less albuminuria and less podocyte loss compared with WT diabetic mice. Furthermore, EGFR^podKO diabetic mice had less TGF-β1 expression, Smad2/3 phosphorylation, and glomerular fibronectin deposition. Immunoblotting of isolated glomerular lysates revealed that the upregulation of cleaved caspase 3 and downregulation of Bcl2 in WT diabetic mice were attenuated in EGFR^podKO diabetic mice. Administration of the SOD mimetic mito-tempol or the NADPH oxidase inhibitor apocynin attenuated the upregulation of p-c-Src, p-EGFR, p-ERK1/2, p-Smad2/3, and TGF-β1 expression and prevented the alteration of cleaved caspase 3 and Bcl2 expression in glomeruli of WT diabetic mice. High-glucose treatment of cultured mouse podocytes induced similar alterations in the production of ROS; phosphorylation of c-Src, EGFR, and Smad2/3; and expression of TGF-β1, cleaved caspase 3, and Bcl2. These alterations were inhibited by treatment with mito-tempol or apocynin or by inhibiting EGFR expression or activity. Thus, results of our studies utilizing mice with podocyte-specific EGFR deletion demonstrate that EGFR activation has a major role in activating pathways that mediate podocyte injury and loss in diabetic nephropathy.     

Disruption of Renal Tubular Mitochondrial Quality Control by Myo-Inositol Oxygenase in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is associated with oxidative stress and mitochondrial injury. Myo-inositol oxygenase (MIOX), a tubular-specific enzyme, modulates redox imbalance and apoptosis in tubular cells in diabetes, but these mechanisms remain unclear. We investigated the role of MIOX in perturbation of mitochondrial quality control, including mitochondrial dynamics and autophagy/mitophagy, under high-glucose (HG) ambience or a diabetic state. HK-2 or LLC-PK1 cells subjected to HG exhibited an upregulation of MIOX accompanied by mitochondrial fragmentation and depolarization, inhibition of autophagy/mitophagy, and altered expression of mitochondrial dynamic and mitophagic proteins. Furthermore, dysfunctional mitochondria accumulated in the cytoplasm, which coincided with increased reactive oxygen species generation, Bax activation, cytochrome C release, and apoptosis. Overexpression of MIOX in LLC-PK1 cells enhanced the effects of HG, whereas MIOX siRNA or d-glucarate, an inhibitor of MIOX, partially reversed these perturbations. Moreover, decreasing the expression of MIOX under HG ambience increased PTEN-induced putative kinase 1 expression and the dependent mitofusin-2–Parkin interaction. In tubules of diabetic mice, increased MIOX expression and mitochondrial fragmentation and defective autophagy were observed. Dietary supplementation of d-glucarate in diabetic mice decreased MIOX expression, attenuated tubular damage, and improved renal functions. Notably, d-glucarate administration also partially attenuated mitochondrial fragmentation, oxidative stress, and apoptosis and restored autophagy/mitophagy in the tubular cells of these mice. These results suggest a novel mechanism linking MIOX to impaired mitochondrial quality control during tubular injury in the pathogenesis of DKD and suggest d-glucarate as a potential therapeutic agent for the amelioration of DKD.