The expression of heat shock proteins (HSP) is a conserved cellular response to a variety of stresses. These proteins have been found to refold denatured polypeptides and stabilize critical cellular processes. In this study, we introduce a new component of the stress response: the increase of receptor-mediated uptake of macromolecules from the external environment. We observed that endocytosis of transferrin, which is involved in the delivery of iron to the cell, was increased after stress induced by heat shock or after incubation with inhibitors of Hsp90 function. In both cases, the increase in endocytosis was reverted by inhibition of transcription, suggesting that gene expression is required. Transfection of cells with Hsp70 gene or inhibition of its expression by siRNA confirmed the role of this HSP in the increase of endocytosis. The mechanism for the enhancement of transferrin uptake was related to an accelerated internalization of the ligand-receptor complex as well as an increase in receptor recycling. These observations constitute a new paradigm for the cellular protection induced by HSP.

Macrophages form a dual pro-bactericidal and anti-inflammatory state. Stress in the setting of infection triggers friendly activation in macrophages. Heat shock plus infection increases macrophage bactericidal activity. Heat shock plus infection increases macrophage extracellular trap formation. Heat shock plus infection increases macrophage production of cathelicidin and IL-10.

Diabetes mellitus type 1 (DMT1) is an autoimmune disease characterized by the destruction of insulinproducing cells in the pancreas. Diabetic patients are more susceptible to recurrent and uncontrolled infections, with worse prognoses than in healthy individuals. Macrophages (Mfs) derived from DMT1 individuals have compromised mounting of inflammatory and immune responses. The mechanisms responsible for these alterations remain unknown. It has been shown that the presence of extra-and intracellular heat shock proteins (hsp) positively modulates immune cell function. Using naive Mfs derived from nonobese diabetic (NOD) mice, a well-established mouse model for DMT1, we demonstrate that heat shock (HS) as well as treatment with geldanamycin (GA), significantly improves diabetic Mf activation, resulting in increased phagocytosis and killing of bacteria. Induction of HS did not affect the aberrant NOD-Mf cytokine profile, which is characterized by elevated IL-10 levels and normal tumor necrosis factor alpha. Our observations were consistent at pre-diabetic (normal random blood glucose) and diabetic (random blood glucose greater than 250 mg/dl) stages, suggesting that HS and GA treatment may compensate for intrinsic genetic alterations present in diabetic cells regardless of the stage of the disease. The mechanisms associated to this phenomenon are unknown, but they may likely be associated with the induction of hsp expression, a common factor between HS and GA treatment. Our results may open a new field for non-classical function of hsp and indicate that hsp expression may be used as a part of therapeutic approaches for the treatment of complications associated with DMT1 as well as other autoimmune diseases.

Background It has been well established that laparoscopic surgery presents several clinical benefits, including reduced pain and a shorter hospital stay. These effects have been associated with a decrease in the inflammatory response. Previous studies have demonstrated that reduced inflammation after laparoscopic surgery is the product of carbon dioxide insufflation, which decreases peritoneal pH. The objective of this study was to investigate the cellular and molecular mechanisms responsible for the reduced response after exposure to acidic environments. Materials and methods A murine macrophage line (J744) was incubated in culture medium at pH 6.0 or pH 7.4 for 3 hours at 37°C. Then, cells were stimulated with lipopolysaccharide (LPS) at pH 7.4, the expression of TNF-α (qRT-PCR or ELISA) and intracellular pH were measured. In addition, CD14 and Toll-like receptor 4 expression and and NF-κB nuclear translocation were analyzed. Results A significant decrease in LPS-induced TNF-α expression levels was observed in cells pre-incubated at pH 6.0 in comparison with cells at neutral pH conditions. This decrease in TNF-α levels was not associated with a reduction in cell surface expression of CD14 and Toll-like receptor 4. Exposure to an extracellular acidic environment resulted in a reduction of IκB phosphorylation and NF-κB nuclear translocation, secondary to a significant drop in cytosolic pH. Conclusions These observations provide a potential mechanism for the reduced expression of TNF-α after exposure to low extracellular pH, which may be related to acidification after CO2 insufflation during laparoscopic surgery. In addition, extracellular acidic pH environments could emerge as an important regulator of macrophage function.

Due to an unfortunate turn of events, the last author's surname appeared incorrectly in the original publication and should have read Crotty Alexander. The correct representation of the authors and their affiliations are listed above and below and should be treated as definitive by the reader.The online version of the original article can be found at http:// dx