Mitochondrial Protein in Cardiac Muscle Cells Linked to Heart Failure, Study Finds

Reducing a protein found in the mitochondria of cardiac muscle cells initiates cardiac dysfunction and heart failure, a finding that could provide insight for new treatments for cardiovascular diseases, a study led by Georgia State University has shown.

The researchers discovered that reducing an outer mitochondrial membrane protein, FUN14 domain containing 1 (FUNDC1), in cardiac muscle cells, also known as cardiomyocytes, activates and worsens cardiac dysfunction. Also, disrupting how FUNDC1 binds to a particular receptor inhibited the release of calcium from another cell structure, the endoplasmic reticulum (ER), into the mitochondria of these cells and resulted in mitochondrial dysfunction, cardiac dysfunction and heart failure. The findings are published in the journal Circulation.

Mitochondria play numerous roles in the body, including energy production, reactive oxygen species generation and signal transduction. Because the myocardium, the muscular wall of the heart, is a high-energy-demand tissue, mitochondria play a central role in maintaining optimal cardiac performance. Growing evidence suggests deregulated mitochondrial activity plays a causative role in cardiovascular diseases.

In the body, mitochondria and ER are interconnected and form their own endomembrane networks. The points where mitochondria and ER make physical contact and communicate are known as mitochondria-associated ER membranes (MAMs). MAMs play a major role in regulating the transfer of calcium between ER and mitochondria. Dysfunctional MAMs are involved in several neuronal disorders, including Alzheimer’s disease and Parkinson’s disease. Until now, the role of MAMs in cardiac pathologies has not been well understood.

“Our study found the formation of MAMs mediated by the mitochondrial membrane protein FUNDC1 was significantly suppressed in patients with heart failure, which provides evidence that FUNDC1 and MAMs actively participate in the development of heart failure,” said Dr. Ming-Hui Zou, director of the Center for Molecular and Translational Medicine at Georgia State and a Georgia Research Alliance Eminent Scholar in Molecular Medicine. “This work has important clinical implications and provides support that restoring proper function of MAMs may be a novel target for treating heart failure.”

The researchers used mouse neonatal cardiomyocytes, mice with a genetic deletion of the FUNDC1 gene, control mice with no genetic deficiencies and the cardiac tissues of patients with heart failure.

The cardiac functions of the mice were monitored using echocardiography at 10 weeks of age. Mice with the genetic deletion of FUNDC1 had markedly reduced ventricular filling velocities, prolonged left ventricular isovolumic relaxation time, diastolic dysfunction, decreased cardiac output (which indicates impaired systolic functions) and interstitial fibrosis of the myocardium, among other issues. The mitochondria in the hearts of mice with FUNDC1 gene deletion were larger and more elongated, a 2.5-fold increase of size compared to mitochondria in the control mice.

To determine if FUNDC1 reduction occurred in human hearts and contributed to heart failure in patients, the researchers examined four heart specimens from heart failure patients and four heart specimens from control donors. They found the levels of FUNDC1 were significantly reduced in patients with heart failure compared to control donors. Also, the contact between ER and mitochondria in failed hearts was significantly reduced. In addition, the mitochondria in heart failure hearts were more elongated compared to those in control donors.

Experimental Drug Blocks Toxic Ion Flow Linked to Alzheimer’s Disease

An international team of researchers has shown that a new small-molecule drug can restore brain function and memory in a mouse model of Alzheimer’s disease. The drug works by stopping toxic ion flow in the brain that is known to trigger nerve cell death. Scientists envision that this drug could be used to treat Alzheimer’s and other neurodegenerative diseases such as Parkinson’s and ALS.

“This is the first drug molecule that can regulate memory loss by directly blocking ions from leaking through nerve cell membranes,” said Ratnesh Lal, a professor of bioengineering at the University of California San Diego and co-senior author of the study.

Various studies have linked Alzheimer’s disease to the accumulation of two particular proteins in the brain called amyloid-beta and tau. One theory is that these protein clusters create pores in nerve cell membranes that allow ions to travel in and out uncontrollably. This would alter ion levels inside the cells and in turn trigger neuronal dysfunction and cell death.

