RNase L

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Temple Researchers Find New Enzyme in Chronic Fatigue Syndrome Patients

Diagnostic Marker for Complex Illness Possible

press release from the CFIDS Association of America

Philadelphia, July 17, 1997. Dr. Robert Suhadolnik and his research team at Temple University School of Medicine reported today that studies of patients with chronic fatigue syndrome (CFS) have led to the identification of a new human enzyme. Suhadolnik, a professor of biochemistry and a member of the university's Fels Institute for Cancer Research and Molecular Biology, says of the new findings: "We are greatly encouraged by the trend we see. All CFS patients tested have this new enzyme, while none of the healthy controls do." The findings, reported today in the Journal of Interferon and Cytokine Research are based on data from a limited number of patients. However, larger studies are already underway and have attracted financial support from the National Institutes of Health.

Chronic fatigue syndrome, also known as chronic fatigue and immune dysfunction syndrome (CFIDS), is a complex illness characterized by incapacitating fatigue, neurological problems and a constellation of other debilitating symptoms. The cause of the illness is unknown and, since no drug has been found to be effective against CFS, treatment is limited to alleviating the symptoms. CFS affects at least 500,000 American adults and children.

The newly discovered enzyme, which has a lower molecular weight than the normal enzyme found in the viral pathway in which this protein is active, may explain common observations in patients with CFS: an inability to control common viruses (like Epstein-Barr virus and human herpesvirus 6) and an inability to maintain cellular energy. According to Suhadolnik, the viral pathway known as the 2-5A synthetase/RNase L antiviral pathway, may control both processes. "This new enzyme in CFS may not function as well as the normal RNase L found in healthy people. It may explain why CFS patients' bodies have a hard time maintaining the energy necessary for cellular growth."

The newly published study also indicates that the presence of the low molecular weight enzyme and the absence of normal enzymes may be related to the severity of CFS symptoms. While all CFS patients tested positive for the low molecular weight enzyme, some also had the normal RNase L. "It is interesting to note," said Suhadolnik, "that extracts from the most severely disabled individuals with CFS in this study contained only the low molecular weight enzyme."

"Because the new enzyme has been found in CFS patients but not in healthy controls, it is potentially the basis for a laboratory test for CFS, which is diagnosed today only through its clinical symptoms," says Dr. Antonio Goncalves, associate vice provost for science and technology at Temple University. The university has filed a patent application for such a test and is seeking a corporate partner to further develop and license the test. Goncalves and Suhadolnik caution, however, that additional studies of much larger patient populations are required before the clinical utility of the test can be demonstrated. The new findings add to mounting evidence of subtle, yet striking, abnormalities found in people with CFS. "We are hopeful that ongoing further studies will lead to a better understanding of some other processes at work in this puzzling illness," said Suhadolnik. This study was funded by the U.S. Public Health Service and The CFIDS Association of America, the nation's largest and most active charitable organization dedicated to conquering chronic fatigue and immune dysfunction syndrome (CFIDS).

Press Release Addendum:

Title: RNase L: Biochemical Evidence for a Novel Low Molecular Weight 2-5A-Dependent RNase L in Chronic Fatigue Syndrome

Authors: Robert J. Suhadolnik, Daniel L. Peterson, Karen O'Brien, Paul R. Cheney, C.V.T. Herst, Nancy L. Reichenbach, Ning Kon, Susan E. Horvath, Kathryn T. Iacono, Martin E. Adelson, Kenny De Meirleir, Pascale De Becker, Ramamurthy

Published in: Journal of Interferon and Cytokine Research; July 17, 1997

Footnotes: This work was supported by research grants from The CFIDS Association of America, Inc., and the U.S. Public Health Service awarded to Robert J. Suhadolnik.


Previous studies from this laboratory have demonstrated a statistically significant dysregulation in several key components of the 2',5'-oligoadenylate [ 2-5A ] synthetase / RNase L and PKR antiviral pathways in chronic fatigue syndrome (CFS ) [Suhadolnik et al., Clinical Infections Diseases 18: S96-104 (1994); Suhadolnik et al., In Vivo 8: 599-604 (1994)]. Two methodologies have been developed to further examine the upregulated Rnase L activity in CFS. First, photoaffinity labeling of extracts of peripheral blood mononuclear cells (PBMC) with the azido 2-5A photoaffinity probe, [32P]pApAp(8-azidoA), followed by immunoprecipitation with a polyclonal antibody against recombinant, human 80-kDa Rnase L and analysis under denaturing conditions. A subset of individuals with CFS was identified with only one 2- 5A binding protein at 37-KDA, whereas in extracts of PBMC from a second subset of CFS PBMC and from healthy controls, photolabeled/immunoreactive 2-5A binding proteins were detected 80,42 and 37 kDa. Second, analytic gel permeation HPLC was completed under native conditions. Extracts of healthy control PBMC revealed 2-5A binding and 2-5A-dependent RNAase L enzyme activity at 80 and 42 kDa as determined by hydrolysis of poly(U)-3'-[32P]pCp. A subset of CFS PMBC contained 2-5A binding proteins with 2-5A-dependent RNAase L enzyme activity at 80,42 and 30 kDa. However, a second subset of CFS PBMC contained 2-5A-dependent RNAase L enzyme activity at only at 30 kDa. Evidence is provided indicating that the RNase L enzyme dysfunction in CFS is more complex than previously reported.

Abstract Summary:

Dr. Suhadolnik and his team have found a new form of RNase L in the peripheral blood mononuclear cell extracts of people who meet the CDC case definition of chronic fatigue syndrome. (RNase L is a protein found in the antiviral pathway.) It is not found in the extracts from healthy persons. Earlier studies by his laboratory found an upregulated 2-5A synthetase/RNase L pathway in CFS patients compared to healthy controls.

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