Exercise Training under Exposure to Low Levels of Fine Particulate Matter: Effects on Heart Oxidative Stress and Extra‐to‐Intracellular HSP70 Ratio

Abstract

Fine particulate matter (PM2.5) promotes heart oxidative stress (OS) and evokes anti-inflammatory responses observed by increased intracellular 70 kDa heat shock proteins (iHSP70). Furthermore, PM2.5 increases the levels of these proteins in extracellular fluids (eHSP70), which have proinflammatory roles. We investigated whether moderate and high intensity training under exposure to low levels of PM2.5 modifies heart OS and the eHSP70 to iHSP70 ratio (H-index), a biomarker of inflammatory status. Male mice (n = 32), 30 days old, were divided into six groups for 12 weeks: control (CON), moderate (MIT) and high intensity training (HIT), exposure to 5 μg of PM2.5 daily (PM2.5), and moderate and high intensity training exposed to PM2.5 (MIT + PM2.5 and HIT + PM2.5 groups). The CON and PM2.5 groups remained sedentary. The MIT + PM2.5 group showed higher heart lipid peroxidation levels than the MIT and PM2.5 groups. HIT and HIT + PM2.5 showed higher heart lipid peroxidation levels and lower eHSP70 and H-index levels compared to sedentary animals. No alterations were found in heart antioxidant enzyme activity or iHSP70 levels. Moderate exercise training under exposure to low levels of PM2.5 induces heart OS but does not modify eHSP70 to iHSP70 ratio (H-index). High intensity exercise training promotes anti-inflammatory profile despite exposure to low levels of PM2.5.

Effects of High-Fat Diet on eHSP72 and Extra-to-Intracellular HSP70 Levels in Mice Submitted to Exercise under Exposure to Fine Particulate Matter

“…Although there are at least two isoforms of HSP70 (the 72 and 73 kDa HSPs, which are well known as the HSPA1A-inducible form and the cognate HSPA8 constitutive form, respectively), the levels of HSPA1A (eHSP72) can be used as representative of total eHSP70 secretion [23]. It is expected that both the inducible and constitutive forms should be delivered into the extracellular space after stressful conditions as acute exercise; however, eHSP72 has been used as biomarker of stress situations in previous studies related to particulate matter pollution, diabetes, and exercise [15, 17, 24]. Also, only HSPA1A ELISA kits have been sufficiently tested worldwide and are accepted to possess enough sensitivity (pg·mL−1 range) to detect minute quantities of HSP70 in plasma.…”

“…After decapitation, blood was immediately collected into heparinized (30 IU·mL −1 final volume) tubes (for metabolite measurements) or in disodium EDTA-treated tubes (2 mg·mL −1 final volume). Hematological parameters were investigated in EDTA samples in a Horiba ABX Micros 60 hematology analyzer (for quantitative cell analysis) [24].…”

“…Although the precise regulation of extra-to-intracellular HSP70 ratio (H-index = eHSP70/iHSP70) is still unknown [15, 23], exercise is a potent mediator of the heat shock response (HSR) [17], when under exposure to PM 2.5 [24]. Thus, in the present study, we aimed to investigate the effects of high-fat diet consumption on eHSP70 and H-index, in mice submitted to acute moderate- and high-intensity exercise, following exposure to PM 2.5 .…”

Recreational physical activity and the problem of particulate matter air pollution

“…This effect was not observed when the mice were subjected to moderate exercises. Low level of eHSP70 is a marker of antiinflammatory profile (36).…”

“…wykazali, że jedynie w grupie myszy poddawanych intensywnemu wysiłkowi, w czasie narażenia na PM 2,5 , zaobserwowano niskie stężenie pozakomórkowych białek szoku termicznego 70 (eHSP70), będące wyrazem profilu antyzapalnego. Efekt ten nie występował u myszy poddawanych umiarkowanemu wysiłkowi (36).…”