A blood plasma biomarker discovered in hospitalized COVID-19 patients may not only predict the severity of adult respiratory distress syndrome (ARDS) but further research may lead to inhibiting the progression, a team of eight University of California researchers announced today.
The UC researchers, primarily from the laboratory of UC Davis distinguished professor Bruce Hammock, found that four compounds in the blood of COVID-19 patients are highly associated with the disease. Their paper, “Plasma Linoleate Diols Are Potential Biomarkers for Severe COVID-19 Infections,” is published as open access in the current edition of Frontiers in Physiology.
ARDS, characterized by fluid build-up in the lungs, is the second leading cause of death in COVID-19 patients, next to viral pneumonia, according to the National Center for Biotechnology Information.
“Different outcomes from COVID-19 infections are both terrifying from a human health perspective and fascinating from a research perspective,” said UC Davis lead author and doctoral candidate Cindy McReynolds of the Hammock lab. “Our data provide an important clue to help determine what impacts the severity of COVID-19 outcomes. Initially, we focused on the immune response and cytokine profile as important drivers in severity, but considering what we now know from our study and others in the field, lipid mediators may be the missing link to answering questions such as why some people are asymptomatic while others die, or why some disease resolves quickly while others suffer from long-haul COVID.”
The compounds, known as leukotoxins and leukotoxin diols, originate from linoleic acid, the body's most abundant dietary fat, said Hammock, who holds a joint appointment in the Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center and directs the National Institute of Environmental Health Sciences (NEIHS) Superfund Research Program at UC Davis. “The leukotoxins (also called EpOMEs) are converted to the leukotoxin diols (also called DiHOMES) by the soluble epoxide hydrolase we work on.”
“So the leukotoxins and leukotoxin diols,” Hammock said, “are indicators of respiratory problems in COVID-19 patients as plasma biomarkers. They also present a pathway for reducing ARDS in COVID-19 if we could inhibit the soluble epoxide hydrolase, a key regulatory enzyme involved in the metabolism of immune resolving fatty acids.”
Professor John Imig, director and eminent scholar of the Medical College of Wisconsin's Drug Discovery Center, who was not involved in the study, said: “The COVID-19 pandemic has demonstrated that coronaviruses can have deadly consequences. Lung distress is a major reason for death in COVID-19 patients infected with the coronavirus (SARS-CoV-2). The findings of McReynolds et al. identified lipids called leukotoxin diols in the blood of COVID-19 patients that could act as a biomarker for lung distress. In addition, leukotoxin diols could be responsible for lung distress in COVID-19 patients. Excitingly, this suggest that therapies to lower leukotoxin diols could treat lung distress and prevent death in COVID-19 patients.”
“The findings presented in this paper bring important attention to a role for oxylipin metabolites in COVID-19 infections,” said Professor A. Daniel Jones of Michigan State University's Department of Biochemistry and Molecular Biology and director of the university's Research Technology Facility's Mass Spectrometry and Metabolomics Core. “Most notably, metabolites known as DiHOMEs which have been previously implicated in lung inflammation show promise for their potential to predict outcomes in COVID patients and guide therapeutic, and perhaps dietary interventions beneficial to human populations.” Jones, who was not involved in the study, serves as secretary of the Metabolomics Association of North America.
The UC Davis scientists used clinical data collected from six patients with laboratory-confirmed SARS-CoV-2 infection and admitted to the UC Davis Medical Center, Sacramento, and 44 healthy samples carefully chosen from the healthy control arm of a recently completed clinical study.
The Hammock lab's 50-year research on soluble epoxide hydrolase (sEH) and its inhibitors led the professor to found and direct EicOsis Human Health, a Davis-based company that is developing a potent soluble epoxide hydrolase inhibitor for pain relief. Epoxy fatty acids control blood pressure, fibrosis, immunity, tissue growth, depression, pain, inflammation and other processes.
But more recently, the Hammock lab has turned its attention to using sEH as a means to resolve inflammation associated with COVID-19 and the fibrosis that can follow.
