Tag: Natural killer cells

Mapping the Complexity of ME/CFS: Evidence for Abnormal Energy Metabolism, Altered Immune Profile and Vascular Dysfunction

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex disorder with no known underlying mechanisms, diagnostic tools, or treatments.  Multiple areas of dysfunction have been extensively studied, but rarely examined together. We recruited age- and sex-matched ME/CFS patients and healthy controls for a multi-modal study examining energy metabolism, immune profiles and plasma protein levels.

Elevated levels of adenosine monophosphate (AMP) were detected in both plasma and immune cells. Additionally, immune cells showed higher levels of adenosine diphosphate (ADP) and a reduced adenosine triphosphate/adenosine diphosphate (ATP/ADP) ratio.

These findings imply decreased ATP generation and the presence of energy stress within the immune cell population. Adaptive immune cell populations were skewed towards less mature effector subsets of CD4+, CD8+ and gd T cells, and proportions of CD1c+CD141-conventional DC type 2 (cDC2) and CD56lowCD16+ terminal natural killer (NK) cells were also reduced. Elevated levels of plasma proteins associated with thrombus formation and vascular reactivity may contribute to the endothelial dysfunction observed in ME/CFS patients. Using Classification and Regression Tree (CART) modelling, we identified variables from each mode of investigation with strong predictive potential for ME/CFS. Together, this study provides new insights into the somatic symptoms and underlying biology of ME/CFS.

Source: Heng, Ruiwen Benjamin and Gunasegaran, Bavani and Krishnamurthy, Shivani and Bustamante, Sonia and Staats, Ananda and Chow, Sharron and Ahn, Seong Beom and Paul-Heng, Moumita and Maciver, Yolande and Smith, Kirsten and Tran, Denise Phuong and Howley, Peter P. and Bilgin, Ayse Aysin and Sharland, Alexandra and Schloeffel, Richard and Guillemin, Gilles J. and Administrator, Sneak Peek, Mapping the Complexity of ME/CFS: Evidence for Abnormal Energy Metabolism, Altered Immune Profile and Vascular Dysfunction. Available at SSRN: https://ssrn.com/abstract=5131664 or http://dx.doi.org/10.2139/ssrn.5131664  https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5131664 (Full text available as PDF file)

The search for a blood-based biomarker for Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome (ME/CFS): from biochemistry to electrophysiology

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disease of unknown aetiology characterised by symptoms of post-exertional malaise (PEM) and fatigue leading to substantial impairment in functioning. Other key symptoms include cognitive impairment and unrefreshing sleep, with many experiencing pain. To date there is no complete understanding of the triggering pathomechanisms of disease, and no quantitative biomarker available with sufficient sensitivity, specificity, and adoptability to provide conclusive diagnosis. Clinicians thus eliminate differential diagnoses, and rely on subjective, unspecific, and disputed clinical diagnostic criteria-a process that often takes years with patients being misdiagnosed and receiving inappropriate and sometimes detrimental care. Without a quantitative biomarker, trivialisation, scepticism, marginalisation, and misunderstanding of ME/CFS continues despite the significant disability for many. One in four individuals are bed-bound for long periods of time, others have difficulties maintaining a job/attending school, incurring individual income losses of thousands, while few participate in social activities.

Main body: Recent studies have reported promising quantifiable differences in the biochemical and electrophysiological properties of blood cells, which separate ME/CFS and non-ME/CFS participants with high sensitivities and specificities-demonstrating potential development of an accessible and relatively non-invasive diagnostic biomarker. This includes profiling immune cells using Raman spectroscopy, measuring the electrical impedance of blood samples during hyperosmotic challenge using a nano-electronic assay, use of metabolomic assays, and certain techniques which assess mitochondrial dysfunction. However, for clinical application, the specificity of these biomarkers to ME/CFS needs to be explored in more disease controls, and their practicality/logistics considered. Differences in cytokine profiles in ME/CFS are also well documented, but finding a consistent, stable, and replicable cytokine profile may not be possible. Increasing evidence demonstrates acetylcholine receptor and transient receptor potential ion channel dysfunction in ME/CFS, though how these findings could translate to a diagnostic biomarker are yet to be explored.

