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International audience; CONTEXT: Postprandial endotoxemia is a metabolic risk factor, which has been shown to originate from the intestinal absorption of gut lipopolysaccharides (LPS) using nonphysiological high-fat tests. OBJECTIVE: This study aimed to determine whether different realistic fat amounts can modulate postprandial dynamics and handling of LPS by varying postprandial lipidemia in humans of different body mass indices. DESIGN, SETTING, AND PARTICIPANTS: In a randomized, controlled, cross-over study in nutrition research center, eight normal-weight (NW) and eight obese age-matched men, without diabetes nor dyslipidemia, ingested breakfasts containing 10 vs 40 g fat. Blood samples, leukocytes, and chylomicron-rich fractions were obtained during 8 h. Plasma and chylomicron-endotoxemia, plasma LPS transporters (LBP, sCD14) and IL-6, nuclear factor kappaB (NF-kappaB) translocation, and IL-6 gene expression of immune cells were measured. MAIN OUTCOME: The postprandial fatty acid handling after ingesting 40 g fat was previously published as primary outcome. The secondary outcomes were inflammatory ones including postprandial endotoxemia, LPS handling, and plasma markers of inflammation after ingesting 10 or 40 g fat. RESULTS: Chylomicronemia increased in all subjects according to ingested fat amount (P \textless .01), but only obese had higher postprandial endotoxemia after 40 g (P \textless .05). Obese subject chylomicrons were more enriched with LPS compared with NW (PBMI \textless .01). We observed neither NF-kappaB translocation, nor variation of IL-6 expression in leukocytes. In both groups, fat amount did not modify postprandial response of plasma IL-6. However, the area under the curve (AUC) of IL-6 in obese was higher than in NW (P \textless .05) parallel to higher fasting LPS-binding protein (LBP; P \textless .05). AUC of IL-6 was correlated with LBP (P \textless .01). CONCLUSION: Postprandial endotoxemia is modulated by ingested fat amount in obese men. LPS handling in plasma through chylomicrons and LBP seems critical in driving the acute inflammatory response. The pathophysiological importance of repeated postprandial endotoxemia excursions and their contribution to a vicious cycle of LBP-driven low-grade inflammation deserve further investigation in the nutritional management of cardio-metabolic risk prevention.

Human brucellosis is most commonly diagnosed by serology based on agglutination of fixed Brucella abortus as antigen. Nucleic acid amplification techniques have not proven capable of reproducibly and sensitively demonstrating the presence of Brucella DNA in clinical specimens. We sought to optimize a monoclonal antibody-based assay to detect Brucella melitensis lipopolysaccharide in blood by conjugating B. melitensis LPS to keyhole limpet hemocyanin, an immunogenic protein carrier to maximize IgG affinity of monoclonal antibodies. A panel of specific of monoclonal antibodies was obtained that recognized both B. melitensis and B. abortus lipopolysaccharide epitopes. An antigen capture assay was developed that detected B. melitensis in the blood of experimentally infected mice and, in a pilot study, in naturally infected Peruvian subjects. As a proof of principle, a majority (7/10) of the patients with positive blood cultures had B. melitensis lipopolysaccharide detected in the initial blood specimen obtained. One of 10 patients with relapsed brucellosis and negative blood culture had a positive serum antigen test. No seronegative/blood culture negative patients had a positive serum antigen test. Analysis of the pair of monoclonal antibodies (2D1, 2E8) used in the capture ELISA for potential cross-reactivity in the detection of lipopolysaccharides of E. coli O157:H7 and Yersinia enterocolitica O9 showed specificity for Brucella lipopolysaccharide. This new approach to develop antigen-detection monoclonal antibodies against a T cell-independent polysaccharide antigen based on immunogenic protein conjugation may lead to the production of improved rapid point-of-care-deployable assays for the diagnosis of brucellosis and other infectious diseases., Author Summary Brucellosis is a OneHealth disease reflecting the risk for human infection by interaction with and relation to affected animal populations. The disease is often difficult to diagnose because of lack of precise or accessible diagnostic reagents, and because culture is complex, hazardous and relatively insensitive. Brucellosis disproportionately affects the poor and dispossessed with human and animal burdens of disease in the Middle East, North Africa, Mongolia and other regions that are simply unknown. The diagnosis of brucellosis most often rests on serological tests—antibody detection—based on agglutination of fixed Brucella abortus. We have developed the basis for developing a new test based on the detection of the B. melitensis lipopolysaccharide, which provides rapid and definitive identification of the presence of the organism in clinically obtainable body fluids. A new approach—protein conjugation to the lipopolysaccharide antigen—was taken to enhance the affinity of the monoclonal antibodies that were generated for the test. These reagents were tested in a mouse model of B. melitensis and in humans from the brucellosis-endemic region of Peru, and provided the data for the basis of further clinical development and clinical trials for the rapid, point-of-care diagnosis of brucellosis that will also provide new tools for assessing the global burden of disease.