Tag: cell danger response

For ME/CFS patients, viral immunities come at a devastating, lifelong cost

Press Release: EurekAlert

Mylagic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disabling and complex illness. Affected persons often cannot pursue ordinary activities — physical or mental — because of an incapacitating loss of energy and other symptoms, and may find themselves confined to bed or house-bound for years.

Anyone can develop ME/CFS, though it most commonly afflicts people between the ages of 40 and 60; women more often than men. In nearly every case, ME/CFS begins after a sequence of severe environmental exposures, injuries or infections. Until relatively recently, the utter mystery and complexity of ME/CFS persuaded some that it was not a “real” condition. In 2015, the National Academy of Medicine declared ME/CFS to be a serious, chronic, complex and systemic disease.

In a new study, to be published in the May 1, 2020 print edition of https://www.immunohorizons.org/content/4/4/201 ImmunoHorizons, a team of researchers at University of California San Diego School of Medicine and three German universities describe an underlying biological basis for ME/CFS, one that illustrates how efforts by the body to boost immune system protections can come at physiological cost elsewhere.

“These findings are important because they show for the first time that there is an antiviral activity in the serum of patients with ME/CFS that is tightly associated with an activity that fragments the mitochondrial network and decreases cellular energy (ATP) production,” said Robert Naviaux, MD, PhD, professor of medicine, pediatrics and pathology at UC San Diego School of Medicine.

Naviaux is co-senior author of the study with Bhupesh K. Prusty, PhD, a scientist in the Department of Microbiology and Institute for Virology and Immunobiology at Julius Maximilians University in Würzburg, Germany.

“This provides an explanation for the common observation that ME/CFS patients often report a sharp decrease in the number of colds and other viral infections they experience after they developed the disease. Our work also helps us understand the long-known, but poorly understood link of ME/CFS to past infections with Human Herpes Virus-6 (HHV-6) or HHV-7,” said Naviaux.

More than 90 percent of people are exposed to HHV-6 by three years of age. The virus DNA can insert itself into a chromosome and remain latent in just a few cells for years, silently being copied each time the cell divides. For most people, this causes no problem.

“However, we found that exposure to new metabolic or environmental chemical stresses caused cells with an integrated copy of HHV-6 to secrete an activity that warned neighboring cells of the threat,” said Naviaux. “The secreted activity not only protected neighboring and distant cells from new RNA and DNA virus infections, but also fragmented the mitochondrial network and lowered their intracellular ATP reserve capacity. Cells without an integrated copy of HHV-6 did not secrete the antiviral activity.

“Our results show that cellular bioenergetic fatigue and cellular defense are two sides to the same coin in ME/CFS. When energy is used for cellular defense, it is not available for normal cell functions like growth, repair, neuroendocrine and autonomic nervous system functions.”

The findings further illuminate a concept called cell danger response theory, which Naviaux and colleagues have been investigating for years. CDR theory posits that chronic disease is the consequence of the natural healing cycle becoming blocked by disruptions at the metabolic and cellular levels. In this case, persons with ME/CFS obtained protections against certain kinds of infections, but at a cost of fragmenting mitochondrial function. Persistence of fragmented mitochondria and the associated abnormalities in cell signaling block normal healing and recovery, and can lead to a lifetime of illness.

Mitochondria are organelles in cells that break down nutrients to create a fuel called adenosine triphosphate (ATP), the primary energy carrier in all living organisms. ATP provides the energy used to drive many cellular processes, including muscle contractions, nerve impulses and chemical synthesis.

“This paper will be a paradigm shift in our understanding of potential infectious causes behind ME/CFS. Human herpesvirus 6 and HHV-7 have long been thought to play a role in this disease, but there was hardly any causative mechanism known before,” said senior co-author Prusty.

“For the first time, we show that even a few HHV-6 infected or reactivated cells can drive a powerful metabolic and mitochondrial remodeling response that can push even the non-virus containing cells towards a hypometabolic (abnormally low metabolic) state. Hypometabolic cells are resistant to other viral infections and to many environmental stresses, but this comes at the cost of severe symptoms and suffering for patients with ME/CFS.”

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Co-authors include: Philipp Schreiner, Stephanie Lamer and Andreas Schlosser, Julius-Maximilians University, Germany; Thomas Harrer, University of Erlangen-Nuremberg; and Carmen Scheibenbogen, Charite-Universitatsmedizin Berlin.

Human Herpesvirus-6 Reactivation, Mitochondrial Fragmentation, and the Coordination of Antiviral and Metabolic Phenotypes in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a multifactorial disorder with many possible triggers. Human herpesvirus (HHV)–6 and HHV-7 are two infectious triggers for which evidence has been growing. To understand possible causative role of HHV-6 in ME/CFS, metabolic and antiviral phenotypes of U2-OS cells were studied with and without chromosomally integrated HHV-6 and with or without virus reactivation using the histone deacetylase inhibitor trichostatin-A. Proteomic analysis was conducted by pulsed stable isotope labeling by amino acids in cell culture analysis.

