Study findings could lead to new clinical laboratory testing biomarkers designed to assess for male infertility
Clinical laboratories are increasingly performing tests that have as their biomarkers the DNA and enzymes found in human microbiota. And microbiologists and epidemiologists know that like other environments within the human body, semen has its own microbiome. Now, a study conducted at the University of California, Los Angeles (UCLA) has found that the health of semen microbiome may be linked to male infertility.
The UCLA researchers discovered a small group of microorganisms within semen that may impair the sperm’s motility (its ability to swim) and affect fertility.
A total of 73 individuals were included in the study. About half of the subjects were fertile and already had children, while the remaining men were under consultation for fertility issues.
“These are people who have been trying to get pregnant with their partner, and they’ve been unsuccessful,” Sriram Eleswarapu, MD, PhD, a urologist at UCLA and co-author of the study, told Scientific American. “This latter group’s semen samples had a lower sperm count or motility, both of which can contribute to infertility.”
“There is much more to explore regarding the microbiome and its connection to male infertility,” said Vadim Osadchiy, MD (above), a resident in the Department of Urology at UCLA and lead author of the study, in a UCLA news release. “However, these findings provide valuable insights that can lead us in the right direction for a deeper understanding of this correlation.” Might it also lead to new biomarkers for clinical laboratory testing for male infertility? (Photo copyright: UCLA.)
Genetic Sequencing Used to Identify Bacteria in Semen Microbiome
Most of the microbes present in the semen microbiome originate in the glands of the male upper reproductive tract, including the testes, seminal vesicles and prostate, and contribute various components to semen. “Drifter” bacteria that comes from urine and the urethra can also accumulate in the fluid during ejaculation. Microbes from an individual’s blood, or his partner’s, may also aggregate in semen. It is unknown how these bacteria might affect health.
“I would assume that there are bacteria that are net beneficial, that maybe secrete certain kinds of cytokines or chemicals that improve the fertility milieu for a person, and then there are likely many that have negative side effects,” Eleswarapu told Scientific American.
The scientists used genetic sequencing to identify different bacteria species present within the semen microbiome. They found five species that were common among all the study participants. But men with more of the microbe Lactobacillus iners (L. iners) were likelier to have impaired sperm motility and experience fertility issues.
This discovery was of special interest to the team because L. iners is commonly found in the vaginal microbiome. In females, high levels of L. iners are associated with bacterial vaginosis and have been linked to infertility in women. This is the first study that found a negative association between L. iners and male fertility.
The researchers plan to investigate specific molecules and proteins contained in the bacteria to find out whether they slow down sperm in a clinical laboratory situation.
“If we can identify how they exert that influence, then we have some drug targets,” Eleswarapu noted.
Targeting Bacteria That Cause Infertility
The team also discovered that three types of bacteria found in the Pseudomonas genus were present in patients who had both normal and abnormal sperm concentrations. Patients with abnormal sperm concentrations had more Pseudomonas fluorescens and Pseudomonas stutzeri and less Pseudomonas putida in their samples.
According to the federal National Institute of Child Health and Human Development (NICHD), “one-third of infertility cases are caused by male reproductive issues, one-third by female reproductive issues, and the remaining one-third by both male and female reproductive issues or unknown factors.” Thus, learning more about how the semen microbiome may be involved in infertility could aid in the development of drugs that target specific bacteria.
“Our research aligns with evidence from smaller studies and will pave the way for future, more comprehensive investigations to unravel the complex relationship between the semen microbiome and fertility,” said urologist Vadim Osadchiy, MD, a resident in the Department of Urology at UCLA and lead author of the study, in a UCLA news release.
More research is needed. For example, it’s unclear if there are any links between the health of semen microbiome and other microbiomes that exist in the body, such as the gut microbiome, that cause infertility. Nevertheless, this research could lead to new biomarkers for clinical laboratory testing to help couples who are experiencing fertility issues.