The new drug, a small molecule called anle138b, blocks these pores from moving ions in and out of nerve cells. Anle138b attaches to both amyloid-beta and tau protein clusters and deactivates the pores created by these clusters.

Researchers administered anle138b to mice with a genetic predisposition for developing an Alzheimer’s-like condition. The mice had symptoms such as abnormal brain function, impaired memory and high levels of either amyloid-beta or tau proteins in the brain. Treatment with anle138b normalized brain activity and improved learning ability in mice.

The study was led by the German Center for Neurodegenerative Diseases, the University Medical Center Göttingen, the Braunschweig University of Technology, the Max Planck Institute for Biophysical Chemistry, the Center for Nanoscale Microscopy and Molecular Physiology of the Brain in Göttingen, Germany, and the University of California San Diego. Researchers published their findings on Dec. 5 in EMBO Molecular Medicine.

Christian Griesinger, a professor at the Max Planck Institute for Biophysical Chemistry and co-senior author of the study, noted, “The drug is able to reach the brain when taken orally. Therefore, it is easy to administer, and we are currently performing toxicology studies to eventually be able to apply anle138b to humans.”

The team cautions that since the drug has so far only been tested in mice, it is unclear how well it would perform in humans. “I would like to emphasize that none of the current animal models fully recapitulate the symptoms seen in Alzheimer’s patients. Thus, care has to be taken when interpreting such data. However, our study offers evidence that anle138b has potential for neuroprotection,” said André Fischer, a senior researcher at the German Center for Neurodegenerative Diseases and the University Medical Center Göttingen, who is also a co-senior author of the study.

While collaborators in Germany will be pursuing clinical studies in human patients with neurodegenerative diseases, Lal and his research group at the UC San Diego Jacobs School of Engineering are particularly interested in testing anle138b on a variety of other diseases that are linked to toxic ion flow caused by amyloid proteins, including diabetes, tuberculosis and certain types of cancer. Lal’s group has performed extensive research on amyloid ion channels and their roles in these diseases. “Blocking the ion leakiness of amyloid channels using anle138b could be an effective therapy for various diseases,” Lal said.

Lal serves as co-director for the Center of Excellence for Nanomedicine and Engineering, a subcenter of the Institute of Engineering in Medicine at UC San Diego. His research group will also work on targeted delivery of the drug using their patent pending “nanobowls,” which are magnetically guided nanoparticles that can be packed with drugs and diagnostic molecules, deliver them to particular sites in the body and release them on demand. Future studies will focus on using these nanobowls to deliver anle138b to the brain, as well as other diseased tissues and organs affected by toxic amyloid-beta ion channels.

Combination Strategy Could Hold Promise for Ovarian Cancer

 Johns Hopkins Kimmel Cancer Center researchers demonstrated that mice with ovarian cancer that received drugs to reactivate dormant genes along with other drugs that activate the immune system had a greater reduction of tumor burden and significantly longer survival than those that received any of the drugs alone.

The study already spurred a clinical trial in ovarian cancer patients. The investigators, led by graduate student Meredith Stone, Ph.D.; postdoctoral fellow Kate Chiappinelli, Ph.D.; and senior author Cynthia Zahnow, Ph.D., believe it could lead to a new way to attack ovarian cancer by strengthening the body’s natural immune response against these tumors. It was published in the Dec. 4, 2017, issue of the Proceedings of the National Academy of Sciences.

Ovarian cancer is currently the leading cause of death from gynecological malignancies in the U.S. “We’ve taken two types of therapies that aren’t very effective in ovarian cancer and put them together to make them better at revving up the immune system and attacking the tumor,” says Zahnow, associate professor of oncology at the Johns Hopkins Kimmel Cancer Center.

Zahnow says that a class of immunotherapy drugs known as checkpoint inhibitors, currently being studied at the Bloomberg~Kimmel Institute for Cancer Immunotherapy, helps the immune system recognize cancers and fight them off. The drugs have shown success in treating melanoma, nonsmall cell lung cancer and renal cell cancers, but they have had only modest effects on ovarian cancer.

