Abstract: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex multifactorial disease that causes increasing morbidity worldwide, and many individuals with ME/CFS symptoms remain undiagnosed due to the lack of diagnostic biomarkers. Its etiology is still unknown, but increasing evidence supports a role of herpesviruses (including HHV-6A and HHV-6B) as potential triggers. Interestingly, the infection by these viruses has been reported to impact the expression of microRNAs (miRNAs), short non-coding RNA sequences which have been suggested to be epigenetic factors modulating ME/CFS pathogenic mechanisms. Notably, the presence of circulating miRNAs in plasma has raised the possibility to use them as valuable biomarkers for distinguishing ME/CFS patients from healthy controls. Thus, this study aimed at determining the role of eight miRNAs, which were selected for their previous association with ME/CFS, as potential circulating biomarkers of the disease. Their presence was quantitatively evaluated in plasma from 40 ME/CFS patients and 20 healthy controls by specific Taqman assays, and the results showed that six out of the eight of the selected miRNAs were differently expressed in patients compared to controls; more specifically, five miRNAs were significantly upregulated (miR-127-3p, miR-142-5p, miR-143-3p, miR-150-5p, and miR-448), and one was downmodulated (miR-140-5p). MiRNA levels directly correlated with disease severity, whereas no significant correlations were observed with the plasma levels of seven pro-inflammatory cytokines or with the presence/load of HHV-6A/6B genome, as judged by specific PCR amplification. The results may open the way for further validation of miRNAs as new potential biomarkers in ME/CFS and increase the knowledge of the complex pathways involved in the ME/CFS development. ETA: Academic Editor: Vincent C. Lombardi pdf https://mdpi-res.com › ijms › ijms-24-10582
Research from Italy and Latvia They note recent research suggesting specific microRNAs might be different in ME/CFS: They therefore set out to examine specific miRNA. This therefore is a replication study, and a step along from the exploratory analyses we have seen with thousands of candidate molecules.
40 ME/CFS - clinically diagnosed from an out patient clinic 20 healthy controls Pro-inflammatory cytokines IFN-y - not different IL-17A - a lot lower in ME/CFS p=0.0003 Il-2 - a lot lower in ME/CFS p=0.0001 IL21 - a lot lower in ME/CFS p=0.001 IL23 - not different, but the numbers look weird. Controls are 1.6 +-235; ME/CFS are 407+-115 (means +-SE) IL6 - a lot lower in ME/CFS p=0.0270 TNF-a - a lot lower in ME/CFS p=0.005 The results look a bit weird to me; I think it's possible that some processing issue resulted in the much lower results in ME/CFS. Certainly, there's nothing there to suggest that ME/CFS is an inflammatory disease. HHV6A/B presence This is not evidence for HHV6A/B being part of ME/CFS pathology. The results are similar to another recent study looking at the presence of HHV6 genetic material in the blood of people with ME/CFS. miRNA Plasma Levels in ME/CFS Patients Of the 8 miRNA, there are some that look a bit different. mir-124 - not different mir-127 - not different authors continued to look at it on the basis of a difference between controls and mild ME/CFS, but there really doesn't look to be a difference mir-140 - lower in ME/CFS p=0.007 in the text earlier, this was reported as higher in ME/CFS than controls after exercise mir-142 - higher in ME/CFS p=0.02 Previously reported as increased in ME/CFS in the Brenu 2014 study (see next post) - potentially a replication mir-143 - not different authors continued to look at it on the basis of a difference between controls and mild ME/CFS, but there really doesn't look to be a difference mir-150 - higher in ME/CFS p=0.03 in the text earlier, another study was reported as finding this higher in ME/CFS than controls after exercise - potentially a replication mir- 448 - higher in ME/CFS p=0.0001 This was one of the proposed autoimmunity markers. It had the clearest difference versus controls mir-551 - not different
High-Throughput Sequencing of Plasma MicroRNA in CFS/ME, 2014, Brenu, Staines, Marshall-Gradisnik et al I've made a thread for that 2014 paper that found that miR-127-3p, miR-142-5p, and miR-143-3p were increased relative to controls. It's a small rather unreliable study, but it's interesting to see the replication of the increased mir-142 result. Andy previously posted this paper: microRNA-142–mediated repression of phosphodiesterase 3B critically regulates peripheral immune tolerance, 2019, Lord et al relevant to the possible mir-142 up-regulation.
article on paper by MERUK Can microRNAs be used to diagnose ME/CFS? https://www.meresearch.org.uk/can-micrornas-be-used-to-diagnose-me-cfs/
That's a good analysis. Here's the Discussion: I don't feel quite so negative towards microRNAs as potential biomarkers though. I'd like to see more work done on them in studies with carefully selected patients (i.e. not using a Fukuda criteria). The technology is there, so some more work on this seems to me to be a worthwhile thing to do. The analysis did not comment on the possible issues with the pro-inflammatory cytokines, other than to note that the authors mention that the use of NSAIDS might have affected the findings.
