Biomarker may lead to clinical laboratory testing that enables clinical pathologists and urologists to diagnose risk for diabetic kidney failure years before it occurs
Clinical laboratories working with nephrologists and urologists to diagnose patients experiencing urinary system difficulties know that albumin (excessive protein found in the urine) is a common biomarker used in clinical laboratory testing for kidney disease. But patients with diabetes generally have low protein in their urine due to that disease. Thus, it is difficult to diagnose early stage kidney failure in diabetic patients.
But now, researchers at the University of Texas Health Science Center at San Antonio (UT Health San Antonio) have discovered a biomarker called adenine (also found in the urine) which, they say, offers the ability to diagnose diabetic patients at risk of kidney failure significantly earlier than other biomarkers.
A UT Health San Antonio news release states, “Urine levels of adenine, a metabolite produced in the kidney, are predictive and a causative biomarker of looming progressive kidney failure in patients with diabetes, a finding that could lead to earlier diagnosis and intervention.”
The study’s senior author Kumar Sharma, MD, professor and Chief of Nephrology at UT Health San Antonio, said, “The finding paves the way for clinic testing to determine—five to 10 years before kidney failure—that a patient is at risk.”
“The study is remarkable as it could pave the way to precision medicine for diabetic kidney disease at an early stage of the disease,” said study lead Kumar Sharma, MD (above), professor and Chief of Nephrology at UT Health San Antonio, in a news release. This would be a boon to clinical laboratories and pathology groups that work with urologists to diagnose and treat diabetic patients who are at-risk for kidney failure. (Photo copyright: UT Health San Antonio.)
Completing the UT Health Study
Sharma and his team worked for five years to discover that the adenine molecule was damaging kidney tissue, News4SA reported. The research required the team to develop new methods for viewing small molecules known as metabolites.
“UT Health San Antonio is one of few centers in the US perfecting a technique called spatial metabolomics on kidney biopsies from human patients,” the news release notes. The kidney biopsies were obtained through the Kidney Precision Medicine Project (KPMP) and were gathered from various US academic centers.
“It’s a very difficult technique, and it took us several years to develop a method where we combine high resolution of the geography of the kidney with mass spectrometry analysis to look at the metabolites,” Sharma said.
Testing by the UT Health team unearthed “endogenous adenine around scarred blood vessels in the kidney and around tubular-shaped kidney cells that were being destroyed. Endogenous substances are those that naturally occur in the body,” the news release notes.
Findings Could Affect Diabetic Care
UT Health San Diego’s study findings could allow for early intervention and change the way diabetes care is managed, Sharma said.
“The study results are significant because until now, the most important marker for kidney disease has been protein (or albumin) in the urine. Up to half of diabetes patients who develop kidney failure never have much protein in their urine. As 90% of patients with diabetes (more than 37 million patients in the US) remain at increased risk despite low levels of albumin in their urine, this study has widespread consequences. It is the first study to identify these patients at an early stage by measuring this new causative marker in the urine,” the UT Health news release states.
“We’re hoping that by identifying patients early in their course, and with new therapies targeting adenine and kidney scarring, we can block kidney disease or extend the life of the kidney much longer,” Sharma said.
Getting Ahead of Kidney Disease
Though many patients recognize their risk for kidney disease, those who do not have protein in their urine may not take the risk seriously enough, Sharma noted.
“They could be feeling a false sense of security that there is no kidney disease occurring in their body, but in fact, in many cases it is progressing, and they often don’t find out until the kidney disease is pretty far advanced. And at that time, it is much harder to protect the kidneys and prevent dialysis,” he said in the new release.
“Once a patient needs dialysis, he or she must have a fistula or catheter placed and go on a dialysis machine three times a week, four hours at a time to clean the blood,” the news release states.
“The death rate is very high, especially in patients with diabetes,” Sharma added. “There is about 40% mortality within five years in patients with diabetes and kidney failure.”
Though measuring adenine in urine is a challenge, Sharma and his team developed a method that can be performed at UT Health San Antonio on at-risk patients with a doctor’s order. The test results go back to the patient’s doctor.
“The test is being approved for clinical use and right now it is an experimental test, but we expect it to be available for all patients in the near future.” Sharma told News4SA.
“What we’re hoping is that by identifying patients early in their course, and with new therapies targeting adenine and kidney scarring, we can block kidney disease or extend the life of the kidney much longer,” Sharma said in the news release.
And so, thanks to the UT Health researchers, pathologists and clinical laboratories may soon see a new diagnostic test biomarker that will help urologists identify diabetic patients at-risk for kidney failure years earlier than previously possible.
At least that’s what researchers at ETH Zurich (ETH), an international university for technology and natural sciences, have concluded. They published the results of their study in Cell.
“Here, we present a chemoproteomic workflow for the systematic identification of metabolite-protein interactions directly in their native environments,” the researchers wrote. “Our data reveal functional and structural principles of chemical communication, shed light on the prevalence and mechanisms of enzyme promiscuity, and enable extraction of quantitative parameters of metabolite binding on a proteome-wide scale.”
