Nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 inflammasome: From action mechanism to therapeutic target in clinical trials

Abstract

The nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome is a critical modulator in inflammatory disease. Activation and mutation of NLRP3 can cause severe inflammation in diseases such as chronic infantile neurologic cutaneous and articular syndrome, Muckle-Wells syndrome, and familial cold autoinflammatory syndrome 1. To date, a great effort has been made to decode the underlying mechanisms of NLRP3 activation. The priming and activation of NLRP3 drive the maturation and release of active interleukin (IL)-18 and IL-1β to cause inflammation and pyroptosis, which can significantly trigger many diseases including inflammatory diseases, immune disorders, metabolic diseases, and neurodegenerative diseases. The investigation of NLRP3 as a therapeutic target for disease treatment is a hot topic in both preclinical studies and clinical trials. Developing potent NLRP3 inhibitors and downstream IL-1 inhibitors attracts wide-spectrum attention in both research and pharmaceutical fields. In this minireview, we first updated the molecular mechanisms involved in NLRP3 inflammasome activation and the associated downstream signaling pathways. We then reviewed the molecular and cellular pathways of NLRP3 in many diseases, including obesity, diabetes, and other metabolic diseases. In addition, we briefly reviewed the roles of NLRP3 in cancer growth and relative immune checkpoint therapy. Finally, clinical trials with treatments targeting NLRP3 and its downstream signaling pathways were summarized.

Key Words: Nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3; Metabolic disease; Inflammation; Cancer; Immunotherapy; Clinical trial

Core Tip: The nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome plays a pivotal role in many diseases such as inflammatory diseases, metabolic disorders, and neurodegenerative diseases. The investigation of NLRP3 as a therapeutic target is involved in many preclinical studies and clinical trials. Among these studies, NLRP3 inhibitors and downstream interleukin-1 inhibitors attract wide-spectrum attention. In addition, NLRP3 activation also impacts cancer development and immunotherapy, serving as a potential therapeutic target for cancer treatment.

INTRODUCTION

Nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) is a protein encoded by the gene Nlrp3, which is mainly expressed in macrophages, monocytes, T cells, myeloid dendritic cells, basophils, Langerhans cells, Hoffbauer cells, and Kupffer cells[1,2]. NLRP3 serves as an intracellular sensor and a key mediator of inflammasome activation, which can cause cell inflammation and pyroptosis[3]. NLRP3 also serves as a regulator for T helper 2 cell differentiation, and its deficiency in T helper 2 cells can promote the pathogenesis of asthma and melanoma tumor proliferation[4].

The triggering stimuli of NLRP3 activation include pathogen-associated molecular patterns (PAMPs), such as molecules associated with viral or bacterial infection, and damage-associated molecular patterns (DAMPs), such as molecules associated with cell death and damage[1]. Upon exposure to the stimuli, NLRP3 together with caspase-1 and adaptor apoptosis-associated speck-like protein containing a caspase recruitment domain form a complex named the NLRP3 inflammasome, followed by the activation process that is mediated by never in mitosis A-related kinase 7 (NEK7) to trigger the cleavage of pro-interleukin (IL)-18 and pro-IL-1β, resulting in the secretion of active mature IL-1β and IL-18 to induce inflammation. Simultaneously, gasdermin D (GSDMD) also goes through the cleavage process by the NLRP3 inflammasome via disconnecting the C-terminal to produce GSDMD-N that can cause the formation of a pore in the plasma membrane and eventually induce pyroptosis[5,6].

NLRP3 plays an essential role in health and disease. The mutation of NLRP3 can cause inflammatory diseases, such as chronic infantile neurologic cutaneous and articular syndrome, Muckle-Wells syndrome, and familial cold autoinflammatory syndrome 1[7,8]. Accumulating studies have also demonstrated that NLRP3 affects the development of many diseases, such as inflammatory bowel disease[9], metabolic disorders (obesity and diabetes)[10-12], cardiovascular diseases[13,14], and neurologic-related diseases [Alzheimer’s disease and Parkinson’s disease (PD)][15,16]. In the following sections, some examples are given to discuss the specific roles of NLRP3 in diseases.

