Male Infertility Caused by Bacterial Lipopolysaccharides1st September 2017
The spermatozoon is the male gamete whose function is to lead the DNA towards the egg (female gamete) and form a zygote that will later turn into the embryo and the fetus. Therefore, the sperm count is considered to be of great importance for public health primarily because it is closely related to male fertility and it is a key component in semen analysis.
There are several studies carried out into male infertility. They point to a worldwide decrease in the quality of human semen due to several factors such as environmental influences; lifestyle, including diet; stress; testicular cancer and inflammation of the male genital tract associated with pathogenic microorganism infections, etc.
Reproductive tract infections account for almost 15% of the cases of male infertility. Bacteria are the most commonly identified pathogens in the semen of infected men. Particularly Gram-negative bacteria, including Escherichia coli, Staphylococcus aureus and Mycobacterium tuberculosis, can infect the testes, epididymis, prostate and other accessory sex glands, which can, in turn, affect spermatogenesis, the development and maturation of Spermatozoa, and therefore reduce the quality of semen. Scientific data rank E. coli as the most frequently isolated bacterium in the ejaculation of infertile men, responsible for 60 to 85% of the cases of chronic bacterial prostatitis with spermatic damage.
Bacterial lipopolysaccharides (LPS) are a major component of the cell wall of the Gram-negative bacteria. These bacteria release LPS molecules, which bind to cell membrane receptors, particularly to Toll-like receptors, and stimulate Pathogen-Associated Molecular Patterns (PAMPs). Several studies confirm the toxicity of LPS on male reproduction, focusing mainly on the toxic effects for testicular function and spermatogenesis. However, the way LPS affect the spermatozoa in vitro is not very well understood.
Another study carried out to investigate the in vitro effects of bacterial endotoxins on mature spermatozoa revealed that LPS significantly inhibit the motility of human sperm and their ability to penetrate through the viscous medium of the female reproductive tract through the decrease in the intracellular cAMP. This decrease in the intracellular cAMP is consistent with previous reports which confirm that the intracellular cAMP is critically involved in LPS-mediated signalling pathways and is significantly decreased by LPS in other cell types. These results suggest that LPS may cause a deregulation in sperm functions even after the production, development and maturation of sperm. The risk of infertility associated with the reproductive toxicity of LPS could increase if bacterial endotoxins accumulate in the mature sperm environment, such as the seminal plasma, prostate fluid, reproductive tract fluid and follicular fluid.
The company “Wako Chemicals”, a distirbutor of research reagents, has the LAL Division, rwhich is dedicated to the detection of bacterial endotoxins or Lipopolysaccharides with the Limulus Amebocyte Lysate (LAL) test. This FDA-licensed facility offers the PYROSTAR™ line, which includes a series of accessories and LAL reagents complying with all the standards, regulations and quality standards set by the FDA.
- The simple Limulus PS Test, for the detection of endotoxins with the Pyrosep™ method.
- The PYROSTAR™ ES-F series, an endotoxin-specific LAL reagent for the in vitro determination of endotoxins without the interference of glucans in the sample. This test is not a diagnostic tool and should not be used to determine endotoxin levels in humans to this end.
- The Limulus KY Color Kit, designed for colorimetric analysis based on time, through a synthetic substrate which generates a yellow colour and which can specifically detect endotoxins with a high level of sensitivity.
- Endotoxin-free water and Control Standard Endotoxin, from E. coli. Used to confirm the sensitivity of the LAL reagent, validate the test methods of the product and prepare inhibition controls.
- For the extraction of endotoxins that cannot be extracted by water or saline solutions, the PYROSTAR™ line has an endotoxin extracting solution for LAL tests. This product contains human serum albumin and is recommended for use in endotoxin testing in medical equipment or devices that may be in contact with blood or protein-containing fluids.
- The Toxinometer® ET-6000 computerized incubation kinetic reader with the Toximaster QC7 software for efficient work and high quality data analysis.
- Endotoxin-free accessories, such as Test Tubes and Lids, Bioclean® Pipette Tips and Wako Bioclean® Plates, among others.
1) Li, Z., Zhang, D., He, Y., Ding, Z., Mao, F., Luo, T., y otros. (2016). Lipopolysaccharide compromises human sperm function by reducing intracellular cAMP. The Tohoku journal of experimental medicine, 238(2), 105-112.
2) Sahnoun, S., Sellami, A., Chakroun, N., Mseddi, M., Attia, H., Rebai, T., y otros. (2017). Human sperm Toll-like receptor 4 (TLR4) mediates acrosome reaction, oxidative stress markers, and sperm parameters in response to bacterial lipopolysaccharide in infertile men. Journal of Assisted Reproduction and Genetics, 1-11.
3) Villegas, J. V., Boguen, R., & Uribe, P. (2017). Effect of Uropathogenic Escherichia coli on Human Sperm Function and Male Fertility. En Escherichia coli-Recent Advances on Physiology, Pathogenesis and Biotechnological Applications. InTech.
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