The largest difference was found for miR-448 which had not been tested in ME/CFS before but it was found to be increased in various auto-immune diseases (the article mentions RA, SLE, SS, UC). Might be something to look out for in other studies.
The precursor miR-448 gene is on the X chromosome. It's upregulated by interferon. It suppresses IDO1 in CD8+ T cells (at least in the colorectal cancer tumour microenvironment, from the abstract below). miR-448 upregulation -> IDO1 downregulation -> decreased CD8+ T cell apoptosis -> more cytotoxic T cells. I.e. miR-448 (via ↓ IDO1) tips toward less cancer and potentially more autoimmunity. --- miR-448 targets IDO1 and regulates CD8+ T cell response in human colon cancer (2019) Lou, Qiong; Liu, Ruixian; Yang, Xiangling; Li, Weiqian; Huang, Lanlan; Wei, Lili; Tan, Huiliu; Xiang, Nanlin; Chan, Kawo; Chen, Junxiong; Liu, Huanliang Indoleamine 2,3-dioxygenase 1 (IDO1) is a critical regulator of T cell function, contributing to immune tolerance. Upregulation of IDO1 has been found in many cancer types; however, the regulatory mechanisms and clinical significance of IDO1 in colon cancer are still unclear. Here, we investigated the role of dysregulated microRNA (miRNA) targeting IDO1 in the colon cancer microenvironment. We elucidated IDO1 function by performing cell-based assays and establishing transplanted tumor models in BALB/c mice and BALB/c nude mice. We evaluated IDO1 protein expression by immunohistochemistry (IHC) in a tissue microarray (TMA) and analyzed IDO1 mRNA expression with The Cancer Genome Atlas (TCGA). We screened miRNAs targeting IDO1 by using a dual luciferase reporter assay. We tested the function of microRNA-448 (miR-448) by using western blotting (WB) and fluorescence-activated cell sorting (FACS). We demonstrated that stable IDO1 overexpression enhanced xenograft tumor growth in BALB/c mice but not in BALB/c nude mice. We also revealed the involvement of posttranscriptional regulation of IDO1 in colon cancer by observing IDO1 protein levels and mRNA levels. Furthermore, ectopic expression of miRNA mimics suggested that miR-448 could significantly downregulate IDO1 protein expression. Notably, we proved that miR-448 suppressed the apoptosis of CD8+ T cells by suppressing IDO1 enzyme function. Our findings indicated that IDO1 suppressed the CD8+ T cell response in colon cancer. miR-448, as a tumor-suppressive miRNA, enhanced the CD8+ T cell response by inhibiting IDO1 expression. The results provide a theoretical basis for the development of new immunotherapy for the treatment of colon cancer. Link | PDF (Journal for ImmunoTherapy of Cancer) --- Some other papers that may relate, which I haven't read yet are — Interactions of IDO and the Kynurenine Pathway with Cell Transduction Systems and Metabolism at the Inflammation–Cancer Interface (2023, Cancers) Metabolic reprogramming by miRNAs in the tumor microenvironment: Focused on immunometabolism (2022, Frontiers in Oncology) miR-aculous new avenues for cancer immunotherapy (2022, Frontiers in Immunology) The Regulatory Effects of MicroRNAs on Tumor Immunity (2022, BioMed Research International) The Role of Indoleamine 2, 3-Dioxygenase 1 in Regulating Tumor Microenvironment (2022, Cancers) Role of microRNAs in remodeling the tumor microenvironment Review (2020, International Journal of Oncology) Suppression of TLR4 by miR-448 is involved in Diabetic development via regulating Macrophage polarization (2019, Journal of Pharmacy and Pharmacology)
There's this paper (not open access): miR-448 regulates potassium voltage-gated channel subfamily A member 4 (KCNA4) in ischemia and heart failure Results: The expression of KCNA4 is diminished in ischemia and human heart failure tissues with ventricular tachycardia. Previously, we have shown that miR-448 is upregulated in ischemia and inhibition can prevent arrhythmic risk after myocardial infarction. The 3'-untranslated region of KCNA4 has a conserved miR-448 binding site. miR-448 bound to this site directly and reduced KCNA4 expression and the transient outward potassium current. Inhibition of miR-448 restored KCNA4. Conclusion: These findings showed a link between Kv1.4 downregulation and miR-448-mediated upregulation in ischemia, suggesting a new mechanism for the antiarrhythmic effect of miR-448 inhibition. It's an interesting link between ischemia and miR-448. That observation that its gene is on the X chromosome is also interesting. I'd really like to see some more replication of the miR studies.