Similarly, another class of drugs known as epigenetic therapies has been used to treat some types of cancer by turning on genes that have been silenced— either by the presence of chemical tags, known as methyl groups, or by being wound too tightly around protein spools, known as histones—but these drugs haven’t been effective against ovarian cancer either.

Zahnow and her colleagues became inspired to investigate a new way to treat ovarian cancer by two recent publications from their group that showed epigenetic drugs turn on immune signaling in ovarian, breast and colon cancer cells (Li et al., Oncotarget 2014). These immune genes are activated when epigenetic therapy turns on segments of ancient retroviruses that activate type 1 interferon signaling in the cells (Chiappinelli et al., Cell 2015).  Stone, Chiappinelli and Zahnow wanted to know if this increase in immune signaling could lead to the recruitment of tumor killing immune cells to the cancer.

Zahnow and her colleagues worked with a mouse model of the disease in which mouse ovarian cancer cells are injected into the animals’ abdomens to mimic human disease. These cells eventually develop into hundreds of small tumors, which cause fluid to collect within the abdomen, a condition known as ascites. Floating in this fluid is a milieu of both cancer and immune cells, offering a convenient way to keep tabs on both the tumor and the animals’ immune response.

The researchers started by pretreating the ovarian cancer cells outside of the animal in a culture dish with a DNA methyltransferase inhibitor (a drug that knocks methyl groups from DNA) called 5-azacytidine (AZA). After injecting these cells into mice, the researchers found that animals receiving the pretreated cells had significantly decreased ascites or tumor burden and significantly more cancer-fighting immune cells in the ascites fluid compared to those injected with untreated cells. These cells also had increased activity in a variety of genes related to immune response. Pretreating these cells with histone deacetylase inhibitors (HDACis), which help DNA uncoil from histones, didn’t affect the animals’ ascites or boost their immune response.

These early findings suggested that changes in gene activity induced by AZA cause the tumor cells themselves to summon immune cells to their location. In addition, when the researchers transplanted untreated cells into mice and treated the animals with both AZA and an HDACi, significantly more immune cells were in the ascites fluid, suggesting that the HDACi was acting on the animals’ immune systems. These mice also had decreased ascites, lower tumor burden and longer survival than mice that received just AZA.

When the researchers treated the mice with both AZA and an HDACi, along with an immune checkpoint inhibitor, they got the greatest response—the highest decreases in ascites and tumor burden, and the longest survival. Further experiments using immunocompromised mice showed that the immune system is pivotal to the action of these drugs, rather than the drugs themselves acting directly to kill tumor cells.

“We think that AZA and the HDACis are bringing the soldiers, or immune cells, to the battle. But the checkpoint inhibitor is giving them the weapons to fight,” says Zahnow, who also collaborated with epigenetics scientist Stephen Baylin, M.D., on this project.

The preclinical data generated through this study is already being used to help patients with ovarian cancer through an ongoing clinical trial to test the effectiveness of combining AZA and a checkpoint inhibitor. Future trials may add an HDACi to determine if it affects outcomes.

“Combining epigenetic therapy and a checkpoint blocker leads to the greatest reduction in tumor burden and increase in survival in our mouse model and may hold the greatest promise for our patients,” says Zahnow.

Phase III Immunotherapy Trial for Migraine Shows Positive Results

An antibody therapy against a key inflammatory molecule involved in migraines reduces the number of headaches that chronic migraine patients experience per month in a phase III trial.

A new study of fremanezumab, an immunotherapy that counteracts one of the molecules released during migraine, was found successful in reducing the number of days that chronic migraine sufferers experienced headaches. The results of the phase III clinical trial were published November 29, 2017 in the New England Journal of Medicine.

The World Health Organization estimates that between 127 and 300 million people around the world experience chronic migraine, defined as 15 or more headaches per month for at least three months. The disease can be debilitating and although a number of interventions exist, many only work for a certain time before they fail to prevent or relieve pain.

