Background: Gram-negative bloodstream infections (BSI) are common complications after kidney transplantation. In this cohort study, we evaluated the long-term effect of Gram-negative BSI on allograft survival in kidney transplant recipients. Methods: Among a cohort of 1820 kidney recipients who were prospectively followed at the Mayo Clinic (Rochester, MN) from January 1, 1996, to December 31, 2007, we identified 120 patients with initial episodes of Gram-negative BSI before allograft failure. Multivariable Cox proportional hazard regression was used to examine the association between Gram-negative BSI, as a time-dependent covariate, and allograft and patient survival. Results: The median age of kidney recipients was 51 years (interquartile range, 39-61 years) and 58% were men. Among patients with Gram-negative BSI, 75% had a urinary tract source of infection and Escherichia coli was the most common microorganism (50%). Gram-negative BSI after transplantation was independently associated with allograft loss due to allograft failure or death (hazard ratio [HR], 2.52; 95% confidence intervals [CI], 1.83-3.47; P<0.001), allograft failure with death-censored (HR, 3.17; 95% CI, 2.11-4.76; P<0.001) and all-cause mortality (HR, 2.25; 95% CI, 1.55-3.26; P<0.001). Conclusions: Prevention and proper management of urinary tract infections in kidney recipients is essential to reduce the risk of more serious complications, including Gram-negative BSI, that are associated with reduced allograft and patient survival.

The CD5 lymphocyte surface receptor is a group B member of the ancient and highly conserved scavenger receptor cysteine-rich superfamily. CD5 is expressed on mature T and B1a cells, where it is known to modulate lymphocyte activation and/or differentiation processes. Recently, the interaction of a few group B SRCR members (CD6, Spα, and DMBT1) with conserved microbial structures has been reported. Protein binding assays presented herein indicate that the CD5 ectodomain binds to and aggregates fungal cells (Schizosaccharomyces pombe, Candida albicans, and Cryptococcus neoformans) but not to Gram-negative (Escherichia coli) or Gram-positive (Staphylococcus aureus) bacteria. Accordingly, the CD5 ectodomain binds to zymosan but not to purified bacterial cell wall constituents (LPS, lipotheicoic acid, or peptidoglycan), and such binding is specifically competed by β-glucan but not by mannan. The K d of the rshCD5/(1→3)-β-D-glucan phosphate interaction is 3.7 ± 0.2 nM as calculated from tryptophan fluorescence data analysis of free and bound rshCD5. Moreover, zymosan binds to membrane-bound CD5, and this induces both MAPK activation and cytokine release. In vivo validation of the fungal binding properties of the CD5 ectodomain is deduced from its protective effect in a mouse model of zymosan-induced septic shock-like syndrome. In conclusion, the present results indicate that the CD5 lymphocyte receptor may sense the presence of conserved fungal components [namely, (1→3)-β-D- glucans] and support the therapeutic potential of soluble CD5 forms in fungal sepsis.

OBJECTIVE:: To examine peripheral leukocyte Dectin-1 regulation in clinically relevant models of fungal and polymicrobial sepsis. DESIGN:: Prospective animal study. SETTING:: University medical school research laboratory. SUBJECTS:: Age, weight, and sex matched ICR/HSD mice. INTERVENTIONS:: Mice were infected with Candida albicans (1 × 10, intravenously) or were subjected to cecal ligation and puncture to induce polymicrobial sepsis. MEASUREMENTS:: Blood, spleen, and peritoneal exudate were harvested and leukocytes were isolated. Leukocytes were evaluated for membrane-associated Dectin-1 expression and cell phenotype by flow cytometry. MAIN RESULTS:: In C. albicans infection, Dectin-1-positive blood and splenic leukocytes were increased from 23.5% to 58.9% over the course of infection. The increased percentage of Dectin-1-expressing cells was primarily attributable to neutrophilia. However, the amount of Dectin-1 expressed by blood and splenic neutrophils in C. albicans-infected mice was decreased by a range of 49.0% to 53.3%. C. albicans infection also resulted in an infiltration of Dectin-1-positive macrophages and neutrophils into the kidney. In contrast, polymicrobial sepsis decreased blood leukocyte Dectin-1-expressing cells by up to 51.4%. This reduction was due to a decrease in Dectin-1-positive neutrophils in the periphery. However, the percentage of Dectin-1-expressing cells in the peritoneal cavity increased by 774% with cecal ligation and puncture. Treatment of isolated neutrophils with three soluble glucans, mannan, lipopolysaccharide, or a variety of cytokines revealed that glucans, alone or in combination, were the only treatment that resulted in a decrease in Dectin-1-positive neutrophils. CONCLUSIONS:: We conclude that peripheral leukocyte Dectin-1 expression is differentially regulated in fungal vs. polymicrobial sepsis. These data demonstrate that leukocyte Dectin-1 levels are modulated in response to infections of fungal and nonfungal origin.

Nonmenstrual toxic shock syndrome (TSS) due to Staphylococcus aureus can lead to significant morbidity and mortality. While drotrecogin alfa (DA) has been employed in patients with Methicillin-resistant Staphylococcus aureus (MRSA) severe sepsis and septic shock, its utility in TSS remains unclear. The authors report a case of severe sepsis in the setting of MRSA-associated TSS that responded to treatment with DA. This case illustrates a potential role for DA in the treatment of toxic shock syndromes and emphasizes the importance of aggressive diagnostic and therapeutic modalities in approaching these conditions.

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No description available.

