Neuritin inhibits astrogliosis to ameliorate diabetic cognitive dysfunction

STAT protein family and cardiovascular diseases: overview of pathological mechanisms and therapeutic implications

Globally, cardiovascular diseases (CVD) are one of the significant causes of death and are considered a major concern of human society. One of the most crucial objectives of scientists is to reveal the mechanisms associated with the pathogenesis of CVD, which has attracted the attention of many scientists. Accumulating evidence showed that the signal transducer and activator of transcription (STAT) signaling pathway is involved in various physiological and pathological processes. According to research on the molecular mechanisms of CVDs, the STAT family of proteins is one of the most crucial players in these diseases. Numerous studies have demonstrated the undeniable relevance of STAT family proteins in various CVDs. The aim of this review is to shed light on how STAT signaling pathways are related to CVD and the potential for using these signaling pathways as therapeutic targets.

Duodenal-jejunal bypass improves hypothalamic oxidative stress and inflammation in diabetic rats via glucagon-like peptide 1-mediated Nrf2/HO-1 signaling

BACKGROUND

Type 2 diabetes mellitus (T2DM) is often accompanied by impaired glucose utilization in the brain, leading to oxidative stress, neuronal cell injury and infla-mmation. Previous studies have shown that duodenal jejunal bypass (DJB) surgery significantly improves brain glucose metabolism in T2DM rats, the role and the metabolism of DJB in improving brain oxidative stress and inflammation condition in T2DM rats remain unclear.

AIM

To investigate the role and metabolism of DJB in improving hypothalamic oxidative stress and inflammation condition in T2DM rats.

METHODS

A T2DM rat model was induced via a high-glucose and high-fat diet, combined with a low-dose streptozotocin injection. T2DM rats were divided into DJB operation and Sham operation groups. DJB surgical intervention was carried out on T2DM rats. The differential expression of hypothalamic proteins was analyzed using quantitative proteomics analysis. Proteins related to oxidative stress, inflammation, and neuronal injury in the hypothalamus of T2DM rats were analyzed by flow cytometry, quantitative real-time PCR, Western blotting, and immunofluorescence.

RESULTS

Quantitative proteomics analysis showed significant differences in proteins related to oxidative stress, inflammation, and neuronal injury in the hypothalamus of rats with T2DM-DJB after DJB surgery, compared to the T2DM-Sham groups of rats. Oxidative stress-related proteins (glucagon-like peptide 1 receptor, Nrf2, and HO-1) were significantly increased (P < 0.05) in the hypothalamus of rats with T2DM after DJB surgery. DJB surgery significantly reduced (P < 0.05) hypothalamic inflammation in T2DM rats by inhibiting the activation of NF-κB and decreasing the expression of interleukin (IL)-1β and IL-6. DJB surgery significantly reduced (P < 0.05) the expression of factors related to neuronal injury (glial fibrillary acidic protein and Caspase-3) in the hypothalamus of T2DM rats and upregulated (P < 0.05) the expression of neuroprotective factors (C-fos, Ki67, Bcl-2, and BDNF), thereby reducing hypothalamic injury in T2DM rats.

CONCLUSION

DJB surgery improve oxidative stress and inflammation in the hypothalamus of T2DM rats and reduce neuronal cell injury by activating the glucagon-like peptide 1 receptor-mediated Nrf2/HO-1 signaling pathway.

The gut microbiota-astrocyte axis: Implications for type 2 diabetic cognitive dysfunction

BACKGROUND

Diabetic cognitive dysfunction (DCD) is one of the most insidious complications of type 2 diabetes mellitus, which can seriously affect the ability to self-monitoring of blood glucose and the quality of life in the elderly. Previous pathological studies of cognitive dysfunction have focused on neuronal dysfunction, characterized by extracellular beta-amyloid deposition and intracellular tau hyperphosphorylation. In recent years, astrocytes have been recognized as a potential therapeutic target for cognitive dysfunction and important participants in the central control of metabolism. The disorder of gut microbiota and their metabolites have been linked to a series of metabolic diseases such as diabetes mellitus. The imbalance of intestinal flora has the effect of promoting the occurrence and deterioration of several diabetes-related complications. Gut microbes and their metabolites can drive astrocyte activation.

