Research could lead to new biomarkers that detect Alzheimer’s much earlier than existing tests and help scientists understand why some people with the disease do not develop dementia
Key biomarkers for detecting the progression of Alzheimer’s disease have typically been based on amyloid-beta (Aβ) plaques. But these plaques show up after the disease has well-progressed and aren’t suited to early detection of the disease.
Now, researchers at the University of Pittsburgh School of Medicine (Pitt) have developed a cerebrospinal fluid (CFS) test that detects changes in tau protein prior to the formation of neurofibrillary tangles (NFTs) that proceed Aβ plaques.
With further research, Pitt’s test could lead to new clinical laboratory biomarkers that help detect the disease earlier and with more accuracy.
“The clumping of tau protein into well-ordered structures, referred to by pathologists as neurofibrillary tangles, is a more defining event for Alzheimer’s disease as it is more strongly associated with the cognitive changes,” as compared to amyloid-beta pathology, according to a Pitt news release.
The researchers showed that their CSF biomarker test worked independent of discovery of brain amyloid deposits and “correlates with severity of cognitive decline” to enable “early-stage disease diagnosis and intervention,” reported Genetic Engineering and Biotechnology News.
“Our test identifies very early stages of tau tangle formation—up to a decade before any tau clumps can show up on a brain scan,” said Thomas Karikari, PhD (above), senior author and assistant professor of psychiatry at Pitt, in a news release. (Photo copyright: University of Pittsburgh.)
Combining Biomarkers May Lead to Better Alzheimer’s Knowledge
The new biomarkers may also work with existing markers that detect amyloid-beta pathology. This could give researchers and healthcare providers a better understanding of the early stages of Alzheimer’s in specific patients.
“Amyloid-beta is a kindling, and tau is a matchstick,” said Thomas Karikari, PhD, senior author and assistant professor of psychiatry at Pitt. Karikari previously researched amyloid-beta.
“A large percentage of people who have brain amyloid-beta deposits will never develop dementia. But once the tau tangles light up on a brain scan, it may be too late to put out the fire, and their cognitive health can quickly deteriorate. Early detection of tangle-prone tau could identify the individuals who are likely to develop Alzheimer’s-associated cognitive decline and could be helped with new generation therapies,” he added.
“P-tau-217 and p-tau-181 are fantastic biomarkers. However, in the early days after we developed these markers, we wondered why they were much more reflective of amyloid pathology than tau pathology,” Karikari told MedPage Today.
“That’s what inspired this work. We believe that methods combining, say, p-tau-217 and p-tau-262 or 356, would provide more complete information on combined early-stage amyloid and tau pathologies in Alzheimer’s disease,” he noted.
Developing the Alzheimer’s Biomarker Test
Karikari and colleagues turned to biochemistry and molecular biology to develop their new test.
Specifically, they emphasized “building blocks of NFTs including oligomers and protomers” which they called “soluble tau assemblies,” Medical News Today explained.
According to the Pitt news release, using autopsied brain tissue, the researchers found:
A core region of the tau protein where NFTs form.
111 amino acids in the region.
New “phosphorylation sites of p-tau-262 and p-tau-356 can inform the status of early-stage tau aggregation that, with an appropriate intervention, could potentially be reversed.”
In other words, p-tau-262 and p-tau-356 “could predict future NFT production, making them potential biomarkers for early disease,” Medical News Today noted.
“Together, our findings inform about the status of early-stage tau aggregation, reveal aggregation-relevant phosphorylation epitopes in tau, and offer a diagnostic biomarker and targeted therapeutic opportunities for Alzheimer’s disease,” the authors wrote in Nature Medicine.
More Research Planned Before Clinical Lab Use
About seven million Americans are affected by Alzheimer’s, according to the Alzheimer’s Association, which expects that number to grow to 13 million by 2050. A cure for the disease does not exist.
More research is needed before the Pitt researchers’ new CSF assay can be used by clinical laboratories. Karikari said the next step is developing blood assays for the biomarkers, MedPage Today reported.
New clinical laboratory test could replace conventional spinal tap for diagnosing neurodegenerative disease
In a proof-of-concept study, University of Pittsburgh (Pitt) scientists validated a clinical laboratory test that measures more than 100 different genetic sequences associated with Alzheimer’s disease. The Pitt researchers believe the new diagnostic platform could help clinicians “capture the multifaceted nature of Alzheimer’s pathology and streamline early disease diagnostics,” according to a news release.
