Systemic, but not local, low-grade endotoxinemia increases plasma sCD163 independently of the cortisol response

Aims/hypothesis The macrophage-specific glycoprotein sCD163 has emerged as a biomarker of low-grade inflammation in the metabolic syndrome and related disorders. High sCD163 levels are seen in acute sepsis as a result of direct lipopolysaccharide-mediated shedding of the protein from macrophage surfaces including Kupffer cells. The aim of this study was to investigate if low-grade endotoxinemia in human subjects results in increasing levels of sCD163 in a cortisol-dependent manner. Methods We studied eight male hypopituitary patients and eight age- and gender-matched healthy controls during intravenous low-dose LPS or placebo infusion administered continuously over 360 min. Furthermore, we studied eight healthy volunteers with bilateral femoral vein and artery catheters during a 360-min infusion with saline and low-dose LPS in each leg respectively. Results: Systemic low-grade endotoxinemia resulted in a gradual increase in sCD163 from 1.65 ± 0.51 mg/L (placebo) to 1.92 ± 0.46 mg/L (LPS) at 220 min, P = 0.005 and from 1.66 ± 0.42 mg/L (placebo) to 2.19 ± 0.56 mg/L (LPS) at 340 min, P = 0.006. A very similar response was observed in hypopituitary patients: from 1.59 ± 0.53 mg/L (placebo) to 1.83 ± 0.45 mg/L (LPS) at 220 min, P = 0.021 and from 1.52 ± 0.53 mg/L (placebo) to 2.03 ± 0.44 mg/L (LPS) at 340 min, P < 0.001. As opposed to systemic treatment, continuous femoral artery infusion did not result in increased sCD163. Conclusion: Systemic low-grade endotoxinemia resulted in increased sCD163 to levels seen in the metabolic syndrome in both controls and hypopituitary patients. This suggests a direct and cortisol-independent effect of LPS on the shedding of sCD163. We observed no effect of local endotoxinemia on levels of serum sCD163.

Sex differences of inflammation in target organs, induced by intraperitoneal injection of lipopolysaccharide, depend on its dose

Purpose

The aim of our research was to study sex differences and the severity of inflammatory changes in target organs and the peculiarities of immunological disorders when low and high doses of lipopolysaccharide (LPS) were administered to rats.

Methods

Male and female 2- to 3-month-old Wistar rats (200–250 g) were injected intraperitoneally with Escherichia coli LPS in one of two doses: 1.5 or 15 mg/kg. In a day after the LPS injection, we studied endotoxin, corticosterone, sex steroids, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) activity levels in the serum; morphological disorders in the lung, liver, thymus, and spleen; ex vivo production of IL-2, IL-4, tumor necrosis factor (TNF), and interferon γ (IFNγ) by splenic cells activated by ConA; and relative amount of T- and B-lymphocytes in the peripheral blood.

Results

After the injection of low-dose LPS, the serum endotoxin level increased only in males and was combined with a more pronounced inflammatory response in the lungs and thymus and an increase in ALT and AST activity levels without any changes in corticosterone level. After the injection of high-dose LPS, the inflammatory and pathological changes in the target organs manifested as severe endotoxemia and sex differences of pathological changes in the lungs and liver were not revealed. The level of production of IL-2, IL-4, IFNγ, and TNF by splenic cells and the number of T-lymphocytes, including cytotoxic cells, in the peripheral blood, decreased in males, which is an evidence of a pronounced suppression of the immune response.

Conclusion

We have shown that the morphofunctional changes in the organs of the immune system in females and males, as well as the intensity of the sex differences of inflammation, depend on the severity of systemic inflammatory response, induced by different doses of LPS.

Lipopolysaccharide-binding protein cannot independently predict type 2 diabetes mellitus: A nested case-control study

BACKGROUND

Cross-sectional studies have reported a close association between serum lipopolysaccharide-binding protein (LBP) and many metabolic disorders. However, no longitudinal study has explored the relationship between LBP and type 2 diabetes mellitus (T2DM). The aim of the present study was to investigate the association between serum LBP levels and the risk of developing T2DM.

METHODS

A 5-year nested case-control study of 3510 individuals was performed as part of the Environment, Inflammation and Metabolic Diseases Study (EIMDS). Clinical data were collected at baseline. Serum levels of LBP and other biochemical factors, such as insulin and high-sensitivity C-reactive protein, were detected 5 years later. Subjects were diagnosed as having T2DM on the basis of results of an oral glucose tolerance test (OGTT) and 1998 World Health Organization criteria. Controls were randomly selected to match cases according to age, gender, and body mass index (BMI) in a 1:1 ratio. Odds ratios (OR) for T2DM were calculated using conditional logistic regression analysis.

RESULTS

Over a 5-year follow-up period, 255 subjects developed T2DM. There was no significant difference in serum LBP levels between the T2DM and control groups at baseline (19.78 ± 6.40 versus 20.53 ± 6.99 μg/mL; P = 0.207). Subjects were divided into three groups based on tertiles of LBP concentrations (n = 170 in each group; T1 = 1.31-17.16 μg/mL LBP; T2 = 17.21-22.37 μg/mL LBP; T3 = 22.49-40.08 μg/mL LBP). There was no significant association between the risk of developing T2DM and any of the LBP tertiles in either a simple model or after adjusting for general status and biochemical factors.

CONCLUSION

After matching for gender, age, and BMI, LBP does not improve prediction of the development of T2DM independently.