Study question: What are the associations between semen apoptotic M540 bodies and other parameters of semen quality and sonographic alterations of the male genital tract in a cohort of infertile subjects?
Summary answer: In infertile subjects, semen M450 bodies are highly correlated with ultrasound and clinical signs of testis abnormalities but not with alterations of other parts of the male genital tract, suggesting a testicular origin of M540 bodies.
What is known already: We have reported the presence in semen of round anucleate elements, named 'M540 bodies', resembling apoptotic bodies as they contain several apoptotic markers.
Study design and size: A consecutive series of 130 males with couple infertility were evaluated, during the same day session, for clinical, scrotal and transrectal color-Doppler ultrasound characteristics, and hormonal and semen parameters, including interleukin 8 (sIL-8) and M540 body levels.
Participants/materials, setting methods: Semen parameters were analyzed by WHO recommended procedures. CDU was performed using the ultrasonographic console Hitachi H21. sIL-8 and serum hormones were evaluated by ELISA methods.
Main results and the role of chance: The average percentage value of M540 bodies was 24.6 ± 18.3. After adjusting for possible confounders (age, waist, calculated free testosterone and smoking habit), M450 body levels negatively correlated with sperm number/ejaculate, progressive motility, normal morphology and sIL-8 levels (adj.r = -0.455, P < 0.0001; adj.r = -0.464, P < 0.0001; adj.r = -0.430, P < 0.001; adj.r = -0.236, P < 0.05, respectively). In a subset of patients with a history of cryptorchidism (n = 8), M540 bodies were higher than in non-cryptorchid men (40.5 ± 14.8 versus 23.6 ± 18.2%; P < 0.02). A negative correlation was found between M540 and ultrasound testis volume (adj.r = -0.241, P < 0.05), whereas a positive association was found with testis inhomogeneity [HR = 1.06 (1.02-1.09); P = 0.002], hypoechogenicity [HR = 1.05 (1.01-1.08); P < 0.02] and FSH levels (adj.r = 0.309, P < 0.01). No relationships were found with CDU characteristic of the prostate, seminal vesicles, epididymis and vas deferens. In a multivariate model, testis inhomogeneity and history of cryptorchidism were independently associated with M540 body levels (adj.r = 0.355, P < 0.01 and adj.r = 0.223, P < 0.05, respectively). Receiver operating characteristic analysis demonstrated that at the threshold of 27%, M540 bodies discriminate subjects with testis inhomogeneity with a sensitivity of 72% and specificity of 73%.
Limitations, reasons for caution: The increased M540 body semen levels in men with a history of cryptorchidism should be confirmed in a larger number of patients.
Wider implications of the findings: M540 bodies may be considered a semen marker of altered testis function and thus their evaluation may be helpful in the diagnosis of male infertility.
Study funding/competing interest(s): This work was supported by grants from Ministry of University and Scientific Research (Prin project to E.B. and FIRB project to S.M.) and Regione Toscana (to G.F.).