“This therapeutic approach offers new hope for people whose migraines cannot be treated with existing medicine,” says Stephen D. Silberstein, M.D., principal investigator of the HALO CM trial, Professor of Neurology and Director of the Jefferson Headache Center at the Vickie & Jack Farber Institute for Neuroscience at Thomas Jefferson University Hospital. “Our worldwide effort to evaluate this novel therapeutic approach has shown positive results and was safe in patients.”

Fremanezumab, a monoclonal antibody developed by Teva Pharmaceuticals, is a biological agent that binds to and blocks the action of a migraine-associated protein called calcitonin gene-related peptide (CGRP). Mounting evidence of its importance in migraines has made CGRP a focal point of research and drug development. The peptide is released at high levels during migraine in response to inflammation, and triggers a cascade effect that stimulates more CGRP release. This results in increasing sensitivity of the brain to pain. By blocking this peptide, doctors hope to break the cycle of increasing inflammation and increased pain sensitivity that contributes to migraine headaches.

Researchers from 132 sites across nine countries enrolled 1130 patients and randomly assigned them to one of three groups: one that received quarterly treatments, a group that received one treatment per month, and one that received placebo injections. The trial lasted for 16 weeks, with a 12-week treatment window.

The results of the trial show that treatment with fremanezumab reduced the number of days patients experience headache by an average of 4.3 days with quarterly treatment and 4.6 days with monthly treatment. “We saw some patients with 100 percent reduction in migraine, others with 75 percent reduction,” says Dr. Silberstein. The level of response varied between patients.

The researchers also looked at how well the therapy worked relative to each patient’s headache burden. They calculated the percent of patients who had more than a 50 percent reduction in the number of days they experienced either a severe or moderate headache per month. Using this measure, the researchers saw that 37.6 percent of patients on the monthly regimen, and 40.8 percent on the quarterly regimen had at least a 50 percent reduction in the number of moderate headaches per month, compared to 18.1 percent in the placebo group.

The therapy had a favorable safety profile with the most common adverse event reported as irritation at injection site, which was reported in the placebo group as well.

“If approved, this treatment would provide physicians with an important new tool to help prevent migraine, reduce a patient’s migraine load, and potentially help patients return to normal” says Dr. Silberstein.

Discovery of key molecules involved in severe malaria

Malaria*1 is one of three major infectious diseases*2 affecting approximately 300 million people every year, accounting for about 500,000 deaths, but effective vaccine development has not been successful. Among malaria parasites infecting humans, Plasmodium falciparum (P. falciparum)*3 causes especially severe disease. In addition, acquired immunity to malaria is inefficient, even after repeated exposures to P. falciparum, but the immune regulatory mechanisms used by P. falciparum remain largely unclear. Therefore, malaria parasites appear to have a mechanism to escape our immune system.

A research group led by Fumiji Saito, Kouyuki Hirayasu, Hisashi Arase at Osaka University found that proteins called RIFIN expressed on erythrocytes infected with P. falciparum help the parasite to suppress the host immune response, causing severe malaria (Fig. 1). These findings are expected to contribute to the development of effective vaccines and therapeutic drugs against malaria.

Malaria parasites infect mainly erythrocytes in the host and proliferate within infected erythrocytes. The team found that proteins called RIFIN*4 expressed on P falciparum-infected erythrocytes bind to a host inhibitory receptor LILRB1*5. Furthermore, RIFIN suppresses the immune response to malaria, resulting in severe complications of malaria.

This research disclosed for the first time in the world that P. falciparum has a new mechanism to suppress the host immune response by using an inhibitory receptor, contributing to the pathogenesis of severe malaria. The results of this research are expected to greatly contribute to the development of therapeutic drug and vaccine against malaria.

*1 Malaria
Infectious diseases caused by malaria parasites

*2 Three major infectious diseases
Malaria, tuberculosis, and HIV/AIDS

*3 Plasmodium falciparum
Malaria parasites infecting humans, and causing the most severe complications of malaria

*4 RIFIN
RIFIN proteins are encoded by the rif (repetitive interspersed family) genes of P. falciparum. There are about 150 rif genes per parasite genome. However, their functions have been still unclear.

