Stress-induced facilitation of host response to bacterial challenge in F344 rats is dependent on extracellular heat shock protein 72 and independent of alpha beta T cells.

Activation of the in vivo stress response can facilitate antibacterial host defenses. One possible mechanism for this effect is stress-induced release of heat shock protein 72 (Hsp72) into the extracellular environment. Hsp72 is a ubiquitous cellular protein that is up-regulated in response to cellular stress, and modulates various aspects of immune function including macrophage inflammatory/bactericidal responses and T-cell function when found in the extracellular environment. The current study tested the hypothesis that in vivo extracellular Hsp72 (eHsp72) at the site of inflammation contributes to stress-induced restricted development of bacteria, and facilitated recovery from bacteria-induced inflammation, and that this effect is independent of alpha beta (αß) T cells. Male F344 rats were exposed to either inescapable electrical tail-shocks or no stress, and subcutaneously injected with Escherichia coli (ATCC 15746). The role of eHsp72 was investigated by Hsp72-immunoneutralization at the inflammatory site. The potential contribution of T cells was examined by testing male athymic (rnu/rnu) nude rats lacking mature αß T cells and heterozygous thymic intact control (rnu/+) rats. The results were that stressor exposure increased plasma concentrations of eHsp72 and facilitated recovery from bacterial inflammation. Immunoneutralization of eHsp72 at the inflammatory site attenuated this effect. Stressor exposure impacted bacterial inflammation and eHsp72 equally in both athymic and intact control rats. These results support the hypothesis that eHsp72 at the site of inflammation, and not αß T cells, contributes to the effect of stressor exposure on subcutaneous bacterial inflammation.

Intravenous enalaprilat for treatment of acute hypertensive heart failure in the emergency department.

BACKGROUND: Afterload reduction with bolus enalaprilat is used by some for management of acute hypertensive heart failure (HF) but existing data on the safety and effectiveness of this practice are limited. The purpose of this study was to evaluate the clinical effects of bolus enalaprilat when administered to patients with acute hypertensive heart failure. FINDINGS: We performed an IRB-approved retrospective cohort study of patients who presented to the emergency department of a large urban academic hospital. Patients were identified by pharmacy record and included if they received enalaprilat intravenous (IV) bolus in the setting of acute hypertensive HF. A total of 103 patients were included. Patients were hypertensive on presentation (systolic blood pressure [SBP] = 195.2 [SD ± 32.3] mmHg) with significantly elevated mean NT-proBNP levels (3797.8 [SD ± 6523.2] pg/ml). The mean dose of enalaprilat was 1.3 [SD ± 0.7] mg, with most patients (76.7%) receiving a single 1.25 mg bolus. By 3 h post-enalaprilat, SBP had decreased substantially (-30.5 mmHg) with only 2 patients (1.9%) developing hypotension. Renal function was unaffected, with no significant change in serum creatinine by 72 h. In the 30 days post-admission, patients spent an average of 23 [SD ± 7.5] days alive and out of hospital. CONCLUSIONS: In this retrospective cohort of acute hypertensive HF patients, bolus IV enalaprilat resulted in a substantial reduction in systolic BP without adverse effect.

Adrenergic receptors mediate stress-induced elevations in extracellular Hsp72.

Heat-shock protein concentrations in the blood increase after exposure to a variety of stressors, including trauma and psychological stress. Although the physiological function of extracellular heat shock protein remains controversial, there is evidence that extracellular heat shock protein 72 (Hsp72) can facilitate immunologic responses. The signal(s) that mediate(s) the in vivo elevation of extracellular Hsp72 in the blood after stressor exposure remain(s) unknown. Here we report that Hsp72 increases in the circulation via an alpha1-adrenergic receptor-mediated signaling pathway. Activation of alpha1-adrenoceptors results in a rapid increase in circulating Hsp72, and blockade of alpha1-adrenoceptors prevents the stress-induced rise in circulating Hsp72. Furthermore, our studies exclude a role for beta-adrenoceptors, glucocorticoids, and ACTH in mediating stress-induced elevations in circulating extracellular Hsp72. Understanding the signals involved in elevating extracellular Hsp72 could facilitate the use of extracellular Hsp72 to bolster immunity and perhaps prevent exacerbation of inflammatory diseases during stress.