Conclusion: Different biochemical and electrophysiological properties which differentiate ME/CFS have been identified across studies, holding promise as potential blood-based quantitative diagnostic biomarkers for ME/CFS. However, further research is required to determine their specificity to ME/CFS and adoptability for clinical use.

Source: Clarke KSP, Kingdon CC, Hughes MP, Lacerda EM, Lewis R, Kruchek EJ, Dorey RA, Labeed FH. The search for a blood-based biomarker for Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome (ME/CFS): from biochemistry to electrophysiology. J Transl Med. 2025 Feb 4;23(1):149. doi: 10.1186/s12967-025-06146-6. PMID: 39905423.  https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-025-06146-6 (Full text)

Abnormal T-Cell Activation And Cytotoxic T-Cell Frequency Discriminates Symptom Severity In Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating but poorly-understood disease. ME/CFS symptoms can range from mild to severe, and include immune system effects alongside incapacitating fatigue and post-exertional disease exacerbation. In this study, we examined immunological profiles of people living with ME/CFS by flow cytometry, focusing on cytotoxic cells, to determine whether people with mild/moderate (n= 43) or severe ME/CFS (n=53) expressed different immunological markers.

We found that people with mild/moderate ME/CFS had increased expression of cytotoxic effector molecules alongside enhanced proportions of early-immunosenescence cells, determined by the CD28 – CD57 – phenotype, indicative of persistent viral infection. In contrast, people with severe ME/CFS had higher proportions of activated circulating lymphocytes, determined by CD69 + and CD38 + expression, and expressed more pro-inflammatory cytokines, including IFNγ, TNF and IL-17, following stimulation in vitro , indicative of prolonged non-specific inflammation.

These changes were consistent across different cell types including CD8 + T cells, mucosal associated invariant T cells and Natural Killer cells, indicating generalised altered cytotoxic responses across the innate and adaptive immune system. These immunological differences likely reflect different disease pathogenesis mechanisms occurring in the two clinical groups, opening up opportunities for the development of prognostic markers and stratified treatments.

Source: Lee JS, Lacerda E, Kingdon C, Susannini G, Dockrell HM, Nacul L, Cliff JM. Abnormal T-Cell Activation And Cytotoxic T-Cell Frequency Discriminates Symptom Severity In Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. medRxiv [Preprint]. 2025 Jan 6:2025.01.02.24319359. doi: 10.1101/2025.01.02.24319359. PMID: 39830245; PMCID: PMC11741448. https://pubmed.ncbi.nlm.nih.gov/39830245/

Meta-analysis of natural killer cell cytotoxicity in myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Reduced natural killer (NK) cell cytotoxicity is the most consistent immune finding in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Meta-analysis of the published literature determined the effect size of the decrement in ME/CFS. Databases were screened for papers comparing NK cell cytotoxicity in ME/CFS and healthy controls. A total of 28 papers and 55 effector:target cell ratio (E:T) data points were collected.

Cytotoxicity in ME/CFS was significantly reduced to about half of healthy control levels, with an overall Hedges’ g of 0.96 (0.75-1.18). Heterogeneity was high but was explained by the range of E:T ratios, different methods, and potential outliers. The outcomes confirm reproducible NK cell dysfunction in ME/CFS and will guide studies using the NK cell model system for pathomechanistic investigations.