Lipid metabolism researcher Ameer Taha of the UC Davis Department of Food Science and Technology pointed out that linoleic acid is an essential fatty acid present in only small amounts in our evolutionary diets. “In addition to nutritional and structural roles of linoleate, minor linoleate metabolites including the leukotoxin diols (also known as DiHOMEs) regulate a number functions including body temperature, cardiac health and vascular permeability. This study cautions that now with dietary linoleate levels at an all-time high, in periods of high stress as with COVID-19, these regulatory functions may become detrimental.”
The paper is the work of Hammock, McReynolds and Jun Yang of the Department of Entomology and Nematology and EicOsis Human Health; Irene Cortes-Puch of the Department of Entomology and Nematology, EicOsis Human Health, and the Department of Internal Medicine's Division of Pulmonary Critical Care and Sleep Medicine; Resmi Ravindran and Imran Khan of the Department of Pathology and Laboratory Medicine; Bruce G. Hammock of UC Davis Department of Veterinary Medicine, Aquatic Health; and Pei-an Betty Shih of the UC San Diego Department of Psychiatry.
“This study resulted from an exciting collaboration with Imran Khan and Angela Haczku of the UC Davis School of Medicine to identify potential biomarkers for differentiating the severity of COVID-19 diseases,” said Yang, the corresponding author.
The research drew financial support from several National Institutes of Health agencies: National Institute of Environmental Health Sciences (NIEHS) Superfund Research Program and R35 grant, National Institute of General Medical Sciences (NIGMS),and the National Institute of Mental Health (NIMH).
- EicOsis: Developing a New Approach to Treat Pain
- Bruce Hammock: Lifetime Achievement Award from the Chancellor
- Cindy McReynolds Receives Major NIH Training Grant
- Cancer Team's Research Paper Named Journal of Clinical Investigation's Editor's Pick (Includes Bruce Hammock and Jun Yang)
- Bruce Hammock at firstname.lastname@example.org
- Cindy McReynolds at email@example.com or firstname.lastname@example.org
- Jun Yang at email@example.com
The American Entomologist announced the award in a recent edition.
Bonning serves as the Davies, Fischer and Eckes Eminent Scholar Chair and director of the Center for Arthropod Management Technologies (CAMTech), a National Science Foundation Industry/University Cooperative Research Center.
A 1990-1994 postdoctoral research associate in the Bruce Hammock lab, where she researched genetic engineering and optimization of baculovirus insecticides, Bonning is the third Hammock lab recipient of the prestigious PBT award. Hammock, now a UC Davis distinguished professor who holds a joint appointment with the Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center, won the award in 1998, the second year of its presentation. Thomas Sparks, Hammock's first graduate student, received it in 2018.
“During the course of her career, Dr. Bonning has made significant advances in (1) fundamental understanding of stink bug digestive physiology, (2) the genetic optimization of baculovirus insecticides, (3) novel approaches for the development of insect resistant transgenic plants,” wrote the nominating team, which included Hammock.
“We were together for a year in Oxford, making the first recombinant baculoviruses," Hammock related. Following her postdoctoral appointments at the Natural Environment Research Council Institute of Virology in Oxford, UK and at UC Davis, Bonning joined the faculty at Iowa State University, serving from 1994 to 2017 when she accepted her current position in Florida.
"Her husband, Jeff Beetham, got his PhD. with me in biochemistry," Hammock said, "and worked on recombinant baculovirus pesticides and cloned and expressed the human soluble epoxide hydrolase, among other projects.”
Recalling the years they were at UC Davis, Hammock commented that he, Bonning and Beethan and the late Sean Duffey (1943-1997) "and crew used to run 5 to 7 miles four times a week." At the time of his death, Duffey was serving as vice chair of the entomology department.
The PBT award is based on research contributions, quality and originality of research; quality of publications; evaluation by colleagues peers and constituents;impact of research findings on the understanding of the subject; participation and leadership in honor and professional societies; and awards, honors and special recognitions.
Chemical ecologist Walter Leal, UC Davis distinguished professor, Department of Molecular and Cellular Biology, and a former chair of the entomology department, received the PBT award in 2008. The list of previous award winners is here.