Clinical laboratory blood tests that detect biomarkers such as phosphorylated tau protein (pTau) have emerged in studies as diagnostic possibilities for Alzheimer’s disease, which is traditionally diagnosed using a lumbar puncture (spinal tap) procedure.
In their paper, neuroscientist Thomas Karikari, PhD, Assistant Professor of Psychiatry at University of Pittsburgh, lead author of the study, and his research team acknowledged that progress has been made in detecting Alzheimer’s disease with blood-based biomarkers. However, they note that “two key obstacles remain: the lack of methods for multi-analyte assessments and the need for biomarkers for related pathophysiological processes like neuroinflammation, vascular, and synaptic dysfunction.”
The Pitt scientists believe the focus on so-called “classical Alzheimer’s blood biomarkers” limits exploration of neurodegenerative disease.
“Alzheimer’s disease should not be looked at through one single lens. Capturing aspects of Alzheimer’s pathology in a panel of clinically validated biomarkers would increase the likelihood of stopping the disease before any cognitive symptoms emerge,” said neuroscientist Thomas Karikari, PhD (above), Assistant Professor of Psychiatry, University of Pittsburgh, and lead author of the study in a news release. Should further studies prove Pitt’s research sound, clinical laboratories may have a replacement test for diagnosing neurodegenerative disease. (Photo copyright: University of Pittsburgh.)
On its website, Alamar Biosciences explains that the disease panel offers neurological researchers:
“Multiplexed analysis of 120 neuro-specific and inflammatory proteins from 10 µl of plasma or CSF (cerebrospinal fluid).
Detection of “critical biomarkers—including pTau-217, GFAP (glial fibrillary acidic protein), NEFL (neurofilament light polypeptide) and alpha-synuclein.”
The NULISAseq test works with “a proprietary sequential immunocomplex capture and release mechanism and the latest advances in next-generation sequencing,” according to the company.
Inside Precision Medicine noted that the Alamar Biosciences assay enabled Pitt scientists to detect:
Biomarkers (usually found in CSF) “correlating with patients’ amyloid positivity status and changes in amyloid burden over time,” and,
Biomarkers including “neuroinflammation, synaptic function, and vascular health, which had not previously been validated in blood samples.”
“The performance of the NULISA platform was independently validated against conventional assays for classic Alzheimer’s biomarkers for each sample. Biomarker profiles over two years were also compared with imaging-based measures of amyloid, tau, and neurodegeneration,” LabMedica reported.
Opportunity to Track Alzheimer’s
Karikari sees the diagnostic platform being used to track individuals’ blood biomarker changes over time.
In their Molecular Neurodegeneration paper, the Pitt researchers wrote, “These (results) were not limited to markers such as pTau217, p-Tau231, p-Tau181, and GFAP, the elevation of which have consistently shown strong associations with brain Aβ [amyloid beta] and/or tau load, but included novel protein targets that inform about the disease state of the individual in different pathological stages across the biological Alzheimer’s disease continuum.”
About seven million Americans are affected by Alzheimer’s disease, according to the Alzheimer’s Association, which estimated that figure will grow to 13 billion by 2050.
Further studies by Karikari may include larger samples and greater diversity among the people studied, Inside Precision Medicine noted.
“[Karikari’s] lab is developing a predictive model that correlates biomarker changes detected using NULISAseq with brain autopsy data and cognitive assessments collected over the course of several years. Their goal is to identify blood biomarkers that can help stage the disease and predict its progression, both for decision-making around clinical management and treatment plans,” the Pitt news release states.
The Pitt scientists have developed a multiplex test that works with 100 different genetic sequences associated with Alzheimer’s. Such advances in the understanding of the human genome are giving scientists the opportunity to combine newly identified gene sequences that have a role in specific disease states.
In turn, as further studies validate the value of these biomarkers for diagnosing disease and guiding treatment decisions, clinical laboratories will have new assays that deliver more value to referring physicians and their patients.
