Serum ferritin as an indicator of the development of encephalopathy in enterohemorrhagic Escherichia coli-induced hemolytic uremic syndrome

Role of Serum Ferritin and PRISM-III in Predicting Mortality in Children with Acute Encephalitis Syndrome in Northern India

The aim of this study was to evaluate the role of serum ferritin (SF) and PRISM-III (Pediatric Risk of Mortality) score in predicting mortality in critically ill children aged 6 months to 15 years diagnosed with acute encephalitis syndrome (AES) admitted to the pediatric intensive care unit (PICU). This prospective observational study was conducted in the PICU of a tertiary teaching hospital in Northern India between July 2018 and June 2019. The primary outcome was to determine the association of admission SF levels with mortality. Secondary outcomes included estimating the prevalence of hyperferritinemia and comparing SF with PRISM-III scores in predicting mortality. Etiology could be established in 85.5% (n = 219) of the 256 children enrolled. Scrub typhus accounted for nearly two-thirds of the cases (60.5%), while dengue and Japanese encephalitis were the next common diagnoses. The median [interquartile range] SF at admission was significantly higher among the nonsurvivors than survivors: 514 [260–1,857] and 318 [189–699] µg/L, respectively (p = 0.029). SF and PRISM-III independently predicted mortality in AES. However, both had poor discriminatory power with area under receiver operating curve (95% confidence interval) of 0.61 (0.51–0.72) and 0.67 (0.56–0.77), respectively. Elevated SF and higher PRISM-III scores independently predicted mortality in children admitted to PICU with AES.

Gene expression profile and injury sites in mice treated with Shiga toxin 2 and lipopolysaccharide as a Shiga toxin-associated hemolytic uremic syndrome model

Shiga toxin 2 (Stx2) and lipopolysaccharide (LPS) contribute to the development of hemolytic uremic syndrome (HUS). Mouse models of HUS induced by LPS/Stx2 have been used for elucidating HUS pathophysiology and for therapeutic development. However, the underlying molecular mechanisms and detailed injury sites in this model remain unknown. We analyzed mouse kidneys after LPS/Stx2 administration using microarrays. Decreased urinary osmolality and urinary potassium were observed after LPS/Stx2 administration, suggestive of distal nephron disorders. A total of 1212 and 1016 differentially expressed genes were identified in microarrays at 6 and 72 h after LPS/Stx2 administration, respectively, compared with those in controls. Ingenuity pathway analysis revealed activation of TNFR1/2, iNOS, and IL-6 signaling at both time points, and inhibition of pathways associated with lipid metabolism at 72 h only. The strongly downregulated genes in the 72-h group were expressed in the distal nephrons. In particular, genes associated with distal convoluted tubule (DCT) 2 /connecting tubule (CNT) and principal cells of the cortical collection duct (CCD) were downregulated to a greater extent than those associated with DCT1 and intercalated cells. Stx receptor globotriaosylceramide 3 (Gb3) revealed no colocalization with DCT1-specific Pvalb and intercalated cell-specific Slc26a4 but did present colocalization with Slc12a3 (present in both DCT1 and DCT2), and Aqp2 in principal cells. Gb3 localization tended to coincide with the segment in which the downregulated genes were present. Thus, the LPS/Stx2-induced kidney injury model represents damage to DCT2/CNT and principal cells in the CCD, based on molecular, biological, and physiological findings.

Pathogenic functions and diagnostic utility of cytokines/chemokines in EHEC-HUS

Hemolytic - uremic syndrome (HUS) is a severe complication of infection by Shiga toxin (STx)-producing enterohemorrhagic Escherichia coli. Hemolytic - uremic syndrome is defined clinically as a triad of non-immune microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injuries. Neurologic complications such as acute encephalopathy are also observed. In humans, endothelial cells, proximal tubular epithelial cells, mesangial cells, podocytes, intestinal epithelial cells, and monocytes / macrophages are susceptible to STx-mediated injury. Shiga toxin induces the secretion of inflammatory cytokines and chemokines from susceptible cells, including tumor necrosis factor-α interleukin (IL)-1, IL-6, and IL-8. These cytokines and chemokines contribute to the pathogenesis of HUS and encephalopathy by enhancing STx-induced cytotoxicity and inducing inflammatory cell infiltration. Serum cytokine/chemokine levels are therefore useful as indicators of disease activity and predictors of progression from acute kidney injury to chronic kidney disease. Anti-inflammation therapy combined with apheresis to remove excessive cytokines / chemokines and methylprednisolone pulse therapy to suppress cytokine/chemokine production may be an effective treatment regimen for severe E. coli-associated HUS. However, this regimen requires careful monitoring of potential side effects, such as infections, thrombus formation, and hypertension.