The 7000-member Entomological Society of America, founded in 1889, is comprised of educators, extension personnel, consultants, students, researchers, and scientists from agricultural departments, health agencies, private industries, colleges and universities, and state and federal governments.
“Inflammation in the brain, or neuorinflammation, is strongly implicated in Alzheimer's disease,” said Hammock, co-author of a research paper, “An Epoxide Hydrolase Inhibitor Reduces Neuroinflammation in a Mouse Model of Alzheimer's Disease,” published Dec. 9 in the journal Science Translational Medicine.
“This paper is getting worldwide attention, and I hope it stimulates research on the role of lipid mediators in brain health” said Hammock, who holds a joint appointment with the Department of Entomology and Nematology and the UC Davis Comprehensive Cancer.
Some 5.8 million Americans have Alzheimer's disease, an irreversible brain disease that slowly destroys memory and thinking skills.
A team of eight scientists, led by Hui Zheng of the Baylor College of Medicine, Houston, explained that the enzyme, soluble epoxide hydrolase (sEH), is elevated in the brains of patients with Alzheimer's disease (AD) and in an amyloid mouse model with AD. Blocking sEH “may replenish the natural epoxy lipids, combat neuroinflammation, and improve cognition,” they said.
Hammock describes sEH as a key regulatory enzyme involved in the metabolism of fatty acids. It regulates a new class of natural chemical mediators, which in turn resolve inflammation while reducing blood pressure and pain. Hammock and his lab have been involved in research on this enzyme for more than 50 years.
“Inflammatory processes are known to be associated with the pathology and neurodegeneration associated with Alzheimer's disease," said Dr. Charles DeCarli, director of UC Davis Health's Alzheimer's Disease Center, a National Institutes of Health-funded research center funded by the National Institutes of Health. "While the exact mechanisms remain elusive, these new data offer a unique avenue for novel therapeutic development and may be the first step in the process of finding an effective treatment for Alzheimer's disease." DeCarli, who was not involved in the Baylor-UC Davis study, is a distinguished professor of neurology in the Department of Neurology and the Center for Neuroscience. He serves as the Victor and Genevieve Orsi Chair in Alzheimer's Research and directs the Imaging of Dementia and Aging laboratory.
In their abstract, the scientists explained that epoxy fatty acids “are derivatives of the arachidonic acid and omega-3 fatty acid metabolism pathways and have anti-inflammatory activities. However, their beneficial efficacy is limited because of their rapid hydrolysis by the soluble epoxide hydrolase (sEH).”
Zheng, director and professor of Baylor's Huffington Center on Aging, also holds joint appointments with Baylor's Department of Molecular and Cellular Biology and the Department of Molecular and Human Genetics. Her laboratory focuses on basic and translational research on Alzheimer's disease. “Our expertise is mouse genetics, and we are known for using sophisticated mouse models and innovative approaches to probe the biology and pathophysiology of AD,” she writes on her website.
Hammock added: "We have been lucky to collaborate with the scientists from Baylor and others around the world to find ways to resolve inflammation and reduce chronic diseases of aging. One of our sEH inhibitors is in human safety trials on a clinical path to treat chronic pain, we are hopeful that the compound also can be repurposed to ameliorate symptoms of diseases in the central nervous system.”
Of the 5.8 million Americans who have Alzheimer's, around 5.3 million are 65 and older, according to the Alzheimer's Association (AA). About two-thirds are women. “African-Americans are about twice as likely to have Alzheimer's disease or other forms of dementia as whites. Hispanics are about 1.5 times as likely to have Alzheimer's disease or other forms of dementia as whites.”
The National Institute on Aging indicates that the prevalence of Alzheimer's disease doubles every five years beyond the age of 65. At present, someone in the U.S. develops Alzheimer's disease every 66 seconds. Worldwide, some 44 million people have Alzheimer's.