As new diagnostic assays are cleared by regulators, clinical laboratories will play a key role in identifying appropriate patients for new less-invasive Alzheimer’s tests
With multiple companies racing to develop a blood-based test for Alzheimer’s disease (AD), clinical laboratories may soon have new less-invasive diagnostic assays for AD on their menus.
Why a race? Because a less-invasive clinical laboratory test that uses a venous blood draw (as opposed to a spinal tap)—and which has increased sensitivity/specificity—has a potentially large market given the substantial numbers of elderly predicted to develop Alzheimer’s over the next decade. It has the potential to be a high volume, high dollar diagnostic test.
In fact, Mordor Intelligence estimates that the market for Alzheimer’s disease therapeutics will grow from $7.7 billion in 2024 to $10.10 billion by 2029.
Alzheimers.gov, an official website of the US government, says, “Researchers have made significant progress in developing, testing, and validating biomarkers that detect signs of the disease process. For example, in addition to PET scans that detect abnormal beta-amyloid plaques and tau tangles [abnormal forms of tau protein] in the brain, NIH-supported scientists have developed the first commercial blood test for Alzheimer’s. This test and others in development can not only help support diagnosis but also be used to screen volunteers for research studies.”
Additionally, the US Food and Drug Administration (FDA) is clearing new Alzheimer’s drugs for clinical use. The pharma companies behind these drugs need clinical laboratory tests that accurately diagnosis the disease and confirm that it would be appropriate for the patient to receive the new therapeutic drugs, a key element of precision medicine.
“The big promise for blood tests is that they will eventually be accessible, hopefully, cost-effective, and noninvasive,” Rebecca Edelmayer, PhD (above), Vice President, Scientific Engagement, Alzheimer’s Association, told USA Today. “The field is really moving forward with use of these types of tests,” she added. Clinical laboratories may soon have these new assays on their test menus. (Photo copyright: Alzheimer’s Association.)
Companies in the Race to Develop Blood-based Alzheimer’s Tests
Researchers found that C2N’s blood test can detect brain amyloid status with “sensitivity, specificity, positive and negative predictive values that approximate those of amyloid positron emission tomography (PET) imaging,” according to a news release.
“The PrecivityAD2 blood test is intended for use in patients aged 55 and older with signs or symptoms of mild cognitive impairment or dementia who are undergoing evaluation of Alzheimer’s disease or dementia. Only a healthcare provider can order the PrecivityAD2 test,” the news release noted.
“The PrecivityAD2 blood test showed strong clinical validity with excellent agreement with brain amyloidosis by PET,” the researchers wrote.
The PrecivityAD2 test, which is mailed directly by C2N to doctors and researchers, is performed at the company’s CLIA-certified lab, according to USA Today, which added that the cost of $1,450 is generally not covered by insurance plans.
Expanding Test Access with IVD Companies
ALZpath, Inc. has a different approach to the Alzheimer’s disease test market. The Carlsbad, Calif.-based company, set up an agreement with in vitro diagnostics (IVD) company Roche Diagnostics for use of its phosphorylated tau (pTau)217 antibody “to develop and commercialize an Alzheimer’s disease diagnostic blood test that will be offered on the Roche Elecsys platform,” according to a news release.
Roche received FDA breakthrough device designation on the Elecsys pTau217 test earlier this year and will work with pharmaceutical company Eli Lilly to commercialize the test.
Estimates show 75% of dementia cases go undetected—a number which could grow to 140 million by 2050, according to data shared by Roche with Fierce Biotech.
“We plan to leverage our installed base of diagnostic systems, which is the largest in the world, to ensure we are able to create access to this test for those who need it the most,” Matt Sause, CEO, Roche Diagnostics, told Fierce Biotech.
Another IVD company, Beckman Coulter, recently signed an agreement to use ALZpath’s pTau217 antibody test in its DxI 9000 Immunoassay Analyzer. In a news release, Kathleen Orland, SVP and General Manager of the Clinical Chemistry Immunoassay Business Unit at Beckman Coulter, said that the test had “high performance in detecting amyloid pathology” and could “integrate into our advanced DxI 9000 platform to support broad-based testing.”
Clinical Laboratory Participation
The FDA is drafting new guidance titled, “Early Alzheimer’s Disease: Developing Drugs for Treatment” that is “intended to assist sponsors in the clinical development of drugs for the treatment of the stages of sporadic Alzheimer’s disease (AD) that occur before the onset of overt dementia.”
