Aging Promotes Chronic Stress-Induced Depressive-Like Behavior by Activating NLRP1 Inflammasome-Driven Inflammatory Signaling in Mice

NLRP1 inflammasome promotes senescence and senescence-associated secretory phenotype

BACKGROUND

Senescence is a cellular aging-related process triggered by different stresses and characterized by the secretion of various inflammatory factors referred to as senescence-associated secretory phenotype (SASP), some of which are produced by the NLRP3 inflammasome. Here, we present evidence that the NLRP1 inflammasome is a DNA damage sensor and a key mediator of senescence.

METHODS

Senescence was induced in fibroblasts in vitro and in mice. Cellular senescence was assessed by Western blot analysis of several proteins, including p16, p21, p53, and SASP factors, released in the culture media or serum. Inflammasome components, including NLRP1, NLRP3 and GSDMD were knocked out or silenced using siRNAs.

RESULTS

In vitro and in vivo results suggest that the NLRP1 inflammasome promotes senescence by regulating the expression of p16, p21, p53, and SASP factors in a Gasdermin D (GSDMD)-dependent manner. Mechanistically, the NLRP1 inflammasome is activated in response to genomic damage detected by the cytosolic DNA sensor cGMP-AMP (cGAMP) synthase (cGAS).

CONCLUSION

Our findings show that NLRP1 is a cGAS-dependent DNA damage sensor during senescence and a mediator of SASP release through GSDMD. This study advances the knowledge on the biology of the NLRP1 inflammasome and highlights this pathway as a potential pharmcological target to modulate senescence.

A Perfect Storm: The Convergence of Aging, Human Immunodeficiency Virus Infection, and Inflammasome Dysregulation

The emergence of combination antiretroviral therapy (cART) has greatly transformed the life expectancy of people living with HIV (PWH). Today, over 76% of the individuals with HIV have access to this life-saving therapy. However, this progress has come with a new challenge: an increase in age-related non-AIDS conditions among patients with HIV. These conditions manifest earlier in PWH than in uninfected individuals, accelerating the aging process. Like PWH, the uninfected aging population experiences immunosenescence marked by an increased proinflammatory environment. This phenomenon is linked to chronic inflammation, driven in part by cellular structures called inflammasomes. Inflammatory signaling pathways activated by HIV-1 infection play a key role in inflammasome formation, suggesting a crucial link between HIV and a chronic inflammatory state. This review outlines the inflammatory processes triggered by HIV-1 infection and aging, with a focus on the inflammasomes. This review also explores current research regarding inflammasomes and potential strategies for targeting inflammasomes to mitigate inflammation. Further research on inflammasome signaling presents a unique opportunity to develop targeted interventions and innovative therapeutic modalities for combating HIV and aging-associated inflammatory processes.

Identification and validation of senescence-related genes in polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is an exceedingly intractable issue affecting female endocrine and reproductive health. However, the etiology and intricate pathological mechanisms of PCOS remain unclear. Nowadays, aging was found to share multiple common pathological mechanisms with PCOS, which causes probing into the pathogenesis of PCOS from senescence. However, no bioinformatics analyses have specifically focused on connection between PCOS and ovarian aging.

METHODS

Differentially expressed aging-related genes in PCOS were identified and then analyzed using function enrichment method. Hub genes were determined based on multiple algorithms, and expression validation of hub genes was performed in both datasets and experiments (human granulosa-like tumor cell line, KGN; human Granulosa Cell, hGCs). Finally, a transcription factor-miRNA-gene network of hub genes was constructed.

RESULTS

Here, we identified 73 aging-related differential expression genes (ARDEGs) by intersecting DEGs in PCOS and senescence-related gene set. Furthermore, we performed biological functions and potential pathways of ARDEGs and potential hub genes were also screened by multiple algorithms. From the perspective of immune dysfunction, we analyzed the correlation between PCOS and immune cells. Finally, TF-miRNA-gene networks were constructed. Finally, TF-miRNA-gene networks were constructed.

CONCLUSIONS

Our work aimed to elucidate the relation between PCOS and cellular senescence based on bioinformatics strategy, deepening the understanding of mechanisms and to seek for novel therapy strategies for improving reproductive lifespan and female health. Exploring the potential molecular mechanism of cell aging in PCOS is expected to bring a new breakthrough for PCOS diagnosis and therapy strategies. And this, might deepen our understanding about intricate mechanisms of ovarian aging.

Autophagy dysfunction contributes to NLRP1 inflammasome-linked depressive-like behaviors in mice

BACKGROUND

Major depressive disorder (MDD) is a common but severe psychiatric illness characterized by depressive mood and diminished interest. Both nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 1 (NLRP1) inflammasome and autophagy have been reported to implicate in the pathological processes of depression. However, the mechanistic interplay between NLRP1 inflammasome, autophagy, and depression is still poorly known.

METHODS

Animal model of depression was established by chronic social defeat stress (CSDS). Depressive-like behaviors were determined by social interaction test (SIT), sucrose preference test (SPT), open field test (OFT), forced swim test (FST), and tail-suspension test (TST). The protein expression levels of NLRP1 inflammasome complexes, pro-inflammatory cytokines, phosphorylated-phosphatidylinositol 3-kinase (p-PI3K)/PI3K, phosphorylated-AKT (p-AKT)/AKT, phosphorylated-mechanistic target of rapamycin (p-mTOR)/mTOR, brain-derived neurotrophic factor (BDNF), phosphorylated-tyrosine kinase receptor B (p-TrkB)/TrkB, Bcl-2-associated X protein (Bax)/B-cell lymphoma-2 (Bcl2) and cleaved cysteinyl aspartate-specific proteinase-3 (caspase-3) were examined by western blotting. The mRNA expression levels of pro-inflammatory cytokines were tested by quantitative real-time PCR. The interaction between proteins was detected by immunofluorescence and coimmunoprecipitation. Neuronal injury was assessed by Nissl staining. The autophagosomes were visualized by transmission electron microscopy. Nlrp1a knockdown was performed using an adeno-associated virus (AAV) vector containing Nlrp1a-shRNA-eGFP infusion.

