Accumulated ROS Activates HIF-1α-Induced Glycolysis and Exerts a Protective Effect on Sensory Hair Cells Against Noise-Induced Damage

Caulerpa chemnitzia polysaccharide exerts immunomodulatory activity in macrophages by mediating the succinate/PHD2/HIF-1α/IL-1β pathway

Algal polysaccharide is an important food functional factor with diverse bioactive and low toxicity. Previous studies have confirmed Caulerpa chemnitzia polysaccharides (CRVP) have immunomodulatory activity, but the immunomodulatory mechanism of CRVP in macrophages has not been thoroughly explored yet. In our research, we found that CRVP has outstanding immunomodulatory activity in macrophages, which is reflected in promoting cell proliferation, upregulating cytokines (IL-1β, IL-6, and TNF-α) expression, and increasing NO and ROS levels. Additionally, the result of joint analysis of untargeted metabolomics showed metabolism played a major role in the immunomodulatory of CRVP and suggested succinic acid was a key metabolite. Further verification indicated that the accumulation of succinic acid in macrophages after administered with CRVP, induced the down-regulation of prolyl hydroxylase domain 2 (PHD2) and up-regulation of hypoxia-inducible factor-1α (HIF-1α), thereby enhancing IL-1β expression. Together, the immunomodulatory activity of CRVP in macrophages via succinate/PHD2/HIF-1α/IL-1β pathway.

The Janus face of HIF-1α in ischemic stroke and the possible associated pathways

Stroke is the most devastating disease, causing paralysis and eventually death. Many clinical and experimental trials have been done in search of a new safe and efficient medicine; nevertheless, scientists have yet to discover successful remedies that are also free of adverse effects. This is owing to the variability in intensity, localization, medication routes, and each patient's immune system reaction. HIF-1α represents the modern tool employed to treat stroke diseases due to its functions: downstream genes such as glucose metabolism, angiogenesis, erythropoiesis, and cell survival. Its role can be achieved via two downstream EPO and VEGF strongly related to apoptosis and antioxidant processes. Recently, scientists paid more attention to drugs dealing with the HIF-1 pathway. This review focuses on medicines used for ischemia treatment and their potential HIF-1α pathways. Furthermore, we discussed the interaction between HIF-1α and other biological pathways such as oxidative stress; however, a spotlight has been focused on certain potential signalling contributed to the HIF-1α pathway. HIF-1α is an essential regulator of oxygen balance within cells which affects and controls the expression of thousands of genes related to sustaining homeostasis as oxygen levels fluctuate. HIF-1α's role in ischemic stroke strongly depends on the duration and severity of brain damage after onset. HIF-1α remains difficult to investigate, particularly in ischemic stroke, due to alterations in the acute and chronic phases of the disease, as well as discrepancies between the penumbra and ischemic core. This review emphasizes these contrasts and analyzes the future of this intriguing and demanding field.

IL-17A Orchestrates Reactive Oxygen Species/HIF1α-Mediated Metabolic Reprogramming in Psoriasis

Immune cell-derived IL-17A is one of the key pathogenic cytokines in psoriasis, an immunometabolic disorder. Although IL-17A is an established regulator of cutaneous immune cell biology, its functional and metabolic effects on nonimmune cells of the skin, particularly keratinocytes, have not been comprehensively explored. Using multiomics profiling and systems biology-based approaches, we systematically uncover significant roles for IL-17A in the metabolic reprogramming of human primary keratinocytes (HPKs). High-throughput liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance spectroscopy revealed IL-17A-dependent regulation of multiple HPK proteins and metabolites of carbohydrate and lipid metabolism. Systems-level MitoCore modeling using flux-balance analysis identified IL-17A-mediated increases in HPK glycolysis, glutaminolysis, and lipid uptake, which were validated using biochemical cell-based assays and stable isotope-resolved metabolomics. IL-17A treatment triggered downstream mitochondrial reactive oxygen species and HIF1α expression and resultant HPK proliferation, consistent with the observed elevation of these downstream effectors in the epidermis of patients with psoriasis. Pharmacological inhibition of HIF1α or reactive oxygen species reversed IL-17A-mediated glycolysis, glutaminolysis, lipid uptake, and HPK hyperproliferation. These results identify keratinocytes as important target cells of IL-17A and reveal its involvement in multiple downstream metabolic reprogramming pathways in human skin.

