Lactate released by inflammatory bone marrow neutrophils induces their mobilization via endothelial GPR81 signaling.

Neutrophils provide first line of host defense against bacterial infections utilizing glycolysis for their effector functions. How glycolysis and its major byproduct lactate are triggered in bone marrow (BM) neutrophils and their contribution to neutrophil mobilization in acute inflammation is not clear. Here we report that bacterial lipopolysaccharides (LPS) or Salmonella Typhimurium triggers lactate release by increasing glycolysis, NADPH-oxidase-mediated reactive oxygen species and HIF-1α levels in BM neutrophils. Increased release of BM lactate preferentially promotes neutrophil mobilization by reducing endothelial VE-Cadherin expression, increasing BM vascular permeability via endothelial lactate-receptor GPR81 signaling. GPR81-/- mice mobilize reduced levels of neutrophils in response to LPS, unless rescued by VE-Cadherin disrupting antibodies. Lactate administration also induces release of the BM neutrophil mobilizers G-CSF, CXCL1 and CXCL2, indicating that this metabolite drives neutrophil mobilization via multiple pathways. Our study reveals a metabolic crosstalk between lactate-producing neutrophils and BM endothelium, which controls neutrophil mobilization under bacterial infection

Histological findings of autoimmune hepatitis

Histology of autoimmune hepatitis (AIH), chronic active hepatitis, is characterized by portal inflammation with interface hepatitis. Although the basic histology of AIH is similar to that of virus-related chronic hepatitis, hepatitic changes are usually prominent in AIH compared with chronic viral hepatitis. Clinicopathological diagnosis of AIH requires exclusion of other causes of liver disease, including hepatitis virus, alcohol, drugs, metabolic disorders, and other autoimmune diseases. At present, some criteria systems considering clinicopathological findings are proposed to categorize patients as having either definite or probably/atypical AIH. Among the pathological items of a simplified AIH scoring system of the International AIH Group, in addition to evident chronic hepatitis with interface hepatitis and hepatic rosette formation, emperipolesis, indicating the close immunological interaction of lymphocytes and hepatocytes, is noted but is sometimes difficult to evaluate. In addition to classical AIH, showing chronic active hepatitis, some AIH patients show a clinically acute hepatitis-like clinical course. These patients have mostly acute exacerbation from chronic active AIH, but acute-onset AIH cases, which histologically exhibit diffuse lobular hepatitis and/or confluent necrosis including perivenular zonal necrosis (zone 3 necrosis, centrizonal necrosis), are also encountered. © 2014 Springer Japan. All rights reserved.(Book Chapter

CIS (change impact score) – a novel outcome measurement tool to quantify the relevance of medical education interventions on professional performance

Outcome measurements play a key role in professional CME (Continuing Medical Education). While assessment of delegate satisfaction and knowledge transfer is a common standard, it appears desirable to address higher levels of evidence. However, measurement of competence and performance is considered complex, difficult and expensive. The CIS (Change Impact Score) is a novel instrument to predict the relevance of the educational intervention to the professional performance of the physician, based on a standardised on-site self-assessment

Primordial GATA6 macrophages function as extravascular platelets in sterile injury.

Most multicellular organisms have a major body cavity that harbors immune cells. In primordial species such as purple sea urchins, these cells perform phagocytic functions but are also crucial in repairing injuries. In mammals, the peritoneal cavity contains large numbers of resident GATA6+ macrophages, which may function similarly. However, it is unclear how cavity macrophages suspended in the fluid phase (peritoneal fluid) identify and migrate toward injuries. In this study, we used intravital microscopy to show that cavity macrophages in fluid rapidly form thrombus-like structures in response to injury by means of primordial scavenger receptor cysteine-rich domains. Aggregates of cavity macrophages physically sealed injuries and promoted rapid repair of focal lesions. In iatrogenic surgical situations, these cavity macrophages formed extensive aggregates that promoted the growth of intra-abdominal scar tissue known as peritoneal adhesions

Kupffer cell-like syncytia replenish resident macrophage function in the fibrotic liver.

Kupffer cells (KCs) are localized in liver sinusoids but extend pseudopods to parenchymal cells to maintain their identity and serve as the body's central bacterial filter. Liver cirrhosis drastically alters vascular architecture, but how KCs adapt is unclear. We used a mouse model of liver fibrosis and human tissue to examine immune adaptation. Fibrosis forced KCs to lose contact with parenchymal cells, down-regulating "KC identity," which rendered them incapable of clearing bacteria. Commensals stimulated the recruitment of monocytes through CD44 to a spatially distinct vascular compartment. There, recruited monocytes formed large aggregates of multinucleated cells (syncytia) that expressed phenotypical KC markers and displayed enhanced bacterial capture ability. Syncytia formed via CD36 and were observed in human cirrhosis as a possible antimicrobial defense that evolved with fibrosis