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Rationale: Capillary leakage frequently occurs during sepsis and after major surgery and is associated with microvascular dysfunction and adverse outcome. Procalcitonin is a well-established biomarker in inflammation without known impact on vascular integrity. Objectives: We determined how procalcitonin induces endothelial hyperpermeability and how targeting procalcitonin protects vascular barrier integrity. Methods: In a prospective observational clinical study, procalcitonin levels were assessed in 50 patients who underwent cardiac surgery and correlated to postoperative fluid and vasopressor requirements along with sublingual microvascular functionality. Effects of the procalcitonin signaling pathway on endothelial barrier and adherens junctional integrity were characterized in vitro and verified in mice. Inhibition of procalcitonin activation by dipeptidyl-peptidase 4 (DPP4) was evaluated in murine polymicrobial sepsis and clinically verified in cardiac surgery patients chronically taking the DPP4 inhibitor sitagliptin. Measurements and Main Results: Elevated postoperative procalcitonin levels identified patients with 2-fold increased fluid requirements (P < 0.01), 1.8-fold higher vasopressor demand (P < 0.05), and compromised microcirculation (reduction to 63.5 ± 2.8% of perfused vessels, P < 0.05). Procalcitonin induced 1.4-fold endothelial and 2.3-fold pulmonary capillary permeability (both Ps < 0.001) by destabilizing VE-cadherin. Procalcitonin effects were dependent on activation by DPP4, and targeting the procalcitonin receptor or DPP4 during sepsis-induced hyperprocalcitonemia reduced capillary leakage by 54 ± 10.1% and 60.4 ± 6.9% (both Ps < 0.01), respectively. Sitagliptin before cardiac surgery was associated with augmented microcirculation (74.1 ± 1.7% vs. 68.6 ± 1.9% perfused vessels in non-sitagliptin-medicated patients, P < 0.05) and with 2.3-fold decreased fluid (P < 0.05) and 1.8-fold reduced vasopressor demand postoperatively (P < 0.05). Conclusions: Targeting procalcitonin's action on the endothelium is a feasible means to preserve vascular integrity during systemic inflammation associated with hyperprocalcitonemia. [ABSTRACT FROM AUTHOR]

Acute kidney injury (AKI) may be induced by different causes, including renal ischemia-reperfusion injury and sepsis, which represent the most common reasons for AKI in hospitalized patients. AKI is defined by reduced urine production and/or increased plasma creatinine. However, this definition does not address the molecular mechanisms of different AKI entities, and uncertainties remain regarding distinct pathophysiological events causing kidney injury in the first place. In particular, sepsis-induced AKI is considered not to be associated with leukocyte infiltration into the kidney, but a direct investigation of this process is missing to this date. In this study, we used two murine AKI models induced by either renal ischemia-reperfusion injury (IRI) or cecal ligation and puncture (CLP) to investigate the contribution of neutrophils to tissue injury and kidney function. By using VEC-Y731F mice, in which neutrophil recruitment is impaired, we analyzed the specific contribution of neutrophil recruitment to the pathogenesis of IRI- and CLP-induced AKI. We observed that the degree of renal injury evaluated by plasma creatinine, urinary biomarkers and histological analyses, following IRI-induction was dependent on neutrophil migration into the kidney, whereas the pathogenesis of CLP-induced AKI was independent of neutrophil recruitment. Furthermore, plasma transfer experiments suggest that the pathogenesis of CLP-induced AKI relies on circulating inflammatory mediators. These results extend our knowledge of the AKI pathogenesis and may help in the development of prophylactic and therapeutic treatments for AKI patients. [ABSTRACT FROM AUTHOR]