Scientists believe useful new clinical laboratory assays could be developed by better understanding the huge number of ‘poorly researched’ genes and the proteins they build
Researchers have added a new “-ome” to the long list of -omes. The new -ome is the “unknome.” This is significant for clinical laboratory managers because it is part of an investigative effort to better understand the substantial number of genes, and the proteins they build, that have been understudied and of which little is known about their full function.
The Unknome Database includes “thousands of understudied proteins encoded by genes in the human genome, whose existence is known but whose functions are mostly not,” according to a news release.
The database, which is available to the public and which can be customized by the user, “ranks proteins based on how little is known about them,” the PLOS Biology paper notes.
It should be of interest to pathologists and clinical laboratory scientists. The fruit of this research may identify additional biomarkers useful in diagnosis and for guiding decisions on how to treat patients.
“These uncharacterized genes have not deserved their neglect,” said Sean Munro, PhD (above), MRC Laboratory of Molecular Biology in Cambridge, England, in a press release. “Our database provides a powerful, versatile and efficient platform to identify and select important genes of unknown function for analysis, thereby accelerating the closure of the gap in biological knowledge that the unknome represents.” Clinical laboratory scientists may find the Unknome Database intriguing and useful. (Photo copyright: Royal Society.)
Risk of Ignoring Understudied Proteins
Proteomics (the study of proteins) is a rapidly advancing area of clinical laboratory testing. As genetic scientists learn more about proteins and their functions, diagnostics companies use that information to develop new assays. But did you know that researchers tend to focus on only a small fraction of the total number of protein-coding DNA sequences contained in the human genome?
The study of proteomics is primarily interested in the part of the genome that “contains instructions for building proteins … [which] are essential for development, growth, and reproduction across the entire body,” according to Scientific American. These are all protein-coding genes.
Proteomics estimates that there are more than two million proteins in the human body, which are coded for 20,000 to 25,000 genes, according to All the Science.
To build their database, the MRC researchers ranked the “unknome” proteins by how little is known about their functions in cellular processes. When they tested the database, they found some of these less-researched proteins important to biological functions such as development and stress resistance.
“The role of thousands of human proteins remains unclear and yet research tends to focus on those that are already well understood,” said Sean Munro, PhD, MRC Laboratory of Molecular Biology in Cambridge, England, in the news release. “To help address this we created an Unknome database that ranks proteins based on how little is known about them, and then performed functional screens on a selection of these mystery proteins to demonstrate how ignorance can drive biological discovery.”
In the paper, they acknowledged the human genome encodes about 20,000 proteins, and that the application of transcriptomics and proteomics has “confirmed that most of these new proteins are expressed, and the function of many of them has been identified.
“However,” the authors added, “despite over 20 years of extensive effort, there are also many others that still have no known function.”
They also recognized limited resources for research and that a preference for “relative safety” and “well-established fields” are likely holding back discoveries.
The researchers note “significant” risks to continually ignoring unexplored proteins, which may have roles in cell processes, serve as targets for therapies, and be associated with diseases as well as being “eminently druggable,” Genetic Engineering News reported.
Setting up the Unknome Database
To develop the Unknome Database, the researchers first turned to what has already come to fruition. They gave each protein in the human genome a “knownness” score based on review of existing information about “function, conservation across species, subcellular localization, and other factors,” Interesting Engineering reported.
It turns out, 3,000 groups of proteins (805 with a human protein) scored zero, “showing there’s still much to learn within the human genome,” Science News stated, adding that the Unknome Database catalogues more than 13,000 protein groups and nearly two million proteins.
The researchers then tested the database by using it to determine what could be learned about 260 “mystery” genes in humans that are also present in Drosophila (small fruit flies).
“We used the Unknome Database to select 260 genes that appeared both highly conserved and particularly poorly understood, and then applied functional assays in whole animals that would be impractical at genome-wide scale,” the researchers wrote in PLOS Biology.
