Inhibition of immunoglobulin secretion from peripheral blood mononuclear cells by glucose-regulated protein94 (Grp94) in allergic subjects.

Glucose-regulated protein94 (Grp94) is the most represented endoplasmic reticulum-resident HSP with the unique property to modulate the immune response. This has opened the way to the use of Grp94 as effective therapeutic agent in both depressed and exaggerated activity of the immune system. We investigated the effect of native Grp94 on peripheral blood mononuclear cells (PBMCs) isolated from blood of two subjects with a different history of bronchial allergic asthma. Whereas in subject 1 an elevated basal level of Ig and altered morphological aspects of PBMCs suggested an intense antigen-driven stimulation of the immune system, subject 2 had an apparently normal basal humoral response. However, Grp94 reduced in a concentration-dependent manner the Ig secretion from PBMCs of both subjects, inhibition being maximal at 100 ng/ml Grp94 after 15 days. The effect was apparently related to inhibition of intra-cellular content of both IgG and IgE, and in subject 1 was still observed a year after the first examination. Dot-blot experiments revealed the presence of anti-Grp94 antibodies in Ig secreted from PBMCs and in plasma of both subjects, confirming the role of Grp94 as antigen responsible for activation of the immune system, even in the absence of clinical signs of asthma. Anti-Grp94 antibodies significantly decreased after PBMC treatment with Grp94 at 100 ng/ml. Results demonstrate that inhibition of the humoral response by Grp94 crucially depends on being Grp94, the antigen challenging the immune system in these allergic subjects, thus supporting the role of Grp94 as immuno-modulatory agent in pathologies with exaggerated immune response.

Human IgGs induce synthesis and secretion of IgGs and neonatal Fc receptor in human umbilical vein endothelial cells.

Human IgGs are increasingly used in the therapy of many different immune and inflammatory diseases, however their mechanism of action still remains unclear in most diseases. To gain insight into the mechanism by which IgGs might also exert their effects on endothelial cells, we tested human IgGs on human umbilical vein endothelial cells (HUVECs). IgGs induced a time-dependent increase in the synthesis and secretion of IgGs, together with a marked angiogenic-like transformation of HUVECs that was maximal after a 20-h incubation. IgGs stimulated IG gene transcription without affecting the process of gene rearrangement, already present in control HUVECs. The mechanism involved the activation of transcription factors with the increased expression of HSP90, HSP70 and inactive MMP-9 responsible for the phenotypic differentiation associated with the most intense IgG synthesis and secretion. However, even a short incubation with IgGs followed by recovery of cells was sufficient to trigger and sustain in time the synthesis and secretion of new IgGs, independently of the angiogenic-like transformation visible only when cells were continuously exposed to IgGs. Under the stimulus of IgGs, specific secretory pathways were also activated in HUVECs together with the expression of FcRn, which was always associated with IgGs of new synthesis, forming complexes that were also secreted. Our results disclose a so far unknown and unexpected mechanism of IgGs on HUVECs that behave as Ig-producing immune cells. Results might have relevance for the effects that IgGs also exert in vivo in physiological conditions.

Identification of high-risk chronic heart failure patients in clinical practice: role of changes in left ventricular function.

BACKGROUND: Left ventricular (LV) dysfunction and remodeling are key pathophysiological features underlying disease progression in chronic heart failure (CHF). HYPOTHESIS: To describe the course of LV dysfunction and identify predictors and prognostic impact of changes in LV volumes and function in stable CHF patients under optimal therapy. METHODS: There were 318 consecutive CHF outpatients who underwent a repeated echocardiographic evaluation at baseline and at 1 year and subsequently followed-up for at least 12 months. The end point of the study was all-cause mortality. RESULTS: Mean LV ejection fraction (LVEF) was 33 ± 7% at baseline and 36 ± 9% at follow-up. Twenty-four percent of patients had an improvement of LVEF >5 absolute points (group 1); 58% remained stable (group 2), 17% worsened at >5 absolute points (group 3). Age, New York Heart Association class, diuretic dose, renal function, and baseline LVEF were independent predictors of LVEF improvement at 1 year. At the Cox analysis, patients in group 3 had a 4-fold higher risk of death when compared with group 1 (hazard ratio: 3.99, 95% confidence interval: 1.6-9.9, P = 0.002), independently of age, etiology, and symptoms severity. CONCLUSIONS: In stable CHF outpatients, LV function improves in 24% of cases; a modest decrease in LV systolic function is associated with a significantly higher risk of all-cause mortality, independent of other markers of disease severity.