Low Expression of Lipoic Acid Synthase Aggravates Silica-Induced Pulmonary Fibrosis by Inhibiting the Differentiation of Tregs in Mice.

Aims: In addition to reducing the respiratory function, crystalline silica (SiO2) disturbs the immune response by affecting immune cells during the progression of silicosis. Regulatory T cell (Treg) differentiation may play a key role in the abnormal polarization of T helper cell (Th)1 and Th2 cells in the development of silicosis-induced fibrosis. Alpha-lipoic acid (ALA) has immunomodulatory effects by promoting Tregs differentiation. Thus, ALA may have a therapeutic potential for treating autoimmune disorders in patients with silicosis. However, little is known regarding whether ALA regulates the immune system during silicosis development. Results: We found that the expression levels of collagen increased, and the antioxidant capacity was lower in the Lias-/-+SiO2 group than in the Lias+/++SiO2 group. The proportion of Tregs decreased in the peripheral blood and spleen tissue in mice exposed to SiO2. The proportion of Tregs in the Lias-/-+SiO2 group was significantly lower than that in the Lias+/++SiO2 group. Supplementary exogenous ALA attenuates the accumulation of inflammatory cells and extracellular matrix in lung tissues. ALA promotes the immunological balance between Th17 and Treg responses during the development of silicosis-induced fibrosis. Innovation and Conclusion: Our findings confirmed that low expression of lipoic acid synthase aggravates SiO2-induced silicosis, and that supplementary exogenous ALA has therapeutic potential by improving Tregs in silicosis fibrosis.

Overexpression of Lias Gene Alleviates Cadmium-Induced Kidney Injury in Mice Involving Multiple Effects: Metabolism, Oxidative Stress, and Inflammation.

Oxidative stress is an important mechanism underlying toxicity induced by cadmium (Cd) exposure. However, there are significant differences of the antioxidant baseline in different populations. This means that different human has different intensity of oxidative stress in vivo after exposure to toxicants. LiasH/H mouse is a specific model which is created by genetically modifying the Lias 3'-untranslated region (3'-UTR). LiasH/H mice express high levels of LA and have high endogenous antioxidant capacity which is approximately 150% higher than wild-type C57BL/6 J mice (WT, Lias+/+). But more importantly, they have dual roles of metal chelator and antioxidant. Here, we applied this mouse model to evaluate the effect of endogenous antioxidant levels in the body on alleviating Cd-induced renal injury including Cd metabolism, oxidative stress, and inflammation. In the experiment, mice drank water containing Cd (50 mg/L), for 12 weeks. Many biomarkers of Cd metabolism, oxidative stress, inflammation, and major pathological changes in the kidney were examined. The results showed overexpression of the Lias gene decreased Cd burden in the body of mice, mitigated oxidative stress, attenuated the inflammatory response, and subsequent alleviated cadmium-induced kidney injury in mice.

Lias overexpression alleviates pulmonary injury induced by fine particulate matter in mice.

Oxidative stress and inflammation are mechanisms underlying toxicity induced by fine particulate matter (PM2.5). The antioxidant baseline of the human body modulates the intensity of oxidative stress in vivo. This present study aimed to evaluate the role of endogenous antioxidants in alleviating PM2.5-induced pulmonary injury using a novel mouse model (LiasH/H) with an endogenous antioxidant capacity of approximately 150% of its wild-type counterpart (Lias+/+). LiasH/H and wild-type (Lias+/+) mice were randomly divided into control and PM2.5 exposure groups (n = 10), respectively. Mice in the PM2.5 group and the control group were intratracheally instilled with PM2.5 suspension and saline, respectively, once a day for 7 consecutive days. The metal content, major pathological changes in the lung, and levels of oxidative stress and inflammation biomarkers were examined. The results showed that PM2.5 exposure induced oxidative stress in mice. Overexpression of the Lias gene significantly increased the antioxidant levels and decreased inflammatory responses induced by PM2.5. Further study found that LiasH/H mice exerted their antioxidant function by activating the ROS-p38MAPK-Nrf2 pathway. Therefore, the novel mouse model is useful for the elucidation of the mechanisms of pulmonary injury induced by PM2.5.

Genome-wide mRNA profiling identifies the NRF2-regulated lymphocyte oxidative stress status in patients with silicosis.