The polymyxin antibiotic colistin has been used in decades for treatment and prevention of infectious diseases in livestock. Nowadays, it is even considered as last-line treatment option for severe human infections caused by multidrug- and carbapenem-resistant Gram-negative bacteria. Therefore, the discovery of plasmid-mediated mobile colistin resistance (mcr) genes raised major public health concern. The aim of our study was to analyze colistin-resistant Salmonella enterica strains from animals, food, feed and the environment collected at the National Reference Laboratory for Salmonella in Germany on the presence of mcr-1 to mcr-9 genes. Altogether 407 colistin-resistant (MIC >2 mg/L) Salmonella isolates received between 2011 and 2018 were selected and screened by PCR using a published mcr-1 to mcr-5 as well as a newly developed mcr-6 to mcr-9 multiplex PCR protocol. 254 of 407 (62.4%) isolates harbored either mcr-1 (n = 175), mcr-4 (n = 53), mcr-5 (n = 18) or mcr-1 and mcr-9 (n = 8). The number of mcr -positive isolates ranged from 19 (2017) to 64 (2012) per year. WGS revealed that none of our isolates harbored the mcr-9.1 gene. Instead, two novel mcr-9 variants were observed, which both were affected by frameshift mutations and are probably non-functional. The mcr -harboring isolates were mainly derived from animals (77.2%) or food (20.1%) and could be assigned to ten different Salmonella serovars. Many of the isolates were multidrug-resistant. Co-occurrence of mcr-1 and AmpC or ESBL genes was observed in eight isolates. Our findings suggest that mcr genes are widely spread among colistin-resistant Salmonella isolates from livestock and food in Germany. Potential transfer of mcr -harboring isolates along the food chain has to be considered critically. [ABSTRACT FROM AUTHOR]

Since the first description of a plasmid-mediated colistin resistance gene (mcr-1) in November 2015 multiple reports of mcr-1 positive isolates indicate a worldwide spread of this newly discovered resistance gene in Enterobacteriaceae. Although the occurrence of mcr-1 positive isolates of livestock, food, environment and human origin is well documented only few systematic studies on the prevalence of mcr-1 are available yet. Here, comprehensive data on the prevalence of mcr-1 in German livestock and food isolates are presented. Over 10.600 E. coli isolates from the national monitoring on zoonotic agents from the years 2010–2015 were screened for phenotypic colistin resistance (MIC value >2 mg/l). Of those, 505 resistant isolates were screened with a newly developed TaqMan-based real-time PCR for the presence of the mcr-1 gene. In total 402 isolates (79.8% of colistin resistant isolates) harboured the mcr-1 gene. The prevalence was depending on the food production chain. The highest prevalence was detected in the turkey food chain (10.7%), followed by broilers (5.6%). A low prevalence was determined in pigs, veal calves and laying hens. The mcr-1 was not detected in beef cattle, beef and dairy products in all years investigated. In conclusion, TaqMan based real-time PCR provides a fast and accurate tool for detection of mcr-1 gene. The overall detection rate of 3.8% for mcr-1 among all E. coli isolates tested is due to high prevalence of mcr-1 in poultry production chains. More epidemiological studies of other European countries are urgently needed to assess German prevalence data. [ABSTRACT FROM AUTHOR]

During inflammation, leukocyte recruitment has to be tightly controlled to prevent overwhelming leukocyte infiltration, activation, and, consequently, organ damage. A central regulator of leukocyte recruitment is Rac1. In this study, we analyzed the effects of the RacGAP ArhGAP15 on leukocyte recruitment. Using ArhGAP15-deficient mice, reduced neutrophil adhesion and transmigration in the TNF-a-inflamed cremaster muscle and a prolongation of chemokine-dependent leukocyte adhesion could be observed. In a murine model of sterile kidney injury, reduced neutrophil infiltration, and serum creatinine levels were apparent. Further in vitro and in vivo analyses revealed a defective intravascular crawling capacity, resulting from increased affinity of the b2-integrin Mac-1 after prolonged chemokine stimulation of neutrophils. LFA-1 activity regulation was not affected. Summarizing, ArhGAP15 specifically regulates Mac-1, but not LFA-1, and affects leukocyte recruitment by controlling postadhesion strengthening and intravascular crawling in a Mac-1-dependent manner. In conclusion, ArhGAP15 is involved in the time-dependent regulation of leukocyte postadhesion in sterile inflammation. [ABSTRACT FROM AUTHOR]