Tag: flow cytometry

Flow Clotometry: Measuring Amyloid Microclots in ME/CFS, Long COVID, and Healthy Samples with Imaging Flow Cytometry

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) has received more attention since the characterization of Long COVID (LC), a condition somewhat similar in symptom presentation and, to some extent, pathophysiological mechanisms. A prominent feature of LC pathology is amyloid, fibrinolysis-resistant fibrin(ogen) fragments, termed microclots. Despite prior identification of microclots in ME/CFS, quantitative analysis has remained challenging due to the reliance on representative micrographs and software processing for estimations.

Addressing this gap, the present study uses a cell-free imaging flow cytometry approach, optimized for the quantitative analysis of Thioflavin T-stained microclots, to precisely measure microclot concentration and size distribution across ME/CFS, LC, and healthy cohorts. We refer to our cell-free flow cytometry technique for detecting microclots as ‘flow clotometry’.

We demonstrate significant microclot prevalence in ME/CFS and LC, with LC patients exhibiting the highest concentration (18- and 3-fold greater than the healthy and ME/CFS groups, respectively). This finding underscores a common pathology across both conditions, emphasizing a dysregulated coagulation system. Moreover, relating to microclot size distribution, the ME/CFS group exhibited a significantly higher prevalence across all area ranges when compared to the controls, but demonstrated a significant difference for only a single area range when compared to the LC group.

This suggests a partially overlapping microclot profile in ME/CFS relative to LC, despite the overall higher concentration in the latter. The present study paves the way for prospective clinical application that aims to efficiently detect, measure and treat microclots.

Source: Etheresia Pretorius, Massimo Nunes, Jan pretorius et al. Flow Clotometry: Measuring Amyloid Microclots in ME/CFS, Long COVID, and Healthy Samples with Imaging Flow Cytometry, 24 June 2024, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-4507472/v1] https://www.researchsquare.com/article/rs-4507472/v1 (Full text)

Accelerating discovery: A novel flow cytometric method for detecting fibrin(ogen) amyloid microclots using long COVID as a model

Abstract:

Long COVID has become a significant global health and economic burden, yet there are currently no established methods or diagnostic tools to identify which patients might benefit from specific treatments. One of the major pathophysiological factors contributing to Long COVID is the presence of hypercoagulability; this results in insoluble amyloid microclots that are resistant to fibrinolysis. Our previous research using fluorescence microscopy has demonstrated a significant amyloid microclot load in Long COVID patients. However, this approach lacked the elements of statistical robustness, objectivity, and rapid throughput.

In the current study, we have used imaging flow cytometry for the first time to show a significantly increased concentration and size of these microclots. We identified notable variations in size and fluorescence between microclots in Long COVID and those of controls even using a 20× objective. By combining cell imaging and the high-event-rate and full-sample analysis nature of a conventional flow cytometer, imaging flow cytometry can eliminate erroneous results and increase accuracy in gating and analysis beyond what pure quantitative measurements from conventional flow cytometry can provide.

Although imaging flow cytometry was used in our study, our results suggest that the signals indicating the presence of microclots should be easily detectable using a conventional flow cytometer. Flow cytometry is a more widely available technique than fluorescence microscopy and has been used in pathology laboratories for decades, rendering it a potentially more suitable and accessible method for detecting microclots in individuals suffering from Long COVID or conditions with similar pathology, such as myalgic encephalomyelitis.

Source: Turner S, Laubscher GJ, Khan MA, Kell DB, Pretorius E. Accelerating discovery: A novel flow cytometric method for detecting fibrin(ogen) amyloid microclots using long COVID as a model. Heliyon. 2023 Aug 29;9(9):e19605. doi: 10.1016/j.heliyon.2023.e19605. PMID: 37809592; PMCID: PMC10558872. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10558872/ (Full text)

Rapid flow cytometric analysis of fibrin amyloid microclots in Long COVID

Abstract:

Long COVID has become a significant global health and economic burden, yet there are currently no established diagnostic tools to identify which patients might benefit from specific treatments. One of the major pathophysiological factors contributing to Long COVID is the presence of hypercoagulability; this results in insoluble amyloid microclots that are resistant to fibrinolysis.

Our previous research using fluorescence microscopy has demonstrated a significant amyloid microclot load in Long COVID patients. However, this approach lacked statistical robustness, objectivity, and rapid throughput. In the current study, we have used imaging flow cytometry for the first time to show significantly increased concentration and size of these microclots.

We identified notable variations in size and fluorescence between microclots in Long COVID and those of controls even using a 20x objective. By combining cell imaging and the high-event-rate nature of a conventional flow cytometer, imaging flow cytometry can eliminate erroneous results and increase accuracy in gating and analysis beyond what pure quantitative measurements from conventional flow cytometry can provide.