BACKGROUND: The immunomodulatory abnormalities of silicosis are related to the lymphocyte oxidative stress state. The potential effect of antioxidant therapy on silicosis may depend on the variation in nuclear factor erythroid 2-related factor 2 (NRF2)-regulated antioxidant genes in peripheral blood mononuclear cells (PBMCs). As NRF2 is a redox-sensitive transcription factor, its possible roles and underlying mechanism in the treatment of silicosis need to be clarified. METHODS: Ninety-two male patients with silicosis and 87 male healthy volunteers were randomly selected. PBMCs were isolated from fresh blood from patients with silicosis and healthy controls. The lymphocyte oxidative stress state was investigated by evaluating NRF2 expression and NRF2-dependent antioxidative genes in PBMCs from patients with silicosis. Key differentially expressed genes (DEGs) and signaling pathways were identified utilizing RNA sequencing (RNA-Seq) and bioinformatics technology. Gene set enrichment analysis was used to identify the differences in NRF2 signaling networks between patients with silicosis and healthy controls. RESULTS: The number of monocytes was significantly higher in patients with silicosis than that of healthy controls. Furthermore, RNA-Seq findings were confirmed using quantitative polymerase chain reaction and revealed that NRF2-regulated DEGs were associated with glutathione metabolism, transforming growth factor-ß, and the extracellular matrix receptor interaction signaling pathway in PBMCs from patients with silicosis. The top 10 hub genes were identified by PPI analysis: SMAD2, MAPK3, THBS1, SMAD3, ITGB3, integrin alpha-V (ITGAV), von Willebrand factor (VWF), BMP4, CD44, and SMAD7. CONCLUSIONS: These findings suggest that NRF2 signaling regulates the lymphocyte oxidative stress state and may contribute to fibrogenic responses in human PBMCs. Therefore, NRF2 might serve as a novel preventive and therapeutic candidate for silicosis.

[Silencing LncRNA SNHG7 alleviates hypoxia/reoxygenation-induced cardiomyocyte damage by regulating the expression of miR-181b-5p].

OBJECTIVE: To study the effect of silencing LncRNA SNHG7 on hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury and its targeted regulation on miR-181b-5p. METHODS: Rat cardiomyocytes H9c2 were cultured in vitro and randomly divided into control group, H/R group, H/R + si-NC group, H/R + si-SNHG7 group, H/R + si-SNHG7 + anti-miR-NC group and H/R + si-SNHG7 + anti-miR-181b-5p group. The content of lactate dehydrogenase (LDH), malondialedhyde (MDA) and the activity of superoxide dismutase (SOD) were detected. Flow cytometry was carried out to detect the rate of apoptosis. qRT-PCR was used to detect the expression of SNHG7 and miR-181b-5p. Dual luciferase report experiment was used to verify the targeting relationship between SNHG7 and miR-181b-5p. Western blotting was used to detect the expression of Bax and Bcl-2. RESULTS: Compared with the control group, the H/R group showed significantly increased SNHG7 expression in cardiomyocytes, reduced miR-181b-5p expression, higher levels of LDH and MDA, reduced activity of SOD, increased cell apoptosis rate, higher level of Bax protein, and reduced level of Bcl-2 protein (all P< 0.05). Compared with the H/R and H/R + si-NC groups, the H/R + si-SNHG7 group had significantly reduced level of LDH and MDA, increased activity of SOD, reduced apoptosis rate, reduced level of Bax protein, increased level of Bcl-2 protein (all P< 0.05). The dual luciferase report experiment confirmed that SNHG7 could target miR-181b-5p. Interference with the expression of miR-181b-5p could reduce the effect of silencing SNHG7 on H/R-induced cardiomyocyte oxidative stress and apoptosis. CONCLUSION: Silencing SNHG7 may inhibit H/R-induced cardiomyocyte oxidative stress and apoptosis by up-regulating the expression of miR-181b-5p, thereby exerting a protective effect on cardiomyocytes.

Alpha-lipoic acid attenuates silica-induced pulmonary fibrosis by improving mitochondrial function via AMPK/PGC1α pathway activation in C57BL/6J mice.

Silicosis is characterized by pulmonary interstitial fibrosis that arises as a result of chronic exposure to silica. The few available treatments only delay its progression. As α-lipoic acid (ALA) has been shown to have various beneficial effects, including mitoprotective, antioxidant, and anti-inflammatory effects, we hypothesized that it may exhibit therapeutic effects in pulmonary fibrosis. Therefore, in the present study, we used a murine model of silicosis to investigate whether supplementation with exogenous ALA could attenuate silica-induced pulmonary fibrosis by improving mitochondrial function. ALA was administered to the model mice via continuous intragastric administration for 28 days, and then the antioxidant and mitoprotective effects of ALA were evaluated. The results showed that ALA decreased the production of reactive oxygen species, protected mitochondria from silica-induced dysfunction, and inhibited extracellular matrix deposition. ALA also decreased hyperglycemia and hyperlipidemia. Activation of the mitochondrial AMPK/PGC1α pathway might be responsible for these ALA-mediated anti-fibrotic effects. Exogenous ALA blocked oxidative stress by activating NRF2. Taken together, these findings demonstrate that exogenous ALA effectively prevents the progression of silicosis in a murine model, likely by stimulating mitochondrial biogenesis and endogenous antioxidant responses. Therefore, ALA can potentially delay the progression of silica-induced pulmonary fibrosis.