Pharma companies intent on launching new drugs for Alzheimer’s will need medical laboratory tests that accurately diagnosis the disease to confirm the medications would be appropriate for specific patients.
Given development of the aforementioned pTau217 antibody tests, and others featuring different diagnostic technologies, it’s likely clinical laboratories will soon be performing new assays for diagnosing Alzheimer’s disease.
Researchers have been exploring the role metabolites play in the development of disease for some time. Alzheimer’s is a progressive, degenerative brain disease typically linked to age, family history, and deposits of certain proteins in the brain that cause the brain to shrink and brain cells to eventually die. Alzheimer’s is the most common form of dementia, accounting for an estimated 60% to 80% of all dementia cases. It has no cure or proven method of prevention, according to the Alzheimer’s Association.
There are nearly seven million people living with Alzheimer’s in the US and 55 million people worldwide live with it or other forms of dementia. Patients are usually over the age of 65, but it can present in younger patients as well.
“Gut metabolites are the key to many physiological processes in our bodies, and for every key there is a lock for human health and disease,” said Feixiong Cheng, PhD (above), founding director of the Cleveland Clinic Genome Center, in a news release. “The problem is that we have tens of thousands of receptors and thousands of metabolites in our system, so manually figuring out which key goes into which lock has been slow and costly. That’s why we decided to use AI.” Findings from the study could lead to new clinical laboratory biomarkers for dementia screening tests. (Photo copyright: Cleveland Clinic Lerner Research Institute.)
Changes to Gut Bacteria
Metabolites are substances released by bacteria when the body breaks down food, drugs, chemicals, or its own tissue, such as fat or muscle. They fuel cellular processes within the body that may be either helpful or harmful to an individual’s health.
The Cleveland Clinic researchers believe that preventing detrimental interactions between metabolites and cells could aid in disease prevention. Previous studies have shown that Alzheimer’s patients do experience changes in their gut bacteria as the disease progresses.
To complete their study, the scientists used AI and machine learning (ML) to analyze more than 1.09 million potential metabolite-receptor pairs to determine the likelihood of developing Alzheimer’s.
They then examined genetic and proteomic data from Alzheimer’s disease studies and looked at different receptor protein structures and metabolite shapes to determine how different metabolites can affect brain cells. The researchers identified significant interactions between the gut and the brain.
They discovered that the metabolite agmatine was most likely to interact with a receptor known as CA3R in Alzheimer’s patients. Agmatine is believed to protect brain cells from inflammation and damage. They found that when Alzheimer’s-affected neurons are treated with agmatine, CA3R levels reduce. Levels of phosphorylated tau proteins, a biomarker for Alzheimer’s disease, lowered as well.
The researchers also studied a metabolite called phenethylamine. They found that it too could significantly alter the levels of phosphorylated tau proteins, a result they believe could be beneficial to Alzheimer’s patients.
New Therapies for Alzheimer’s, Other Diseases
One of the most compelling results observed in the study was the identification of specific G-protein-coupled receptors (GPCRs) that interact with metabolites present in the gut microbiome. By focusing on orphan GPCRs, the researchers determined that certain metabolites could activate those receptors, which could help generate new therapies for Alzheimer’s.
“We specifically focused on Alzheimer’s disease, but metabolite-receptor interactions play a role in almost every disease that involves gut microbes,” said Feixiong Cheng, PhD, founding director of the Cleveland Clinic Genome Center in the news release. “We hope that our methods can provide a framework to progress the entire field of metabolite-associated diseases and human health.”
The team plans to use AI technology to further develop and study the interactions between genetic and environmental factors on human health and disease progression. More research and studies are needed, but results of the Cleveland Clinic study suggest new biomarkers for targeted therapies and clinical laboratory tests for dementia diseases may soon follow.
Findings could lead to clinical laboratory tests that help physicians identify microbes lacking in the microbiomes of their Parkinson patients
Microbiologists and clinical laboratory scientists know that gut microbiome can be involved in the development of Parkinson’s disease, a progressive neurological disorder that affects the nervous system due to damage caused to nerve cells in the brain. There is no cure for the illness. But a new treatment developed by researchers at the VIB Center for Inflammation Research at the University of Ghent in Belgium, may help to alleviate the symptoms.
