Increased expression and functionality of the gap junction in peripheral blood lymphocytes is associated with hypertension-mediated inflammation in spontaneously hypertensive rats

Abstract

BackgroundImbalances in circulating T lymphocytes play critical roles in the pathogenesis of hypertension-mediated inflammation. Connexins (Cxs) in immune cells are involved in the maintenance of homeostasis of T lymphocytes. However, the association between Cxs in peripheral blood T lymphocytes and hypertension-mediated inflammation remains unknown. This study was designed to investigate the role of Cxs in T lymphocytes in hypertension-mediated inflammation in spontaneously hypertensive rats (SHRs).MethodsThe systolic blood pressure (SBP) in Wistar-Kyoto (WKY) rats and SHRs was monitored using the tail-cuff method. The serum cytokine level was determined using ELISA. The proportions of different T-lymphocyte subtypes in the peripheral blood, the expressions of Cx40/Cx43 in the T-cell subtypes, and the gap junctional intracellular communication (GJIC) of peripheral blood lymphocytes were measured using flow cytometry (FC). The accumulations of Cx40/Cx43 at the plasma membrane and/or in the cytoplasm were determined using immunofluorescence staining. The in vitro mRNA levels of cytokines and GJIC in the peripheral blood lymphocytes were respectively examined using real-time PCR and FC after treatment with Gap27 and/or concanavalin A (Con A).ResultsThe percentage of CD4+ T cells and the CD4+/CD8+ ratio were high, and the accumulation or expressions of Cx40/Cx43 in the peripheral blood lymphocytes in SHRs were higher than in those of WKY rats. The percentage of CD8+ and CD4+CD25+ T cells was lower in SHRs. The serum levels of IL-2, IL-4 and IL-6 from SHRs were higher than those from WKY rats, and the serum levels of IL-2 and IL-6 positively correlated with the expression of Cx40/Cx43 in the peripheral blood T lymphocytes from SHRs. The peripheral blood lymphocytes of SHRs exhibited enhanced GJIC. Cx43-based channel inhibition, which was mediated by Gap27, remarkably reduced GJIC in lymphocytes, and suppressed IL-2 and IL-6 mRNA expressions in Con A stimulated peripheral blood lymphocytes.ConclusionsOur data suggest that Cxs may be involved in the regulation of T-lymphocyte homeostasis and the production of cytokines. A clear association was found between alterations in Cxs expression or in Cx43-based GJIC and hypertension-mediated inflammation.

β‑estradiol alleviates hypertension‑ and concanavalin A‑mediated inflammatory responses via modulation of connexins in peripheral blood lymphocytes

“…The primary findings of the present study were that β-estradiol significantly prevented inflammation and target organ damage (kidneys and arteries) in male SHRs. Furthermore, while hypertension appears to promote imbalances in the adaptive immune response through increased expression of Cxs (Cx40 and Cx43), which have previously been demonstrated to be pro-inflammatory (10–16), β-estradiol appeared to alleviate hypertension-mediated imbalances of the adaptive immune response and T cell mitogenic stimuli-induced adaptive immune response, at least in part, by suppressing the expression of Cxs or the function of Cx gap junctions. β-estradiol inhibited the release of pro-inflammatory cytokines induced by spontaneous hypertension or T cell activation.…”

“…The effect of β-estradiol on the GJIC between peripheral blood lymphocytes was measured using a calcein acetoxymethyl ester (calcein AM) transfer assay as described previously (10,11). Briefly, PBMCs (1×10 6 cells/ml) isolated from WKY rats were incubated in a 6-well plate with a 2.5 µM solution of calcein AM (cat.…”

“…Although the role of T lymphocytes in hypertension-mediated inflammation is clearly defined by a large body of experimental data, the evidence that inflammation and an adaptive immune response are induced by hypertension is rather limited. The authors' laboratory has demonstrated that gap junctional communication via connexins (Cxs) in peripheral blood lymphocytes of SHRs (10) and hypertensive patients (11) is involved in the hypertension-mediated inflammatory response, and that Cx expression is positively correlated with the proliferation of T lymphocyte and production of pro-inflammatory cytokines in the peripheral blood of patients with hypertension and SHRs (10–13). Data from the authors' laboratory and other groups have also revealed that inhibition of Cx43-mediated gap junctional communication can reduce the activation and proliferation of T lymphocytes and production of pro-inflammatory cytokines under various pro-inflammatory stimuli (10,11,14–16).…”

Targeting the 4-1BB costimulatory molecule through single chain antibodies promotes the human T-cell response

“…To create standard curves and regression analysis of mean absorbance, standard cytokine solutions were run in parallel. The optical density at 450 nm was measured for each well using a microtiter plate reader (BP-800; Bioship) and the cytokine concentration was obtained from standard curves of recombinant human IL-2, IL-4 and IFN-γ [35].…”

A Working Hypothesis Regarding Identical Pathomechanisms between Clinical Efficacy and Adverse Reaction of Clozapine via the Activation of Connexin43

“…Pneumonia is an inflammatory condition of the lungs, commonly caused by infection and less commonly by other numerous functional abnormalities including immune-functional deficiencies and certain medications [ 161 ]. Both clinical and preclinical studies demonstrated that upregulated gap-junction/hemichannel containing Cx43 and Cx40 in T-lymphocytes were involved in non-infectious pulmonary inflammation [ 162 , 163 , 164 ]. Additionally, the inhibition of the expression and/or function of Cx ( Figure 3 ) [ 162 , 163 , 164 ] improved the proinflammatory reaction via decreasing the proportion of CD4+ T-lymphocytes with the levels of proinflammatory cytokines [ 162 , 163 , 164 , 165 , 166 ].…”