Hongjie Wang

Neuropathic pain associated with diabetic peripheral neuropathy (DPN) is a common and hard-to-treat complication of diabetes. Ion channels of plasma membrane are major mechanisms and targets for DPN pain. This study explores the role of a major lysosomal ion channel, TRPML1, in DPN pain. Mouse models of DPN pain and TRPML1 knockout were combined with pharmacological inhibition and detection of molecular expression and function. Major findings included 1) BKS db/db increased expression and function of TRPML1 in dorsal root ganglion (DRG); 2) lysosomes of DRG neurons expressed functional TRPML1 currents; 3) global knockout (gKO) or conditional knockout (cKO) in DRG neurons of TRPML1 prevented mechanical allodynia in male mice fed a high-fat diet; 4) a TRPML1 inhibitor significantly reversed mechanical allodynia in BKS db/db mice through intraperitoneal injection and in streptozotocin (STZ) mice through intrathecal injection; and 5) gKO or astrocyte cKO of TRPML1 prevented STZ-induced mechanical allodynia in male and female mice. The results suggest that TRPML1 in DRG neurons and astrocytes contributes to type 2 and type 1 DPN pain, respectively (type 1 and type 2 DPN pain refer to neuropathic pain associated with type 1 diabetes and type 2 diabetes or pre-diabetes). This study may serve as a proof of concept to explore the role of lysosomal ion channels in painful DPN, painless DPN, and chronic pain. Article Highlights: A lysosomal ion channel, TRPML1, contributes to neuropathic pain associated with diabetic peripheral neuropathy (DPN). TRPML1 of dorsal root ganglion neurons contributes to type 2 DPN pain. Astrocyte TRPML1 contributes to type 1 DPN pain. Lysosomal ion channels may be novel mechanisms and targets for DPN pain.

Parkinson’s disease (PD) is a progressive neurodegenerative disorder marked by dopaminergic (DA) neuron loss and neuroinflammation. Current therapies fail to halt disease progression, which underscores the need for new treatments. This study investigated the neuroprotective effects and mechanisms of Gastrodia elata polysaccharide (GEP) in MPTP-induced PD mice. GEP was administered for two weeks, and motor function was assessed using behavioral tests. Immunohistochemical and Western Blot analyses evaluated DA neuron survival, microglial activation, and NLRP3 inflammasome components. GEP-medicated serum (GMS) was applied to SH-SY5Y neuroblastoma cells exposed to neuroinflammatory conditions, and metabolomic analysis identified key metabolites. GEP improved motor function, reduced DA neuron loss, and increased tyrosine hydroxylase expression. It suppressed microglial activation, decreased NLRP3 inflammasome components, and lowered pro-inflammatory cytokines (IL-1β, IL-6, TNF-α). GMS reduced ROS levels, enhanced mitochondrial membrane potential, and promoted autophagy in SH-SY5Y cells. Metabolomic analysis revealed elevated dopamine levels in GMS, linked to NLRP3 inflammasome inhibition, and reduced neuroinflammation. GMS also activated the PINK1/Parkin pathway to promote mitochondrial autophagy and prevent apoptosis. GEP alleviates PD symptoms by targeting neuroinflammation, mitochondrial dysfunction, and dopamine regulation, which highlights its potential as a therapeutic candidate. Further research is needed to explore its long-term efficacy and clinical applications.

Mitochondria serve as the energy provider and enable life activities, and they are the only organelles containing extra-chromosomal DNA. Each mitochondrion contains multiple copies of its genome, which is usually referred to as mitochondrial DNA (mtDNA). mtDNA encodes necessary electron transport chain complex subunits, as well as the essential RNAs for their translation within the organelle. Therefore, the precondition for intact mitochondrial function and cardiomyocyte survival is the integrity of mtDNA. Accumulating evidence suggests that the disruption of mtDNA integrity is involved in ischemia/reperfusion-induced mitochondrial dysfunction and cardiomyocyte injury. Here, we review the current opinions about the pathways of mtDNA integrity maintenance and discuss the role of mtDNA integrity in cardiomyocyte injury reacting to ischemia/reperfusion. We also discuss the mechanisms by which mtDNA mediates ischemia/reperfusion-induced cardiomyocyte injury, together with therapeutic strategies by targeting mtDNA.

Postherpetic neuralgia (PHN) is a common, severe, and hard-to-treat chronic pain condition in clinics. Although PHN is developed from herpes zoster (HZ), the developing mechanism is unknown. A previous study investigated blood metabolomic and proteomic profiling in patients with PHN and HZ. The current study aims to explore the blood transcriptomic signature of PHN compared to HZ patients. Whole blood from eight PHN and 15 HZ patients was used for RNA-Seq analysis. There were 82 and 1,788 genes detected specifically in the PHN and HZ groups, respectively. PHN-specific genes are involved in viral infection, lipid and carbohydrate metabolism, and immune response. For genes coexpressed in PHN and HZ patients, there were 407 differential expression genes (DEGs), including 205 upregulated (UP DEGs) and 202 downregulated (DOWN DEGs) in PHN compared to HZ groups. DEGs are involved in viral infection, type I interferon (IFN), and hemoglobin and oxygen carrier activity. UP DEGs are associated with regulatory T cells (Tregs), activated NK cells, and neutrophils, while DOWN DEGs are associated with Tregs, resting NK cells, and monocytes. The results suggest that the metabolism of lipid, glycan, and nucleotides, type I IFN signaling, and altered neutrophil activation are associated with and might contribute to the development of PHN in HZ. It is also suggested that persistent or altered activation of nonspecific immunity may contribute to the development of PHN from HZ.

Metabolic syndrome is associated with cardiovascular dysfunction, including elevated sympathetic outflow. However, the underlying brain mechanisms are unclear. The nucleus tractus solitarius (NTS) critically regulates autonomic reflexes related to cardiovascular function and contains neurons projecting to the caudal ventrolateral medulla (CVLM). Nitric oxide (NO) is a diffusible free-radical messenger in the vascular, immune, and nervous systems. In this study, we determine if NO in the NTS is involved in the synaptic plasticity underlying the elevated sympathetic outflow in fructose-induced hypertension. We retrogradely labeled CVLM-projecting NTS neurons through the injection of FluoSpheres into the CVLM in a fructose-fed rat model to determine the cellular mechanism involved in increased sympathetic outflow. Fructose feeding increased the blood pressure and glucose levels, which represent metabolic syndrome. We found that fructose feeding reduces the NO precursor L-arginine-induced increase in the firing activity of CVLM-projecting NTS neurons. Furthermore, fructose feeding reduces the L-arginine-induced increase in presynaptic spontaneous glutamatergic synaptic inputs to NTS neurons, while NO donor DEA/NO produces an increase in glutamatergic synaptic inputs in fructose-fed rats similar to that in vehicle-treated rats. In addition, fructose feeding reduces the NO-induced depressor response and sympathoinhibition. These data suggested that fructose feeding reduced NO production and, thus, the subsequent NO-induced glutamate releases in the NTS and depressor response. The findings of this study provide new insights into the central mechanisms involved in the neural control of cardiovascular and autonomic functions in the NTS in metabolic syndrome.