Sperm DNA damage: The possible link between obesity and male infertility, an update of the current literature

Assessing the Prevalence of Male Obesity-Associated Gonadal Dysfunction in Severe Obesity: A Focus on the Impact of Bariatric Surgery and Surgical Approaches

PURPOSE

Obesity is an important risk factor for secondary hypogonadism in men. Several studies evaluated the impact of bariatric surgery on gonadal function in men, proving an improvement in testosterone levels, without yet a global consensus on the impact of different surgical approaches. Objectives of the study are: to estimate the prevalence of obesity-associated gonadal dysfunction among men with severe obesity; to evaluate the response to bariatric surgery in terms of resolution of this condition, distinguishing between restrictive and restrictive-malabsorptive surgery.

METHODS

We conducted a retrospective evaluation of 413 males with severe obesity (BMI 44.7 ± 8.3 kg/m2). A subgroup of them (61.7%) underwent bariatric surgery. Anthropometric assessment (weight, BMI, waist and hip circumference), metabolic (glyco-lipidic asset and urate) and hormonal (morning gonadotropin and total testosterone) assessments were carried out at baseline and 3-6 months post-surgery.

RESULTS

Using a TT threshold of 2.64 ng/ml, 256 out of 413 (62%) patients were categorized as having biochemical hypogonadism. At multivariate analysis, the only parameter significantly associated with biochemical hypogonadism, was BMI value (p = 0.001). At 3-6 months after surgery, during the acute weight loss phase, only 20.1% of patients still had biochemical hypogonadism. At multivariate analysis, which included age, presurgical BMI, pre-surgical TT, surgical approach and %EWL, presurgical TT levels (p = 0.0004), %EWL (p = 0.04), and mixed restrictive-malabsorptive surgery (p = 0.01), were independently associated with the recovery of gonadal function.

CONCLUSIONS

The results of this study underscore the potential reversibility of obesity-associated gonadal dysfunction through bariatric surgery, highlighting the importance of considering surgical approach.

Obesity increases genomic instability at DNA repeat-mediated endogenous mutation hotspots

Obesity is associated with increased cancer risk, yet the underlying mechanisms remain elusive. Obesity-associated cancers involve disruptions in metabolic and cellular pathways, which can lead to genomic instability. Repetitive DNA sequences capable of adopting alternative DNA structures (e.g., H-DNA) stimulate mutations and are enriched at mutation hotspots in human cancer genomes. However, it is not known if obesity impacts DNA repeat-mediated endogenous mutation hotspots. We address this gap by measuring mutation frequencies in obese and normal-weight transgenic reporter mice carrying either a control human B-DNA- or an H-DNA-forming sequence (from a translocation hotspot in c-MYC in Burkitt lymphoma). Here, we discover that H-DNA-induced DNA damage and mutations are elevated in a tissue-specific manner, and DNA repair efficiency is reduced in obese mice compared to those on the control diet. These findings elucidate the impact of obesity on cancer-associated endogenous mutation hotspots, providing mechanistic insight into the link between obesity and cancer.

Effects of Calorie Restriction on Preserving Male Fertility Particularly in a State of Obesity

PURPOSE OF REVIEW

Highlight the importance of exploring nutritional interventions that could be applied as alternative or supplementary therapeutic strategies to enhance men's fertility.

RECENT FINDINGS

Lifestyle choices have prompted extensive discussions regarding its implications and applications as a complementary therapy. The growing concern over the decline in sperm quality underscores the urgency of investigating these alternative interventions. Calorie restriction (CR) has emerged as a promising strategy to improve male fertility. The efficacy of CR depends on factors like age, ethnicity and genetics. Clinical studies, such as CALERIE, have shown an improvement in serum testosterone level and sexual drive in men with or without obesity. Additionally, CR has been shown to positively impact sperm count and motility; however, its effects on sperm morphology and DNA fragmentation remain less clear, and the literature has shown discrepancies, mainly due to the nature of technically dependent assessment tools. The review advocates a personalized approach to CR, considering individual health profiles to maximize its benefits. It underscores the need for routine, accessible diagnostic techniques in male reproductive health. It suggests that future research should focus on personalized dietary interventions to improve male fertility and overall well-being in individuals with or without obesity and unravel CR's immediate and lasting effects on semen parameters in men without obesity.

The influence of lifestyle and biological factors on semen variability

PURPOSE

Semen parameters are subjected to within-individual variability over time. The driving factors for this variability are likely multi-factorial, with healthier lifestyle associated with better semen quality. The extent in which variations in individual's lifestyle contributes to within-individual semen variability is unknown.

METHODS

A total of 116 repeat semen samples from 29 men aged 19-37 over 6 months were collected. Basic semen analysis as per 5th WHO manual and extended semen parameters (sperm DNA fragmentation, redox potential and lipid peroxidation, sperm binding to hyaluronan and hyperactive motility) were assessed. An additional 39 lifestyle/biological factors (weight, blood pressure, etc.) were collected at each sample including validated health questionnaires SF36 Health Status, Australian Recommend Food Score, and International Physical Activity Questionnaire.

RESULTS

Only 10 out of the 39 lifestyle factors varied within men across samples including age (P = 0.0024), systolic blood pressure (P = 0.0080), social functioning (P = 0.0340), energy (P = 0.0069), non-alcoholic caffeinated beverages (P = 0.0010), and nutrition (P < 0.0001). The only semen parameter that varied between collections was sperm morphology (coefficient of variation 23.8 (6.1-72.0), P < 0.05). We only observed weak (r < 0.3) to moderate (r > 0.3- < 0.6) correlations between lifestyle factors, including body mass index, waist circumference, nutrition, exercise, blood pressure and semen parameters including sperm count, progressive motility, and sperm DNA fragmentation (P < 0.05).

CONCLUSION

In healthy men from the general population, semen quality and associated lifestyle factors do not significantly vary over 6 months, indicating that one semen sample is likely sufficient for determining male fertility in this population.