by Anna Fregonara
A specific strain of lactobacilli would be able to alter the percentage of motile spermatozoa, favoring an inflammatory microenvironment hostile to fertility
There is still little talk about it, even if scientific research is growing, but it could be important for couples hoping to become parents. The microbiota of seminal fluid, that community of microbacteria that lives, for example, also in our intestines or on the skin and which, if in balance, works for our well-being, could have a potential role in fertility.
Lactobacillus inert e l’infiammazione
Researchers from the University of California, we read in Nature Scientific Reports, analyzed semen samples from 73 men aged 18 or older, recruited for a fertility evaluation or vasectomy consultation after having already had children. The 27 men with impaired sperm motility showed a greater abundance of Lactobacillus iners, compared to the 46 men whose sperm motility was normal. Previous research has revealed that Lactobacillus iners can produce lactic acid, potentially leading to a locally pro-inflammatory environment that could negatively affect sperm motility. Furthermore, it is known that the presence of this bacterium in certain quantities is vital, for example, in the vaginal microbiota, but, if in excess, can reduce fertility rates and promote bacterial vaginosis.
The Californian researchers also saw that in 20 samples with reduced sperm concentration, the bacteria Pseudomonas fluorescens and Pseudomonas stutzeri appeared more common than in 53 samples with normal sperm counts.
Men and infertility
However, the findings indicate that closely related microbes may not always have the same direct correlation with fertility. «Male infertility means the inability of a man to induce spontaneous pregnancy in a given period of time (12-24 months) characterized by unprotected sexual activity, naturally considering a female partner with a preserved ovulatory phase, tubal patency, no abnormality of the uterus and cervical mucus. The isolated male factor represents approximately 1/3 of the causes of couple infertility. The composition of the microbiota of the seminal fluid influences fertility”, explains Sandro La Vignera, endocrinologist and PhD in Andrological Sciences, associate professor of Endocrinology at the University of Catania and author of several scientific research on this topic. «The data is accumulating, the level of evidence in this field is certainly constantly growing. The study of the microbiota of seminal fluid represents an aspect of diagnostics dedicated to the analysis of non-routine male infertility. However, it has great potential in improving the understanding of the so-called “idiopathic” or “sine causa” forms, i.e. men who are apparently normozoospermic, but with spermatozoa incapable of fertilizing. The study, although limited by a small number of cases, goes into the merits of identifying a specific strain of lactobacilli capable of altering the percentage of motile spermatozoa through a mechanism – that of the excessive accumulation of lactic acid – favoring the creation of an inflammatory and oxidative, two “enemies” of fertility”.
Risk factors
Fertility depends on various aspects. «Female age still represents the element that most influences the parameter of natural fertilization», continues the expert. «Good oocyte quality is crucial to compensate for moderate sperm defects. In the male context, the risk factors that often become chronic, without generating major disorders, are: increased concentration of leukocytes in the seminal fluid (leukocytospermia); advanced varicocele without other concomitant causative factors in the same patient; reduction in testosterone levels; metabolic factors, particularly visceral obesity; cigarette smoking; excessive alcohol consumption; sexually transmitted diseases; inappropriate use of drugs interfering with testicular endocrine function”.
An easy to measure but little used parameter
«In Italy and around the world, approximately one in four men shows a slight reduction in testicular volume, a factor closely related to sperm count, and alteration of at least one first level seminal parameter including concentration, motility, morphology», says the endocrinologist. «The culture of primary prevention of male infertility is missing. The transition age represents a gray area. The moment of transition from the pediatrician to the family doctor with an adequate testicular volume is essential. There is no habit of transferring to the subject the data of the orchidometer curve, detectable through an instrument called orchidometer, very easy to use, which, instead, should have the same value as the height curve, certainly better known and shared by the doctors themselves ».
Treatments could change
The most studied microbiota is the intestinal one, whose transplantation, orally, is exploited to fight, for example, infections such as Clostridium difficile. «We are not yet at these levels in the field of male fertility», specifies the specialist. «The understanding of the existence of some species of lactobacilli capable of altering testicular endocrine function, however, can represent an important basis for contributing to new therapeutic avenues to correct alterations in sperm parameters and improve male fertility». «Seminal plasma has its own constitutional microbiota and microbiome (the genes of microorganisms) composition. It varies depending on the state of health of the accessory sexual glands: prostate, seminal vesicles and epididymis. They are responsible for the production of the greatest quantity of seminal plasma, in particular the seminal vesicles can produce up to 60% of it.”
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February 14, 2024 (modified February 14, 2024 | 4:58 pm)
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