“We initially selected all genes that had a knownness score of ≤1.0 and are conserved in both humans and flies, as well as being present in at least 80% of available metazoan genome sequences. … After testing for viability, the nonessential genes were then screened with a panel of quantitative assays designed to reveal potential roles in a wide range of biological functions,” they added.
“Our screen in whole organisms reveals that, despite several decades of extensive genetic screens in Drosophila, there are many genes with essential roles that have eluded characterization,” the researchers conclude.
Clinical Laboratory Testing Using the Unknome Database
Future use of the Unknome Database may involve CRISPR technology to explore functions of unknown genes, according to the PLOS Biology paper.
Munro told Science News the research team may work with other research efforts aimed at understanding “mysterious proteins,” such as the Understudied Proteins Initiative.
The Unknome Database’s ability to be customized by others means researchers can create their own “knownness” scores as it applies to their studies. Thus, the database could be a resource in studies of treatments or medications to fight diseases, Chemistry World noted.
According to a statement prepared for Healthcare Dive by SomaLogic, a Boulder, Colorado-based protein biomarker company, diagnostic tests that measure proteins can be applied to diseases and conditions such as:
“The 27-protein model has potential as a ‘universal’ surrogate end point for cardiovascular risk,” the researchers wrote in Science Translational Medicine.
Proteomics definitely has its place in clinical laboratory testing. The development of MRC-LMB’s Unknome Database will help researchers’ increase their knowledge about the functions of more proteins which should in turn lead to new diagnostic assays for labs.
These new insights might lead to a new line of clinical laboratory testing, particularly if the results could guide the patient to microbiome-based repellents that would remain effective for months once applied
Researchers are beginning to identify what compounds make individuals more attractive to mosquitos. That is a first step in the development of a biomarker that could be developed into a clinical laboratory test. Question is: would there be enough consumers wanting to do a lab test to determine if they were highly attractive to mosquitos, thus making this a revenue-generating test for labs?
The SA article reported on their study published in the journal Cell titled, “Differential Mosquito Attraction to Humans Is Associated with Skin-Derived Carboxylic Acid Levels.” The researchers, according to SA, found that individual humans have “a unique scent profile made up of different chemical compounds” and that “mosquitoes were most drawn to people whose skin produces high levels of carboxylic acids.” The researchers also found that “attractiveness to mosquitoes remained steady over time, regardless of changes in diet or grooming habits.”
At a minimum, there would be widespread consumer interest to at least understand why some individuals get more mosquito bites than others. What may be of particular interest to microbiologists is the statement by molecular biologist Omar Akbari, PhD, of the University of California, San Diego, who told Scientific American that by “taking human-colonizing skin bacteria … and engineering them in such a way that they can either express a repellent compound or be able to degrade something that’s attractive,” a mosquito repellant could be developed that would last for months once applied.
“This study clearly shows that these acids are important,” neurogeneticist Matthew DeGennaro, PhD (above), told CNN. “… how the mosquitoes perceive these carboxylic acids is interesting because these particular chemicals … are hard to smell at a distance. It could be that these chemicals are being altered by … the skin microbiome … if we understand why mosquitoes find a host, we can design new repellents that will block the mosquitoes from sensing those chemicals, and this could be used to improve our current repellents.” Clinical laboratory testing will be needed to produce biomarkers for developing such improved repellents. (Photo copyright: Laboratory of Tropical Genetics.)
Clinical Laboratory Testing Needed to Identify Levels of Carboxylic Acids
To complete their study, the researchers had 64 participants wear nylon stockings for six hours on their arms to get their unique scent into the fabric. The scent on the stockings was not discernible to the human nose, but it was to the mosquitos.
Two pieces of the nylon were then placed in a closed container with Aedes aegypti mosquitoes. The researchers found that certain samples were more popular with the mosquitos than others. Upon further analysis the researchers found that the most popular samples came from subjects with higher levels of carboxylic acids, and the least popular had the lowest levels. The scientists ran the test with the same participants several times over three years and the results remained largely the same.
