Low-level laser therapy improves the inflammatory profile of rats with heart failure

Following heart failure (HF), immune activation leads to an imbalance between pro-inflammatory and anti-inflammatory cytokines. Low-level laser therapy (LLLT) has been used as an anti-inflammatory treatment in several disease conditions. However, the effect of LLLT on the skeletal muscle of rats with HF remains unclear. The present report aimed to evaluate the influence of LLLT on the inflammatory profile of rats with HF. The left coronary artery was ligated to induce HF and a sham operation was performed in the control groups. Male Wistar rats (n = 49) were assigned to one of six groups: placebo sham rats (P-Sham; n = 8), LLLT at a dose of 3 J/cm² sham rats (3 J/cm²-Sham; n = 8), LLLT at a dose of 21 J/cm² sham rats (21 J/cm²-Sham; n = 8), placebo HF rats (P-HF; n = 9), LLLT at a dose of 3 J/cm² HF rats (3 J/cm²-HF; n = 8), and LLLT at a dose of 21 J/cm² HF rats (21 J/cm²-HF; n = 8). Four weeks after myocardial infarction or sham surgery, rats were subjected to LLLT (InGaAlP 660 nm, spot size 0.035 cm², output power 20 mW, power density 0.571 W/cm², energy density 3 or 21 J/cm², exposure time 5.25 s and 36.75 s) on the right gastrocnemius for 10 consecutive days. LLLT reduced plasma IL-6 levels (61.3 %; P < 0.01), TNF-α/IL-10 (61.0 %; P < 0.01) and IL-6/IL-10 ratios (77.3 %; P < 0.001) and increased IL-10 levels (103 %; P < 0.05) in the 21 J/cm²-HF group. Moreover, LLLT reduced the TNF-α (20.1 % and 21.3 %; both P < 0.05) and IL-6 levels (54.3 % and 37.8 %; P < 0.01 and P < 0.05, respectively) and the IL-6/IL-10 ratio (59.7 % and 42.2 %; P < 0.001 and P < 0.05, respectively) and increased IL-10 levels (81.0 % and 85.1 %; both P < 0.05) and the IL-10/TNF-α ratio (171.5 % and 119.8 %; P < 0.001 and P < 0.05, respectively) in the gastrocnemius in the 3 J/cm²-HF and 21 J/cm²-HF groups. LLLT showed systemic and skeletal muscle anti-inflammatory effects in rats with HF.