Involvement of NF-κB1 and the Non-canonical NF-κB Signaling Pathway in the Pathogenesis of Acute Kidney Injury in Shiga-toxin-2-induced Hemolytic-uremic Syndrome in Mice

Abstract

The hemolytic-uremic syndrome (HUS) is a thrombotic microangiopathy which can occur as a severe systemic complication after an infection with Shiga-toxin-(Stx)-producing Escherichia coli (STEC). Elevated levels of proinflammatory cytokines associated with the classical nuclear factor kappa-light-chain-enhancer of activated Bcells (NF-kB) signaling pathway were detected in the urine of HUS patients. Thus, we hypothesize that the immune response of the infected organism triggered by Stx can affect the kidneys and contributes to acute kidney injury. Hitherto, the role of the classical and non-canonical NF-kB signaling pathway in HUS has not been evaluated systematically in vivo. We aimed to investigate in a murine model of Shiga toxin-induced HUS-like disease, whether one or both pathways are involved in the renal pathology in HUS. In kidneys of mice subjected to Stx or sham-treated mice, protein or gene expression analyses were performed to assess the expression of receptors activating the classical and non-canonical pathway, such as Fn14 and CD40, levels of NF-kB1/RelA and NF-kB2/RelB including its upstream signaling proteins, and expression of cytokines as target molecules of both pathways. In line with a higher expression of Fn14 and CD40, we detected an enhanced translocation of NF-kB1 and RelA as well as NF-kB2 and RelB into the nucleus accompanied by an increased gene expression of the NF-kB1-target cytokines Ccl20, Cxcl2, Ccl2, Cxcl1, IL-6, TNF-a, Cxcl10, and Ccl5, indicating an activation of the classical and non-canonical NF-kB pathway. Thereby, we provide, for the first time, in vivo evidence for an involvement of both NF-kB signaling pathways in renal pathophysiology of STEC-HUS.

Network-Based Expression Analyses and Experimental Verifications Reveal the Involvement of STUB1 in Acute Kidney Injury

“…In AKI with sterile inflammation, B cells produce CCL7 to recruit neutrophils and monocytes to the injured kidney ( Inaba et al, 2020 ). In our analysis, CCL5 , CCL19 , CCL21 , CXCR5 , and CXCL2 were upregulated in AKI, which was consistent with that reported in previous studies ( Sanz et al, 2010 ; Winterberg et al, 2013 ; Wohlfahrtova et al, 2015 ; Sobbe et al, 2020 ). Moreover, Hedgehog signaling was reported to be upregulated and protected tubular cells in various AKI models, such as ischemia/reperfusion ( Zhuo et al, 2019 ) and obstructive kidney injury ( Rauhauser et al, 2015 ).…”

Stx2 Induces Differential Gene Expression and Disturbs Circadian Rhythm Genes in the Proximal Tubule

“…Sobbe et al [61] showed that both the classical (RelA-p50) and alternative (RelB-p52) NF-κB pathways were active in Stx-injected mice detecting upregulation of RelA-target cytokines CCL20, CXCL1 and CXCL10 that were also differentially expressed in our dataset (Figure 5L).…”

Stx2 induces differential gene expression by activating several pathways and disturbs circadian rhythm genes in the proximal tubule

“…Sobbe et al . [60] showed that both the classical (RelA-p50) and alternative (RelB-p52) NF-κB pathways were active in Stx-injected mice detecting upregulation of RelA-target cytokines CCL20, CXCL1 and CXCL10 that were also differentially expressed in our d ataset (figure 5L).…”