Peroxynitrite/PKR Axis Modulates the NLRP3 Inflammasome of Cardiac Fibroblasts

Hematopoiesis Revolves Around the Primordial Evolutional Rhythm of Purinergic Signaling and Innate Immunity - A Journey to the Developmental Roots

A cell's most significant existential task is to survive by ensuring proper metabolism, avoiding harmful stimuli, and adapting to changing environments. It explains why early evolutionary primordial signals and pathways remained active and regulate cell and tissue integrity. This requires energy supply and a balanced redox state. To meet these requirements, the universal intracellular energy transporter purine nucleotide-adenosine triphosphate (ATP) became an important signaling molecule and precursor of purinergic signaling after being released into extracellular space. Similarly, ancient proteins involved in intracellular metabolism gave rise to the third protein component (C3) of the complement cascade (ComC), a soluble arm of innate immunity. These pathways induce cytosol reactive oxygen (ROS) and reactive nitrogen species (RNS) that regulate the redox state of the cells. While low levels of ROS and RNS promote cell growth and differentiation, supra-physiological concentrations can lead to cell damage by pyroptosis. This balance explains the impact of purinergic signaling and innate immunity on cell metabolism, organogenesis, and tissue development. Subsequently, along with evolution, new regulatory cues emerge in the form of growth factors, cytokines, chemokines, and bioactive lipids. However, their expression is still modulated by both primordial signaling pathways. This review will focus on the data that purinergic signaling and innate immunity carry on their ancient developmental task in hematopoiesis and specification of hematopoietic stem/progenitor cells (HSPCs). Moreover, recent evidence shows both these regulatory pathways operate in a paracrine manner and inside HSPCs at the autocrine level.

COX-2/sEH-Mediated Macrophage Activation Is a Target for Pulmonary Protection in Mouse Models of Chronic Obstructive Pulmonary Disease

Effective inhibition of macrophage activation is critical for resolving inflammation and restoring pulmonary function in patients with chronic obstructive pulmonary disease (COPD). In this study, we identified the dual-enhanced cyclooxygenase-2 (COX-2)/soluble epoxide hydrolase (sEH) as a novel regulator of macrophage activation in COPD. Both COX-2 and sEH were found to be increased in patients and mice with COPD and in macrophages exposed to cigarette smoke extract. Pharmacological reduction of the COX-2 and sEH by 4-(5-phenyl-3-{3-[3-(4-trifluoromethylphenyl)-ureido]-propyl}-pyrazol-1-yl)-benzenesulfonamide (PTUPB) effectively prevented macrophage activation, downregulated inflammation-related genes, and reduced lung injury, thereby improving respiratory function in a mouse model of COPD induced by cigarette smoke and lipopolysaccharide. Mechanistically, enhanced COX-2/sEH triggered the activation of the NACHT, LRR, and PYD domains-containing protein 3 inflammasome, leading to the cleavage of pro-IL-1β into its active form in macrophages and amplifying inflammatory responses. These findings demonstrate that targeting COX-2/sEH-mediated macrophage activation may be a promising therapeutic strategy for COPD. Importantly, our data support the potential use of the dual COX-2 and sEH inhibitor PTUPB as a therapeutic drug for the treatment of COPD.

Role of NLRP3 Inflammasome in Stroke Pathobiology: Current Therapeutic Avenues and Future Perspective