The abstract: “Neuroinflammation has been increasingly recognized to play a critical role in Alzheimer's disease (AD). The epoxy fatty acids (EpFAs) are derivatives of the arachidonic acid metabolism pathway and have anti-inflammatory activities. However, their efficacy is limited because of their rapid hydrolysis by the soluble epoxide hydrolase (sEH). We report that sEH is predominantly expressed in astrocytes and is elevated in postmortem brain tissue from patients with AD and in the 5xFAD β amyloid mouse model of AD. The amount of sEH expressed in AD mouse brains correlated with a reduction in brain EpFA concentrations. Using a specific small-molecule sEH inhibitor, 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU), we report that TPPU treatment protected wild-type mice against LPS-induced inflammation in vivo. Long-term administration of TPPU to the 5xFAD mouse model via drinking water reversed microglia and astrocyte reactivity and immune pathway dysregulation. This was associated with reduced β amyloid pathology and improved synaptic integrity and cognitive function on two behavioral tests. TPPU treatment correlated with an increase in EpFA concentrations in the brains of 5xFAD mice, demonstrating brain penetration and target engagement of this small molecule. These findings support further investigation of TPPU as a potential therapeutic agent for the treatment of AD.”
Researchers from Harvard Medical School and the University of California, Davis, blocked the progression of cancer growth caused by environmental carcinogens and food contaminants by resolving an eicosanoid/cytokine storm triggered by cell debris.
The research, from the laboratories of physician-researcher Dipak Panigrahy of Harvard Medical School and UC Davis distinguished professor Bruce Hammock, is published in the current edition of the Proceedings of the National Academy of Sciences.
“We advanced the hypothesis that cell debris from chemotherapy, resection of tumors and even immunotherapy can make these therapies a double-edged sword stimulating cancer growth and metastasis while treating it,” said Hammock, who holds a joint appointment in the UC Davis Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center.
In their paper, “Resolution of Eicosanoid/Cytokine Storm Prevents Carcinogen and Inflammation-Initiated Hepatocellular Cancer Progression,” the scientists covered the potent environmental carcinogen and food contaminant aflatoxin. Aflatoxins are toxins produced by certain fungi that are found in such agricultural crops as corn, peanuts, cottonseed, and nuts.
“Not only is this fungal metabolite genotoxic but it is also a tumor promoter,” said Hammock, defining a genotoxic agent as “a chemical that damages cellular DNA, resulting in mutations or cancer.”
Lead authors Anna Fishbein of Harvard University, a recently enrolled medical student in the Georgetown University School of Medicine, and Weicang Wang, a postdoctoral scholar in the Hammock lab, said aflatoxin exerts some of its cancer-promoting effects by generating cell debris which activate a pathway leading to eicosanoid and cytokine storms. These two classes of natural chemical mediators, they explained, control many of our defenses against pathogens, but when out of control, these storms lead to growth and metastasis of liver cancer.
“We demonstrated that debris generated by aflatoxin B1accelerates tumor dormancy escape in liver cancer models by stimulating a macrophage-derived eicosanoid and cytokine storm of pro-inflammatory mediators,” said Fishbein. “Thus, targeting a single inflammatory mediator or eicosanoid pathway is unlikely to prevent carcinogen-induced tumor progression.”
The researchers showed that the inhibition of the soluble epoxide hydrolase (sEH) pathway or the combined inhibition sEH and cyclooxygenase-2 (COX-2) pathways prevented the carcinogen debris-induced storm of both cytokines and lipid mediators by macrophages--specialized detect-and-destroy cells.
In animal models, the dual COX-2/sEH inhibitor PTUPB prevented the onset of debris-stimulated liver cancer. The dual inhibition of COX-2/sEH pathways may be “a novel approach” to control cancer of the liver, the researchers said.
“We also showed that carcinogen-generated debris stimulates an endoplasmic reticulum (ER) stress response which may promote HCC progression. Importantly, PTUPB prevents the ER stress response,” Wang added. “We created a novel model of debris-stimulated liver cancer designed to study new strategies for the prevention and treatment of carcinogen-induced cancers with tremendous potential to translate to the clinic.”
