Tag: Davis

Erythrocyte Deformability As a Potential Biomarker for Chronic Fatigue Syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is arguably the last major disease we know almost nothing about. It is a multi-systemic illness of unknown etiology affecting millions of individuals worldwide, with the capacity to persist for several years. ME/CFS is characterized by disabling fatigue of at least 6 months, accompanied serious fatigue and musculoskeletal pain, in addition to impaired short-term memory or concentration, and unrefreshing sleep or extended post-exertional. While the etiology of the disease is still debated, evidence suggest oxidative damage to immune and hematological systems as one of the pathophysiological mechanisms of the disease. Erythrocytes are potent scavengers of oxidative stress, and their shape changes appreciably in response to oxidative stress and certain inflammatory conditions including obesity and diabetes. The shape of erythrocytes change from biconcave discoid to an ellipsoid due shear flow in microcapillaries that provides a larger specific surface area-to-volume ratio for optimal microvascular perfusion and tissue oxygenation establishing the importance not only of total hematocrit but also of the capacity for large deformations in physiology. Clinically, ME/CFS patients show normal arterial oxygen saturation but nothing much is known about microvascular perfusion. In this work, we tested the hypothesis that the erythrocyte deformability in ME/CFS is adversely affected, using a combination of biophysical and biochemical techniques.

We tested the deformability of RBCs using a high-throughput microfluidic device which mimics blood flow through microcapillaries. We perfused RBCs (suspension in plasma) from ME/CFS patients and from age and sex matched healthy controls (n=9 pairs of donors) through a high-throughput microfluidic platform of 5µm width and 3-5 µm height. We recorded the movement of the cells at high speed (4000 fps), followed by image analysis to assess the following parameters: entry time (time required by the cells to completely enter the test channels), average transit velocity (velocity of the cells inside the test channels) and elongation index (ratio of the major diameter before and after deformation in the test channel). We observed that RBCs from ME/CFS patients had higher entry time (~12%, p<0.0001), lower average transit velocity (~17%, p<0.0001) and lower elongation index (~14%, p<0.0001) as compared to RBCs from healthy controls. Taken together, this data shows that RBCs from ME/CFS patients have reduced deformability. To corroborate our findings, we also measured the erythrocyte sedimentation rate (ESR) for these donors which show that the RBCs from ME/CFS patients had lower (~40%, p<0.01) sedimentation rates.

To understand the basis for differences in deformability, we investigated the changes in the fluidity of the membrane using a lateral diffusion assay using pyrenedecanoic acid (PDA), and observed that RBCs from ME/CFS patients have lower membrane fluidity (~30%, p<0.01). Apart from the fluidity, Zeta potential measurements showed that ME/CFS patients had lower net negative surface charge on the RBC plasma membrane (~18%, p<0.0001). Higher levels of reactive oxygen species (ROS) in RBCs from ME/CFS patients (~30%, p<0.008) were also observed, as compared to healthy controls. Using scanning electron microscopy (SEM), we also observed changes in RBC morphology between ME/CFS patients and healthy controls (presence of different morphological subclasses like biconcave disc, leptocyte, acanthocyte and burr cells; area and aspect ratio; levels of RBC aggregation). Despite these changes in RBC physiology, the hemoglobin levels remained comparable between healthy donors and ME/CFS patients. Finally, preliminary studies show that RBCs from recovering ME/CFS patients do not show such differences in cellular physiology, suggesting a connection between RBC deformability and disease severity.

Taken together, our data demonstrates that the significant decrease in deformability of RBCs from ME/CFS patients may have origins in oxidative stress, and suggests that altered microvascular perfusion can be a possible cause for ME/CFS symptoms. Our data also suggests that RBC deformability may serve as a potential biomarker for ME/CFS, albeit further studies are necessary for non-specific classification of the disease.

Source: Saha, A. K., Schmidt, B. R., Wilhelmy, J., Nguyen, V., Do, J., Suja, V. C., Nemat-Gorgani, M., Ramasubramanian, A. K., & Davis, R. W. (2018).Erythrocyte Deformability As a Potential Biomarker for Chronic Fatigue Syndrome. Blood, 132(Suppl 1), 4874. Accessed November 28, 2018. https://doi.org/10.1182/blood-2018-99-117260.