*5 LILRB1
One of the immune inhibitory receptors that suppress the activation of immune cells and prevent autoimmune responses by recognizing self-molecules like major histocompatibility complex (MHC) class I. Human cytomegalovirus is also known to have a viral MHC class I-like molecule (UL18) that suppresses the immune response via LILRB1 for immune escape.

2-Drug Combination May Boost Immunotherapy Responses in Lung Cancer Patients

Johns Hopkins Kimmel Cancer Center researchers and colleagues have identified a novel drug combination therapy that could prime nonsmall cell lung cancers to respond better to immunotherapy. These so-called epigenetic therapy drugs, used together, achieved robust anti-tumor responses in human cancer cell lines and mice.

During the study, published Nov. 30, 2017, in the journal Cell, a team of researchers led by graduate student Michael Topper; research associate Michelle Vaz, Ph.D.; and senior author Stephen B. Baylin, M.D., combined a demethylating drug called 5-azacytidine that chemically reignites some cancer suppressor genes’ ability to operate, with one of three histone deacetylase inhibitor drugs (HDACis). The HDACis work against proteins called histone deacetylases that are involved in processes, such as cell copying and division, and can contribute to cancer development. The combination therapy triggered a chemical cascade that increased the attraction of immune cells to fight tumors and diminished the work of the cancer gene MYC. Based on these findings, investigators have launched a clinical trial of the combination therapy in patients with advanced, nonsmall cell lung cancer.

The development of therapeutic approaches for patients with lung cancer has been a critical medical need, says Baylin, the Virginia and Daniel K. Ludwig Professor of Cancer Research at the Kimmel Cancer Center. While immune checkpoint therapy has been “a tremendous step forward, less than half of patients with lung cancer have benefited to date,” he says.

“In our study, the two-drug epigenetic therapy combination worked exceedingly well, even before putting in the immune checkpoint inhibitors,” Baylin says. “In animal models of lung cancer, the two agents either prevented cancer from emerging or blunted the effects of more aggressive cancers. In both scenarios, a large component of the results involved an increase in immune recognition of the tumors.”

In a series of experiments, researchers studied the combination of 5-azacytidine with the HDACis entinostat, mocetinostat or givinostat in human cancer cell lines and in mouse models of nonsmall cell lung cancers. The treatments were found to alter the tumor microenvironment. In cancer cell lines, 5-azacytidine worked against the cancer gene MYC, causing down regulation of the entire MYC signaling program. Adding the HDACis further depleted MYC, and together the drugs subsequently caused actions that prevented cancer cell proliferation, simultaneously attracted more immune system T cells to the area of the tumor and activated these cells for tumor recognition.

In mouse models, the strongest response was observed when using 5-azacytidine plus givinostat. In one mouse model with a mutant form of nonsmall cell lung cancer, this drug combination given for three months yielded prevention of benign, precursor tumors from becoming cancers and caused 60 percent reduction of overall area of benign tumor appearance in the lungs. By contrast, a group of mice with the same form of lung cancer that were given a mock treatment universally developed large, cancerous lesions in the lungs.

In a second model of mice with established, aggressive, nonsmall cell lung cancer, treatment with an alternating schedule of 5-azacytidine with givinostat and of 5-azacytidine with mocetinostat not only reduced the growth of established, rapidly growing primary tumors but also dramatically reduced metastatic occurrence.

Baylin and colleagues at Memorial Sloan Kettering Cancer Center in New York and Fox Chase Cancer Center in Philadelphia have started a phase I/Ib clinical trial to evaluate if giving mocetinostat with a 5-azacytidinelike drug called guadecitabine can boost immune checkpoint therapy responses in patients with advanced, nonsmall cell lung cancers. The trial is part of the Van Andel Research Institute–Stand Up To Cancer Epigenetics Dream Team and is funded by Merck through the Stand Up To Cancer  (SU2C) Catalyst program, an initiative led by SU2C to bring innovative cancer treatments to patients quickly. Matthew Hellmann, M.D., an author on the paper, will lead this trial at Memorial Sloan Kettering, and Jarushka Naidoo, M.B.B.Ch., assistant professor of oncology, will lead at Johns Hopkins. For more information, click here.