Characterizing the NLRP3 Inflammasome in Mood Disorders: Overview, Technical Development, and Measures of Peripheral Activation in Adolescent Patients

Abstract

The NOD-, LRR-, and pyrin-domain-containing protein 3 (NLRP3) inflammasome is a node of intracellular stress pathways and a druggable target which integrates mitochondrial stress and inflammatory cascades. While a body of evidence suggests the involvement of the NLRP3 inflammasome in numerous diseases, a lack of reliable measurement techniques highlights the need for a robust assay using small quantities of biological samples. We present a literature overview on peripheral activation of the NLRP3 inflammasome in mood disorders, then outline a process to develop and validate a robust assay to measure baseline and activated intracellular levels of “apoptosis-associated speck-like protein containing a CARD” (ASC) as a key component of an inflammatory profile in peripheral blood mononuclear cells (PBMC). A consistent association between high NLRP3 mRNA levels and relevant cytokines was seen in the literature. Using our method to measure ASC, stimulation of PBMC with lipopolysaccharide and nigericin or adenosine triphosphate resulted in microscopic identification of intracellular ASC specks, as well as interleukin 1 (IL-1) beta and caspase-1 p10 in the periphery. This was abolished by dose-dependent pre-treatment with 100 nM MCC950. We also report the use of this technique in a small pilot sample from patients with bipolar disorder and depressive disorders. The results show that levels of intracellular ASC and IL-1 beta are sensitive to change upon activation and maintained over time, which may be used to improve the detection of NLRP3 activation and guide personalized therapeutic strategy in the treatment of patients.

Chronic fatigue, depression and anxiety symptoms in Long COVID are strongly predicted by neuroimmune and neuro-oxidative pathways which are caused by the inflammation during acute infection

“…While the infection rate with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) fell globally (Moghadas, Vilches et al 2021, Andrews, Stowe et al 2022), a new concern arose among many post-infected individuals having Long COVID symptoms (Lerner, Robinson et al 2021). Several studies reported a cluster of persistent symptoms extending beyond full recovery of coronavirus disease (COVID-19) (Deng, Zhou et al 2021, Huang, Huang et al 2021, Lopez-Leon, Wegman-Ostrosky et al 2021). These symptoms either appear following up to 2 (infection-related), 3 (acute-post-COVID), or 6 (prolonged post-COVID) months or more (chronic post-COVID) after the acute infectious phase (Fernández-de-Las-Peñas, Palacios-Ceña et al 2021).…”

“…These symptoms either appear following up to 2 (infection-related), 3 (acute-post-COVID), or 6 (prolonged post-COVID) months or more (chronic post-COVID) after the acute infectious phase (Fernández-de-Las-Peñas, Palacios-Ceña et al 2021). Many individuals (74-.87.4%) with Long COVID suffer from a variety of mental and physiosomatic symptoms after recovery from the acute phase (Carfì, Bernabei et al 2020, Arnold, Hamilton et al 2021), including chronic fatigue, affective symptoms (low mood and anxiety), cognitive dysfunctions and sleep disturbances, along with somatic manifestations such as autonomic symptoms, muscle pain, muscle tension, headache, a flu-like malaise, gastro-intestinal symptoms (GIS), shortening of breath, persistent cough, and chest pain (Cirulli, Schiabor Barrett et al 2020, Garrigues, Janvier et al 2020, Arnold, Hamilton et al 2021, Bellan, Soddu et al 2021, Cares-Marambio, Montenegro-Jiménez et al 2021, Davis, Assaf et al 2021, Deng, Zhou et al 2021, Huang, Huang et al 2021, Renaud-Charest, Lui et al 2021, Sandler, Wyller et al 2021, Shah, Hillman et al 2021, Simani, Ramezani et al 2021, van den Borst, Peters et al 2021).…”

“…It is important to note that neuro-immune and nitro-oxidative toxicity play a key role in the pathophysiology of chronic fatigue syndrome (CFS), major depression (MDD), and generalized anxiety disorder (GAD) (Maes, Bonifacio et al 2018, Maes and Carvalho 2018, Almulla and Maes 2022, Maes, Kubera et al 2022). There is now also evidence that upregulation of the NLRP3 inflammasome plays a key role in MDD (Kaufmann, Costa et al 2017, Zhou, Fernando et al 2021), fatigue (Zhang, Du et al 2016, Zhang, Ma et al 2017), cognitive impairments (Kuwar, Rolfe et al 2021), and anxiety (Aghaie, Moradifar et al 2021, Smith, Trageser et al 2021). Nevertheless, there are no data whether the NLRP3 inflammasome and lowered Ca are involved in the physio-affective phenome of Long COVID.…”

Novel splice‑site variants c.393G>A, c.278_2A>G in exon 2 and Q705K variant in exon 3 of NLRP3 gene are associated with bipolar I disorder

“…The most prevalent of these variants are rs35829419, rs10754558, rs4612666, rs4925648 and rs10925019. It has been stated in the literature that NLRP3 variants are associated with several inflammatory diseases, including rheumatoid arthritis, psoriatic arthritis, type 1 diabetes, multiple sclerosis, preeclampsia and mood disorders (13)(14)(15)(16)(17)(18). However, in a meta-analysis study, certain variants were shown to exert a protective effect (11).…”

The NLRP3-Inflammasome in Health and Disease

“…Therefore, the authors developed and validated an assay to measure the intracellular formation of ASC specks in activated PBMC and IL-1β and caspase-1 levels in the periphery over 6 months in adolescents with bipolar and depressive disorders. Despite the small sample size, the results are interesting as, although all patients demonstrated significant increases in ASC specks and extracellular IL-1β production, the authors observed an inter-individual difference in activation magnitudes, suggesting that NLRP3 inhibitors could be candidates for individualized early intervention and combination therapy in patients affected by mood disorders [ 23 ].…”