Source: Baraniuk JN, Eaton-Fitch N, Marshall-Gradisnik S. Meta-analysis of natural killer cell cytotoxicity in myalgic encephalomyelitis/chronic fatigue syndrome. Front Immunol. 2024 Oct 17;15:1440643. doi: 10.3389/fimmu.2024.1440643. PMID: 39483457; PMCID: PMC11524851. https://pmc.ncbi.nlm.nih.gov/articles/PMC11524851/ (Full text)

Unbiased immune profiling reveals a natural killer cell-peripheral nerve axis in fibromyalgia

Abstract:

The pathophysiology of fibromyalgia syndrome (FMS) remains elusive, leading to a lack of objective diagnostic criteria and targeted treatment. We globally evaluated immune system changes in FMS by conducting multiparametric flow cytometry analyses of peripheral blood mononuclear cells and identified a natural killer (NK) cell decrease in patients with FMS. Circulating NK cells in FMS were exhausted yet activated, evidenced by lower surface expression of CD16, CD96, and CD226 and more CD107a and TIGIT. These NK cells were hyperresponsive, with increased CCL4 production and expression of CD107a when co-cultured with human leukocyte antigen null target cells. Genetic and transcriptomic pathway analyses identified significant enrichment of cell activation pathways in FMS driven by NK cells. Skin biopsies showed increased expression of NK activation ligand, unique long 16-binding protein, on subepidermal nerves of patients FMS and the presence of NK cells near peripheral nerves. Collectively, our results suggest that chronic activation and redistribution of circulating NK cells to the peripheral nerves contribute to the immunopathology associated with FMS.

Source: Verma V, Drury GL, Parisien M, Özdağ Acarli AN, Al-Aubodah TA, Nijnik A, Wen X, Tugarinov N, Verner M, Klares R 3rd, Linton A, Krock E, Morado Urbina CE, Winsvold B, Fritsche LG, Fors EA, Piccirillo C, Khoutorsky A, Svensson CI, Fitzcharles MA, Ingelmo PM, Bernard NF, Dupuy FP, Üçeyler N, Sommer C, King IL, Meloto CB, Diatchenko L; HUNT-All In Pain. Unbiased immune profiling reveals a natural killer cell-peripheral nerve axis in fibromyalgia. Pain. 2021 Sep 24:10.1097/j.pain.0000000000002498. doi: 10.1097/j.pain.0000000000002498. Epub ahead of print. PMID: 34913882; PMCID: PMC8942876. https://pubmed.ncbi.nlm.nih.gov/34913882/

Evaluation of natural killer cell assay performance on shipped blood specimens

Abstract:

Documenting the importance of NK cell function as a biomarker for diseases and physiologic conditions including myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), will require assays amenable to clinical implementation and standardization. Research studies typically perform NK functional assays on the day of sample collection. This pilot study was conducted to compare assay formats and specimen processing to identify those that are most tolerant of conditions required for shipping and amenable to standardization as shown by inter-assay and inter-laboratory correlation of results.

We compared performance within and between assays that measure NK cell function using direct cytotoxicity [chromium-51 release (CRCA) or fluorescence (Flow Cytometry Cytotoxicity Assay, FCCA)] or an indirect surrogate marker (CD107a surface expression)]. Additional variables for within/between assay comparisons included time of testing (same day as specimen collection or next day within 24 h), specimen types [whole blood or isolated peripheral blood mononuclear cells (PBMCs)], and processing method (fresh or cryopreserved). Statistical measures included number of samples tested in assay conditions (n), medians (x͂), interquartile range (IQR), Pearson correlation coefficient (R2), and correlation p-value (p).

Samples came from 3 clinics and included 31 participants. Same day testing was only available for the subset of participants enrolled from the site of the laboratory performing CRCA. Results from same day CRCA testing of whole blood were considered the gold standard [n = 10, x͂=10.0%, IQR = 7.2%], and correlated well with PBMCs isolated next day [n = 26, x͂= 15.6%, IQR = 13.1%] [R2 = 0.59, p = 0.03]. Next day CRCA results were compromised using whole blood or frozen PBMCs. Next day FCCA cytotoxicity in PBMC [n = 30, x͂=34.1%, IQR = 15.5%] correlated with same day CRCA PMBC [R2 = 0.8, p = 0.001] and next day CRCA PMBC [R2 = 0.5, p < 0.0001]. CD107a expression after induction by PMA and ionomycin did not correlate with other cytotoxicity measures. NK function can be measured in PBMCs isolated after overnight shipping/storage at ambient temperature and CRCA and FCCA results on this sample type are well correlated.

