Velatooru Loka Reddy, Arroyave Esteban, Rippee-Brooks Meagan D, Burch Megan, Yang Ethan, Zhu Bing, Walker David H, Zhang Yang, Fang Rong
Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, USA.
Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch, Galveston, Texas, USA.
Infect Immun. 2025 Jan 31;93(1):e0046824. doi: 10.1128/iai.00468-24. Epub 2024 Dec 16.
spp. cause life-threatening diseases in humans. The fundamental pathophysiological changes in fatal rickettsial diseases are disrupted endothelial barrier and increased microvascular permeability. However, it remains largely unclear how rickettsiae induce microvascular endothelial injury. In the present study, we demonstrated that infection disrupts the continuous immunofluorescence expression of the interendothelial tight junction protein, zonula occludens-1 (ZO-1), in infected monolayers of microvascular endothelial cells (MVECs), accompanied by significantly diminished total expression levels of ZO-1. Interestingly, activated inflammasome in MVECs, as evidenced by cleaved caspase-1 and IL-1β in the cell lysates in association with significantly elevated expression levels of nucleotide binding and oligomerization domain, leucine-rich repeat, and pyrin containing protein 3 (NLRP3). Furthermore, selective inhibition of NLRP3 by MCC950 significantly suppressed the activation and cleavage of caspase-1 induced by in endothelial cells, which further prevented the disruption of interendothelial junctions and reduction of ZO-1 expression. Of note, pharmaceutical inhibition of NLRP3 mitigated the disrupted endothelial integrity caused by , measured by fluorescein isothiocyanate-dextran passage in a Transwell assay, independent of bacterial growth and cellular cytotoxicity. Taken together, our results suggest that affected microvascular endothelial junction integrity likely via diminishing and interrupting the junctional protein ZO-1 in association with activating NLRP3 inflammasome. These data not only highlight the potential of ZO-1 as a biomarker for -induced microvascular injury but also provide insight into targeting NLRP3 inflammasome/ZO-1 signaling as a potentially adjunctive therapeutic approach for severe rickettsioses.
某些立克次氏体物种可导致人类患上危及生命的疾病。致命性立克次氏体疾病的基本病理生理变化是内皮屏障破坏和微血管通透性增加。然而，立克次氏体如何诱导微血管内皮损伤在很大程度上仍不清楚。在本研究中，我们证明感染会破坏微血管内皮细胞（MVECs）感染单层中内皮紧密连接蛋白闭锁小带-1（ZO-1）的连续免疫荧光表达，同时ZO-1的总表达水平显著降低。有趣的是，MVECs中炎性小体被激活，细胞裂解物中裂解的半胱天冬酶-1和白细胞介素-1β可证明这一点，同时核苷酸结合寡聚化结构域、富含亮氨酸重复序列和含pyrin蛋白3（NLRP3）的表达水平显著升高。此外，用MCC950选择性抑制NLRP3可显著抑制内皮细胞中由[病原体名称未给出]诱导的半胱天冬酶-1的激活和裂解，这进一步防止了内皮间连接的破坏和ZO-1表达的减少。值得注意的是，通过Transwell实验中异硫氰酸荧光素-葡聚糖的通透情况来衡量，对NLRP3的药物抑制减轻了由[病原体名称未给出]引起的内皮完整性破坏，这与细菌生长和细胞毒性无关。综上所述，我们的结果表明，[病原体名称未给出]可能通过减少和中断连接蛋白ZO-1并激活NLRP3炎性小体来影响微血管内皮连接完整性。这些数据不仅突出了ZO-1作为[病原体名称未给出]诱导微血管损伤生物标志物的潜力，还为将NLRP3炎性小体/ZO-1信号作为严重立克次氏体病潜在辅助治疗方法提供了见解。