During a clinical trial, VIB Center for Inflammation Research (VIB-IRC) scientists discovered that fecal microbiota transplantation (FMT), also known as a stool transplant, can improve motor skills in some Parkinson’s patients, according to Neuroscience News.
Parkinson’s disease (PD) develops when a protein called alpha-synuclein misfolds and forms into bundled clusters damaging nerve cells in the brain that produce dopamine. These formations, which are believed to appear in the gastrointestinal wall in the early stages of PD, then reach the brain via the vagus nerve leading to typical PD symptoms in patients.
“Our study provides promising hints that FMT can be a valuable new treatment for Parkinson’s disease,” Roosmarijn Vandenbroucke, PhD (above), Principal Investigator, VIB-UGent Center for Inflammation Research and full professor, UGent Department of Biomedical molecular biology, Faculty of Sciences, told Neuroscience News. “More research is needed, but it offers a potentially safe, effective, and cost-effective way to improve symptoms and quality of life for millions of people with Parkinson’s disease worldwide.” Clinical laboratories will likely be involved in identifying the best microbes for the FMT treatments. (Photo copyright: University of Ghent.)
Correlation between Gut Microbiome and Neurogenerative Disease
To perform their clinical study—referred to as GUT-PARFECT—the IRC researchers first recruited patients with early-stage PD and healthy donors who provided stool samples to the Ghent Stool Bank. The PD patients received the healthy stool via a tube inserted into the nose which led directly into the small intestine.
The FMT procedures were performed on 46 patients with PD between December 2020 and December 2021. The participants in this group ranged in ages from 50 to 65. There were 24 PD patients in the placebo group, and a total of 22 donors provided the healthy stool. Clinical evaluations were performed at baseline, three, six, and 12 months.
After 12 months, the group that received the transplants showed a reduction in symptoms compared to the placebo group. Their motor score on the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) improved by a mean of 5.8 points. The improvement registered on the same scale for the placebo group was 2.7 points.
Developed in the 1980s, the MDS-UPDRS is a scale utilized to evaluate various aspects of PD by measuring patient responses via a questionnaire rating several issues (such as cognitive impairment, apathy, depression, and anxiousness) common in PD patients from normal to severe. It is divided into four parts:
Part I: Non-motor experiences of daily living.
Part II: Motor experiences of daily living.
Part III: Motor examination.
Part IV: Motor complications.
During the final six months of the research, the improvement in motor symptoms became even greater. To the VIB-IRC researchers this implied that an FMT may have long-lasting effects on PD patients. The FMT study group also experienced less constipation, a condition that can be bothersome for some PD patients.
“Our results are really encouraging!” said the study’s first author, Arnout Bruggeman, MD, PhD student, VIB-UGent Center for Inflammation Research, in a UGent News release. “After twelve months, participants who received the healthy donor stool transplant showed a significant improvement in their motor score, the most important measure for Parkinson’s symptoms.”
Findings Could Lead to Other Targeted Therapies for PD
The VIB-IRC researchers believe there is a correlation between the gut microbiome and Parkinson’s disease.
“Our findings suggested a single FMT induced mild, but long-lasting beneficial effects on motor symptoms in patients with early-stage PD. These findings highlight the potential of modulating the gut microbiome as a therapeutic approach and warrant a further exploration of FMT in larger cohorts of patients with PD in various disease stages,” the IRC researchers wrote in eClinicalMedicine.
“Our next step is to obtain funding to determine which bacteria have a positive influence. This could lead to the development of a ‘bacterial pill’ or other targeted therapy that could replace FMT in the future,” Debby Laukens, PhD, Associate Professor, Ghent University, told Neuroscience News.
According to the Parkinson’s Foundation website, nearly one million people in the US live with PD. It is second only to Alzheimer’s disease in the category of neurodegenerative diseases.
More research and studies are needed before the VIB-IRC’s stool transplant treatment can be used in clinical care. As researchers learn more about which specific strains of bacteria are doing the beneficial work in PD patients, that data could eventually lead to clinical laboratory tests performed to help physicians identify which microbes are lacking in the microbiomes of their PD patients, and if fecal transplants could help those patients.
