Demotion of canonical/non-canonical inflammasome and pyroptosis alleviates ischemia/reperfusion-induced acute kidney injury: Novel role of the D2/D3 receptor agonist ropinirole

Monocyte/macrophage pyroptosis and C5b-9-induced cyst enlargement in Pkd1-/- mice

BACKGROUND AND HYPOTHESIS

The levels of C5b-9, terminal products of complement activation, were significantly elevated in autosomal dominant polycystic kidney disease (ADPKD). However, the precise mechanisms by which C5b-9 facilitates cyst growth remain incompletely elucidated.

METHODS

Three groups of chronic-onset Pkd1-/- mice were established: one group received intravenous injections of 0.5 mg/kg C5b-9, another was administered 1.0 mg/kg monoclonal anti-C9 antibodies, and a control group received 1 mg/kg IgG isotype control. All treatments were administered biweekly for two months (postnatal day 180-240). Renal macrophages from distinct subsets were sorted using fluorescence-activated cell sorting. To deplete macrophages, liposome clodronate was injected intraperitoneally. Sublethal irradiation followed by bone marrow reconstruction was performed in Pkd1-/- mice to evaluate the role of bone marrow-derived macrophages (BMDMs) in ADPKD progression.

RESULTS

(i) In vitro, sublytic C5b-9 did not affect the viability of renal tubular epithelial cells, but significantly induced M1-like polarization and pyroptosis of BMDMs. (ii) In vivo, C5b-9 notably triggered pyroptosis of Ly6C+ monocytes and a reduction in circulating monocyte numbers as cysts enlarged. (iii) Residual Ly6C+ monocytes infiltrated renal tissues and differentiated into Ly6C+ macrophages, which exhibited a greater susceptibility to pyroptosis compared to Ly6C- macrophages. (iv) Although limited evidence has recently suggested that Ly6C- monocytes may also be affected by C5b-9, upregulation of CCR2 in Ly6C- macrophages was observed in C5b-9-treated Pkd1-/- mice, implying that Ly6C- monocytes could represent a significant source of M2 macrophages.

CONCLUSIONS

C5b-9 infusion promoted renal tubular epithelial cell proliferation by inducing pyroptosis of Ly6C+ monocytes/macrophages, contributing to progressive cyst enlargement in chronic-onset PKD mice.

Cold-Induced RNA-Binding Protein (CIRP) Affects Cerebral Ischemia-Reperfusion Injury Through NF-κB Pathway

The pathological and physiological mechanisms for effectively mitigating ischemia-reperfusion (I/R) injury and preserving brain structure and function remain unclear. This study investigates the regulatory mechanism underlying cold-induced RNA-binding protein (CIRP)-mediated NF-κB pathway in cerebral I/R injury and neuronal inflammatory injury. The infarct volume of I/R CIRP-/- mice was significantly mitigated, and the inflammatory factor IL-18 expression in mice serum and the NLRP3 and IL-1β expression in brain tissue was significantly decreased as opposed to the I/R WT mice. The in vitro outcomes manifested that inhibiting CIRP expression led to a significant hindrance in cell apoptosis, a significant drop in the inflammatory factors levels in the cell supernatant, and a significant decline in the expression of pyroptosis-linked proteins ASC, cleaved caspase-1, and gasdermin D (GSDMD) in cells. Following administration of the NF-κB pathway inhibitor PDTC, there was a significant hindrance in cell apoptosis, as well as a significant drop in the inflammatory factors levels IL-1β, TNF-α, and IL-18 in the cell supernatant. After treating BV-2 cells with HT22 cell conditioned medium under OGD condition, the content of LDH in BV-2 cells was increased. Intervention of CIRP expression in HT22 cells resulted in reduced damage to BV-2 cells and decreased expression of M1 marker CD86. CIRP may be involved in neuronal damage in I/R and in vitro OGD models via the NF-κB /NLRP3 pathway, and it may affect microglial polarization.

The dual role of dopamine and serotonin in cancer progression and inflammation: Mechanisms and therapeutic potential

This review examines the critical functions of dopamine and serotonin in the regulation of inflammation and cancer, emphasizing their potential as therapeutic targets. Traditionally recognized for their roles in neural communication, these neurotransmitters are now understood to play substantial roles in immune modulation and tumor progression. We conducted a systematic review of studies published between 2013 and 2024, using databases such as PubMed, Google Scholar, and Scopus, to assess dopamine and serotonin synthesis, receptor activity, and involvement in disease pathways. Findings indicate that dopamine, through its D1 and D2 receptors, exerts both pro- and anti-inflammatory effects, influencing tumor growth and immune responses in cancers such as breast and pancreatic. Similarly, serotonin, particularly through receptors HTR2A and HTR2B, has demonstrated dual roles in cancer progression, impacting the growth and metastasis of cancers such as gastric and colorectal. This review also addresses the interaction between dopamine and serotonin signaling pathways, which may collectively alter immune cell function and tumor microenvironment dynamics, suggesting a promising direction for combined therapeutic approaches. By synthesizing current data on dopamine and serotonin pathways, this review aims to inform the development of targeted therapies that modulate immune responses in inflammation-driven cancers. Our findings underscore the potential of neurotransmitter-based interventions as a novel strategy for managing cancer and inflammatory diseases.

NLRP3 Inflammasome: A central player in renal pathologies and nephropathy

The cytoplasmic oligomer NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome has been implicated in most inflammatory and autoimmune diseases. Here, we highlight the significance of NLRP3 in diverse renal disorders, demonstrating its activation in macrophages and non-immune tubular epithelial and mesangial cells in response to various stimuli. This activation leads to the release of pro-inflammatory cytokines, contributing to the development of acute kidney injury (AKI), chronic renal injury, or fibrosis. In AKI, NLRP3 inflammasome activation and pyroptotic renal tubular cell death is driven by contrast and chemotherapeutic agents, sepsis, and rhabdomyolysis. Nevertheless, inflammasome is provoked in disorders such as crystal and diabetic nephropathy, obesity-related renal fibrosis, lupus nephritis, and hypertension-induced renal damage that induce chronic kidney injury and/or fibrosis. The mechanisms by which the inflammatory NLRP3/ Apoptosis-associated Speck-like protein containing a Caspase recruitment domain (ASC)/caspase-1/interleukin (IL)-1β & IL-18 pathway can turn on renal fibrosis is also comprehended. This review further outlines the involvement of dopamine and its associated G protein-coupled receptors (GPCRs), including D1-like (D1, D5) and D2-like (D2-D4) subtypes, in regulating this inflammation-linked renal dysfunction pathway. Hence, we identify D-related receptors as promising targets for renal disease management by inhibiting the functionality of the NLRP3 inflammasome.