Tag: lactate

Categories : NeurologyTags :

Wide-ranging Animal Studies Link pH Changes to Cognitive and Psychiatric Disorders

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A global collaborative research group has identified brain energy metabolism dysfunction leading to altered pH and lactate levels as common hallmarks in numerous animal models of neuropsychiatric and neurodegenerative disorders. These include models of intellectual disability, autism spectrum disorders, schizophrenia, bipolar disorder, depressive disorders, and Alzheimer’s disease. The findings were published in eLife.

The research group, comprising 131 researchers from 105 laboratories across seven countries, sheds light on altered energy metabolism as a key factor in various neuropsychiatric and neurodegenerative disorders. While considered controversial, an elevated lactate level and the resulting decrease in pH is now also proposed as a potential primary component of these diseases. Unlike previous assumptions associating these changes with external factors like medicationa, the research group’s previous findings suggest that they may be intrinsic to the disorders. This conclusion was drawn from five animal models of schizophrenia/developmental disorders, bipolar disorder, and autism, which are exempt from such confounding factorsb. However, research on brain pH and lactate levels in animal models of other neuropsychiatric and neurological disorders has been limited. Until now, it was unclear whether such changes in the brain were a common phenomenon. Additionally, the relationship between alterations in brain pH and lactate levels and specific behavioural abnormalities had not been clearly established.

This study, encompassing 109 strains/conditions of mice, rats, and chicks, including animal models related to neuropsychiatric conditions, reveals that changes in brain pH and lactate levels are a common feature in a diverse range of animal models of conditions, including schizophrenia/developmental disorders, bipolar disorder, autism, as well as models of depression, epilepsy, and Alzheimer’s disease. This study’s significant insights include:

I. Common Phenomenon Across Disorders: About 30% of the 109 types of animal models exhibited significant changes in brain pH and lactate levels, emphasising the widespread occurrence of energy metabolism changes in the brain across various neuropsychiatric conditions.

II. Environmental Factors as a Cause: Models simulating depression through psychological stress, and those induced to develop diabetes or colitis, which have a high comorbidity risk for depression, showed decreased brain pH and increased lactate levels. Various acquired environmental factors could contribute to these changes.

III. Cognitive Impairment Link: A comprehensive analysis integrating behavioural test data revealed a predominant association between increased brain lactate levels and impaired working memory, illuminating an aspect of cognitive dysfunction.

IV. Confirmation in Independent Cohort: These associations, particularly between higher brain lactate levels and poor working memory performance, were validated in an independent cohort of animal models, reinforcing the initial findings.

V. Autism Spectrum Complexity: Variable responses were noted in autism models, with some showing increased pH and decreased lactate levels, suggesting subpopulations within the autism spectrum with diverse metabolic patterns.

“This is the first and largest systematic study evaluating brain pH and lactate levels across a range of animal models for neuropsychiatric and neurodegenerative disorders. Our findings may lay the groundwork for new approaches to develop the transdiagnostic characterisation of different disorders involving cognitive impairment,” states Dr Hideo Hagihara, the study’s lead author.

Professor Tsuyoshi Miyakawa, the corresponding author, explains, “This research could be a stepping stone towards identifying shared therapeutic targets in various neuropsychiatric disorders. Future studies will centre on uncovering treatment strategies that are effective across diverse animal models with brain pH changes. This could significantly contribute to developing tailored treatments for patient subgroups characterized by specific alterations in brain energy metabolism.”

The exact mechanism behind the reduction in pH and the increase in lactate levels remains elusive. But the authors suggest that, since lactate production increases in response to neural hyperactivity to meet the energy demand, this might be the underlying reason.

Source: Fujita Health University

Categories : CancerTags :

Tumours Use Lactate to Bully Surrounding Cells into Helping Them

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Cancer-associated fibroblasts surrounding a prostate tumour. Credit: Moscat/Diaz-Meco labs.

Some tumours can force neighbouring cells into supporting cancer growth by releasing lactate into their local environment, according to a study published in Cell Reports. The findings could lead to drugs that target that defence mechanism to help cancer patients ؘ– and also boost a current class of cancer drugs.

In the study, the researchers determined how developing tumours recruit nearby cells called fibroblasts to work as their enablers. Fibroblasts form part of the stroma, organs’ connective tissue, and normally have important repair and maintenance functions. But cancer-associated fibroblasts (CAFs) acquire properties that allow them to assist tumours in ways that make the tumours more malignant and harder to kill.

The researchers also discovered that PARP-1 inhibitors, a widely used class of cancer drugs, mimic one of the key steps in CAF recruitment, and can hamstring their own effectiveness by inadvertently switching local fibroblasts to this cancer-enabling mode.

“Future therapeutics that block this cancer-associated state of fibroblasts might be useful on their own or as a way to improve the effectiveness of PARP-1 inhibitors,” said study co-senior author Dr Maria Diaz-Meco.