NLRP3 IN INFLAMMATION

The underlying molecular mechanism of NLRP3 activation includes two steps: priming and activation (Figure 1). First, NLRP3 serves as a sensor, which is triggered by the binding of stimuli, including PAMPs/DAMPs and pattern recognition receptors such as toll-like receptors (TLR) and IL-1R on cellular membrane surface[17]. Then, this leads to the activation of either nuclear factor kappa B (NF-κB) or mitogen-activated protein kinase signaling pathway or both to increase the expression levels of NLRP3, pro-IL-18, and pro-IL-1β and their translocation from the nucleus to the cytoplasm. In the cytoplasm, the assembling of NLRP3 complex consisting of the components of inactive NLRP3, adaptor apoptosis-associated speck-like protein containing a caspase recruitment domain, and caspase-1 is initiated[18,19]. The activation of NLRP3 signaling is initiated by NEK7 and a variety of activators, such as PAMPs, DAMPs, endoplasmic reticulum stress-induced release of Ca²⁺, mitochondrial reactive oxygen species (ROS)-related K⁺ efflux and Ca²⁺ signaling, and cathepsin B released by damaged lysosomes[20-22]. The catalytic domain of NEK7 can bind with NLRP3 and disrupt the NLRP3 oligomers, which results in the formation of the NEK7/NLRP3 complex. The NEK7/NLRP3 complex undergoes the process of NLRP3 inflammasome assembly and pro-caspase-1 activation leading to the release of mature caspase-1. Caspase-1 (also known as IL-1β-converting enzyme) is a protease that can cleave inactive pro-IL-18 and pro-IL-1β into their active forms IL-18 and IL-1β. Upon activation, the NLRP3 inflammasome contributes to inflammation that is mediated by the release of mature IL-18 and IL-1β as well as cell pyroptosis due to a pore formation in the cellular plasma membrane caused by GSDMD-N[23,24].

Figure 1 Molecular signaling of nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 priming and activation. Pathogen-associated molecular patterns (PAMPs) recognized by pattern recognition receptors [such as toll-like receptors (TLRs)) can activate the nuclear factor kappa B (NF-kappaB) signaling pathway and mitogen-activated protein kinase (MAPK) signaling pathway, which both initiate the nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) priming process, including the upregulation of NLRP3 and pro-interleukin (IL)-1β protein expression. Meanwhile, the assembled NLRP3 inflammasome also cleaves the gasdermin D (GSDMD) by disconnecting the C-terminal to produce GSDMD-N, leading to cell pyroptosis. Additionally, endoplasmic reticulum (ER) stress-induced Ca²⁺ efflux, the imbalance of Ca²⁺ and K⁺-associated mitochondrial reactive oxygen species (ROS) stress, and lysosome damage-produced cathepsin B can serve as triggers for NLRP3 activation to accelerate the assembly of the NLRP3 inflammasome. The cartoons in this figure were prepared using Biorender (https://biorender.com). ASC: Apoptosis-associated speck-like protein containing a caspase recruitment domain; NEK7: Never in mitosis A-related kinase 7; NEMO: Nuclear factor kappa B essential modulator; PRRS: Pattern recognition receptors.

A recently published study revealed that the NLRP3 variant “R779C” plays a critical role in the early onset of inflammatory bowel disease, which is tested in a dextran sulfate sodium-induced acute colitis model and biopsies derived from human patients with the R779C variant[25]. The R779C variant has been shown in patients with gastrointestinal symptoms, accompanying significantly enhanced levels of IL-1β and IL-18 production and pyroptosis. NLPR3 ubiquitination plays a key role in this process. The R779C variant not only binds with BRCA1/BRCA2-containing complex subunit 3 with a high binding affinity but gains the function of binding with Josephin Domain Containing 2, which is not shown in the non-variant wildtype. Both BRCA1/BRCA2-containing complex subunit 3 and Josephin Domain Containing can promote the ubiquitination of NLRP3 to promote its activation. This finding was further verified using a colitis model, which demonstrated that the R779C variant increased the susceptibility and severity of intestinal inflammation[25].