The Role of Hypoxia-inducible Factor-1 in Bladder Cancer

Bladder cancer (BC) is one of the most common malignant tumors worldwide and poses a significant hazard to human health. During the development of BC, hypoxia plays a crucial role. Hypoxia-inducible factor (HIF) is a key transcription factor for hypoxic adaptation, which regulates the transcription of various genes, including inflammation, angiogenesis, and glycolytic metabolism. Recent studies have shown the precise role of HIF in various biological behaviors of BC. More importantly, a new antitumor medication targeting HIF-2 has been used to treat renal cancer. However, therapies targeting HIF-1 in BC have not yet been developed. In this review, we discussed how HIF-1 is expressed and affects the growth, metastasis, and angiogenesis of BC. At the same time, we investigated several HIF-1 inhibitors that provide new perspectives for targeting HIF-1.

SIRT3/GLUT4 signaling activation by metformin protect against cisplatin-induced ototoxicity in vitro

Cisplatin is highly effective for killing tumor cells. However, as one of its side effects, ototoxicity limits the clinical application of cisplatin. The mechanisms of cisplatin-induced ototoxicity have not been fully clarified yet. SIRT3 is a deacetylated protein mainly located in mitochondria, which regulates a variety of physiological processes in cells. The role of SIRT3 in cisplatin-induced hair cell injury has not been founded. In this study, primary cultured cochlear explants exposed to 5 μM cisplatin, as well as OC-1 cells exposed to 10 μM cisplatin, were used to establish models of cisplatin-induced ototoxicity in vitro. We found that when combined with cisplatin, metformin (75 μM) significantly up-regulated the expression of SIRT3 and alleviated cisplatin-induced apoptosis of hair cells. We regulated the expression of SIRT3 to explore the role of SIRT3 in cisplatin-induced auditory hair cell injury. Overexpression of SIRT3 promoted the survival of auditory hair cells and alleviated the apoptosis of auditory hair cells. In contrast, knockdown of SIRT3 impaired the protective effect of metformin and exacerbated cisplatin injury. In addition, we found that the protective effect of SIRT3 may be achieved by regulating GLUT4 translocation and rescuing impaired glucose uptake caused by cisplatin. Our study confirmed that upregulation of SIRT3 may antagonize cisplatin-induced ototoxicity, and provided a new perspective for the study of cisplatin-induced ototoxicity.

Proteomic Analysis Reveals That Mitochondria Dominate the Hippocampal Hypoxic Response in Mice

Hypoxic stress occurs in various physiological and pathological states, such as aging, disease, or high-altitude exposure, all of which pose a challenge to many organs in the body, necessitating adaptation. However, the exact mechanisms by which hypoxia affects advanced brain function (learning and memory skills in particular) remain unclear. In this study, we investigated the effects of hypoxic stress on hippocampal function. Specifically, we studied the effects of the dysfunction of mitochondrial oxidative phosphorylation using global proteomics. First, we found that hypoxic stress impaired cognitive and motor abilities, whereas it caused no substantial changes in the brain morphology or structure of mice. Second, bioinformatics analysis indicated that hypoxia affected the expression of 516 proteins, of which 71.1% were upregulated and 28.5% were downregulated. We demonstrated that mitochondrial function was altered and manifested as a decrease in NADH dehydrogenase (ubiquinone) 1 alpha subcomplex 4 expression, accompanied by increased reactive oxygen species generation, resulting in further neuronal injury. These results may provide some new insights into how hypoxic stress alters hippocampal function via the dysfunction of mitochondrial oxidative phosphorylation.

A Review on Peripheral Tinnitus, Causes, and Treatments from the Perspective of Autophagy

Tinnitus is the perception of phantom noise without any external auditory sources. The degeneration of the function or activity of the peripheral or central auditory nervous systems is one of the causes of tinnitus. This damage has numerous causes, such as loud noise, aging, and ototoxicity. All these sources excite the cells of the auditory pathway, producing reactive oxygen species that leads to the death of sensory neural hair cells. This causes involuntary movement of the tectorial membrane, resulting in the buzzing noise characteristic of tinnitus. Autophagy is an evolutionarily conserved catabolic scavenging activity inside a cell that has evolved as a cell survival mechanism. Numerous studies have demonstrated the effect of autophagy against oxidative stress, which is one of the reasons for cell excitation. This review compiles several studies that highlight the role of autophagy in protecting sensory neural hair cells against oxidative stress-induced damage. This could facilitate the development of strategies to treat tinnitus by activating autophagy.