Neuroinflammation is a key pathophysiological feature of stroke-associated brain injury. A local innate immune response triggers neuroinflammation following a stroke via activating inflammasomes. The nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome has been heavily implicated in stroke pathobiology. Following a stroke, several stimuli have been suggested to trigger the assembly of the NLRP3 inflammasome. Recent studies have advanced the understanding and revealed several new players regulating NLRP3 inflammasome-mediated neuroinflammation. This article discussed recent advancements in NLRP3 assembly and highlighted stroke-induced mitochondrial dysfunction as a major checkpoint to regulating NLRP3 activation. The NLRP3 inflammasome activation leads to caspase-1-dependent maturation and release of IL-1β, IL-18, and gasdermin D. In addition, genetic or pharmacological inhibition of the NLRP3 inflammasome activation and downstream signaling has been shown to attenuate brain infarction and improve the neurological outcome in experimental models of stroke. Several drug-like small molecules targeting the NLRP3 inflammasome are in different phases of development as novel therapeutics for various inflammatory conditions, including stroke. Understanding how these molecules interfere with NLRP3 inflammasome assembly is paramount for their better optimization and/or development of newer NLRP3 inhibitors. In this review, we summarized the assembly of the NLRP3 inflammasome and discussed the recent advances in understanding the upstream regulators of NLRP3 inflammasome-mediated neuroinflammation following stroke. Additionally, we critically examined the role of the NLRP3 inflammasome-mediated signaling in stroke pathophysiology and the development of therapeutic modalities to target the NLRP3 inflammasome-related signaling for stroke treatment.

Does attenuated plasmodial sporozoite-mediated protection require peroxynitrite?

Attenuated plasmodial sporozoite-induced immune response includes intrahepatic nitric oxide (NO) production, which promotes apoptosis of infected hepatocytes and consequent parasite clearance. NO in excess reacts with superoxide, forming peroxynitrite, a powerful cytotoxic agent. Here, I suggest that peroxynitrite proapoptotic action may contribute to the attenuated malarial sporozoite-mediated protection.

Discovery and identification of EIF2AK2 as a direct key target of berberine for anti-inflammatory effects

Using chemoproteomic techniques, we first identified EIF2AK2, eEF1A1, PRDX3 and VPS4B as direct targets of berberine (BBR) for its synergistically anti-inflammatory effects. Of them, BBR has the strongest affinity with EIF2AK2 via two ionic bonds, and regulates several key inflammatory pathways through EIF2AK2, indicating the dominant role of EIF2AK2. Also, BBR could subtly inhibit the dimerization of EIF2AK2, rather than its enzyme activity, to selectively modulate its downstream pathways including JNK, NF-κB, AKT and NLRP3, with an advantage of good safety profile. In EIF2AK2 gene knockdown mice, the inhibitory IL-1β, IL-6, IL-18 and TNF-α secretion of BBR was obviously attenuated, confirming an EIF2AK2-dependent anti-inflammatory efficacy. The results highlight the BBR's network mechanism on anti-inflammatory effects in which EIF2AK2 is a key target, and inhibition of EIF2AK2 dimerization has a potential to be a therapeutic strategy against inflammation-related disorders.

Changes in Alcohol Consumption following Direct-Acting Antiviral Treatment for Hepatitis C in VA Patients with Comorbid Alcohol Use Disorder and PTSD

OBJECTIVE

To investigate whether direct-acting antivirals (DAA) for hepatitis C viral infection (HCV): glecaprevir/pibrentasvir (GLE/PIB), ledipasvir/sofosbuvir (LDV/SOF), and sofosbuvir/velpatasvir (SOF/VEL) are associated with reduced alcohol consumption among veterans with alcohol use disorder (AUD) and co-occurring post-traumatic stress disorder (PTSD).

METHODS

We measured change in Alcohol Use Disorder Identification Test-Consumption Module (AUDIT-C) scores in a retrospective cohort of veterans with PTSD and AUD receiving DAAs for HCV.

RESULTS

One thousand two hundred and eleven patients were included (GLE/PIB n = 174, LDV/SOF n = 808, SOF/VEL n = 229). Adjusted frequencies of clinically meaningful improvement were 30.5% for GLE/PIB, 45.5% for LDV/SOF, and 40.5% for SOF/VEL. The frequency was lower for GLE/PIB than for LDV/SOF (OR = 0.59; 95% CI [0.40, 0.87]) or SOF/VEL (OR = 0.66; 95% CI [0.42, 1.04]).

CONCLUSIONS

DAA treatment for HCV was associated with a substantial reduction in alcohol use in patients with AUD and co-occurring PTSD. Further exploration of the role of DAAs in AUD treatment is warranted.

