駒田 敬則

Preeclampsia (PE) is characterized by maternal hypertension accompanied with multi-organ dysfunction, such as maternal hepatic and renal dysfunction. Abnormal placental conditions may play a key role in regulating maternal organ function by promoting systemic inflammation. This study aimed to test the hypothesis that placenta-derived secretions contribute to hepatic and renal injury through interorgan communication using a PE-like mouse model. Pregnant mice were infused with angiotensin II (Ang II) from gestational day (GD) 12 (GD1 defined as the day of plug detection). Ang II infusion induced maternal hypertension, as well as liver injury (elevated serum amyloid A [SAA] secretion and alanine aminotransferase levels) and kidney injury (tubular damage with KIM-1 protein expression and immune cell infiltration). Treatment with placental-conditioned medium (CM) from Ang II-infused mice, but not from the control mice, stimulated SAA expression in liver cells. On the other hand, the effects of placental-CM from both the control and Ang II groups on kidney tubular cells were comparable. These findings suggest that placenta-derived secretions in the Ang II-induced PE-like phenotype specifically promote excessive SAA production in the liver. Furthermore, SAA administration in pregnant mice did not cause tubular injury but did promote renal immune cell infiltration, indicating that elevated hepatic SAA levels may contribute to maternal kidney inflammation. Taken together, these results suggest the presence of an in vivo organ network involving the placenta, liver, and kidneys during pregnancy, where dysfunction in one organ may exacerbate the pathogenesis of PE.

Pathologic potassium (K+) deficiency causes kidney inflammation and injury, known as hypokalemic nephropathy (HN), the underlying pathogenesis of which is obscure. NLR family pyrin domain-containing 3 (NLRP3) inflammasomes are platforms that sense the reduction of intracellular K+, engaging inflammation and tissue injury. The present study investigated whether or not systemic K+ deficiency induces NLRP3 inflammasome activation in HN. Clinically diagnosed HN in humans manifested up-regulation of NLRP3 and apoptosis-associated speck-like protein-containing a CARD (ASC) in the kidney epithelia. A K+ depletion model in mice demonstrated that kidney-resident NLRP3 and ASC play key roles in triggering early inflammation in HN kidneys. Unexpectedly, the K+ depletion-induced kidney inflammation was not dependent on inflammasome activation. A single-cell RNA-sequencing analysis revealed ASC up-regulation, NF-κB activation, and an increased level of tumor necrosis factor-like weak inducer of apoptosis receptor fibroblast growth factor-inducible 14 (FN14) in the HN kidneys, primarily in the distal nephron/collecting duct epithelial cells. Although kidney epithelial cells did not drive NLRP3 inflammasomes, NLRP3 and ASC alternatively enhanced with-no-lysine kinase-dependent NF-κB signaling in response to tumor necrosis factor-like weak inducer of apoptosis under a low-K+ milieu. These findings indicate a unique proinflammatory cascade mediated by NLRP3 and ASC beyond the framework of inflammasomes, which broadens the understanding of electrolyte-associated immunity in the kidney.

Atopic dermatitis (AD) is a chronic inflammatory skin disorder caused by immune dysregulation that involves the release of various pro-inflammatory cytokines. Patients with AD frequently exhibit basophil infiltration in the affected skin. Although the role of the NLRP3 inflammasome in innate immune cells has been extensively studied, the contribution of the basophil inflammasome to the pathophysiology of AD remains to be elucidated. In this study, we demonstrated that IL-33 primes the NLRP3 inflammasome in basophils, leading to the production and release of mature IL-1β. Mechanistically, we showed that IL-33 stimulation induced pro-IL-1β and NLRP3 expression via the NF-κB and p38 MAPK pathways and that basophils released mature IL-1β through the canonical inflammasome activation pathway, which requires NLRP3, ASC, caspase-1, and gasdermin D (GSDMD). In an oxazolone (OXA)-induced AD mouse model, we found that basophils acted as key initiators of inflammation by producing IL-1β in the lesion, and that basophil depletion, genetic ablation of Nlrp3 or Il1b, or basophil-specific genetic ablation of Nlrp3 ameliorated ear swelling and neutrophil infiltration. Collectively, these findings establish basophils as a significant early source of NLRP3 inflammasome-driven IL-1β, contributing to the pathogenesis of AD. Targeting the IL-33/ST2L axis or NLRP3 inflammasome activation in basophils may offer a promising therapeutic strategy for managing AD.