AIMS

We reviewed the pathological progress of DCD related to the "gut microbiota-astrocyte" axis in terms of peripheral and central inflammation, intestinal and blood-brain barrier (BBB) dysfunction, systemic and brain energy metabolism disorders to deepen the pathological research progress of DCD and explore the potential therapeutic targets.

CONCLUSION

"Gut microbiota-astrocyte" axis, unique bidirectional crosstalk in the brain-gut axis, mediates the intermediate pathological process of neurocognitive dysfunction secondary to metabolic disorders in diabetes mellitus.

Cryptococcus neoformans Infection Induces IL-17 Production by Promoting STAT3 Phosphorylation in CD4+ T Cells

Cryptococcus neoformans infection in the central nervous system is a severe infectious disease with poor outcomes and high mortality. It has been estimated that there are 220,000 new cases each year. Over 90% of C. neoformans meningitis cases were diagnosed in AIDS patients with CD4⁺ T cell count <100 cells/μl; however, the mechanism of cryptococcal meningitis in patients with normal immune functions remains unclear. IL-17 is a pro-inflammatory cytokine and plays an important role in anti-fungal immunity. Here we report that significantly high levels of IL-17 were predominantly detected in the cerebrospinal fluid of patients with either AIDS- or non-AIDS-associated C. neoformans meningitis but not in patients with tuberculous meningitis or non-neurosyphilis. Antifungal therapy minimized the IL-17 level in the cerebrospinal fluid. An in vitro mechanistic study showed that C. neoformans stimulation of healthy peripheral blood mononuclear cells prompted IL-17 production, and CD4⁺ T cells were the predominant IL-17-producing cells. IL-17 production by C. neoformans stimulation was STAT3 signaling dependent. Inhibition of STAT3 phosphorylation attenuated the C. neoformans-mediated IL-17 expression. Our data highlighted the significance of CD4⁺ T cells in antifungal immunity and suggested IL-17 as a diagnostic biomarker of C. neoformans infection and STAT3 as a checkpoint for antifungal targeted therapies.

Nicotine Activating α4β2 Nicotinic Acetylcholine Receptors to Suppress Neuroinflammation via JAK2-STAT3 Signaling Pathway in Ischemic Rats and Inflammatory Cells

Nicotine plays a role in inhibiting inflammatory factors, which contributes to improving cognitive impairment by activating α₄β₂ nAChRs in ischemic rats, but the underlying mechanism has not been fully elucidated. Janus tyrosine kinase 2-signal transducer and activator of transcription 3 (JAK2-STAT3) signaling pathway is involved in cognitive improvement, and there seems to be a relationship between nAChRs and JAK2-STAT3 as well. The aim of this study is to explore the role of JAK2-STAT3 signaling pathway in nicotine-mediated anti-inflammatory effect. Nicotine, DHβE (the strongest competitive antagonist of α₄β₂ nAChRs), and AG490 (a specific JAK2-STAT3 blocker) were used to intervene and treat ischemic rats and HEK-293 T-hα₄β₂ cells. The Morris water maze (MWM) test and 2-[¹⁸F]-A-85380 PET imaging were performed to detect the cognitive function and α₄β₂ nAChRs density in ischemic rats. The results demonstrated that nicotine intervention increased the density of α₄β₂ nAChRs and improved cognitive impairment, but this effect was blocked by AG490, and the receptors were still upregulated. Essentially, when the JAK2-STAT3 signaling pathway was blocked, nicotine could only upregulate the expression of α₄β₂ nAChRs, but not improve the cognitive function. PCR and Western blot analysis further confirmed these results. The cell experiments also showed that nicotine could reduce inflammatory factors stimulated by LPS and upregulate the expression of pJAK2 and pSTAT3 in HEK-293 T-hα₄β₂ cells, while AG490 and DHβE reversed the effect of nicotine. To sum up, our work indicated that JAK2-STAT3 signaling pathway played an important role in nicotine-induced cognitive improvement by upregulating α₄β₂ nAChRs in ischemic rats.