The Role of NLRP3 Inflammasome in Diabetic Cardiomyopathy and Its Therapeutic Implications

Diabetic cardiomyopathy (DCM) is a serious complication of diabetes mellitus (DM). However, the precise molecular mechanisms remain largely unclear, and it is still a challenging disease to diagnose and treat. The nucleotide-binding oligomerization domain and leucine-rich repeat pyrin 3 domain (NLRP3) inflammasome is a critical part of the innate immune system in the host to defend against endogenous danger and pathogenic microbial infections. Dysregulated NLRP3 inflammasome activation results in the overproduction of cytokines, primarily IL-1β and IL-18, and eventually, inflammatory cell death-pyroptosis. A series of studies have indicated that NLRP3 inflammasome activation participates in the development of DCM, and that corresponding interventions could mitigate disease progression. Accordingly, this narrative review is aimed at briefly summarizing the cell-specific role of the NLRP3 inflammasome in DCM and provides novel insights into developing DCM therapeutic strategies targeting the NLRP3 inflammasome.

Pyroptosis in acute pancreatitis and its therapeutic regulation

Pyroptosis defines a new type of GSDMs-mediated programmed cell death, distinguishes from the classical concepts of apoptosis and necrosis-mediated cell death and is prescribed by cell swelling and membrane denaturation, leading to the extensive secretion of cellular components and low-grade inflammatory response. However, NLRP3 inflammasome activation can trigger its downstream inflammatory cytokines, leading to the activation of pyroptosis-regulated cell death. Current studies reveal that activation of caspase-4/5/11-driven non-canonical inflammasome signaling pathways facilitates the pathogenesis and progression of acute pancreatitis (AP). In addition, a large number of studies have reported that NLRP3 inflammasome-dependent pyroptosis is a crucial player in driving the course of the pathogenesis of AP. Excessive uncontrolled GSDMD-mediated pyroptosis has been implicated in AP. Therefore, the pyroptosis-related molecule GSDMD may be an independent prognostic biomarker for AP. The present review paper summarizes the molecular mechanisms of pyroptotic signaling pathways and their pathophysiological impacts on the progress of AP. Moreover, we briefly present some experimental compounds targeting pyroptosis-regulated cell death for exploring novel therapeutic directions for the treatment and management of AP. Our review investigations strongly suggest that targeting pyroptosis could be an ideal therapeutic approach in AP.

GPR43 regulation of mitochondrial damage to alleviate inflammatory reaction in sepsis

Sepsis is a common critical illness in ICU and always a great difficulty in clinical treatment. GPR43 (G protein-coupled receptor 43) participates in regulating appetite and gastrointestinal peptide secretion to modulate fat decomposition and formation. However, the biological contribution of GPR43 on inflammation of sepsis has not been previously investigated. We investigated the mechanisms of GPR43 gene, which plays a possible role in distinguishing sepsis and contributes to the pathogenesis of sepsis-induced inflammatory reaction. Furthermore, we performed studies with mice induced to sepsis by Cecal Ligation and Puncture (CLP), Knockout GPR43 (GPR43-/-) mice, and Wild Type (WT) mice induced with CLP. In addition, lung tissues and cell samples were analyzed by histology, Quantitative Polymerase Chain Reaction (Q-PCR), Enzyme-linked Immunosorbent (ELISA) Assay, and western blot. GPR43 agonist could significantly reduce inflammation reactions and trigger lung injury in mice with sepsis. As for GPR43-/- mice, the risks of sepsis-induced inflammatory reactions and corresponding lung injury were promoted. On the one hand, the up-regulation of GPR43 gene reduced ROS mitochondrial damage to inhibit inflammatory reactions via the inactivation of NLRP3 Inflammasome by PPARγ/ Nox1/EBP50/ p47phox signal channel. On the other hand, the down-regulation of GPR43 promoted inflammatory reactions in vitro model through the acceleration of ROS-dependently mitochondrial damage by PPARγ/ Nox1/EBP50/ p47phox/ NLRP3 signal channel. These findings indicate that the inhibition of GPR43 as a possible important factor of sepsis may shed lights on the mechanism of sepsis-induced inflammation reaction.