Source: Querec TD, Abrams J, Stewart JJ, Barnes Z, Balbin E, Klimas N, Fletcher MA, Brown L, Bertolli J, Unger ER. Evaluation of natural killer cell assay performance on shipped blood specimens. J Immunol Methods. 2021 Apr 2:113049. doi: 10.1016/j.jim.2021.113049. Epub ahead of print. PMID: 33819446. https://pubmed.ncbi.nlm.nih.gov/33819446/

A systematic review of natural killer cells profile and cytotoxic function in myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

BACKGROUND: Compromised natural killer (NK) cell cytotoxic function is a well-documented and consistent feature of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Other outcomes evaluated in NK cells of ME/CFS patients, however, remain equivocal. The aim of this study was to conduct a systematic review of the literature regarding NK cell phenotype, receptor expression, cytokine production and cytotoxicity in ME/CFS patients and determine the appropriateness as a model for ME/CFS.

METHODS: Medline (EBSCOHost), Scopus, EMBASE and PubMed databases were systematically searched to source relevant papers published between 1994 and March 2018. This review included studies examining NK cells’ features in ME/CFS patients compared with HC following administration of specific inclusion and exclusion criteria. Secondary outcomes included genetic analysis in isolated NK cells or quality of life assessment. Quality assessment was completed using the Downs and Black checklist in addition to The Joanna Briggs Institute checklist.

RESULTS: Seventeen eligible publications were included in this review. All studies were observational case control studies. Of these, 11 investigated NK cell cytotoxicity, 14 investigated NK cell phenotype and receptor profiles, three examined NK cell cytokine production, six investigated NK cell lytic protein levels and four investigated NK cell degranulation. Impaired NK cell cytotoxicity remained the most consistent immunological report across all publications. Other outcomes investigated differed between studies.

CONCLUSION: A consistent finding among all papers included in this review was impaired NK cell cytotoxicity, suggesting that it is a reliable and appropriate cellular model for continued research in ME/CFS patients. Aberrations in NK cell lytic protein levels were also reported. Although additional research is recommended, current research provides a foundation for subsequent investigations. It is possible that NK cell abnormalities can be used to characterise a subset of ME/CFS due to the heterogeneity of both the illness itself and findings between studies investigating specific features of NK function.

Source: Eaton-Fitch N, du Preez S, Cabanas H, Staines D, Marshall-Gradisnik S. A systematic review of natural killer cells profile and cytotoxic function in myalgic encephalomyelitis/chronic fatigue syndrome. Syst Rev. 2019 Nov 14;8(1):279. doi: 10.1186/s13643-019-1202-6. https://www.ncbi.nlm.nih.gov/pubmed/31727160

Decreased Expression of the CD57 Molecule in T Lymphocytes of Patients with Chronic Fatigue Syndrome

Abstract:

The chronic fatigue syndrome (CFS) is characterized by a prolonged incapacitating fatigue, headaches, sleep disturbances, and decreases in cognition, besides alterations in other physiological functions. At present, no specific biological markers have been described in this pathology.

In the present study, we analyzed in lymphocytes the CD57 expression for the diagnosis of CFS, evaluating both the percentage of blood lymphocytes expressing CD57 and the average amount of the molecule expressed per cell. The study demonstrated a marked and significant decrease in the expression of CD57 in lymphocytes of CFS patients regarding healthy controls. In T lymphocytes, the decrease was significant both in the percentage of cells expressing CD57 (7.5 ± 1.2 vs 13.3 ± 1.6, p = 0.024) and in a more relevant way in the amount of CD57 molecule expressed per cell (331 ± 59 vs 1003 ± 104, p ≤ 0.0001). In non-T lymphocytes, the decrease was significant only in the amount of CD57 expressed per cell (379 ± 114 vs 691 ± 95, p = 0.007).

