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Published on: June 29, 2021
Soluble products of Escherichia coli induce mitochondrial dysfunction-related sperm membrane lipid peroxidation which
Arcangelo Barbonetti1, Maria Rosaria Caterina Vassallo2, Benedetta Cinque3
1Andrology Unit, Department of Life, Health and Environment Sciences, University of L'Aquila, L'Aquila, Italy ; San Raffaele Sulmona Institute, Sulmona, Italy.
Abstract:
Unidentified soluble factors secreted by E. coli, a frequently isolated microorganism in genitourinary infections, have been reported to inhibit mitochondrial membrane potential (ΔΨm), motility and vitality of human spermatozoa. Here we explore the mechanisms involved in the adverse impact of E. coli on sperm motility, focusing mainly on sperm mitochondrial function and possible membrane damage induced by mitochondrial-generated reactive oxygen species (ROS). Furthermore, as lactobacilli, which dominate the vaginal ecosystem of healthy women, have been shown to exert anti-oxidant protective effects on spermatozoa, we also evaluated whether soluble products from these microorganisms could protect spermatozoa against the effects of E. coli. We assessed motility (by computer-aided semen analysis), ΔΨm (with JC-1 dye by flow cytometry), mitochondrial ROS generation (with MitoSOX red dye by flow cytometry) and membrane lipid-peroxidation (with the fluorophore BODIPY C11 by flow cytometry) of sperm suspensions exposed to E. coli in the presence and in the absence of a combination of 3 selected strains of lactobacilli (L. brevis, L. salivarius, L. plantarum). A Transwell system was used to avoid direct contact between spermatozoa and microorganisms. Soluble products of E. coli induced ΔΨm loss, mitochondrial generation of ROS and membrane lipid-peroxidation, resulting in motility loss. Soluble factors of lactobacilli prevented membrane lipid-peroxidation of E. coli-exposed spermatozoa, thus preserving their motility. In conclusion, sperm motility loss by soluble products of E. coli reflects a mitochondrial dysfunction-related membrane lipid-peroxidation. Lactobacilli could protect spermatozoa in the presence of vaginal disorders, by preventing ROS-induced membrane damage.
Insights
Escherichia coli soluble factors harm sperm motility by damaging mitochondria and causing lipid peroxidation. Lactobacilli soluble factors protect sperm by preventing this damage, preserving motility.
Area of Science:
- Reproductive Biology
- Microbiology
- Biochemistry
Background:
- Genitourinary infections with E. coli can negatively impact sperm function.
- E. coli secreted factors are known to inhibit sperm mitochondrial membrane potential, motility, and vitality.
- Lactobacilli, dominant in healthy vaginal flora, possess antioxidant properties beneficial to spermatozoa.
Purpose of the Study:
- To investigate the mechanisms by which E. coli soluble factors impair sperm motility, focusing on mitochondrial function and reactive oxygen species (ROS).
- To determine if soluble products from selected lactobacilli strains can protect human spermatozoa against E. coli-induced damage.
- To assess the role of mitochondrial-generated ROS and membrane lipid peroxidation in E. coli's adverse effects on sperm.
Main Methods:
- Sperm suspensions were exposed to soluble factors from E. coli and a combination of L. brevis, L. salivarius, and L. plantarum in a Transwell system.
- Sperm motility was assessed using computer-aided semen analysis.
- Mitochondrial membrane potential (ΔΨm) and mitochondrial ROS generation were measured by flow cytometry using JC-1 and MitoSOX red dyes, respectively.
- Membrane lipid peroxidation was evaluated using the BODIPY C11 fluorophore via flow cytometry.
Main Results:
- Soluble products from E. coli significantly reduced sperm mitochondrial membrane potential (ΔΨm), increased mitochondrial ROS generation, and induced membrane lipid peroxidation, leading to decreased sperm motility.
- Exposure to soluble factors from lactobacilli prevented E. coli-induced membrane lipid peroxidation in spermatozoa.
- Lactobacilli treatment preserved sperm motility despite exposure to E. coli soluble factors.
Conclusions:
- Sperm motility loss induced by E. coli soluble factors is linked to mitochondrial dysfunction and subsequent membrane lipid peroxidation.
- Soluble factors from lactobacilli offer a protective effect against E. coli-induced sperm damage by inhibiting ROS-mediated membrane lipid peroxidation.
- Lactobacilli may play a crucial role in maintaining sperm health in the context of vaginal dysbiosis by counteracting detrimental microbial factors.
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