Overexpression of lipoic acid synthase gene alleviates diabetic nephropathy of Leprdb/db mice.

INTRODUCTION: Diabetic nephropathy (DN) develops in about 40% of patients with type 2 diabetes and remains the leading cause of end-stage renal disease. The mechanisms of DN remain to be elucidated. Oxidative stress is thought to be involved in the development of DN but antioxidant therapy has produced conflicting results. Therefore, we sought to define the role of antioxidant in retarding the development of DN in this study. RESEARCH DESIGN AND METHODS: We generated a new antioxidant/diabetes mouse model, LiasH/HLeprdb/db mice, by crossing db/db mice with LiasH/H mice, which have overexpressed Lias gene (~160%) compared with wild type, and also correspondingly increased endogenous antioxidant capacity. The new model was used to investigate whether predisposed increased endogenous antioxidant capacity was able to retard the development of DN. We systemically and dynamically examined main pathological alterations of DN and antioxidant biomarkers in blood and kidney mitochondria. RESULTS: LiasH/HLeprdb/db mice alleviated major pathological alterations in the early stage of DN, accompanied with significantly enhanced antioxidant defense. The model targets the main pathogenic factors by exerting multiple effects such as hypoglycemic, anti-inflammation, and antioxidant, especially protection of mitochondria. CONCLUSION: The antioxidant animal model is not only very useful for elucidating the underlying mechanisms of DN but also brings insight into a new therapeutic strategy for clinical applications.

Overexpression of the Lias gene attenuates hepatic steatosis in Leprdb/db mice.

Oxidative stress is proposed to be involved in nonalcoholic fatty liver disease (NAFLD). However, antioxidant therapy results in controversial outcomes. Therefore, we generated a new antioxidant/NAFLD mouse model, LiasHigh/HighLeprdb/db mice, by crossbreeding Leprdb/db mice, an obesity mouse model, with LiasHigh/High mice, generated by overexpression of lipoic acid synthase gene (Lias) and having increased endogenous antioxidant capacity, to investigate whether the new model could block the development of NAFLD. We have systemically characterized the novel model based on the main features of human NAFLD, determined the impact of enhanced endogenous antioxidant capacity on the retardation of NAFLD and elucidated the underlying mechanisms using various biological and pathological methods. We found that LiasHigh/HighLeprdb/db mice ameliorated many pathological changes of NAFLD compared with the control. In particular, LiasHigh/HighLeprdb/db mice displayed the improved liver mitochondrial function, reflecting the decline of mitochondrial microvesicular steatosis, and reduced oxidative stress, which mainly contributes to the alleviation of pathologic alterations of the NAFLD progression. Our new model shows that mitochondrial dysfunction is a major pathogenesis for liver steatosis. Overexpression of Lias gene effectively reduces oxidative stress and protects mitochondria, and consequently attenuates NAFLD/NASH.

Overexpression of endogenous lipoic acid synthase attenuates pulmonary fibrosis induced by crystalline silica in mice.

Oxidative stress and inflammatory processes are proposed to mediate the development of silicosis. However, antioxidant therapy has not produced consistent results during the treatment of silicosis. α-Lipoic acid synthesized by lipoic acid synthase is a powerful anti-oxidant and helps protect mitochondria. Thus far, the effect of endogenous α-Lipoic acid on silicosis has not been elucidated yet. We established an experimental model of silicosis with wildtype and LiasH/H mice, a new antioxidant mouse model which has overexpressed Lias gene (∼150 %) relative to its wild type counterpart. We systemically examined main pathological changes of pulmonary fibrosis, and explored α-lipoic acid effects on oxidative stress, inflammatory and pulmonary fibrosis biomarkers in silica-instillated mice. In LiasH/H mice over-expression of lipoic acid alleviated the severity of major pathological alterations in the early stage of pulmonary fibrosis induced by silica compared with wild type mice. Silica significantly increased oxidative stress in both wild type and LiasH/H mice. The antioxidant defense was strengthen including increased NRF2 and LIAS production in LiasH/H mice. Relieved oxidative stress resulted in decreased inflammatory response and secretion of chemokines. LiasH/H mice reduced chronic inflammatory response and inhibition of NF-κB activity after silica instillation. The LiasH/H mouse model overexpression of lipoic acid synthase gene retarded the development of silica-induced pulmonary fibrosis. Strengthen antioxidant defense by increased lipoic acid synthase is a potential strategy for protection against silica-induced pulmonary fibrosis.