Although imaging flow cytometry was used in our study, our results suggest that the signals indicating the presence of microclots should be easily detectable using a conventional flow cytometer. Flow cytometry is a more widely available technique which has been used in pathology laboratories for decades, rendering it a potentially more suitable and accessible method for detecting microclots in individuals suffering from both Long COVID and other conditions with similar pathology, such as myalgic encephalomyelitis.

Source: Turner, Simone and Laubscher, Gert Jacobus and Khan, M. Asad and Kell, Douglas and Pretorius, Etheresia, Rapid Flow Cytometric Analysis of Fibrin Amyloid Microclots in Long COVID. Available at SSRN: https://ssrn.com/abstract=4405265 or http://dx.doi.org/10.2139/ssrn.4405265 https://assets.researchsquare.com/files/rs-2731434/v1/0b4877b0-99fa-499c-9d65-3b6e43865d86.pdf?c=1680099696 (Full text)

Delayed-type hypersensitivity and chronic fatigue syndrome: the usefulness of assessing T-cell activation by flow cytometry–preliminary study

Abstract:

Chronic fatigue syndrome or benign myalgic encephalomyelitis has been extensively described and investigated. Although numerous immunological abnormalities have been linked with the syndrome, none have been found to be specific.

This article describes the detection of delayed-type hypersensitive responses to certain common environmental antigens in almost fifty per cent of patients with this syndrome. Such hypersensitivity can be detected by the intradermal administration of antigens derived from commensal organisms like the yeast Candida albicans albicans, and then monitoring for a systemic reaction over the following six to forty-eight hours.

This approach can be consolidated by performing lymphocyte activation tests in parallel and measuring in vitro T-cell activation by Candida albicans albicans antigens by three-colour flow cytometry based on CD3, CD4 and either CD69 or CD25. Another useful parameter is the kinetics of neopterin excretion in the urine over the course of the skin test. The results showed that the intensity of the DTH response correlated with the number of T-cells activated in vitro.

Various factors have been implicated in the fatigue of many patients, notably lack of sleep. However, it remains difficult to establish causality in either one direction or the other. This work is in the spirit of a multifactorial approach to the group of conditions referred to as “chronic fatigue syndrome”.

 

Source: Brunet JL, Liaudet AP, Later R, Peyramond D, Cozon GJ. Delayed-type hypersensitivity and chronic fatigue syndrome: the usefulness of assessing T-cell activation by flow cytometry–preliminary study. Allerg Immunol (Paris). 2001 Apr;33(4):166-72. http://www.ncbi.nlm.nih.gov/pubmed/11434196

 

Dysfunction of natural killer activity in a family with chronic fatigue syndrome

Abstract:

A family was identified with 5 of 6 siblings and 3 other immediate family members who had developed chronic fatigue syndrome (CFS) as adults. All 8 met criteria for the CFS case definition as recommended by the Centers for Disease Control and Prevention.

Sixty-eight blood samples were obtained over a period of 2 years from 20 family members (8 affected, 12 unaffected) and 8 normal controls. All blood samples were tested for NK activity in 4-h 51Cr-release assays and for the number of circulating CD3-CD56(+) and CD3-CD16(+) by flow cytometry.

NK activity of the affected immediate family members (cases, n = 8) was significantly lower (P = 0.006, two-sided) than that of the concurrently tested normal controls. The results for unaffected family members were intermediate between these two groups, and the pairwise comparison of unaffected family members to either cases or controls showed no statistically significant difference (P = 0.29, two-sided). No differences were seen between the groups in the absolute number of CD3-CD56(+) or CD3-CD16(+) lymphocytes in the peripheral blood.

Familial CFS was associated with persistently low NK activity, which was documented in 6/8 cases and in 4/12 unaffected family members. In the family with 5 of 6 siblings who had documented CFS, 2 of their offspring had pediatric malignancies. Low NK activity in this family may be a result of a genetically determined immunologic abnormality predisposing to CFS and cancer.

 

Source: Levine PH, Whiteside TL, Friberg D, Bryant J, Colclough G, Herberman RB. Dysfunction of natural killer activity in a family with chronic fatigue syndrome. Clin Immunol Immunopathol. 1998 Jul;88(1):96-104. http://www.ncbi.nlm.nih.gov/pubmed/9683556

 

Chronic fatigue syndrome. Immunological findings vary between populations

Comment on: Longitudinal study of outcome of chronic fatigue syndrome. [BMJ. 1994]

 

Editor,-We were interested in Andrew Wilson and colleagues’ paper investigating predictors of the long term outcome of the chronic fatigue syndrome in patients in Australia. We have investigated the association between immune activation and presumed cutaneous anergy in 68 Scottish patients with the syndrome (19 cases conformed to the Centers for Disease Control’s criteria, 18 cases had been diagnosed by a consultant, 28 cases had been diagnosed by a general practitioner, and three patients referred themselves) and 22 family contacts. We assessed delayed hypersensitivity responses (using Multitest antigens and tuberculin skin tests) and evaluated peripheral blood activation markers (CD8, CD38/ CD llb/HLA-DR) using flow cytometry. Patients were classified into three groups on the basis of current severity of illness and mobility.