From a nutritional standpoint, aflatoxin is a common food contaminant, Wang said. “But good agricultural practice and post-harvest technology keep the levels very low. However, in much of the world, aflatoxin levels are so high that many crops are discarded. In other cases, these contaminated grain and nut crops enter the human food chain, where they cause acute toxicity, severe anemia and of course later lead to cancer.”
UC Davis co-author and nutritional scientist Yuxin Wang (who is the wife of Weicang Wang) said that “finding a way to modulate the events that lead to the eicosanoid storm would have a major effect on children's health in many developing countries.”
Fishbein and Allison Gartung of the Panigrahy lab not only used the soluble epoxide hydrolase inhibitors from the Hammock lab but also used some prototype drugs synthesized by chemist Sung Hee Hwang of the UC Davis School of Veterinary Medicine “which proved to be even better,” Hammock said.
“These compounds are a synthetic combination of cyclooxygenase inhibitors like celebrex with epoxide hydrolase inhibitors,” Hammock said. “Since epoxide hydrolase inhibitors stabilize the endoplasmic reticulium stress response and transcriptionally down regulate inflammatory cyclooxygenase we expected them to synergize with cyclooxygenase inhibitors. We were surprised and pleased with the dramatic interaction of these inhibitors when combined in the same molecule in reducing the cytokine and eicosanoid production by in response to cell debris.”
“The observations from Harvard show that by inhibiting soluble epoxide hydrolase, we can block the activation of these inflammatory cascades leading to tumor promotion, growth and metastasis,” Hammock said. “We have a compound in human clinical trials that inhibits sEH, which should be clinically available in a few years. In addition. we have found natural inhibitors of the epoxide hydrolase in a variety of plants, including crop plants. This may allow us to reduce the cancer risk and block the gastrointestional erosion and bleeding caused by dietary aflatoxin using natural means.”
Other members of the 15-member team are UC Davis researchers Jun Yang, Yuxin Wang and Sung Hee Hwang; Harvard researchers Haixia Yang, Victoria Hallisey, Jianjun Deng, Sanne Verheul, Allison Gartung, Diane Bielenberg and Mark Kiernan (now of Bristol-Myers Squibb); and Sui Huang, Institute for Systems Biology, Seattle. Hammock and Panigrahy are the corresponding authors.
The research drew strong financial support as the Panigrahy's laboratory is generously supported by the Credit Unions Kids at Heart Team, the CJ Buckley Pediatric Brain Tumor Fund, and the Joe Andruzzi Foundation; and Hammock's UC Davis grants from the National Institute of Environmental Health (NIEHS) Superfund Research Program, and the NIEHS RIVER Award (Revolutionizing Innovative, Visionary, Environmental Health Research).
Hammock, a member of the UC Davis faculty since 1980, has directed the UC Davis Superfund Research Program for nearly four decades. It supports scores of pre- and postdoctoral scholars in interdisciplinary research in five different colleges and graduate groups on campus. Last year Hammock received a $6 million, eight-year “Outstanding Investigator” federal grant for his innovative and visionary environmental health research: The award is part of the Revolutionizing Innovative, Visionary Environmental Health Research (RIVER) Program of NIEHS.
“Toxic environmental carcinogens promote cancer via genotoxic and nongenotoxic pathways, but nongenetic mechanisms remain poorly characterized. Carcinogen-induced apoptosis may trigger escape from dormancy of microtumors by interfering with inflammation resolution and triggering an endoplasmic reticulum (ER) stress response. While eicosanoid and cytokine storms are well-characterized in infection and inflammation, they are poorly characterized in cancer. Here, we demonstrate that carcinogens, such as aflatoxin B1 (AFB1), induce apoptotic cell death and the resulting cell debris stimulates hepatocellular carcinoma (HCC) tumor growth via an ‘eicosanoid and cytokine storm.' AFB1-generated debris up-regulates cyclooxygenase-2 (COX-2), soluble epoxide hydrolase (sEH), ER stress-response genes including BiP, CHOP, and PDI in macrophages. Thus, selective cytokine or eicosanoid blockade is unlikely to prevent carcinogen-induced cancer progression. Pharmacological abrogation of both the COX-2 and sEH pathways by PTUPB prevented the debris-stimulated eicosanoid and cyto- kine storm, down-regulated ER stress genes, and promoted macrophage phagocytosis of debris, resulting in suppression of HCC tumor growth. Thus, inflammation resolution via dual COX-2/sEH inhibition is an approach to prevent carcinogen-induced cancer.”