The study of CD57 antigen in blood lymphocytes is a useful marker that could cooperate in the diagnosis of CFS patients. Its decrease in T lymphocytes provides most valuable results than the results in other lymphocyte subpopulations.

Source: Espinosa P, Urra JM. Decreased Expression of the CD57 Molecule in T Lymphocytes of Patients with Chronic Fatigue Syndrome. Mol Neurobiol. 2019 Mar 21. doi: 10.1007/s12035-019-1549-7. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/30895436 

Association of T and NK Cell Phenotype With the Diagnosis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a pathological condition characterized by incapacitating fatigue and a combination of neurologic, immunologic, and endocrine symptoms. At present its diagnosis is based exclusively on clinical criteria.

Several studies have described altered immunologic profiles; therefore, we proposed to further examine the more significant differences, particularly T and NK cell subpopulations that could be conditioned by viral infections, to discern their utility in improving the diagnosis and characterization of the patients. The study included 76 patients that fulfilled the revised Canadian Consensus Criteria (CCC 2010) for ME/CFS and 73 healthy controls, matched for age and gender. Immunophenotyping of different T cell and natural killer cell subpopulations in peripheral blood was determined by flow cytometry.

ME/CFS patients showed significantly lower values of T regulatory cells (CD4+CD25++(high)FOXP3+) and higher NKT-like cells (CD3+CD16+/-CD56+) than the healthy individuals. Regarding NK phenotypes, NKG2C was significantly lower and NKCD69 and NKCD56 bright were significantly higher in the patients group. A classification model was generated using the more relevant cell phenotype differences (NKG2C and T regulatory cells) that was able to classify the individuals as ME/CFS patients or healthy in a 70% of cases.

The observed differences in some of the subpopulations of T and NK cells between patients and healthy controls could define a distinct immunological profile that can help in the diagnostic process of ME/CFS patients, contribute to the recognition of the disease and to the search of more specific treatments. However, more studies are needed to corroborate these findings and to contribute to establish a consensus in diagnosis.

Source: Rivas JL, Palencia T, Fernández G, García M. Association of T and NK Cell Phenotype With the Diagnosis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Front Immunol. 2018 May 9;9:1028. doi: 10.3389/fimmu.2018.01028. eCollection 2018.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5954087/  (Full article)

Transient Receptor Potential Ion Channels in the Etiology and Pathomechanism of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis

Abstract:

Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a disabling condition of unknown cause having multi-system manifestations. Our group has investigated the potential role of transient receptor potential (TRP) ion channels in the etiology and pathomechanism of this illness. Store-operated calcium entry (SOCE) signaling is the primary intracellular calcium signaling mechanism in non-excitable cells and is associated with TRP ion channels. While the sub-family (Canonical) TRPC has been traditionally associated with this important cellular mechanism, a member of the TRPM sub-family group (Melastatin), TRPM3, has also been recently identified as participating in SOCE in white matter of the central nervous system. We have identified single nucleotide polymorphisms (SNPs) in TRP genes in natural killer (NK) cells and peripheral blood mononuclear cells (PBMCs) in CFS/ME patients. We also describe biochemical pathway changes and calcium signaling perturbations in blood cells from patients. The ubiquitous distribution of TRP ion channels and specific locations of sub-family group members such as TRPM3 suggest a contribution to systemic pathology in CFS/ME.

Source: D. Staines, S. Du Preez, H. Cabanas, C. Balinas, N. Eaton, R. Passmore, R. Maksoud, J. Redmayne, S. Marshall-Gradisnik. Transient Receptor Potential Ion Channels in the Etiology and Pathomechanism of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis. IJCM, Vol.9 No.5, May 2018. DOI: 10.4236/ijcm.2018.95038