Another recent study demonstrated that the NLRP3 inflammasome has an important role in neuronal disease. PD is a neurodegenerative disease characterized by the aggregation of misfolded α-synuclein followed by the death of dopamine neurons. The accumulation of α-synuclein can mediate NLRP3 activation by regulating the ROS signaling pathway and cathepsin B production. The amplified assembling and activation of the NLRP3 inflammasome in cells can aggravate the death of dopamine neurons. Inhibition of NLRP3 assembling and activation can prevent parkin-associated neurodegeneration of dopamine neurons in familial and sporadic PD models[26].

Inflammatory liver disease, such as metabolic dysfunction-associated steatotic liver disease (MASLD), is often accompanied by chronic liver inflammation[27]. A recent study found that the antioxidant agent lycopene had a preventative function against MASLD via the inhibition of the hepatic NF-κB/NLRP3 signaling pathway in a high-fat and high-fructose diet-induced mouse model[28]. This study also demonstrated that dietary intervention-mediated suppression of liver inflammation is associated with the alteration of gut microbiota[28], indicating the association between the gut microbiota and NLRP3 inflammasome activation[29].

Autoinflammatory disease cryopyrin-associated periodic syndrome (CAPS) is caused by the mutation of NLRP3 and subsequent production of IL-1β. The gain-of-function CAPS-associated NLRP3 mutant, NLRP3 p.D303N variant, can continually activate the NLRP3 inflammasome. The NLRP3 p.D303N variant also has the ability of continuous expression in a mouse model of CAPS without any triggers. Triggers such as PAMPs and DAMPS initiate the activation of NF-κB to increase IL-1β production in macrophages expressing NLRP3 p.D303N. The upregulated NF-κB signaling pathway further promotes the activation of the NLRP3 inflammasome[30]. Overall, the NLRP3 inflammasome plays a pivotal role in inflammatory diseases, autoimmune diseases, and neuronal diseases.

NLRP3 IN METABOLIC DISEASES

NLRP3 plays a substantial role in elevating insulin resistance by impacting the phosphoinositide 3-kinase/protein kinase B signaling pathway, which leads to a decreased level of glucose uptake[31]. Adipose tissue inflammation and immune cell infiltration are highly accompanied by the activation of the NLRP3 inflammasome in metabolic diseases such as diabetes and obesity (Figure 2). One study revealed that the expression level of NLRP3 was increased in visceral adipose tissues in comparison with subcutaneous tissues in obese individuals. The elevated level of tumor necrosis factor-α and the excessive free fatty acids in the adipose tissue of individuals with obesity and type 2 diabetes mellitus (T2DM) can trigger NF-κB-associated NLRP3 priming[32,33].

Figure 2 Molecular and cellular signaling pathways of nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 in obesity, diabetes, and other metabolic diseases. In adipose tissue, interferon (IFN)-g and tumor necrosis factor (TNF)-α secreted from T helper (Th) 1 cells can promote macrophage differentiation from M2 to M1 phenotype. M1 macrophage infiltration results in the activation of nuclear factor kappa B (NF-kappaB) signaling pathway to induce nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) priming. Simultaneously, calcium influx and reactive oxygen species (ROS) production can increase the recruitment of more macrophages. In addition, excessive levels of TNF-α and free fatty acids (FFAs) can activate the NF-kappaB signaling leading to NLRP3 priming and activation. Oxidized low-density lipoprotein (OX-LDL) and short-chain fatty acid (SFA) can bind with CD36 to accelerate the release of cathepsin causing the NLRP3 activation. Lipids such as palmitate, ceramides, and cholesterol can interact with toll-like receptor (TLR) 2/4 to inactivate the adenosine monophosphate-activated protein kinase (AMPK) pathway, resulting in mitochondrial ROS and NLRP3 activation. Additionally, adenosine triphosphate (ATP)-associated imbalance of Na⁺, Ca²⁺, and K⁺ also contributes to the activation of the NLRP3 inflammasome. NLRP3 activation raises the levels of interleukin (IL)-1β, which increases insulin resistance and decreases glucose uptake. The cartoons in this figure were prepared using Biorender (https://biorender.com). GLUT: Glucose transporter type; TNFR: Tumor necrosis factor receptor.