As of July 8, the commentary, “Inflammation Resolution: a Dual-Pronged Approach to Averting Cytokine Storms in COVID-19?”—the work of a nine-member team of Harvard University and UC Davis researchers—has been downloaded 11,444 times since its publication May 8, 2020. It is online at https://rdcu.be/b33IN.
In comparison, the most downloaded publication in CMR in 2019 received 5,712, statistics show.
Editor-in-Chief and Professor Kenneth Honn, who selected their commentary as the top paper of the month, said it drew more downloads the first week of publication than any other in the journal's history. The work is based on more than 40 years of eicosanoid research from the Hammock lab and more than 40 years of eicosanoid research from the Charles Serhan lab at Harvard Medical School.
“COVID-19 results in excessive inflammation and a cytokine storm caused by the human body's reaction to the SARS-CoV-2 virus,” said lead author Dipak Panigrahy, a Harvard University physician and researcher who collaborates with the Hammock laboratory.
“Controlling the body's inflammatory response to COVID-19 will likely be as important as anti-viral therapies or a vaccine,” Panigraphy said. “Stimulation of inflammation resolutions via pro-resolution lipid mediators that are currently in clinical trials for other inflammatory diseases is a novel approach to turning off the inflammation and preventing the cytokine storm caused by COVID-19.”
The drug is an inhibitor to the soluble epoxide hydrolase (sEH) enzyme, a key regulatory enzyme involved in the metabolism of fatty acids.
Panigraphy and Hammock said they are receiving “tons of calls, media requests and emails” from all over the world, including Norway, Japan, United Kingdom, Germany, France, Mexico and Belgium.
Pioneering research from the Panigrahy and Hammock labs shows that cell debris from surgery, chemotherapy, toxin exposure and other causes lead to production of high levels of pro-inflammatory mediators commonly called cytokines as well as eicosanoids.
“A rapid immune response is critical to controlling this virus,” Panigrahy emphasized.
“We believe it holds promise to combat the inflammation involved with this disease,” said co-author Hammock, a UC Davis distinguished professor who holds a joint appointment with the Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center. “It hit me in March that what we really need to do is not so much block cytokines as to move upstream to modulate them and resolve them rather than block inflammation.”
“We can increase the concentration of natural pro-resolving mediators termed EETs which act on a biological system to produce other pro-resolution mediators which modulate inflammation and actively resolve the process,” explained Hammock, who founded the Davis-based company EicOsis Human Health LLC, to bring the inhibitor to human clinical trials, which are underway in Texas.
The co-authors include two physician-researchers: Patricia Sime of the Division of Pulmonary and Critical Care Medicine, Virginia Commonwealth University, Richmond, and Irene Cortés-Puch of the Division of Pulmonary, Critical Care and Sleep Medicine, UC Davis Medical Center, and an EicOsis project scientist.
“It is this resolution of inflammation and the subsequent repair that is critical to restore patient health,” said Serhan, whose studies with collaborator Sime show that immune resolution and repair are active processes in the lungs and other tissues. What drives the process, Serhan said, is the production of specific pro-resolving agents (SPMs).
Other co-authors of the paper are Molly Gilligan and Allison Gartung of the Panigrahy lab; Sui Huang of the Institute for Systems Biology, Seattle; and Richard Phipps, independent scholar, Richmond, Va.
National Institutes of Health (NIH) grants, including a National Institute of Environmental Health Science (River Award) to Hammock, helped fund the research. The Panigrahy laboratory is generously supported by the Credit Unions Kids at Heart Team; the C.J. Buckley Pediatric Brain Tumor Fund; and the Joe Andruzzi Foundation.