[Renal Injury and Its Mechanisms in Lepr db/ db Mice].

OBJECTIVE: To study the mechanism of renal injury in Lepr db/ db mice with the leptin receptor homozygous deficiency. METHODS: Ten male of 28-week-old Lepr db/+ mice with leptin receptor heterozygous deficiency were selected as control group and ten male Lepr db/ db mice with leptin receptor homozygous deficiency were used in this study. After fasting for 8 hours, the body mass, fasting blood glucose (FBG) and glycosylated hemoglobulin (HbA1c) of the mice were measured. Blood of the mice was obtained from femoral artery before euthanasia. Serum creatinine (CRE), blood urea nitrogen (BUN), superoxide dismutase (SOD), glutathione (GSH) and malonaldehyde (MDA) were detected by corresponding kits, and serum interleukin-1ß (IL-1ß), monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) were measured using enzyme-linked immunosorbent assay (ELISA) method. The kidney was taken for pathological observation. The expression levels of nuclear factor E2-related factor 2 (Nrf2) and nuclear factor kappa B (NF-κB) in renal were analyzed by Western blot. The mitochondria of renal was isolated by the corresponding kit. Meanwhile, the expression level of lipoic acid synthase (LIAS) in renal mitochondria was measured by Western blot. RESULTS: The body mass, FPG, HbA1c, CRE and BUN levels of the Lepr db/ db mice were significantly increased in comparison with the Lepr db/+ mice ( P<0.05). Compared with the Lepr db/+ mice, the Lepr db/ db mice renal exhibited glomerular hypertrophy, thickened basement membrane and capillary wall, the mesangial matrix expansion and mesangial cell hyperplasia. Compared with the Lepr db/+ mice, the serum level of GSH in the Lepr db/ db mice was decreased significantly ( P<0.05). The levels of MDA and concentrations of MCP-1, IL-1ß and TNF-α in serum of the Lepr db/ db mice were higher than those of the Lepr db/+ mice ( P<0.05). Compared with the Lepr db/+ mice, the expression of LIAS and Nrf2 protein in the Lepr db/ db mice renal were decreased ( P<0.05), while the expression of NF-κB protein was increased ( P<0.05). CONCLUSION: LIAS, Nrf2 and NF-κB might play significant roles through regulation of oxidative stress and inflammation in the renal injury of Lepr db/ db mice.

Chitosan oligosaccharides alleviate PM2.5-induced lung inflammation in rats.

Air pollution of particulate matter (PM), especially PM2.5, has become a major public health problem in China. Exploration of therapeutic and preventive measures against PM2.5 toxicity is of practical significance. The aim of this study was to examine the inhibitory effects of chitosan oligosaccharides (COS) on PM2.5-induced lung inflammation in rats. Forty SPF (specific pathogen-free) male Wistar rats weighing 200-220 g were randomly divided into four groups: control group, COS group, PM2.5 group, and PM2.5+COS group. COS was pre-administered to rats by gavage at a single dose of 500 mg/kg 2 h before intratracheal instillation of PM2.5 at a single dose of 1.2 mg/kg daily for 3 consecutive days. Normal saline (NS) was used as negative control. Twenty-four hours after the last instillation of PM2.5, rats were sacrificed and subjected to bronchoalveolar lavage (BAL). The BAL fluids (BALF) were collected for measurement of levels of total proteins, lactate dehydrogenase (LDH), interleukin-1 (IL-1ß), IL-8, and tumor necrosis factor-ɑ (TNF-ɑ) using colorimetric or ELISA kits. Levels of total proteins, LDH activities, and pro-inflammatory mediators including IL-1ß, IL-8, and TNF-ɑ in BALF of rats in PM2.5 group significantly increased in comparison with those of the control group. Pre-treatment of rats with COS markedly blocked PM2.5-induced increase in LDH, IL-8, and TNF-ɑ levels in BALF. In conclusion, PM2.5 exposure induces rat lung inflammation, which could be ameliorated by the pre-treatment of COS.