Oxidized low-density lipoproteins and short-chain fatty acids can also trigger NLRP3 activation through mitochondria and endoplasmic reticulum stress as well as lysosomes[34]. Similarly, the lipids palmitate, ceramide, and cholesterol can bind with TLR2/4 to suppress the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway, leading to autophagy and mitochondrial ROS stress, NLRP3 inflammasome activation, IL-1 production, and eventually increasing insulin resistance and decreasing glucose uptake[35,36]. Furthermore, adipocyte death, infiltration of M1 macrophages, and excessive secretion of inflammatory cytokines and adenosine triphosphates during adipose tissue damage are the major triggers of NLRP3 priming and activation[37,38].

Inflammation accelerates immune cell infiltration in adipose tissues including T cells, which can secrete interferon gamma to trigger the initiation of NF-κB signaling and NLRP3 priming. Simultaneously, T cells contribute to the activation of macrophages, regulating calcium influx. Calcium influx and ROS production can further promote the production of cytokines, chemokines, and adipokines to recruit more macrophages and induce their activation. Moreover, interferon gamma and tumor necrosis factor-α secreted from T helper 1 cells can promote macrophage differentiation from the M2 phenotype to the M1 phenotype. These activated and infiltrated M1 macrophages in adipose tissues increase insulin resistance.

Additionally, mitochondrial dysfunction contributes to the activation of the NLRP3 inflammasome[39-42]. A study using a high-fat diet mouse model demonstrated that inhibition of NLRP3 activation reduced hepatic steatosis in MASLD via the AMPK-autophagy signaling pathway[43]. Inhibiting NLRP3 inflammasome activation showed a protective effect against dietary-induced obesity, which suggests NLRP3 plays a significant role in obesity development[44]. In patients with T2DM, an upregulation of IL-18, IL-1β, and caspase-1 expression is detected, and the anti-diabetic drug metformin can impair the activation of the NLRP3 inflammasome, resulting in a decrease of mature IL-1β level via AMPK-mediated signaling pathway[45]. Therefore, NLRP3 contributes to metabolic diseases such as diabetes and obesity.

NLRP3 IN CANCER AND IMMUNOTHERAPY

Given the important roles of NLRP3 in inflammation, pyroptosis, and immune regulation, it is recognized as one of the attractive hallmarks in cancer development and immunotherapy[46,47]. Studies have demonstrated the association between NLRP3 activation and activation with cancer progression. For instance, it has been revealed that NLRP3 is overexpressed in colorectal cancer and plays a key role in promoting tumor proliferation and migration by modulating the epithelial-mesenchymal transition process[48]. A recently published study conducted by a team using traditional medicine Yiqi Jiedu Huayu decoction to treat chronic atrophic gastritis showed that Yiqi Jiedu Huayu decoction can suppress the precancerous lesion by inhibiting NLRP3 inflammasome-mediated cell pyroptosis via suppressing TLR 4/NF-κB and IL-6/signal transducer and activator of transcription 3 signaling pathways[49]. This finding suggests the potential role of NLRP3 inflammasome in chronic atrophic gastritis and potential gastric cancer[49]. Another recent publication also demonstrated that NLRP3 inflammasome inactivation contributes to the inhibition of tumor motility, angiogenesis, and growth in hepatocellular carcinoma[50].

Emerging studies report that the upregulation of NLRP3 may neutralize or dampen the anti-tumor effect. For example, an in vivo study using a liver cancer model revealed that upregulation of NLRP3 reversed the anti-tumor effect of eriodictyol treatment[50]. Based on an analysis conducted in Pan-Cancer, the results showed that there was a significant association between NLRP3 and immune evasion via regulating the expression of programmed death-ligand 1 and lymphocyte activating 3 immune checkpoints[51]. However, in vitro and in vivo studies are required for further evaluation.