VIDEO: Ronald W. Davis, PhD’s presentation at the IIMEC13

Dr. Ron Davis presented a research update at the International Invest in ME Conference 13 (IIMEC13) in London. His presentation reviewed the latest progress on research funded by OMF. View Dr. Davis’s full presentation here. 

(Gratefully shared with permission from Invest in ME Research.)

The full IIMEC13 conference DVD can be ordered here.

To hear a research update and meet our amazing scientists in person, join us for the Community Symposium on the Molecular Basis of ME/CFS at Stanford University sponsored by OMF on Saturday, September 29. In-person registration has been extended until Tuesday, September 18. If you are able to join us in person, please register here.

To watch the Community Symposium on the free Livestream. Register here.

A Glimpse into Dr. Ron Davis’ Talk in London

From Open Medicine Foundation.
June 1, 2018

Dear Friends,

I prepared this statement for Ashley Haugen to read yesterday at the Western Massachusetts  Department of Public Health screening of Unrest. This is new information from the Severely ill Patient Study (SIPS) that I also presented in London:

“We have made considerable progress in analyzing the data from the severely ill patient study. This has taken some time because we have only had one bioinformatic scientist analyzing the massive amount of data.

We have found that there are a considerable number of mutations that are more common in ME/CFS patients than in healthy controls. This would suggest that these mutations make a patient more susceptible to having ME/CFS. It could also indicate that some of the mutations are responsible for the severity of the patients we studied. We also see a large number of metabolomic changes that have been previously seen in less severe patients. These metabolomic differences between healthy controls and our severely ill patients are often much bigger than in studies with less severe patients. A more detailed analysis of this data may aid us in developing treatments.

One area we are currently studying using the genetic and metabolomic data is the possibility there may be one or more metabolic traps. This is a metabolic state that a patient can develop, possibly caused by physical stress such as infection. Once a patient is in this state they cannot easily get out by rest.

We are conducting system biology and pathway analysis that shows that a metabolic trap is possible, and that some of the observed mutations make it more likely. If this is the case we should be able to push the patients out of this state by a specific metabolic intervention. We are very hopeful that this could be a one time treatment, take only a few days, and be relatively inexpensive.”

Sending greetings from London,

Ronald W. Davis, PhD
Director, OMF ME/CFS Scientific Advisory Board
Director, Stanford Genome Technology Center

Value of Circulating Cytokine Profiling During Submaximal Exercise Testing in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic Encephalomyelitis or Chronic Fatigue Syndrome (ME/CFS) is a heterogeneous syndrome in which patients often experience severe fatigue and malaise following exertion. Immune and cardiovascular dysfunction have been postulated to play a role in the pathophysiology. We therefore, examined whether cytokine profiling or cardiovascular testing following exercise would differentiate patients with ME/CFS.

Twenty-four ME/CFS patients were matched to 24 sedentary controls and underwent cardiovascular and circulating immune profiling. Cardiovascular analysis included echocardiography, cardiopulmonary exercise and endothelial function testing. Cytokine and growth factor profiles were analyzed using a 51-plex Luminex bead kit at baseline and 18 hours following exercise. Cardiac structure and exercise capacity were similar between groups.

Sparse partial least square discriminant analyses of cytokine profiles 18 hours post exercise offered the most reliable discrimination between ME/CFS and controls (κ = 0.62(0.34,0.84)). The most discriminatory cytokines post exercise were CD40L, platelet activator inhibitor, interleukin 1-β, interferon-α and CXCL1. In conclusion, cytokine profiling following exercise may help differentiate patients with ME/CFS from sedentary controls.

Source: Kegan J. Moneghetti, Mehdi Skhiri, Kévin Contrepois, Yukari Kobayashi, Holden Maecker, Mark Davis, Michael Snyder, Francois Haddad & Jose G. Montoya. Value of Circulating Cytokine Profiling During Submaximal Exercise Testing in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Scientific Reports volume 8, Article number: 2779 (2018). doi:10.1038/s41598-018-20941-w. Received:02 November 2017. Accepted:26 January 2018. Published online:09 February 2018. https://www.nature.com/articles/s41598-018-20941-w (Full article)