Antiviral properties that were induced by HHV-6 transactivation were studied in virus-naive A549 cells challenged by infection with influenza-A (H1N1) or HSV-1. Mitochondria were fragmented and 1-carbon metabolism, dUTPase, and thymidylate synthase were strongly induced by HHV-6 reactivation, whereas superoxide dismutase 2 and proteins required for mitochondrial oxidation of fatty acid, amino acid, and glucose metabolism, including pyruvate dehydrogenase, were strongly inhibited. Adoptive transfer of U2-OS cell supernatants after reactivation of HHV-6A led to an antiviral state in A549 cells that prevented superinfection with influenza-A and HSV-1. Adoptive transfer of serum from 10 patients with ME/CFS produced a similar fragmentation of mitochondria and the associated antiviral state in the A549 cell assay.

In conclusion, HHV-6 reactivation in ME/CFS patients activates a multisystem, proinflammatory, cell danger response that protects against certain RNA and DNA virus infections but comes at the cost of mitochondrial fragmentation and severely compromised energy metabolism.

Source: Philipp Schreiner, Thomas Harrer, Carmen Scheibenbogen, Stephanie Lamer, Andreas Schlosser, Robert K. Naviaux and Bhupesh K. Prusty. Human Herpesvirus-6 Reactivation, Mitochondrial Fragmentation, and the Coordination of Antiviral and Metabolic Phenotypes in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. ImmunoHorizons April 1, 2020, 4 (4) 201-215; DOI: https://doi.org/10.4049/immunohorizons.2000006 https://www.immunohorizons.org/content/4/4/201  (Full text)

Chronic diseases driven by metabolic dysfunction

Press Release: University of California – San Diego, September 9, 2018. Much of modern Western medicine is based upon the treatment of acute, immediate harm, from physical injury to infections, from broken bones and the common cold to heart and asthma attacks.

But progress in treating chronic illness, where the cause of the problem is often unknown — and, in fact, may no longer even be present — has lagged. Chronic conditions like cancer, diabetes and cardiovascular disease defy easy explanation, let alone remedy. The Centers for Disease Control and Prevention estimate that more than half of adults and one-third of children and teens in the United States live with at least one chronic illness. Chronic medical conditions, according to the National Institutes of Health, cause more than half of all deaths worldwide.

In a new paper, available online in Mitochondrion in advance of publication, Robert K. Naviaux, MD, PhD, professor of medicine, pediatrics and pathology at University of California San Diego School of Medicine, posits that chronic disease is essentially the consequence of the natural healing cycle becoming blocked, specifically by disruptions at the metabolic and cellular levels.

“The healing process is a dynamic circle that starts with injury and ends with recovery. The molecular features of this process are universal,” said Naviaux, who also directs the Mitochondrial and Metabolic Disease Center at UC San Diego. “Emerging evidence shows that most chronic illnesses are caused by the biological reaction to an injury, not the initial injury or the agent of the injury. The illness occurs because the body is unable to complete the healing process.”

For example, said Naviaux, melanoma — the deadliest form of skin cancer — can be caused by sun exposure that occurred decades earlier, damaging DNA that was never repaired. Post-traumatic stress disorder can flare months or years after the original head injury has healed. A concussion sustained before an earlier concussion has completely resolved typically results in more severe symptoms and prolonged recovery, even if the second impact is less than the first.

“Progressive dysfunction with recurrent injury after incomplete healing occurs in all organ systems, not just the brain,” said Naviaux. “Chronic disease results when cells are caught in a repeating loop of incomplete recovery and re-injury, unable to fully heal. This biology is at the root of virtually every chronic illness known, including susceptibility to recurrent infections, autoimmune diseases like rheumatoid arthritis, diabetic heart and kidney disease, asthma, chronic obstructive pulmonary disease, Alzheimer’s dementia, cancer and autism spectrum disorder.”

For more than a decade, Naviaux and colleagues have been investigating and developing a theory based on cell danger response (CDR), a natural and universal cellular reaction to injury or stress. In the new paper, Naviaux describes the metabolic features of the three stages of CDR that comprise the healing cycle.

“The purpose of CDR is to help protect the cell and jump-start the healing process,” said Naviaux, by essentially causing the cell to harden its membranes, cease interaction with neighbors and withdraw within itself until the danger has passed.

“But sometimes CDR gets stuck. At the molecular level, cellular equilibrium is altered, preventing completion of the healing cycle and permanently changing the way the cell responds to the world. When this happens, cells behave as if they are still injured or in imminent danger, even though the original cause of the injury or threat has passed.”