Carboxylic acid is an organic compound found in humans in sebum, the oily layer protecting our skin. The level at which humans release carboxylic acid varies from person to person. And there is no discernible way the human nose can determine whether a person has the level of carboxylic acid on the skin that mosquitos find desirable. The answer would need to be determined by a diagnostic test performed in a clinical laboratory.
Although the development of a test to determine someone’s susceptibility to mosquitos may be far away, there could be significant consumer interest in developing such a test.
“The question of why some people are more attractive to mosquitoes than others—that’s the question that everybody asks,” Leslie B. Vosshall, PhD, Chief Scientific Officer, Howard Hughes Medical Institute, who led the research team to find out why some people are more attractive to mosquitos than others, told Scientific American. “My mother, my sister, people in the street, my colleagues—everybody wants to know.” She credits their interest as the inspiration for embarking on the study.
“Understanding what makes someone a ‘mosquito magnet’ will suggest ways to rationally design interventions such as skin microbiota manipulation to make people less attractive to mosquitoes. We propose that the ability to predict which individuals in a community are high attractors would allow for more effective deployment of resources to combat the spread of mosquito-borne pathogens,” the researchers wrote in their Cell paper.
Preventing Spread of Deadly Diseases
Although mosquitos are an annoyance, they also can be dangerous vectors of disease.
“Every bite of these mosquitoes puts people into public health danger. Aedes aegypti mosquitoes are vectors for dengue, yellow fever, and Zika,” Vosshall told CNN. “Those people who are magnets are going to be much more likely to be infected with viruses.”
Further research into these early findings may help develop diagnostic tests to protect against the spread of these diseases and identify individuals who are more attractive to the mosquitos, and therefore, more likely to contract and spread disease.
Being able to identify which individuals are mosquito magnets could help keep individuals safe from dangerous diseases, and development of a better repellent could also make outdoor summer events more bearable for the (unfortunately) popular among the pests. Medical laboratory tests associated with determining an individual’s susceptibility to mosquito bites could give clinical laboratories a new way to add value to consumers and patients.
At-home genetic test kits face scrutiny for providing information that may provide consumers with an incomplete picture of their genetic health risks and ancestry
Genetic testing for disease risk and heritage are hugely popular. But though clinical laboratory and pathology professionals understand the difference between a doctor-ordered genetic health risk (GHR) test and a direct-to-consumer (DTC) genetic test, the typical genetic test customer may not. And misunderstanding the results of a DTC at-home genetic test can lead to confusion, loss of privacy, and potential harm, according to Consumer Reports.
To help educate consumers about the “potential pitfalls” of at-home DTC testing kits offered by companies such as Ancestry and 23andMe, Consumer Reports has published an article, titled, “Read This Before You Buy a Genetic Testing Kit.” The article covers “four common claims from the manufacturers of these products, whether they deliver, and what to know about their potential pitfalls.”
Are Genetic Ancestry Tests Accurate?
Ancestry and 23andMe are the DTC genetic test industry leaders, with databases of genetic information about 18 million individuals and 10 million individuals respectively. According to a Consumer Reports survey, as of October 2020 about one in five Americans had taken a DTC genetic test. Reported reasons for doing so included:
66% of respondents wanted to learn more about their ancestry.
20% wanted to locate relatives.
18% wanted to learn more about their health.
11% wanted to learn if they have or are a carrier for any medical conditions.
3% wanted to get a medical test they could not get through their doctor.
Though DTC genetic tests remain popular, Consumer Reports is now warning consumers to view the genealogical or medical insights gleaned through these tests with caution. “If you go in there thinking that this test is going to tell you who you are, you’re going to be wrong,” Wendy Roth, PhD (above), Associate Professor of Sociology at the University of Pennsylvania, told the publication. (Photo copyright: University of Pennsylvania.)