Myeloid-derived suppressor cells (MDSC)expand during sepsis, suppress both innate and adaptive immunity, and promote chronic immunosuppression, which characterizes the late/chronic phase of sepsis. We previously reported that the transcription factors Stat3 and C/EBPβ synergize to induces the expression of microRNA (miR)-21 and miR-181b to promote MDSC expansion in a mouse model of polymicrobial sepsis that progresses from an early/acute proinflammatory phase to a late/chronic immunosuppressive stage. We also showed that Gr1+CD11b+ cells, the precursors of MDSCs, from mice genetically deficient in the inflammatory protein S100A9 lack miR-21 or miR-181b in late sepsis, and are not immunosuppressive. In the present study, we show that S100A9 induces miR-21 and miR-181b during the late sepsis phase. We find that S100A9 associates with and stabilizes the Stat3-C/EBPβ protein complex that activates the miRNA promoters. Reconstituting Gr1+CD11b+ cells from S100A9 knockout mice with late sepsis with S100A9 protein restores the Stat3-C/EBPβ protein complex and miRNA expressions, and switches the Gr1+CD11b+ cells into the immunosuppressive, MDSC phenotype. Importantly, we find that this process requires IL-10 mediated signaling, which induces S100A9 translocation from the cytosol to the nucleus. These results demonstrate that S100A9 promotes MDSC expansion and immunosuppression in late/chronic sepsis by inducing the expression of miR-21 and miR-181b.

The myeloid-related protein S100A9 reprograms Gr1+CD11b+ myeloid precursors into myeloid-derived suppressor cells (MDSCs) during murine sepsis. Here, we show that the immunosuppressive cytokine IL-10 supports S100A9 expression and its nuclear localization in MDSCs to function as immune repressors. To support this new concept, we showed that antibody mediated IL-10 blockade in wild-type mice after sepsis induction inhibited MDSC expansion during late sepsis, and that ectopic expression of S100A9 in Gr1+CD11b+ cells from S100A9 knockout mice switched them into the MDSC phenotype only in the presence of IL-10. Knockdown of S100A9 in MDSCs from wild-type mice with late sepsis confirmed our findings in the S100A9 knockout mice. We also found that while both IL-6 and IL-10 can activate S100A9 expression in naive Gr1+CD11b+ cells, only IL-10 can induce S100A9 nuclear localization. These results support that IL-10 drives the molecular path that generates MDSCs and enhances immunosuppression during late sepsis, and inform that targeting this immune repressor path may improve sepsis survival in mice.

Sepsis inflammation accelerates myeloid cell generation to compensate for rapid mobilization of the myeloid progenitors from bone marrow. This inflammation-driven myelopoiesis, however, generates myeloid progenitors with immunosuppressive functions that are unable to differentiate into mature, innate immune cells. The myeloid-derived suppressor cells (MDSCs) expand markedly in the later phases of sepsis, suppress both innate and adaptive immunity, and thus, elevate mortality. Using a murine model with myeloid-restricted deletion of the C/EBPβ transcription factor, we show that sepsis-induced generation of MDSCs depends on C/EBPβ. C/EBPβ myeloid cell–deficient mice did not generate MDSCs or develop immunosuppression and survived sepsis. However, septic mice still generated Gr1+ CD11b+ myeloid progenitors at the steady-state levels similar to the control sham mice, suggesting that C/EBPβ is not involved in healthy, steady-state myelopoiesis. C/EBPβ-deficient Gr1+ CD11b+ cells generated fewer monocyte- and granulocyte-like colonies than control mice did, indicating reduced proliferation potential, but differentiated normally in response to growth factors. Adoptive transfer of C/EBPβ-deficient Gr1+ CD11b+ cells from late septic mice exacerbated inflammation in control mice undergoing early sepsis, confirming they were not immunosuppressive. These results show that C/EBPβ directs a switch from proinflammatory to repressor myeloid cells and identifies a novel treatment target.

Background. Cardiac dysfunction is present in >40% of sepsis patients and is associated with mortality rates of up to 70%. Recent evidence suggests that glycolytic metabolism plays a critical role in host defense and inflammation. Activation of Toll-like receptors on immune cells can enhance glycolytic metabolism. This study investigated whether modulation of glycolysis by inhibition of hexokinase will be beneficial to septic cardiomyopathy. Methods. Male C57B6/J mice were treated with a hexokinase inhibitor (2-deoxy-d-glucose [2-DG], 0.25-2 g/kg, n = 6-8) before cecal ligation and puncture (CLP) induced sepsis. Untreated septic mice served as control. Sham surgically operated mice treated with or without the 2-DG inhibitor served as sham controls. Cardiac function was assessed 6 hours after CLP sepsis by echocardiography. Serum was harvested for measurement of inflammatory cytokines and lactate. Results. Sepsis-induced cardiac dysfunction was significantly attenuated by administration of 2-DG. Ejection fraction and fractional shortening in 2-DG-treated septic mice were significantly (P < .05) greater than in untreated CLP mice. 2-DG administration also significantly improved survival outcome, reduced kidney and liver injury, attenuated sepsis-increased serum levels of tumor necrosis factor α and interleukin 1β as well as lactate, and enhanced the expression of Sirt1 and Sirt3 in the myocardium, which play an important role in mitochondrial function and metabolism. In addition, 2-DG administration suppresses sepsis-increased expression of apoptotic inducers Bak and Bax as well as JNK phosphorylation in the myocardium. Conclusions. Glycolytic metabolism plays an important role in mediating sepsis-induced septic cardiomyopathy. The mechanisms may involve regulation of inflammatory response and apoptotic signaling.