Immunological changes in human skeletal muscle and blood after eccentric exercise and multiple biopsies

Abstract

1. A role of the immune system in muscular adaptation to physical exercise has been suggested but data from controlled human studies are scarce. The present study investigated immunological events in human blood and skeletal muscle by immunohistochemistry and flow cytometry after eccentric cycling exercise and multiple biopsies. 2. Immunohistochemical detection of neutrophil- (CD11b, CD15), macrophage- (CD163), satellite cell- (CD56) and IL-1beta-specific antigens increased similarly in human skeletal muscle after eccentric cycling exercise together with multiple muscle biopsies, or multiple biopsies only. 3. Changes in immunological variables in blood and muscle were related, and monocytes and natural killer (NK) cells appeared to have governing functions over immunological events in human skeletal muscle. 4. Delayed onset muscle soreness, serum creatine kinase activity and C-reactive protein concentration were not related to leukocyte infiltration in human skeletal muscle. 5. Eccentric cycling and/or muscle biopsies did not result in T cell infiltration in human skeletal muscle. Modes of stress other than eccentric cycling should therefore be evaluated as a myositis model in human. 6. Based on results from the present study, and in the light of previously published data, it appears plausible that muscular adaptation to physical exercise occurs without preceding muscle inflammation. Nevertheless, leukocytes seem important for repair, regeneration and adaptation of human skeletal muscle.

Figures

Figure 1

Demonstration of regenerating muscle cells (A) and activated satellite cells (B) by the expression of CD56 in human muscle tissue.

Figure 5

Regression model for an increased neutrophil number (CD11b) in human skeletal muscle due to three biopsies or biopsies + eccentric cycling exercise. Ecc. V̇O2, V̇O2 during eccentric cycling; Post, post exercise.

Figure 6

Regression model for an increased percentage of satellite cells (CD56) in human skeletal muscle due to three biopsies + eccentric cycling exercise. No model could be determined for the effect of biopsies only. Lym, lymphocytes; Mon, monocytes; Post, post exercise; ΔPre-Post, change in pre- vs. post-exercise values.

Figure 7

Regression model for an increased percentage of satellite cells (CD56) in human skeletal muscle due to four biopsies + eccentric cycling exercise. No change in the percentage of satellite cells occurred at 48 h due to the effect of biopsies only.

Figure 8

Regression model for an increased number of macrophages (CD163) in human skeletal muscle due to four biopsies or biopsies + eccentric cycling exercise.

Figure 9

Regression model for an increased number of macrophages (CD163) in human skeletal muscle due to five biopsies. There was no change in macrophage number due to biopsies + eccentric exercise. 4d, 4 days; m, muscle.

Figure 10

Regression model for an increased IL-1β expression in human skeletal muscle due to one biopsy + eccentric cycling exercise. No model was found for one biopsies alone. 4d, 4 days.

Figure 2

Infiltration of macrophages in human muscle tissue, located at the periphery of the biopsy.

Figure 3

Staining of IL-1β in human skeletal muscle. IL-1β appears located in muscle cells (A) and non-muscle cells (B).

Figure 4

IL-6 expression in human skeletal muscle cells (A).