Correlation of IGF2 levels with sperm quality, inflammation, and DNA damage in infertile patients

Abstract

Insulin-like growth factor 2 (IGF2) is a critical endocrine mediator implicated in male reproductive physiology. To investigate the correlation between IGF2 protein levels and various aspects of male infertility, specifically focusing on sperm quality, inflammation, and DNA damage, a cohort of 320 male participants was recruited from the Women's Hospital, Zhejiang University School of Medicine (Hangzhou, China) between 1 st January 2024 and 1 st March 2024. The relationship between IGF2 protein concentrations and sperm parameters was assessed, and Spearman correlation and linear regression analysis were employed to evaluate the independent associations between IGF2 protein levels and risk factors for infertility. Enzyme-linked immunosorbent assay (ELISA) was used to measure IGF2 protein levels in seminal plasma, alongside markers of inflammation (tumor necrosis factor-alpha [TNF-α] and interleukin-1β [IL-1β]). The relationship between seminal plasma IGF2 protein levels and DNA damage marker phosphorylated histone H2AX (γ-H2AX) was also explored. Our findings reveal that IGF2 protein expression decreased notably in patients with asthenospermia and teratospermia. Correlation analysis revealed nuanced associations between IGF2 protein levels and specific sperm parameters, and low IGF2 protein concentrations correlated with increased inflammation and DNA damage in sperm. The observed correlations between IGF2 protein levels and specific sperm parameters, along with its connection to inflammation and DNA damage, underscore the importance of IGF2 in the broader context of male reproductive health. These findings lay the groundwork for future research and potential therapeutic interventions targeting IGF2-related pathways to enhance male fertility.

Figure 1

Examination of IGF2 mRNA and IGF2 protein expression in sperm and seminal plasma of the spermatozoa. (a) Sperm subjected to discontinuous Percoll density gradient centrifugation was analyzed by light microscopy. (b) Gel electrophoresis of PCR products indicate notable IGF2 mRNA expression in sperm. (c) ELISA analysis of seminal plasma IGF2 protein expression in all 367 samples; patients with asthenospermia and teratospermia, as well as normal control participants. (d) Western blot analysis showing IGF2 protein expression in sperm of normal controls (Normal 1–3) and patients with both asthenospermia and teratospermia (Patient 1–3). PCR: polymerase chain reaction; GAPDH: glyceraldehyde 3-phosphate dehydrogenase; IGF2: insulin-like growth factor 2; ELISA: enzyme-linked immunosorbent assay.

Figure 2

Correlation analysis of seminal plasma IGF2 protein levels with sperm indicators. (a) Correlation analysis of seminal plasma IGF2 protein levels with sperm indicators in the asthenospermia group. The numbers in the table represent the correlation coefficients. (b) Correlation analysis of seminal plasma IGF2 protein levels with sperm indicators in the teratospermia group. The numbers in the table represent the correlation coefficients. ^*P < 0.05, ^**P < 0.01, ^***P < 0.001, ^****P < 0.0001. IGF2: insulin-like growth factor 2; PR: progressive motility; PR + NP: progressive motility + nonprogressive motility; DFI: DNA fragmentation index.

Figure 3

Investigation of the correlation between seminal plasma IGF2 protein levels and inflammation and DNA damage. (a) Spearman correlation and linear regression analysis were used to explore the correlation between TNF-α protein levels and seminal plasma IGF2 protein concentrations. (b) Spearman correlation and linear regression analysis were used to explore the correlation between IL-1β protein levels and seminal plasma IGF2 protein concentrations. (c) Spearman correlation and linear regression analysis were used to explore the correlation between γ-H2AX mRNA levels and seminal plasma IGF2 protein concentrations. (d) Western blot analysis of γ-H2AX protein expression in sperm of normal controls (Normal 1–3) and patients with both asthenospermia and teratospermia (Patient 1–3). (e) Correlation analysis of seminal plasma IGF2 protein levels with the number of round cells. (f) Seminal plasma IGF2 protein concentration was similar across varying degrees of varicocele. All P > 0.05. IGF2: insulin-like growth factor 2; TNF-α: tumor necrosis factor-alpha; γ-H2AX: phosphorylated histone H2AX; IL-1β: interleukin-1β.