Heat stress combined with lipopolysaccharide alter the activity and superficial molecules of peripheral monocytes

Abstract

The purpose of this study was to focus on the underlying relationship between the hyperactivity for the peripheral monocytes and heat stroke by investigating the inflammatory oxidative activity of and the expression of superficial molecules. Peripheral blood samples were collected from 10 healthy adult volunteers. Human blood monocytes were isolated by density gradient centrifugation and sequent adherent culture. The objectives were divided into four groups: 43°C heat stress combined with lipopolysaccharide (LPS) group, 43°C heat stress group, LPS group, and control group. There were 10 cases in each group. An enzyme-linked immunosorbent assay (ELISA) test was used to measure the concentrations of supernatant inflammatory mediators (tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-10 (IL-10)). After loaded by 2,7-Dichlorodi-hydrofluorescein-diacetate (DCFHDA) fluorescent probe, intracellular reactive oxygen species (ROS) levels were determined by a flow cytometry. After fluorescent microspheres incubation, the phagocytosis of monocytes was observed under a fluorescent microscope. Respectively, the flow cytometry and Western blot were used to evaluate the level of triggering receptor expressed on myeloid cells-1 (TREM-1) and Toll-like receptor-4 (TLR-4) on the monocytes. Furthermore, the mRNA expression of TREM-1 and TLR-4 was detected by real-time polymerase chain reaction (RT-PCR). The heat stress combined with LPS stimulation promoted the peripheral monocytes to produce inflammatory mediators (TNF-α, IL-1β, and IL-10) and release ROS. Otherwise, such complex strike significantly suppressed the phagocytic activity of monocytes in peripheral blood. Moreover, the expression of TREM-1, TLR-4 and CD86 was measured by the flow cytometry on peripheral monocytes which were respectively promoted by the union of heat stress and LPS. The results of Western blot and RT-PCR demonstrated the similar kinetics on these superficial molecules (TREM-1, TLR-4, and CD86) stimulated by the combination of heat stress and LPS. The underlying mechanism of the dysfunction for the peripheral monocytes may be related to the abnormal expression of superficial molecules TREM-1, TLR-4, and CD86 on the monocytes induced by heat stress and LPS.

Common and Differential Dynamics of the Function of Peripheral Blood Mononuclear Cells between Holstein and Jersey Cows in Heat-Stress Environment

“…In vitro studies have also demonstrated that heat stress decreases the phagocytic activities of immune cells. Under heat stress, the phagocytic activity of peripheral monocytes from humans is reduced after LPS stimulation [ 45 ]. In addition, decreased phagocytosis in bovine immune cells under hot conditions was demonstrated by using the opsonization of fluorescein-labeled Escherichia coli [ 46 ].…”

Heat stress combined with lipopolysaccharide induces pulmonary microvascular endothelial cell glycocalyx inflammatory damage in vitro

“…Heat stress and lipopolysaccharide (HS + LPS) were employed to construct the in vitro models of heat stroke in our previous study. 16 All the HPMEC were categorized into four groups with eight wells in each group: control group (CON group), heat stroke group (HS group), heparanase group (HPSE group), and unfractionated heparin group (UFH group). After conventional culture for 72 h, the cell in the CON group was cultured in normal conditions, without receiving heat stress or LPS (Sigma).…”

“…To investigate HPMEC apoptosis and heparansulfate proteoglycan (HSPG) concentration, flow cytometry was performed in each group according to our previous methods. 16 Cells in each group were washed with phosphate‐buffered saline (PBS) for 15 min, centrifuged, and resuspended with 500 μL AnnexinV‐fluorescein isothiocyanate (FITC) (UElandy) binding buffer per tube. The cells were further stained with 5 μL AnnexinV‐FITC, then mixed and incubated in the dark at 4°C for 15 min.…”

Heat stress combined with lipopolysaccharide induces pulmonary microvascular endothelial cell glycocalyx inflammatory damage in vitro

“…Pretreatment before molding Heat stress and lipopolysaccharide (HS+LPS) were employed to construct the in vitro models of heat stroke in our previous study. 15 . All the HPMEC were categorized into 4 groups with 8 wells in each group: control group (CON group), heat stroke group (HS group), heparanase group (HPSE group), and unfractionated heparin group (UFH group).…”