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.
Dogs’ acute sense of smell can even surpass effectiveness of some clinical laboratory testing in detecting certain diseases in humans
When it comes to COVID-19 testing, a recent Italian study demonstrates that trained dogs can detect SARS-CoV-2 with accuracy comparable to rapid molecular tests used in clinical laboratories. The researchers wanted to determine if dogs could be more effective at screening people for COVID-19 at airports, schools, and other high-traffic environments as a way to detect the coronavirus and reduce the spread of this infectious disease.
Scientists at the State University of Milan in Italy conducted a study that shows dogs can be trained to accurately identify the presence of the COVID-19 infection from both biological samples and by simply smelling an individual.
For their validation study, the Italian team trained three dogs named Nala, Otto, and Helix, “to detect the presence of SARS-CoV-2 in sweat samples from infected people. At the end of the training, the dogs achieved an average sensitivity of 93% and a specificity of 99%, showing a level of accuracy highly consistent with that of the RT-PCR [reverse transcription polymerase chain reaction] used in molecular tests and a moderate to strong reproducibility over time,” Nature reported.
RT-PCR tests are the current gold-standard for SARS-CoV-2 detection. This is yet another example of scientists training dogs to smell a disease with “acceptable” accuracy. This time for COVID-19.
“We only recruited dogs that showed themselves predisposed and positively motivated to carry out this type of activity. One of the fundamental aspects was not to cause stress or anxiety in the subjects used,” Federica Pirrone, PhD (above), Associate Professor, Department of Veterinary Medicine and Animal Sciences, University of Milan, and one of the authors of the study told Lifegate. “Training always takes place using positive reinforcement of a food nature: whether it’s a particularly appetizing morsel, a biscuit, or something that associates the dog’s search with a rewarding prize.” In some instances, dogs have been shown to be as good or more effective at detecting certain diseases than clinical laboratory testing. (Photo copyright: Facebook.)
Dogs More Accurate than Rapid Antigen Testing
Nala and four other dogs (Nim, Hope, Iris and Chaos) were later trained by canine technicians from Medical Detection Dogs Italy (MDDI) to identify the existence of the SARS-CoV-2 virus by directly smelling people waiting in line in pharmacies to get a nasal swab to test for the coronavirus.
Working with their handlers, the five dogs accurately signaled the presence or absence of the virus with 89% sensitivity and 95% specificity. That rate is “well above the minimum required by the WHO [World Health Organization] for rapid swabs for SARS-CoV-2,” according to Nature.
“The results of studies published so far on the accuracy of canine smell in detecting the presence of SARS-CoV-2 in biological samples (e.g., saliva, sweat, urine, trachea-bronchial secretions) from infected people suggest that sniffer dogs might reach percentages of sensitivity and specificity comparable to, or perhaps even higher, than those of RT-PCR,” the scientists wrote in Scientific Reports.
“However, although most of these studies are of good quality, none of them provided scientific validation of canine scent detection, despite this being an important requirement in the chemical analysis practice. Therefore, further applied research in this field is absolutely justified to provide definitive validation of this biodetection method,” the researchers concluded.
Other Studies into Using Dogs for Detecting Disease
Scientists from the Division of Biological and Health Sciences, Department of Agriculture and Livestock at the University of Sonora; and the Canine Training Center Obi-K19, both in Hermosillo, Mexico, conducted the study “as part of a Frontiers of Science Project of the National Council of Science and Technology (CONACYT), in which in addition to analyzing sweat compounds, trained dogs are put to sniff the samples and make detections in people who show symptoms or could be positive for coronavirus,” Mexico Daily Post reported.
The researchers trained four dogs with sweat samples and three dogs with saliva samples of COVID-19 positive patients. The samples were obtained from a health center located in Hermosillo, Sonora, in Mexico. The dogs were restricted to spend five minutes per patient and the researchers calculated the performance of the dogs by measuring sensitivity, specificity, and their 95% confidence intervals (CI).
The researchers concluded that all four of the dogs could detect COVID-19 from either sweat or saliva samples “with sensitivity and specificity rates significantly different from random [sampling] in the field.” According to the Frontiers in Medicine study, the researchers found their results promising because, they said, it is reasonable to expect the detection rate would improve with longer exposure to the samples.
The objective of the Mexican researchers is for the dogs to ultimately reach the sensitivity range requested by WHO for the performance of an antigen test, which is at least 80% sensitivity and 97% specificity. If that goal is achieved, dogs could become important partners in the control of the COVID-19 pandemic, the scientists wrote.