As Consumer Reports notes, doctor-ordered genetic health risk (GHR) testing typically aims to answer a specific question about a patient’s risk for a certain disease. DTC at-home genetic testing, on the other hand, examines a “whole range of variants that have been linked—sometimes quite loosely—to a number of traits, some not related to your health at all.
“Think of it this way: When your doctor orders genetic testing, it’s akin to fishing for a particular fish, in a part of the ocean where it’s known to live,” Consumer Reports noted, “A DTC test is more like throwing a net into the ocean and seeing what comes back.”
In its article, Consumer Reports addressed four common DTC genetic test claims:
The Tests Can Find Far-Flung Relatives: While the tests can unearth people in its database whom you might be related to, 9% of respondents in the Consumer Reports survey discovered unsettling information about a relative.
Testing Can Uncover Where Your Ancestors Are From: Genetic tests may show the percentage of your DNA that comes from Europe or Asia or Africa, but accuracy depends on how many DNA samples a company has from a particular region. As genetic test manufacturers’ reference databases widen, a customer’s genetic ancestry test results can “change over time.” Also, finding a particular variation in genetic code does not definitively place someone in a specific region, or ethnic or racial group.
Genetic Tests Can Reveal Your Risk for Certain Diseases: Testing companies such as 23andMe are authorized by the Food and Drug Administration (FDA) to offer physician-mediated tests, which are analyzed in a federally-certified clinical laboratory. However, test results may provide a false sense of security because DTC tests look for only select variants known to cause disease.
The Tests Can Tell What Diet Is Best for You: Incorporating genetic information into diet advice has the potential to be transformative, but the science is not yet there to offer personalized nutritional advice.
Consumer Reports pointed to a 2020 study published in the MDPI journal Nutrients, titled, “Direct-to-Consumer Nutrigenetics Testing: An Overview,” which evaluated 45 DTC companies offering nutrigenetics testing and found a need for “specific guidelines” and “minimum quality standards” for the services offered. For example, the study authors noted that more than 900 genetic variants contribute to obesity risk. However, weight-loss advice from DTC test companies was based on a “limited set of genetic markers.”
In the Consumer Reports article, Mwenza Blell, PhD, a biosocial medical anthropologist and Rutherford Fellow and NUAcT Fellow at Newcastle University in the United Kingdom, said “genetic ancestry tests are closer to palm reading than science.”
Seattle Cancer Care Alliance and an Associate Professor of Oncology at the University of Washington, fears consumers “miss important limitations on a test’s scope” or “misunderstand critical nuances in the results.”
Cheng says the ability to use flexible or health savings accounts (HSAs) to cover the cost of 23andMe’s GHR assessments, as well as the FDA’s approval of 23andMe’s Personal Genome Service Pharmacogenetic Reports test on medication metabolism, may have added to the confusion.
“This may further mislead people into thinking these tests are clinically sound. Again, they are not,” Cheng wrote.
As an oncologist, Cheng is particularly concerned about consumer GHR testing for heritable cancer risk, which screen for only a handful of genetic variants.
“The results are inadequate for most people at high risk of cancers associated with inherited mutations in BRCA1 or BRCA2 genes, including families whose members have experienced ovarian cancer, male breast cancer, multiple early breast cancers, pancreatic cancer, or prostate cancer,” Cheng wrote. “Put simply, this recreational test has zero value for the majority of people who may need it for true medical purposes.”
DTC genetic health-risk assessments may one day lead to consumers collecting samples at home for tests that aid in the diagnosis of disease. In the meantime, clinical laboratory professionals can play a role in educating the public about the limitations of current DTC genetic test offerings.
Initial skin test research shows promise but larger clinical studies needed before diagnostic tool could be ready for use by medical laboratories and pathologists
Researchers in Mexico developed a skin test that could lead to the early diagnosis of Alzheimer’s disease and pave the way for new therapies to treat a disease ranked as the sixth leading cause of death in the United States.