RESULTS

CSDS exposure caused a bidirectional change in hippocampal autophagy function, which was activated in the initial period but impaired at the later stage. In addition, CSDS exposure increased the expression levels of hippocampal NLRP1 inflammasome complexes, pro-inflammatory cytokines, p-PI3K, p-AKT and p-mTOR in a time-dependent manner. Interestingly, NLRP1 is immunoprecipitated with mTOR but not PI3K/AKT and CSDS exposure facilitated the immunoprecipitation between them. Hippocampal Nlrp1a knockdown inhibited the activity of PI3K/AKT/mTOR signaling, rescued the impaired autophagy and ameliorated depressive-like behavior induced by CSDS. In addition, rapamycin, an autophagy inducer, abolished NLRP1 inflammasome-driven inflammatory reactions, alleviated depressive-like behavior and exerted a neuroprotective effect.

CONCLUSIONS

Autophagy dysfunction contributes to NLRP1 inflammasome-linked depressive-like behavior in mice and the regulation of autophagy could be a valuable therapeutic strategy for the management of depression.

Therapeutic potential of NOX inhibitors in neuropsychiatric disorders

RATIONALE

Neuropsychiatric disorders encompass a broad category of medical conditions that include both neurology as well as psychiatry such as major depressive disorder, autism spectrum disorder, bipolar disorder, schizophrenia as well as psychosis.

OBJECTIVE

NADPH-oxidase (NOX), which is the free radical generator, plays a substantial part in oxidative stress in neuropsychiatric disorders. It is thought that elevated oxidative stress as well as neuroinflammation plays a part in the emergence of neuropsychiatric disorders. Including two linked with membranes and four with subunits of cytosol, NOX is a complex of multiple subunits. NOX has been linked to a significant source of reactive oxygen species in the brain. NOX has been shown to control memory processing and neural signaling. However, excessive NOX production has been linked to cardiovascular disorders, CNS degeneration, and neurotoxicity. The increase in NOX leads to the progression of neuropsychiatric disorders.

RESULT

Our review mainly emphasized the characteristics of NOX and its various mechanisms, the modulation of NOX in various neuropsychiatric disorders, and various studies supporting the fact that NOX might be the potential therapeutic target for neuropsychiatric disorders.

CONCLUSION

Here, we summarizes various pharmacological studies involving NOX inhibitors in neuropsychiatric disorders.

NLRP1 inflammasome modulates senescence and senescence-associated secretory phenotype

Senescence is a cellular aging-related process triggered by different stresses and characterized by the secretion of various inflammatory factors referred to as the senescence-associated secretory phenotype (SASP). Here, we present evidence that the inflammasome sensor, NLRP1, is a key mediator of senescence induced by irradiation both in vitro and in vivo. The NLRP1 inflammasome promotes senescence by regulating the expression of p16, p21, p53, and SASP in Gasdermin D (GSDMD)-dependent manner as these responses are reduced in conditions of NLRP1 insufficiency or GSDMD inhibition. Mechanistically, the NLRP1 inflammasome is activated downstream of the cytosolic DNA sensor cGMP-AMP (cGAMP) synthase (cGAS) in response to genomic damage. These findings provide a rationale for inhibiting the NLRP1 inflammasome-GSDMD axis to treat senescence-driven disorders.

The Role and Mechanism of Hyperoside against Depression-like Behavior in Mice via the NLRP1 Inflammasome

BACKGROUND AND OBJECTIVES

Hypericum perforatum (HP) is widely used for depressive therapy. Nevertheless, the antidepressant effect and potential mechanism of hyperoside (Hyp), the main active component of HP, have not been determined.

MATERIALS AND METHODS

We performed ultra-performance liquid chromatography-quadrupole-time-of-flight-tandem mass spectrometry (UPLC-Q-TOF-MS/MS) technology to analyze the components in HP. Using data mining and network pharmacology methods, combined with Cytoscape v3.7.1 and other software, the active components, drug-disease targets, and key pathways of HP in the treatment of depression were evaluated. Finally, the antidepressant effects of Hyp and the mechanism involved were verified in chronic-stress-induced mice.

RESULTS

We identified 12 compounds from HP. Hyp, isoquercetin, and quercetin are the main active components of HP. The Traditional Chinese Medicine Systems Pharmacology Database (TCMSP), the Analysis Platform, DrugBank, and other databases were analyzed using data mining, and the results show that the active components of HP and depression are linked to targets such as TNF-, IL-2, TLR4, and so on. A potential signaling pathway that was most relevant to the antidepressant effects of Hyp is the C-type lectin receptor signaling pathway. Furthermore, the antidepressant effects of Hyp were examined, and it is verified for the first time that Hyp significantly alleviated depressive-like behaviors in chronic-stress-induced mice, which may be mediated by inhibiting the NLRP1 inflammasome through the CXCL1/CXCR2/BDNF signaling pathway.

CONCLUSION

Hyp is one of the main active components of HP, and Hyp has antidepressant effects through the NLRP1 inflammasome, which may be connected with the CXCL1/CXCR2/BDNF signaling pathway.