Macrophages of the sperm granuloma 3 months after vasectomy in the Albino Swiss rat

A Narrative Review Discussing Vasectomy-Related Impact upon the Status of Oxidative Stress and Inflammation Biomarkers and Semen Microbiota

Background: Male contraceptive approaches besides tubal sterilization involve vasectomy and represent the method of choice among midlife men in developing countries thanks to many advantages. However, the subsidiary consequences of this intervention are insufficiently explored since the involved mechanisms may offer insight into a much more complex picture. Methods: Thus, in this manuscript, we aimed to reunite all available data by searching three separate academic database(s) (PubMed, Web of Knowledge, and Scopus) published in the past two decades by covering the interval 2000–2023 and using a predefined set of keywords and strings involving “oxidative stress” (OS), “inflammation”, and “semen microbiota” in combination with “humans”, “rats”, and “mice”. Results: By following all evidence that fits in the pre-, post-, and vasectomy reversal (VR) stages, we identified a total of n = 210 studies from which only n = 21 were finally included following two procedures of eligibility evaluation. Conclusions: The topic surrounding this intricate landscape has created debate since the current evidence is contradictory, limited, or does not exist. Starting from this consideration, we argue that further research is mandatory to decipher how a vasectomy might disturb homeostasis.

Ethylene dimethane sulfonate (EDS) ablation of Leydig cells in adult rat depletes testosterone resulting in epididymal sperm granuloma: Testosterone replacement prevents granuloma formation

Sperm granuloma may develop in the epididymis following vasectomy or chemical insults. Inflammation due to sperm granuloma causes abdominal and scrotal pain. Prolonged and persistent inflammation in the epididymis due to sperm granuloma may lead to infertility. Extravasation of germ cells into the interstitium of epididymis following damage of the epididymal epithelium is one of the primary reasons for sperm granuloma-associated pathology. Since testosterone is vital for the maintenance of epididymal epithelium, we investigated the pathology of sperm granuloma and its relationship with testosterone. Adult rats were treated with a Leydig cell-specific toxicant ethylene dimethane sulfonate (EDS) to eliminate testosterone. At 7 days post-EDS, disrupted epididymal epithelium and sperm granuloma were observed in the caput epididymis. Sperm granuloma and caput were collagen-filled indicating fibrosis. Numerous round apoptotic cells were localized inside the caput lumen and dispersed through the sperm granuloma. Tnp1 (round spermatid marker) was significantly higher in the epididymis of the EDS-treated group compared to controls suggesting the apoptotic cells were round spermatids. Increases in CD68⁺ macrophages and T cells (CD4 and CD8) support an inflammatory immune infiltration in post-EDS epididymis. However, testosterone replacement following EDS prevented the sperm granuloma-associated pathology. We suggest that the immune response in the sperm granuloma may be due to the increased numbers of apoptotic round spermatids or other testicular tissue components that may be released, in addition to the regression of epididymal epithelium due to testosterone loss. Thus, testosterone replacement prevents EDS-induced sperm granuloma and ameliorates sperm granuloma-associated pathology.

Macrophage Populations in l-Cysteine-Induced Rat Sperm Granulomas

Histopathologically, sperm granulomas consist of a central mass of degenerating spermatozoa surrounded by many epithelioid macrophages and lymphocytes. Using monoclonal antibodies (ED1, ED2, and OX6), the authors investigated immunohistochemically the participation of different macrophage populations in epididymal sperm granulomas induced in pubertal rats by repeated injection of L-cysteine. Monocyte-like and epithelioid macrophages expressed the ED1 antigen found on activated lysosomal membranes in rat blood monocytes and exudate macrophages, but did not express the ED2 antigen found on the membrane antigens of rat resident macrophages. Cells expressing MHC class II antigens (as detected by the OX6 antibody) were present in the granulomas in moderate numbers, particularly in the early stages. Ultrastructurally, fragmented spermatozoa were observed in the cytoplasm of epithelioid macrophages. These findings suggest that macrophages appearing in rat sperm granulomas originate mainly from blood monocytes, and that they have a high phagocytic activity and a potential for antigen presentation.

Relationship of interstitial edema with L-cysteine-induced sperm granulomas in the pubertal rat epididymis

Although the pathogenesis of sperm granulomas is complicated, the leakage of spermatozoa into extraluminal tissues is regarded as a crucial event. It has been previously shown that pubertal rats injected with L-cysteine develop interstitial edema followed by sperm granulomas in the epididymis. In this study we investigated the relationships between these two lesions in 6-week old rats given daily intraperitoneal injections of L-cysteine (1,000 mg/kg body weight) for 4 weeks. Rats were examined during weeks 0, 1, 2, 3 and 4 after the first injection. Interstitial edema (moderate or severe) and sperm granulomas were seen in the corpus and cauda epididymis of L-cysteine-treated rats in study weeks 2, 3, and 4. There was no marked alteration of basement membrane of the epididymal ducts in the edematous tissues as shown by immunohistochemistry with an antilaminin antibody. However, the extravasation of Evans blue dye given I hour before necropsy suggested that the severe interstitial edema was due to increased vascular permeability. In addition, a small number of neutrophils were seen in the edematous tissues, suggesting that they might play a role in the increased vascular permeability and leakage of epididymal fluid. Interestingly, slight interstitial edema was observed in the caput epididymis in both control and L-cysteine-treated rats in early study weeks 0, 1, and 2. It is speculated that this change was related to the leakage of epididymal fluid due to increased intraluminal pressure depending on rat epididymal maturation. Taken together, these findings suggest that the severe interstitial edema results from increased vascular permeability. This, along with increased intraluminal pressure, might be the trigger for duct rupture, the prerequisite for sperm granuloma formation associated with excessive doses of L-cysteine.

Cellular responses to vasectomy

A number of cell populations in the reproductive tract show a response to vasectomy. Some cell types show similar responses in man and all laboratory species, whereas others show marked species variations. This chapter describes these effects in a broadly chronological order and, in a general way, considers changes close to the site of vasectomy first and the longer term effects on the testis itself later. Following vasectomy, epididymal distension and sperm granuloma formation result from raised intraluminal pressure. The sperm granuloma is a dynamic structure and a site of much spermatozoal phagocytosis by its macrophage population. In many species, spermatozoa in the obstructed ducts are destroyed by intraluminal macrophages, and degradation products, rather than whole sperm, are absorbed by the epididymal epithelium. Humoral immunity against spermatozoal antigens following vasectomy is well established and there is evidence of modest T-lymphocyte activity. The role of lymphocytes in the reproductive tract epithelium and interstitium following vasectomy is poorly defined. In laboratory animals, there is evidence that pressure-mediated damage to the seminiferous epithelium can follow sperm granuloma formation and obstruction in the epididymal head. However, the contribution of lymphocytes and antisperm antibodies to testicular damage after vasectomy is far from clear. A number of studies have suggested that testicular changes may follow vasectomy in man but their validity and mechanism of occurrence require further study.