Regulation of Monocyte Activation by PPARα Through Interaction With the cGAS-STING Pathway

The effect of spinal cord STING/ATG5-mediated autophagy activation on the development of diabetic neuropathic pain in rats

Diabetic neuropathic pain (DNP) is associated with concurrent spinal cord autophagy activation, mTOR pathway activation, and neuroinflammation. However, the mechanistic interplay between these processes remains unclear, as mTOR activation typically suppresses autophagy under physiological conditions. This study investigates the role of spinal STING/ATG5-mediated autophagy in DNP pathogenesis and its relationship with mTOR signaling and neuroinflammatory pathways. Utilizing a rat model of DNP, we observed significant increases in spinal autophagosome density, LC3-II/LC3-I ratio, and STING/ATG5 expression, accompanied by elevated p-mTOR/mTOR ratios, compared to healthy controls. Notably, Beclin-1 expression remained unchanged. Pharmacological inhibition of STING or ATG5 silencing via intrathecal administration attenuated mechanical allodynia and reduced LC3-II/LC3-I ratios, whereas STING activation exacerbated pain behaviors while further upregulating STING/ATG5 expression and LC3-II/LC3-I ratios, but paradoxically decreased p-mTOR/mTOR ratios. mTOR inhibition with rapamycin alleviated DNP symptoms and suppressed TNF-α/IL-1β-mediated neuroinflammation, yet failed to modulate LC3-II/LC3-I ratios despite increasing Beclin-1 expression. Crucially, STING/ATG5 pathway manipulation did not alter pro-inflammatory cytokine levels, while rapamycin's analgesic effects correlated with anti-inflammatory activity. These findings demonstrate that STING/ATG5-driven autophagy contributes to DNP progression through a mechanism independent of both canonical mTOR-dependent autophagy regulation and inflammatory cytokine modulation. Conversely, mTOR inhibition exerts therapeutic effects predominantly via anti-inflammatory pathways rather than autophagy regulation. This study identifies a novel non-canonical autophagy pathway in DNP pathophysiology and clarifies distinct mechanistic bases for STING/ATG5-versus mTOR-targeted interventions.

Fenofibrate inhibits activation of cGAS-STING pathway by alleviating mitochondrial damage to attenuate inflammatory response in diabetic dry eye

The cyclic GMP-AMP synthase (cGAS) and Stimulator of Interferon Genes (STING) signaling pathway are critical regulators of inflammation. This study aims to investigate the role of the cGAS-STING signaling pathway in diabetic dry eye (DDE) disease and further explore the therapeutic efficacy and underlying mechanism of fenofibrate in DDE. Using single-cell RNA sequencing (scRNA-Seq) data from the Gene Expression Omnibus (GEO) database, combined with the STZ-induced DDE mouse model and high-glucose conditions in immortalized human corneal epithelial cells (HCE-T), we observed mitochondrial damage and significantly elevated cytoplasmic mitochondrial DNA (mtDNA) in the diabetic cornea, and identified that the cGAS-STING signaling pathway plays a pivotal role in the pathogenesis of DDE. Notably, we found that the inhibitor H151 reversed the ocular surface inflammatory response via the cGAS-STING pathway. Further investigation revealed that fenofibrate alleviated corneal inflammatory response by reducing the production of reactive oxygen species (ROS), restoring mitochondrial membrane potential (MMP), decreasing mtDNA cytoplasmic leakage, and subsequently suppressing the activation of the cGAS-STING signaling pathway. In conclusion, this study highlights the crucial role of the cGAS-STING signaling pathway in DDE and proposes that fenofibrate alleviates mitochondrial damage to inhibit this pathway, offering novel strategy for the treatment of DDE.

Novel Therapeutic Approaches for Treatment of Diabetic Retinopathy and Age-Related Macular Degeneration

Retina, a light-sensitive layer of tissue of the eye, requires high levels of oxygen for its physiology. Retinal ischemia occurs due to inadequate supply of blood to the retina and choroid. Retinal ischemia is implicated in the development or progression of many ocular diseases, such as diabetic retinopathy (DR) and age-related macular degeneration (AMD). To date, anti-vascular endothelial growth factor (VEGF) treatment has been widely used to manage neovascular diseases associated with retinal ischemia. Nonetheless, a substantial number of patients with DR or AMD still suffer from incomplete response and adverse effects related to its therapy with limitations. Therefore, research scientists have been developing and finding novel treatments to protect against or prevent vision loss in those diseases. In this review article, we summarize the recent novel therapeutic approaches for the treatment of ischemic retinopathy (e.g., cell therapy, advanced molecular targeting, or drug delivery). This summary enables further research to obtain more solid evidence of novel effective drug development in retinal ischemic diseases.

Long-Term Minocycline Treatment Exhibits Enhanced Therapeutic Effects on Ischemic Stroke by Suppressing Inflammatory Phenotype of Microglia Through the EMB/MCT4/STING Pathway

BACKGROUND

Neuroinflammation caused by excessive activation of microglia is a significant cause of poor prognosis in ischemic stroke patients. Minocycline, a microglial cell inhibitor, has neuroprotective effects in stroke, but its optimal treatment duration and specific mechanisms of action remain unclear. This study aimed to compare the efficacy of different minocycline treatment durations on stroke and explore their mechanisms of action.