A study indicated that there was a synergistic effect of NLRP3 inhibitor together with anti-programmed cell death protein 1 (anti-PD-1) therapy compared to the anti-PD-1 monotherapy in melanoma treatment[52]. This study also revealed that NLRP3 can increase tumor infiltration of myeloid-derived suppressor cells that enable tumor cells to escape from the activation of CD8⁺ T cells and natural killer cells. Inhibition of NLRP3 expression can reduce the myeloid-derived suppressor cell infiltration to improve the efficacy of immunotherapy[52]. Another study used the NLRP3 inhibitor “MCC950” and Nlrp3-deficient mice to investigate the role of NLRP3 in modulating the immunotherapeutic efficacy of anti-PD-1 and anti-cytotoxic T lymphocyte-associated protein-4 in melanoma and lung cancer. The results demonstrated that the efficacy of anti-PD-1 and anti-cytotoxic T lymphocyte-associated protein-4 immunotherapies increased in NLRP3-deficient mice compared with wild-type mice[53]. Thus, targeting NLRP3 treatment holds great promise in improving cancer therapy.

CROSSLINK BETWEEN METABOLIC DISEASES AND CANCER

NLRP3 plays a critical role in crosslinking between metabolic diseases and the risk of cancer development and progression as well as cancer immunotherapeutic efficacy[35,54]. For example, the metabolic abnormalities induced by chronic inflammation and tissue injury impact mitochondrial functions, resulting in ROS stress, mitochondrial functional disruption, and epigenetic instability, which are important factors in driving cancer development and progression[55-57]. On a molecular level, there are numerous crosslinks between metabolic disorders and cancer progression, including alteration of molecular signaling pathways[39]. For instance, the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signaling pathway[58,59], mitogen-activated protein kinase signaling pathway[60], and AMPK signaling pathway[61] are important molecular pathways that are shared by metabolic diseases and cancers. Metabolic disease and cancer reciprocally influence each other through these molecular pathways.

NLRP3-RELATED CLINICAL TRIALS

The exploration of potent NLRP3 inhibitors and IL-1 inhibitors attracts wide attention in both research and pharmaceutical fields[62,63]. Currently, various NLRP3 inhibitors are investigated, mainly focusing on the anti-inflammatory signaling pathways (Table 1). The Food and Drug Administration (FDA)-approved drugs for treating Nlrp3 mutation-associated diseases include rilonacept (IL-1 antagonist), canakinumab (IL-1β blocker), and anakinra (IL-1 receptor antagonist), which block inflammation. Rilonacept is an FDA-approved drug for the treatment of familial cold auto-inflammatory syndrome (for example, CAPS) disease. Rilonacept inhibits the IL-1 signaling pathway, as it has a high binding affinity with both IL-1α and IL-1β[64]. Similarly, canakinumab (ACZ885) is a monoclonal antibody that can inhibit IL-1β, which has been approved by the FDA for the treatment of CAPS such as Muckle-Wells syndrome, one type of disease commonly associated with NLRP3 gene mutation[65]. In 2001, anakinra was first approved for the treatment of rheumatoid arthritis. It was then approved for the treatment of neonatal-onset multisystem inflammatory disease (also known as chronic infantile neurologic cutaneous and articular syndrome) in 2013, and it was also approved for the treatment of deficiency of IL-1 receptor antagonist disease in 2020[65,66].

Table 1 Clinical trials targeting nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 inflammasome and nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3-related downstream signaling pathway.