Dr Diaz-Meco collaborated in the study with the laboratory of co-senior author Dr Jorge Moscat.

Developing tumours are known to often modify their local environments for their own survival and growth. Cancer-associated fibroblasts are a central component of the tumour microenvironment in prostate, lung, colon and other cancer types. Targeting these cells is therefore seen as a promising complementary approach to standard cancer treatment – and one that could work very broadly against cancers of different cellular and genetic origins.

“Cancer-associated fibroblasts support tumour growth by providing growth factors and essential metabolites to the tumour, by fending-off anti-tumour immune cells, and in many other ways,” Dr Moscat said. “The result is a tumour that is more malignant and treatment-resistant.”

Several years ago, the researchers discovered that a protein called p62, produced in fibroblasts, normally suppresses the CAF state, though many tumours find a way to restore this state by reducing fibroblast p62 production. In the new study, they showed that tumours achieve this by secreting high levels of an organic compound called lactate, also known as lactic acid.

Lactate is a normal by-product of certain energy-production processes in cells, which are often hyperactive in tumours. In experiments with prostate cancer cells, the researchers detailed the molecular chain of events by which tumour-secreted lactate disrupts the normal metabolism of fibroblasts, leading to reduced p62 gene activity and the activation of the tumour-enabling CAF state.

The finding is significant because it illuminates a major cancer-promoting pathway, which in principle can be targeted with future drugs as a standalone or add-on treatment strategy.

A second, surprising finding was that a key step leading from tumour lactate secretion to fibroblast p62 suppression turned out to be the inhibition of a DNA-repair enzyme called PARP-1, which has the same effect as PARP-1 inhibitors – suggesting that these drugs might be working partly against themselves by creating a more tumour-friendly microenvironment.

In vitro and animal testing confirmed that the PARP-1 inhibitor olaparib does reduce p62 in fibroblasts, and pushes them into the CAF state, in turn increase tumours’ resistance to the drug’s primary cancer-killing effect.

Thus, the researchers emphasised, future treatments that reprogram CAF cells to the non-cancer state or prevent their development might greatly enhance PARP-1 inhibitors’ anti-tumour effectiveness.

“We’re now studying several potential CAF-blocking therapeutics in our labs,” Dr Moscat said.

Source: Weill Cornell Medical College

Categories : Lab Tests and ImagingTags :

New Biosensor Rapidly Measures ATP and Lactate in Blood Samples

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The prototype of the ATP and lactate sensor developed in the study (left); and the integrated sensor chip that detects ATP and lactate levels (right). Credit: Akihiko Ishida, Hokkaido University

Scientists at Hokkaido University have developed a prototype sensor that could help doctors rapidly measures levels of adenosine triphosphate (ATP) and lactate in blood samples from patients, aiding in the rapid assessment of the severity of conditions such as sepsis.

The scientists detailed their prototype biosensor in the journal Biosensors and Bioelectronics.

ATP is a molecule found in every living cell that stores and carries energy. In red blood cells, ATP is produced by a biochemical pathway called the Embden–Meyerhof pathway. Severe illnesses such as multiple organ failure, sepsis and influenza reduce the amounts of ATP produced by red blood cells.

As such, the severity of these illnesses could be gauged by monitoring the amounts of ATP and lactates in a patient’s blood. “In 2013, our co-authors at Tokushima University proposed the ATP-lactate energy risk score (A-LES) for measuring ATP and lactate blood levels to assess acute influenza severity in patients,” explained Akihiko Ishida, an applied chemist at Hokkaido University. “However, current methods to measure these levels and other approaches for measuring disease severity can be cumbersome, lengthy or not sensitive enough. We wanted to develop a rapid, sensitive test to help doctors better triage their patients.”

The researchers developed a biosensor that can detect levels of ATP and lactate in blood with great high sensitivity in as little as five minutes. The process is straightforward. Chemicals are added to a blood sample to extract ATP from red blood cells. Enzymes and substrates are then added to convert ATP and lactate to the same product that can be detected by specially modified electrodes on a sensor chip; the amount of by-product present in the sample increases the electrical current measured.

Schematic representation of the proposed sensor for sequentially detecting ATP and lactate levels in the blood. Through a series of chemical reactions, ATP and lactate are converted to hydrogen peroxide, the breakdown of which to water H2O causes the sensor chip to generate a signal that is detected by the sensor.

The team conducted parallel tests and found that other components present in blood, such as ascorbic acid, pyruvic acid, adenosine diphosphate (ADP), urate and potassium ions, don’t interfere with the ability of the electrodes to accurately detect ATP and lactate. They also compared their sensor with those currently available and found it allowed for the relatively simple and rapid measurement of the two molecules.

“We hope our sensor will enable disease severity monitoring and serve as a tool for diagnosing and treating patients admitted to intensive care units,” said Ishida.

The researchers plan to further simplify the measurement process by integrating an ATP extraction method into the chip itself, as well as reducing the size of the sensor system.

Source: Hokkaido University