Interactomics address interactions between proteins and small molecules, according to an article published in Technology Networks. The terms “interactomics” and “omics” were inspired by research that described, for the first time, the interactions and relationships of all proteins and metabolites (A.K.A, small molecules) in the whole proteome.
Medical laboratories and anatomic pathologists have long understood the interactions among proteins, or between proteins and DNA or RNA. However, metabolite interactions with packages of proteins are not as well known.
These new omics could eventually be an important source of diagnostic biomarkers. They may, one day, contribute to lower cost clinical laboratory testing for some diseases, as well.
Metabolite-Protein Interactions are Key to Cellular Processes
The ETH researchers were motivated to explore the interplay between small molecules and proteins because they have important responsibilities in the body. These cellular processes include:
“Metabolite-protein interactions control a variety of cellular processes, thereby playing a major role in maintaining cellular homeostasis. Metabolites comprise the largest fraction of molecules in cells. But our knowledge of the metabolite-protein interaction lags behind our understanding of protein-protein or protein-DNA interactomes,” the researchers wrote in Cell.
Leveraging Limited Proteolysis and Mass Spectrometry
The researchers used limited proteolysis (LiP) technology with mass spectrometry to discover metabolite-protein interactions. Results aside, experts pointed out that the LiP technology itself is significant.
“It is one of the few methods that enables the unbiased and proteome-wide profiling of protein conformational changes resulting from interaction of proteins with compounds,” stated a Biognosys blog post.
Biognosys, a proteomics company founded in 2008, was originally part of a lab at ETH Zurich.
The ETH team focused on the E. coli bacterial cell in particular and how its proteins and enzymes interact with metabolites.
“Although the metabolism of E. coli and associated molecules is already very well known, we succeeded in discovering many new interactions and the corresponding binding sites,” Paola Picotti, PhD, Professor of Molecular Systems Biology at ETH Zurich, who led the research, told Technology Networks. “The data that we produce with this technique will help to identify new regulatory mechanisms, unknown enzymes and new metabolic reactions in the cell,” she concluded. (Photo copyright: ETH Zurich.)
More than 1,000 New Interactions Discovered
The study progressed as follows, according to Technology Networks’ report:
“Cellular fluid, containing proteins, was extracted from bacterial cells;
“Strikingly, more than 80% of the reported interactions were novel and about one quarter of the measured proteome interacted with at least one of the 20 tested metabolites. This indicates that the metabolite-protein interaction network is vast and largely uncharted,” Papp stated in an ETH Zurich Faculty of 1000 online article.
According to Technology Networks, “Picotti has already patented the method. The ETH spin-off Biognosys is the exclusive license holder and is now using the method to test various drugs on behalf of pharmaceutical companies.”
The pharmaceutical industry is reportedly interested in the approach as a way to ascertain drug interactions with cellular proteins and their effectiveness in patient care.
The ETH Zurich study is compelling, especially as personalized medicine takes hold and more medical laboratories and anatomic pathology groups add molecular diagnostics to their capabilities.
Researchers are discovering numerous ways the expanding field of metabolomics could transform the future of healthcare. However, to fully exploit the potential of human metabolome, developers must choose from various approaches to research.
“The metabolites we’re dealing with have vast differences in chemical properties, which means you need multi-platform approaches and various types of instrumentation,” James MacRae, PhD, Head of Metabolomics at the Francis Crick Institute in London, told Technology Networks. “We can either use an untargeted approach—trying to measure as much as possible, generating a metabolic profile—or else a more targeted approach where we are focusing on specific metabolites or pathways,” he added.
A multi-platform approach means different diagnostic technologies required to assess an individual’s various metabolomes, which, potentially, could result in multi-biomarker assays for medical laboratories.
Measuring All Metabolites in a Cell or Bio System
Metabolomics is the study of small molecules located within cells, biofluids, tissues, and organisms. These molecules are known as metabolites, and their functions within a biological system are cumulatively known as the metabolome.
Metabolomics, the study of metabolome, can render a real-time representation of the complete physiology of an organism by examining differences between biological samples based on their metabolite characteristics.
“Metabolomics is the attempt to measure all of the metabolites in a cell or bio system,” explained MacRae in the Technology Networks article. “You have tens of thousands of genes, of which tens of thousands will be expressed—and you also have the proteins expressed from them, which will then also be modified in different ways. And all of these things impact on a relatively small number of metabolites—in the thousands rather than the tens of thousands. Because of that, it’s a very sensitive output for the health or physiology of your sample.
“With that in mind, metabolomics has great potential for application in most, if not all, diseases—from diabetes, heart disease, cancer, HIV, autoimmune disease, parasitology, and host-pathogen interactions,” he added.
The graphic above is taken from a study published in the Journal of the American College of Cardiology (JACC). It notes, “State-of-the-art metabolomic technologies give us the ability to measure thousands of metabolites in biological fluids or biopsies, providing us with a metabolic fingerprint of individual patients. These metabolic profiles may serve as diagnostic and/or prognostic tools that have the potential to significantly alter the management of [chronic disease].” (Image and caption copyright:Journal of the American College of Cardiology.)
