Changes in Specific Biomarkers Indicate Cardiac Adaptive and Anti-inflammatory Response of Repeated Recreational SCUBA Diving

Abstract

Objective: Recreational SCUBA (rSCUBA) diving has become a highly popular and widespread sport. Yet, information on molecular events underlying (patho)physiological events that follow exposure to the specific environmental conditions (hyperbaric conditions, coldness, immersion, and elevated breathing pressure), in which rSCUBA diving is performed, remain largely unknown. Our previous study suggested that repeated rSCUBA diving triggers an adaptive response of cardiovascular and immune system. To elucidate further molecular events underlying cardiac and immune system adaptation and to exclude possible adverse effects we measured blood levels of specific cardiac and inflammation markers.

Methods: This longitudinal intervention study included fourteen recreational divers who performed five dives, one per week, on the depth 20-30 m that lasted 30 min, after the non-dive period of 5 months. Blood samples were taken immediately before and after the first, third, and fifth dives. Copeptin, immunoglobulins A, G and M, complement components C3 and C4, and differential blood count parameters, including neutrophil-to-lymphocyte ratio (NLR) were determined using standard laboratory methods. Cell-free DNA was measured by qPCR analysis and N-glycans released from IgG and total plasma proteins (TPP), were analyzed by hydrophilic interaction ultra-performance liquid chromatography.

Results: Copeptin level increased after the first dive but decreased after the third and fifth dive. Increases in immunoglobulins level after every dive and during whole studied period were observed, but no changes in C3, C4, and cfDNA level were detected. NLR increased only after the first dive. IgG and TPP N-glycosylation alterations toward anti-inflammatory status over whole studied period were manifested as an increase in monogalyctosylated and core-fucosylated IgG N-glycans and decrease in agalactosylated TPP N-glycans.

Conclusion: rSCUBA diving practiced on a regular basis promotes anti-inflammatory status thus contributing cardioprotection and conferring multiple health benefits.

Keywords: N-glycosylation; cell-free DNA; complement C3 and C4; copeptin (CPP); immunoglobulin; neutrophil-to-lymphocyte ration (NLR); recreational SCUBA (rSCUBA) diving.

FIGURE 1

Example of IgG (A) and total plasma proteins (B) N-glycan chromatogram with the most abundant structures shown for each glycan peak.

FIGURE 2

Interval plot (mean ± SE) showing changes in copeptin (CPP) serum concentrations throughout all sampling time points. *Statistically significant as compared to the corresponding pre-dive value.

FIGURE 3

Interval plots (mean ± SE) showing changes in absolute number of neutrophilic granulocytes (Neu) (A) and lymphocytes (Ly) (B) absolute numbers, as well as neutrophil-to-lymphocyte ratio (NLR) (C) across all sampling time points.

FIGURE 4

Interval plots (mean ± SE) showing changes in immunoglobulin (Ig) IgA (A), IgG (B), and IgM (C), as well as C3 (D) and C4 (E) complement components serum concentrations across all sampling time points.

FIGURE 5

Interval plots (mean ± SE) showing changes in 9 different derived IgG N-glycan traits across all sampling time points. *Statistically significant as compared to week 1 (W1). i – refers to IgG glycans, G0 – agalactosylation, G1 – monogalactosylation, G2 – digalactosylation, S0 – neutral glycans, S1 – monosialylation, S2 – disialylation, B – bisecting glycans, CF – core-fucosylation, OM – oligomannose glycans.

FIGURE 6

Interval plots (mean ± SE) showing changes in 14 different derived total plasma proteins (TPP) N-glycan traits across all sampling time points. *Statistically significant as compared to week 1 (W1). LB – low branching glycans, HB – high branching glycans, G0 – agalactosylation, G1 – monogalactosylation, G2 – digalactosylation, G3 – trigalactosylation, G4 – tetragalactosylation, S0 – neutral glycans, S1 – monosialylation, S2 – disialylation, S3 – trisialylation, S4 – tetrasialylation, CF – core fucosylation, AF - antennary fucosylation.

FIGURE 7

Interval plots (median ± SE) showing changes in cell-free DNA (cfDNA) plasma concentration (A) and cell-free DNA integrity index (CFI) (B) across all sampling time points.