PGJ2 inhibition of LPS-induced inflammatory mediator expression from rat alveolar macrophages

Melatonin attenuates expression of cyclooxygenase-2 (COX-2) in activated microglia induced by lipopolysaccharide (LPS)

Lipopolysaccharide (LPS) is a known neurotoxin and utilized most extensively as a microglial activator for induction of inflammatory neurodegeneration. Melatonin (MEL) is the main secretory product of pineal gland reported to be responsible for a variety of physiological functions. However, the molecular mechanisms underlying the influence of MEL on microglia activation remain unclear. The aim of this study was to investigate the effect of MEL on cyclooxygenase-2 (COX-2) levels in LPS-induced microglia. The results of RT-PCR and Western blot analysis showed that MEL significantly inhibited LPS-mediated upregulation of COX-2 in microglia. Data from ELISA demonstrated that prostaglandin E2 (PGE2), the downstream effector of COX-2, concentrations were also reduced. In addition, MEL was found to decrease activation of ERK1/2, JNK, p38 MAPK, and NF-κB, the upstream signal pathways of COX-2. Taken together, evidence indicates that MEL may attenuate upregulation of COX-2 by blocking the MAPK/NF-κB signaling pathway in LPS-stimulated microglia.

Comprehensive biology of antipyretic pathways

Pyrogens, the fever inducing substances accidently enter into a human body through contamination from medical or pharmaceutical products may create mild to severe complications including septicaemia and shocking syndromes. To avoid such drastic situations all the pharmaceuticals and medical devices are analysed for presence of pyrogens prior to their release into market. The entry of exogenous pyrogens like bacterial endotoxins induces the release of endogenous pyrogens or inflammatory cytokines that activate immune system to defend against these pathogens. Generation of heat is considered as one of the important defence mechanism of body achieved through receptor mediated interaction of endogenous pyrogens at the thermoregulatory centre of hypothalamus. However, uncontrolled fever and febrile reaction may cause lethal effects to the subject itself. So a well sophistically functioning antipyretic mechanism is necessary to achieve thermoregulation. The coordinated interaction of antipyretic cytokines and other mediators are active in human immune system which play a crucial role in maintaining thermal homeostasis. The multiple interacting antipyretic signals and their mechanism are the major subjects of this review.

Lipidomic profiling of subchronic As4S4exposure identifies inflammatory mediators as sensitive biomarkers in rats

Arsenic sulfide compounds provide nearly all of the world's supply of arsenic.

Lipopolysaccharides may aggravate apoptosis through accumulation of autophagosomes in alveolar macrophages of human silicosis

Silica dust mainly attacks alveolar macrophages (AMs) and increases the apoptosis of AMs in silicosis patients. However, it is still unclear whether autophagy is affected. Autophagy mainly has defensive functions in response to stress, contributing to cell survival in adverse conditions, and conversely it has also been implicated in cell death. Lipopolysaccharide (LPS) induces autophagy and apoptosis in macrophages. The role of LPS in autophagy and apoptosis in AMs of silicosis patients is unknown. In this study, we collected AMs from 53 male workers exposed to silica and divided them into an observer (control) group, and stage I, II and III patient groups. We found increased levels of LC3B, SQSTM1/p62 and BECN1，whereas the phosphorylation of MTOR，and levels of LAMP2, TLR4, MYD88, TICAM1, as well as the number of lysosomes decreased with the development of silicosis. LPS stimulation triggered autophagy and increased levels of SQSTM1 in AMs. The autophagy inhibitor, 3-methyladenine (3MA), inhibited LPS-induced apoptosis in the AMs of silicosis patients. Moreover, 3MA reversed the LPS-induced decrease in BCL2 and the increase in BAX and CASP3 levels in AMs. These results suggest that autophagosomes accumulate in AMs during silicosis progression. LPS can induce the formation of autophagosomes through a TLR4-dependent pathway, and LPS may exacerbate the apoptosis in AMs. Blockade of the formation of autophagosomes may inhibit LPS-induced apoptosis via the intrinsic apoptotic pathway in AMs. These findings describe novel mechanisms that may lead to new preventive and therapeutic strategies for pulmonary fibrosis.

Mechanisms for how inhaled multiwalled carbon nanotubes suppress systemic immune function in mice

The potential health effects of inhaling carbon nanotubes are important because of possible exposures in occupational settings. Previously, we have shown mice that have inhaled multiwalled carbon nanotubes have suppressed systemic immune function. Here, we show the mechanisms for this immune suppression. Mice were exposed to 0, 0.3 or 1 mg m(-3) multiwalled carbon nanotubes for 6 h per day for 14 consecutive days in whole-body inhalation chambers. Only those exposed to a dose of 1 mg m(-3) presented suppressed immune function; this involved activation of cyclooxygenase enzymes in the spleen in response to a signal from the lungs. Spleen cells from exposed animals partially recovered their immune function when treated with ibuprofen, a drug that blocks the formation of cyclooxygenase enzymes. Knockout mice without cyclooxygenase enzymes were not affected when exposed to multiwalled carbon nanotubes, further confirming the importance of this enzyme in suppression. Proteins from the lungs of exposed mice suppressed the immune function of spleen cells from normal mice, but not those from knockout mice. Our findings suggest that signals from the lung can activate signals in the spleen to suppress the immune function of exposed mice.