Data obtained so far from these studies indicate that biosensing dogs may represent an effective method of screening for COVID-19 as well as other diseases. More studies and clinical trials are needed before the widespread use of dogs might become feasible. Nevertheless, scientists all over the world are finding that Man’s best friend can be a powerful ally in the fight against the spread of deadly diseases.
In the meantime, the gold standard in COVID-19 testing will continue to be the FDA-cleared assays used by clinical laboratories throughout the United States.
If the link between certain types of gut bacteria and improved effectiveness of certain cancer treatments can be leveraged, then medical laboratories could soon have another diagnostic tool to use in supporting physicians with cancer care
The goal of both studies was to determine whether there was a link between gut bacteria and the efficacy of cancer drugs known as PD-1 inhibitors. These drugs are used for several types of cancer, including:
Melanoma;
Lung;
Bladder; and,
Stomach cancers.
They function by freeing up the immune system to attack cancer cells.
Greater Bacterial Diversity in Gut Brings Improved Response to PD-1 Inhibitors
One of the studies, “Gut Microbiome Modulates Response to Anti–PD-1 Immunotherapy in Melanoma Patients,” found that a microbiome populated with “good” bacteria can elevate the potency of certain drug treatments. The researchers discovered that the gut bacteria in patients who responded well to PD-1 inhibitors differed from that found in patients who did not respond to the treatment.
For this study, researchers at the MD Anderson Cancer Center at the University of Texas collected oral, gut, and fecal microbiome samples and tumor biopsies from 112 patients with advanced melanoma. Clinical laboratorians took the samples before and after PD-1 treatments. They divided the patients into two groups—responders and non-responders—and profiled each microbiome using genetic sequencing.
“What we found was impressive: There were major differences both in the diversity and composition of the gut microbiome in responders versus non-responders,” Jennifer Wargo, MD, MMSc, leader of the study, told STAT. “Those who did well had greater bacterial diversity in their gut, whereas those whose tumors didn’t much shrink had fewer varieties of microbes present.”
Melanoma patients who experienced success with PD-1 therapy had a more diverse microbiome and higher concentrations of bacteria known as Ruminococcus and Faecalibacterium. Patients involved in the study who did not respond well to PD-1 therapy had the presence of another bacterium called Bacteroidales.
Jennifer Wargo, MD (above center) with her team at the MD Anderson laboratories. The researchers cautioned that clinical trials are needed before a definitive conclusion can be reached on whether altering gut bacteria can improve the effectiveness of PD-1 therapy. “If you’re changing the microbiome, depending on how you do it, it may not help you—and it might harm you,” Wargo emphasized in STAT. “Don’t try this at home.” (Photo copyright: MD Anderson.)
Antibiotics Can Reduce Effectiveness of PD-1Therapy
Researchers for this study, led by Laurence Zitvogel, MD, PhD, of the Gustave Roussy Cancer Campus in Villejuif, France, examined 249 patients who were given a PD-1 inhibitor for lung, kidney, or urinary tract cancers. A little over one fourth of these patients had recently taken antibiotics, which can strip the gut of essential bacteria necessary to treat infections.
The team found that patients who had ingested an antibiotic relapsed faster and did not live as long as patients who had not taken an antibiotic before receiving PD-1 therapy. When they analyzed variances between patients who responded well to treatment versus patients who did not, they detected the presence of Akkermansia muciniphila, a mucin-degrading bacterium, in the responders.
Personalized Treatment Based on Each Patient’s Gut Microbiome
The culmination of this type of research raises questions about how cancer medications may interact with microbiomes.
“Should we be profiling the gut microbiome in cancer patients going into immunotherapy?” asked Wargo in the STAT article. “And, should we also be limiting, or closely monitoring, the antibiotic use in these patients?
“This is all very context-specific, and multiple different factors need to be considered on how best to change the microbiome,” she continued. “When it comes to optimizing cancer therapy, treatments will have to be heavily personalized, based on what a patient’s gut microbiome looks like already.”
Diagnostic tests that could determine whether a certain drug will be beneficial for a patient would perform a critical role in healthcare decision-making. Since cancer drug treatments can cost tens of thousands of dollars or more, it would be advantageous to know which therapies would be optimal for individual patients. The hope is that in the future, clinicians, working with anatomic pathologists and clinical laboratories, will have the tools needed to ascertain if patient’s microbiomes will best work with a particular drug and if they would likely encounter any side effects.