METHODS

We investigated the effects of various durations of minocycline treatment on microglial polarization using cellular and animal models. The mechanisms of long-term minocycline therapy for neuroprotective effects were explored through in vitro and in vivo experiments.

RESULTS

In stroke models, long-term minocycline treatment showed a stronger inhibitory effect on neuroinflammation and improved neuron viability compared with short-term treatment. Further in vitro and in vivo results indicated that long-term minocycline treatment downregulated microglial glycolysis levels through the EMB/MCT4 axis, promoting the transformation of microglia to an anti-inflammatory phenotype by inhibiting the activation of the STING pathway, thereby improving post-stroke neuroinflammation.

CONCLUSION

Long-term minocycline therapy exerts neuroprotective effects in ischemic stroke by regulating the EMB/MCT4/STING axis and inhibiting the inflammatory phenotype of microglia through downregulating cellular glycolysis levels. Extending the treatment duration of minocycline appropriately may further improve ischemic stroke outcomes.

Increase of circulating cell free mitochondrial DNA in amateur boxers after sparring matches

OBJECTIVES

To determine if circulating mitochondrial deoxyribonucleic acid levels increase after sport activity involving blows to the head, such as boxing, and if it could play a role in inflammatory cascade regulation in response to trauma.

DESIGN

Observational, longitudinal.

METHODS

We measured mitochondrial deoxyribonucleic acid levels and integrity in ten non-professional male boxers before and after three weekly sparring matches. We set up a protocol to separate three different plasma fractions enriched in mitochondria-containing vesicles, mitochondrial deoxyribonucleic acid bound to proteins and naked mitochondrial deoxyribonucleic acid. We quantified the levels of the main cytokines involved in inflammatory response and the levels of neurofilament light, a well-known marker of brain damage.

RESULTS

Circulating mitochondrial deoxyribonucleic acid levels increased after each match. In the second fraction, we also observed an increase over the weeks. Mitochondrial deoxyribonucleic acid is less intact after each match if compared with pre-match integrity, especially the naked form which is not protected within vesicles or mitochondria. Circulating levels of interleukin-6, interleukin-1beta and interleukin-10 increased after each match linking traumatic brain injuries to inflammatory state. Neurofilament light chain showed a similar trend to mitochondrial deoxyribonucleic acid.

CONCLUSIONS

As mitochondrial deoxyribonucleic acid displays an inflammatory effect and neurofilament light chain is more specific for brain injury, we concluded that the simultaneous analysis of these two parameters could be helpful to monitor the effects of traumatic brain injury in contact sports, and that mitochondrial deoxyribonucleic acid is a promising candidate biomarker to study the inflammatory state of patients who suffered repeated traumatic brain injuries.

Mechanism and therapeutic targets of circulating immune cells in diabetic retinopathy

Diabetic retinopathy (DR) continues to be the leading cause of preventable vision loss among working-aged adults, marked by immune dysregulation within the retinal microenvironment. Typically, the retina is considered as an immune-privileged organ, where circulating immune cells are restricted from entry under normal conditions. However, during the progression of DR, this immune privilege is compromised as circulating immune cells breach the barrier and infiltrate the retina. Increasing evidence suggests that vascular and neuronal degeneration in DR is largely driven by the infiltration of immune cells, particularly neutrophils, monocyte-derived macrophages, and lymphocytes. This review delves into the mechanisms and therapeutic targets associated with these immune cell populations in DR, offering a promising and innovative approach to managing the disease.

Role of cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathway in diabetes and its complications

Diabetes mellitus (DM) is one of the major causes of mortality worldwide, with inflammation being an important factor in its onset and development. This review summarizes the specific mechanisms of the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway in mediating inflammatory responses. Furthermore, it comprehensively presents related research progress and the subsequent involvement of this pathway in the pathogenesis of early-stage DM, diabetic gastroenteropathy, diabetic cardiomyopathy, non-alcoholic fatty liver disease, and other complications. Additionally, the role of cGAS-STING in autonomic dysfunction and intestinal dysregulation, which can lead to digestive complications, has been discussed. Altogether, this study provides a comprehensive analysis of the research advances regarding the cGAS-STING pathway-targeted therapeutic agents and the prospects for their application in the precision treatment of DM.

The cGAS-STING pathway: a therapeutic target in diabetes and its complications

Diabetic wound healing (DWH) represents a major complication of diabetes where inflammation is a key impediment to proper healing. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway has emerged as a central mediator of inflammatory responses to cell stress and damage. However, the contribution of cGAS-STING activation to impaired healing in DWH remains understudied. In this review, we examine the evidence that cGAS-STING-driven inflammation is a critical factor underlying defective DWH. We summarize studies revealing upregulation of the cGAS-STING pathway in diabetic wounds and discuss how this exacerbates inflammation and senescence and disrupts cellular metabolism to block healing. Partial pharmaceutical inhibition of cGAS-STING has shown promise in damping inflammation and improving DWH in preclinical models. We highlight key knowledge gaps regarding cGAS-STING in DWH, including its relationships with endoplasmic reticulum stress and metal-ion signaling. Elucidating these mechanisms may unveil new therapeutic targets within the cGAS-STING pathway to improve healing outcomes in DWH. This review synthesizes current understanding of how cGAS-STING activation contributes to DWH pathology and proposes future research directions to exploit modulation of this pathway for therapeutic benefit.