The Circulating CDC42 Expression in Sepsis: Relation to Disease Susceptibility, Inflammation, Multiple Organ Dysfunctions and Mortality Risk.

OBJECTIVE: Cell division cycle 42 (CDC42) modulates inflammation and multiple organ dysfunction by regulating T-cell differentiation and macrophage polarization. This research intended to explore the association of blood CDC42 expression with septic risk, multi-organ dysfunctions, and mortality. METHODS: 145 sepsis patients and 50 health controls were recruited, then CDC42 expression in peripheral blood mononuclear cell (PBMC) from them was measured by RT-qPCR. RESULTS: CDC42 was decreased in sepsis patients versus health controls (P<0.001); meanwhile, the receiver operating characteristic (ROC) curve showed that CDC42 had a certain value to predict sepsis risk with an area under the curve (AUC) (95% confidence interval (CI): 0.797 (0.725-0.869). Furthermore, CDC42 was negatively correlated with C-reactive protein (P<0.001), tumor necrosis factor-alpha (P<0.001) and interleukin-17A (P<0.001) but less with interleukin-6 (P=0.056). Moreover, CDC42 was negatively related to the SOFA score (P<0.001) and its several subscales (respiratory system, liver, cardiovascular, and renal system) (P<0.05). Furthermore, CDC42 was lower in septic deaths versus survivors (P<0.001); meanwhile, the ROC curve exhibited a certain ability of CDC42 in estimating 28-day mortality with an AUC (95%CI) of 0.766 (0.676-0.855). CONCLUSION: Circulating CDC42 exhibits potency to be a prognostic biomarker reflecting multi-organ dysfunctions and higher mortality risk in sepsis.

Sulfated tyrosines 27 and 29 in the N-terminus of human CXCR3 participate in binding native IP-10.

AIM: Human CXCR3, a seven-transmembrane segment (7TMS), is predominantly expressed in Th1-mediated responses. Interferon-gamma-inducible protein 10 (IP-10) is an important ligand for CXCR3. Their interaction is pivotal for leukocyte migration and activation. Tyrosine sulfation in 7TMS is a posttranslational modification that contributes substantially to ligand binding. We aimed to study the role of tyrosine sulfation of CXCR3 in the protein's binding to IP-10. METHODS: Plasmids encoding CXCR3 and its mutants were prepared by PCR and site-directed mutagenesis. HEK 293T cells were transfected with plasmids encoding CXCR3 or its variants using calcium phosphate. Transfected cells were labeled with [(35)S]-cysteine and methionine or [(35)S]-Na(2)SO(3) and then analyzed by immunoprecipitation to measure sulfation. Experiments with (125)I-labeled IP-10 were carried out to evaluate the affinity of CXCR3 for its ligand. Calcium influx assays were used to measure intercellular signal transduction. RESULTS: Our data show that sulfate moieties are added to tyrosines 27 and 29 of CXCR3. Mutation of these two tyrosines to phenylalanines substantially decreases binding of CXCR3 to IP-10 and appears to eliminate the associated signal transduction. Tyrosine sulfation of CXCR3 is enhanced by tyrosyl protein sulfotransferases (TPSTs), and it is weakened by shRNA constructs. The binding ability of CXCR3 to IP-10 is increased by TPSTs and decreased by shRNAs. CONCLUSIONS: This study identifies two sulfated tyrosines in the N-terminus of CXCR3 as part of the binding site for IP-10, and it underscores the fact that tyrosine sulfation in the N-termini of 7TMS receptors is functionally important for ligand interactions. Our study suggests a molecular target for inhibiting this ligand-receptor interaction.