There are four major fields of study that are collectively referred to as the “omics.” In addition to metabolomics, the remaining three are:
• Genomics: the study of DNA and genetic information within a cell;
• Proteomics: the large-scale study of proteins; and,
Researchers caution that metabolomics should be used in conjunction with other methods to analyze data for the most accurate results.
“Taking everything together—metabolic profiling, targeted assays, label incorporation and computational models, and also trying to associate all of this with proteomics and
genomics and transcriptomic data—that’s really what encapsulates both the power and also the challenges of metabolomics,” MacRae explained.
Metabolome in Precision Medicine
Metabolomics may also have the ability to help researchers and physicians fine-tune therapies to meet the specific needs of individual patients.
“Our genome is generally static and says what might happen in the future. And the metabolome at the other end is the opposite—very dynamic, saying what just happened or could be about the happen,” Dunn explained. “So, we could apply it to identify prognostic biomarkers, for example, to predict if someone is at greater risk of developing diabetes five to ten years from now. And if you know that, you can change their lifestyle or environment to try and prevent it.”
Metabolomics continues to tap the many diagnostic possibilities posed by the human metabolome. And, the resulting human biomarkers derived from the research could result in a rich new vein of medical laboratory assays.
Surprising source of positive medical lab test results was discovered by a special team including pathologists, medical technologists, nurses, and physicians
Some innovative sleuthing by clinical laboratory professionals at University of North Carolina School of Medicine (UNCSM) hospitals has helped solve a marijuana mystery involving neonatal screenings. An unexpected spike in “false positive” cannabis exposure screening results in newborns at the facilities triggered a study by UNCSM scientists.
Revised Screening Protocol Leads to Jump in False Positives
According to a story in MedCity News , in July 2011, the UNCSM clinical laboratories received a call from nurses in the neonatal nursery. They had noticed an increase in positive results in screenings for tetrahydrocannabinol-delta 9-carboxylic acid (THC). THC is the principal psychoactive component of the cannabis plant. (more…)
One Medicare contractor is proposing a new policy that would effectively end payment to labs and physicians for routine testing for Vitamin D deficiency. In its proposed local coverage determination (LCD), the Medicare carrier indicates that it would cover Vitamin D testing only for patients with chronic kidney disease, osteomalacia, hypercalcemia, and rickets. The LCD states that other testing for Vitamin D would be denied.
The draft (or proposed) LCD is dated February 6 and was posted on the Web site of National Government Services (NGS), one of the nation’s largest Medicare contractors. Medicare has asked for comments through February 21. If accepted as proposed, the denials for routine Vitamin D testing would begin on June 1, according to the LCD. In the posted draft, Medicare added a disclaimer saying that LCDs are not necessarily a reflection of the current policies or practices.
National Government Services (NGS) serves 200,000 providers and suppliers, along with nearly 24.5 million Medicare beneficiaries in 25 states and five U.S. territories. Not all Medicare providers will be affected by the LCD that NGS posted. Other Medicare carriers may have posted a similar LCD.
The draft of the NGS LCD says, “Measurement of vitamin D levels is indicated for patients with chronic kidney disease, osteomalacia, hypercalcemia, and rickets. Measurement of vitamin D levels is not indicated for screening. Measurement of any other Vitamin D metabolites (CPT codes 82307 & 82652) is not indicated, and will be denied.”
The draft LCD further states, “An excess of Vitamin D is unusual, but may lead to hypercalcemia. Vitamin D deficiency may lead to a variety of disorders, the most infamous of which is rickets. Treatment of Vitamin D deficiency is relatively straightforward, negating the need for measuring Vitamin D levels in many cases. Evaluating patients’ Vitamin D levels is accomplished by measuring the level of 25-hydroxyvitamin D. Measurement of other metabolites is not medically necessary.”
The Vitamin D Council, a nonprofit organization in Atascadero, California, reported the news on February 13. “If this rule passes, the change will quickly extend to all Medicare districts,” predicted the newsletter. “Private insurers will then follow suit, denying payment for Vitamin D blood tests, even for the diagnoses of Vitamin D deficiency. This rule change flies in the face of an enormous amount of research, some of it published in the last few months. For example, several weeks ago, the British Journal of Cancer reported that in men with prostate cancer, those with highest Vitamin D blood levels were seven times more likely to survive than were men with the lowest levels.”
It may be that Medicare officials are reacting to the significant increase in the volume of Vitamin D testing seen during the past two years. Much of this increased test volume is a result of ongoing media coverage about the importance of Vitamin D and new stories encouraging people to visit their doctors and request that their Vitamin D levels be checked.
For the laboratory industry, this is not an auspicious development. In the past, Medicare has used restrictions on coverage as a way to constrain utilization of certain procedures, thus helping it to control costs. Some lab industry experts are already speculating that this may be the reason why, at this time, one of Medicare’s largest carriers has published a proposed LCD that would limit reimbursement for Vitamin D testing only to a limited number of clinical situations. The Dark Report and Dark Daily will follow this developing story closely in the coming weeks