Last year, Naviaux conducted a small, randomized clinical trial of 10 boys diagnosed with autism, treating them with a single dose of a century-old drug that inhibits adenosine triphosphate (ATP), a small molecule produced by cellular mitochondria that serves as a warning siren of danger. When the abnormal ATP signaling was silenced, the treated boys in the trial displayed dramatically improved communication and social behaviors. They spoke, made eye contact and ceased repetitive motions. But the benefits were transient, fading and disappearing as the drug exited their systems. Naviaux’s team is preparing for a larger, longer trial in 2019.

In his new paper, Naviaux describes in detail how he, based on growing evidence, believes metabolic dysfunction drives chronic disease. Progression through the healing cycle, he said, is controlled by mitochondria — organelles within cells best known for their production of most of the energy cells need to survive — and metabokines, signaling molecules derived from metabolism to regulate cellular receptors, including more than 100 linked to healing.

“It’s abnormalities in metabokine signaling that cause the normal stages of the cell danger response to persist abnormally, creating blocks in the healing cycle,” said Navaiux, who noted CDR theory also explains why some people heal more quickly than others and why a chronic disease seemingly treated successfully can relapse. It’s a form of metabolic “addiction” in which the recovering cell becomes conditioned to its impaired state.

Naviaux suggests science may be on the cusp of writing a second book of medicine, one that focuses on the prevention of chronic illness and new treatments for chronic disease that can help some people recover completely, where old approaches produced only small improvements with symptoms that persisted for life.

“The idea would be to direct treatments at the underlying processes that block the healing cycle,” he said. “New treatments might only be given for a short period of time to promote healing, not unlike applying a cast to promote the healing of a broken leg. When the cast is removed, the limb is weak, but over time, muscles recover and bone that was once broken may actually be stronger.”

“Once the triggers of a chronic injury have been identified and removed, and on-going symptoms treated, we need to think about fixing the underlying issue of impaired healing. By shifting the focus away from the initial causes to the metabolic factors and signaling pathways that maintain chronic illness, we can find new ways to not only end chronic illness but prevent it.”

Journal Reference: Robert K. Naviaux. Metabolic features and regulation of the healing cycle—A new model for chronic disease pathogenesis and treatment. Mitochondrion, 2018; DOI: 10.1016/j.mito.2018.08.001

Metabolic features of the cell danger response

Editor’s note: Dr. Naviaux has theorized that the cell danger response lies at the heart of ME/CFS pathophysiology.

Abstract:

The cell danger response (CDR) is the evolutionarily conserved metabolic response that protects cells and hosts from harm. It is triggered by encounters with chemical, physical, or biological threats that exceed the cellular capacity for homeostasis. The resulting metabolic mismatch between available resources and functional capacity produces a cascade of changes in cellular electron flow, oxygen consumption, redox, membrane fluidity, lipid dynamics, bioenergetics, carbon and sulfur resource allocation, protein folding and aggregation, vitamin availability, metal homeostasis, indole, pterin, 1-carbon and polyamine metabolism, and polymer formation. The first wave of danger signals consists of the release of metabolic intermediates like ATP and ADP, Krebs cycle intermediates, oxygen, and reactive oxygen species (ROS), and is sustained by purinergic signaling. After the danger has been eliminated or neutralized, a choreographed sequence of anti-inflammatory and regenerative pathways is activated to reverse the CDR and to heal.

When the CDR persists abnormally, whole body metabolism and the gut microbiome are disturbed, the collective performance of multiple organ systems is impaired, behavior is changed, and chronic disease results. Metabolic memory of past stress encounters is stored in the form of altered mitochondrial and cellular macromolecule content, resulting in an increase in functional reserve capacity through a process known as mitocellular hormesis. The systemic form of the CDR, and its magnified form, the purinergic life-threat response (PLTR), are under direct control by ancient pathways in the brain that are ultimately coordinated by centers in the brainstem. Chemosensory integration of whole body metabolism occurs in the brainstem and is a prerequisite for normal brain, motor, vestibular, sensory, social, and speech development.

An understanding of the CDR permits us to reframe old concepts of pathogenesis for a broad array of chronic, developmental, autoimmune, and degenerative disorders. These disorders include autism spectrum disorders (ASD), attention deficit hyperactivity disorder (ADHD), asthma, atopy, gluten and many other food and chemical sensitivity syndromes, emphysema, Tourette’s syndrome, bipolar disorder, schizophrenia, post-traumatic stress disorder (PTSD), chronic traumatic encephalopathy (CTE), traumatic brain injury (TBI), epilepsy, suicidal ideation, organ transplant biology, diabetes, kidney, liver, and heart disease, cancer, Alzheimer and Parkinson disease, and autoimmune disorders like lupus, rheumatoid arthritis, multiple sclerosis, and primary sclerosing cholangitis.

Source: Robert K.Naviaux. Metabolic features of the cell danger response. Mitochondrion. Volume 16, May 2014, Pages 7-17. https://www.sciencedirect.com/science/article/pii/S1567724913002390 (Full article)