NCT number	Phases	Conditions	Interventions (drug)	Mechanism of action	Study status
NCT01045772	2	MWS, Schnitzler syndrome	Rilonacept	IL-1 antagonist	Completed
NCT00288704	3	FCAS, familial cold urticaria, MWS, genetic diseases, inborn	Rilonacept 160 mg	IL-1 antagonist	Completed
NCT00094900	2	Inflammation, familial mediterranean fever, adult-onset still’s disease	Rilonacept	IL-1 antagonist	Completed
NCT01276522	2	Schnitzler syndrome	Canakinumab (ACZ885)	IL-1β blocker	Completed
NCT04510493	3	Coronavirus infection, type 2 diabetes mellitus	Canakinumab (ACZ885)	IL-1β blocker	Completed
NCT00991146	3	Cryopyrin-associated periodic syndromes, FCAS, MWS, neonatal onset multisystem inflammatory disease	Canakinumab (ACZ885)	IL-1β blocker	Completed
NCT00685373	3	Cryopyrin-associated periodic syndromes, FCAS, MWS, neonatal onset multisystem inflammatory disease	Canakinumab (ACZ885)	IL-1β blocker	Completed
NCT01105507	3	Cryopyrin associated periodic syndrome	Canakinumab (ACZ885)	IL-1β blocker	Completed
NCT01302860	3	Cryopyrin-associated periodic syndromes, FCAS, MWS, neonatal onset multisystem inflammatory disease	Canakinumab (ACZ885)	IL-1β blocker	Completed
NCT01576367	3	Cryopyrin-associated periodic syndromes, FCAS, MWS, neonatal onset multisystem inflammatory disease	Canakinumab (ACZ885)	IL-1β blocker	Completed
NCT00465985	3	MWS	Canakinumab (ACZ885)	IL-1β blocker	Completed
NCT00214851	1	Familial cold urticaria	Kineret (anakinra)	IL-1Ra	Completed
NCT05880355	1	Myocardial infarction	Dapansutrile	NLRP3 inflammasome inhibition	Not recruiting
NCT06047262	2	Type 2 diabetes mellitus	Dapansutrile	NLRP3 inflammasome inhibition	Recruiting
NCT05658575	2 and 3	Acute gout flare, gout attack, gout flare, gouty arthritis, gout, arthritis, joint pain	Dapansutrile	NLRP3 inflammasome inhibition	Recruiting
NCT06212271	1	Peripheral artery disease	Colchicine	Inhibit multiple proinflammatory mechanisms	Not recruiting
NCT04322565	2	Coronavirus infections, pneumonia, viral	Colchicine	Inhibit multiple proinflammatory mechanisms	Completed
NCT05734612	3	Reperfusion injury, myocardial	Colchicine	Inhibit multiple proinflammatory mechanisms	Enrolling-by-invitation
NCT04867226	2	Coronavirus infection	Colchicine 0.5 mg	Inhibit multiple proinflammatory mechanisms	Completed
NCT06426537	1	ST-elevation myocardial infarction	Colchicine 0.5 mg oral tablet	Inhibit multiple proinflammatory mechanisms	Completed
NCT04756128	2	COVID-19	Colchicine 0.6 mg, naltrexone	Inhibit multiple proinflammatory mechanisms and opiate antagonist	Completed
NCT05855746	3	Acute myocarditis	Colchicine pill	Inhibit multiple proinflammatory mechanisms	Not recruiting
NCT05130892	4	NLRP3, hs-CRP, percutaneous coronary intervention	Colchicine, tranilast, oridonin	Inhibit multiple proinflammatory mechanisms	Completed
NCT06097663	2	Coronary heart disease, clonal hematopoiesis of indeterminate potential	MAS825, FV890	Bispecific monoclonal antibody anti-IL-1β/IL-18, and NLRP3 inhibitor	Recruiting
NCT05552469	1	Myeloid diseases	DFV890	NLRP3 inhibitor	Recruiting
NCT04868968	2	FCAS	DFV890	NLRP3 inhibitor	Completed
NCT04886258	2	Symptomatic knee osteoarthritis	DFV890	NLRP3 inhibitor	Recruiting
NCT04086602	1	Healthy volunteers, cryopyrin associated periodic syndrome	IZD334 (MCC950 related agent)	NLRP3 inflammasome inhibitor	Completed
NCT04972188	1	Healthy	ZYIL1 capsule	NLRP3 inflammasome inhibitor	Completed
NCT05186051	2	Cryopyrin associated periodic syndrome	ZYIL1 capsule	NLRP3 inflammasome inhibitor	Completed
NCT05781698	2	Inflammatory bowel diseases	Mesalamine, fenofibrate	Anti-inflammatory agent and lower “bad” cholesterol and fats (such as LDL, triglycerides) and raise “good” cholesterol (HDL) in the blood	Recruiting
NCT03468322	2	Inherited epidermolysis bullosa	AC-203	NLRP3 inflammasome inhibition	Completed
NCT05812781	2	Cryopyrin associated periodic syndrome	VTX2735	Peripheral NLRP3 inhibitor	Completed

COVID-19: Coronavirus disease 2019; FCAS: Familial cold autoinflammatory syndrome; HDL: High-density lipoprotein; hs-CRP: High-sensitivity C-reactive protein; IL: Interleukin; IL-1Ra: Interleukin-1 receptor antagonist; LDL: Low-density lipoprotein; MWS: Muckle-Wells syndrome; NLRP3: Nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3.

