Innate/inflammatory bioregulation and clinical effectiveness of whole-body hyperthermia (balneotherapy) in elderly patients with osteoarthritis.

Objectives: Balneotherapy with mud application (mud therapy) is a common hydrothermal intervention for the treatment and rehabilitation of elderly patients with osteoarthritis, leading to anti-inflammatory effects. The main purpose of this investigation was to study a role for regulatory T cells in these anti-inflammatory effects. The second objective was to assess whether the neutrophil-mediated innate response is affected by these anti-inflammatory effects.
Methods: Thirty-six elderly patients with knee osteoarthritis underwent a 10-day cycle of balneotherapy at a spa center. They received daily sessions of whole-body mud therapy at 40-42 °C, using mineral-medicinal water and mud. IL-8 and TGF-β serum concentrations, percentage of circulating CD4 ⁺ CD25 ⁺ FOXP3 ⁺ and CD8 ⁺ CD28 ^- regulatory T cells, and neutrophil phagocytic capacity were evaluated at baseline and at the end of the intervention. Clinical assessments included knee flexion and extension angle, pain, stiffness, physical function and health-related quality of life.
Results: All clinical outcomes significantly improved. Circulating concentrations of IL-8 and TGF-β decreased, which correlated with decreased pain and improved knee flexion, respectively. Percentage of CD4 ⁺ regulatory T cells decreased, whereas CD8 ⁺ regulatory T cells increased. Neutrophil functional capacity increased.
Conclusions: Balneotherapy with mud application was effective in the management of osteoarthritis symptoms. The anti-inflammatory effect mediated by cytokines contributed to the improvement in pain and joint function; and changes in the circulating percentage of regulatory T cells seem to be involved in the anti-inflammatory effects. Improvement in neutrophil function after mud therapy reflects an optimal bioregulatory effect on the inflammatory and innate responses.