You can read the rest of this comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2540184/pdf/bmj00440-0055b.pdf

 

Source: Abbot NC, Spence VA, Lowe JG, Potts RC, Hassan AH, Belch JJ, Beck JS. Chronic fatigue syndrome. Immunological findings vary between populations. BMJ. 1994 May 14;308(6939):1299. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2540184/

 

Immunologic abnormalities associated with chronic fatigue syndrome

Abstract:

Several aspects of cellular immunity in patients with clinically defined chronic fatigue syndrome (CFS) were evaluated and compared with those in healthy individuals.

Flow cytometric analyses revealed normal expression of total T (CD3+), B (CD19+), and NK (natural killer) (CD16+, CD56+) markers on the surface of peripheral blood mononuclear cells (PMC) from patients with CFS.

However, compared with those of healthy individuals, patients’ CD8+ T cells expressed reduced levels of CD11b and expressed the activation markers CD38 and HLA-DR at elevated levels. In many of the individuals in whom expression of CD11b was reduced the expression of CD28 was increased.

These findings indicate expansion of a population of activated CD8+ cytotoxic T lymphocytes. A marked decrease in NK cell activity was found in almost all patients with CFS, as compared with that in healthy individuals. No substantial abnormalities in monocyte activity or T cell proliferation were observed. The results of this study suggest that immune cell phenotype changes and NK cell dysfunction are common manifestations of CFS.

 

Source: Barker E, Fujimura SF, Fadem MB, Landay AL, Levy JA. Immunologic abnormalities associated with chronic fatigue syndrome. Clin Infect Dis. 1994 Jan;18 Suppl 1:S136-41. http://www.ncbi.nlm.nih.gov/pubmed/8148441

 

Lymphocyte phenotype and function in the chronic fatigue syndrome

Abstract:

Lymphocytes of 18 patients meeting the Centers for Disease Control (CDC) case definition for the chronic fatigue syndrome (CFS), 10 similar, chronically fatigued patients not fully conforming to the CDC case definition, and 17 matched, healthy individuals were studied to determine the presence of abnormalities of peripheral cell phenotype and function.

Extensive phenotypic analyses of B- and T-cell subsets, natural killer (NK) cells, and macrophages were performed using single-, dual-, and three-color flow cytometry. Compared to controls, in CFS patients the percentage of CD4 T cells and CD4,CD45RA, or naive T cells, was reduced. The CD4,CD45RO, or memory T-cell, subset was numerically normal but expressed increased levels of adhesion markers (CD29, CD54, and CD58). CFS patient lymphocytes showed reduced proliferative responses to phytohemagglutinin, concanavalin A, and staphylococcal enterotoxin B. Lymphocytes from fatigue patients not meeting the CDC definition showed similar abnormalities.

These data indicate that peripheral T cells manifest an increased state of differentiation in CFS and related conditions. This may arise as a consequence of an underlying neuropsychiatric and/or neuroendocrine disorder or because of exposure to antigens or superantigens of an infectious agent.

 

Source: Straus SE, Fritz S, Dale JK, Gould B, Strober W. Lymphocyte phenotype and function in the chronic fatigue syndrome. J Clin Immunol. 1993 Jan;13(1):30-40. http://www.ncbi.nlm.nih.gov/pubmed/8095270

 

Chronic fatigue syndrome: clinical condition associated with immune activation

Abstract:

There is much conflicting immunological and viral data about the causes of chronic fatigue syndrome (CFS); some findings support the notion that CFS may be due to one or more immune disorders that have resulted from exposure to an infectious agent.

In the present study, flow cytometry and several different recognising T, B, and natural killer (NK) cell populations as well as activation and cell adhesion antigens were used to study 147 individuals with CFS.

Compared with healthy controls, a reduced CD8 suppressor cell population and increased activation markers (CD38, HLA-DR) on CD8 cells were found. The differences were significant (p = 0.01) in patient with major symptoms of the disease. These immunological indices were not observed in 80 healthy individuals, in 22 contacts of CFS patients, or in 43 patients with other diseases.

No correlation of these findings in CFS patients with any known human viruses could be detected by serology. The findings suggest that immune activation is associated with many cases of CFS.

 

Source: Landay AL, Jessop C, Lennette ET, Levy JA. Chronic fatigue syndrome: clinical condition associated with . Lancet. 1991 Sep 21;338(8769):707-12. http://www.ncbi.nlm.nih.gov/pubmed/1679864