The emerging investigation in new drugs targeting NLRP3-associated signaling pathways has drawn great interest in both preclinical studies and clinical trials. For example, the NLRP3 inflammasome inhibitor, dapansutrile, is under a clinical trial investigation for the treatment of myocardial infarction, T2DM, and gout-related disease[67]. Colchicine was originally approved as an anti-inflammatory drug for gout back in 1961. Since it has the potent function of inhibiting multiple proinflammatory mechanisms, colchicine was then intensively studied in different conditions such as peripheral artery disease, acute myocarditis, coronavirus infections, pneumonia, reperfusion injury, and myocardial coronavirus infection. In 2023, it was approved by the FDA for reducing the risk of atherosclerotic cardiovascular disease in cardiovascular patients and high-risk populations[68,69].

Bispecific monoclonal antibody MAS825 is designed for anti-IL-1β and anti-IL-18 treatments, and the NLRP3 inhibitor DFV890 is under the investigation for treatment of coronary heart disease and clonal hematopoiesis of indeterminate potential[70]. The clinical trials for DFV890 are studied in myeloid diseases, familial cold autoinflammatory syndrome, and symptomatic knee osteoarthritis[71]. IZD334 (MCC950-related agent) and ZYIL1 capsule, NLRP3 inflammasome inhibitors, are under clinical trials for evaluating their safety, tolerability, pharmacokinetic, and pharmacodynamic in the treatment of CAPS[72,73].

Fenofibrate was previously approved by the FDA for treating hypertriglyceridemia, primary hypercholesterolemia, or mixed dyslipidemia. Currently, a clinical trial is investigating the drug for repurposing for patients with inflammatory bowel diseases, such as ulcerative colitis. The underlying rationale is that fenofibrate serves as an anti-inflammatory agent that can reduce the unfavored cholesterol and fats (such as low-density lipoprotein and triglycerides) and increase the level of beneficial cholesterol (high-density lipoprotein) in the blood. This modulates the mammalian target of rapamycin/NLRP3 inflammasome[74-76]. In addition, AC-203 has been examined in the treatment of inherited epidermolysis bullosa due to the function of the NLRP3 inflammasome inhibition. Peripheral NLRP3 inhibitor, VTX2735, has been evaluated for CAPS patients. In summary, targeting the NLRP3 inflammasome and downstream signaling is critical for the treatment of NLRP3-related diseases, while more preclinical studies and clinical trial investigations are needed[77].

CONCLUSION

The NLRP3 inflammasome plays a significant role in inflammatory-associated disease, metabolic disease, cancer development, and immune infiltration-associated conditions. More mechanistic evaluation is needed to accelerate the translation from preclinical studies to clinical trials. Therapeutic agents such as NLRP3 inhibitors and bispecific antibodies have potent pharmaceutical applications in the future. The efficacy of immunotherapies can be improved by enhancing the host immunity via mediation of metabolism[78]. Metabolism, such as glucose, lactate, and fatty acid metabolism, can regulate the regulatory T cell functions, which can be targeted for cancer immunotherapy[79]. Thus, the immunotherapy response can be boosted. In obesity, the lack of oxidative phosphorylation can destroy the proinflammatory tissue macrophages in adipose tissues during inflammation, which reduces the obesity-associated pathologies[80]. Through modulating the tissue macrophage metabolic pathway, obesity-related inflammation can be alleviated. Since immunity can be enhanced through modulating and improving the metabolism function, given that many factors and conditions are associated with metabolism, multidisciplinary research is favored. For example, nutrition intervention, lifestyle, and reduction in exposure to certain pathogens and xenobiotics can reduce the stimulators of inflammation and decrease the risk of metabolic-associated diseases, resulting in an enhancement in host systemic immunity.