Cytokine signatures in chronic fatigue syndrome patients: a Case Control Study

[Cheesus]

Cytokine signatures in chronic fatigue syndrome patients: a Case Control Study and the effect of anakinra treatment

Abstract
Background
Cytokine disturbances have been suggested to be associated with the Chronic Fatigue Syndrome/Myalgic encephalomyelitis (CFS/ME) for decades.

Methods
Fifty female CFS patients were included in a study on the effect of the interleukin-1-receptor antagonist anakinra or placebo during 4 weeks. EDTA plasma was collected from patients before and directly after treatment. At baseline, plasma samples were collected at the same time from 48 healthy, age-matched female neighborhood controls. A panel of 92 inflammatory markers was determined in parallel in 1 μL samples using a ‘proximity extension assay’ (PEA) based immunoassay. Since Transforming growth factor beta (TGF-β) and interleukin-1 receptor antagonist (IL-1Ra) were not included in this platform, these cytokines were measured with ELISA.

Results
In CFS/ME patients, the ‘normalized protein expression’ value of IL-12p40 and CSF-1 was significantly higher (p value 0.0042 and 0.049, respectively). Furthermore, using LASSO regression, a combination of 47 markers yielded a prediction model with a corrected AUC of 0.73. After correction for multiple testing, anakinra had no effect on circulating cytokines. TGF-β did not differ between patients and controls.

Conclusions
In conclusion, this study demonstrated increased IL-12p40 and CSF-1 concentrations in CFS/ME patients in addition to a set of predictive biomarkers. There was no effect of anakinra on circulating cytokines other than IL-1Ra.

https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-017-1371-9

 

[Cheesus]

Interesting quote:

IL-12b, also known as IL-12p40, was significantly higher in CFS/ME patients compared to healthy controls (p = 0.005). The IL-12p40 subunit is expressed by activated dendritic cells (DC) and combines with either subunit p35 or p19, to form IL-12 or IL-23 [37]. IL-12 targets T-cells and NK-cells, in which it induces IFN-γ production [38]. IL-23 has an important role in Th17 production, has an effect on memory T-cells, and appears to be critical in cerebral autoimmune inflammation [39].

 

[pattismith]

Thank you Cheesus,

since IL-12p40 was the only increased marker, I suppose that neither IFN-gamma, IL-22 or IL-17 were increased?

In that case, I wonder if there is any problem in the incorporation of this subunit to form both IL-2 and IL-23 ??

Is there a problem in the dendritic cells that cannot combines subunits together or a lack of subunit p35 and p19?

 

[Murph]

This study has done a really good job of controlling for concerns about sample handling. Hopefully it sets a new standard in that regard.

But it has a single major weakness. They tested 92 inflammatory markers and pull out two results statistically signifcant at p<.05, but that appears to be without control for multiple comparisons.

They were very close to having one significant result. The relevant p values are 0.0042 and 0.049

Now, there is a reference to controlling for multiple comparison when it comes to searching for the effect of the treatment, ankinra, and there is a reference to controlling for the large number of variables when they try to develop a regression model to distinguish cases from controls. But no mention of bonferroni or his pals at all when it come to those raw p-values. (I stand to be corrected if someone can spot evidence of correction in the paper.)

In summary I'm not 100% convinced this study found any true or permanent differences in cytokines between patients and controls. The introduction to their study points out that elevated IL-12 is an inconsistent finding.

Studies are largely contradicting, and a recent systematic review on circulating cytokines did not find evidence for altered cytokine concentrations in CFS/ME, with the exception of transforming growth factor-beta (TGF-β) [14]. TGF-β appeared to be elevated in 63% of the selected studies. This was also found in a recent study on cytokine signatures in CFS [15]. Other cytokines were only elevated in a minority of studies, for example interleukin-1α (IL-1α) in 27% of the studies, interleukin 12 (IL-12) in 18%, interleukin 23 (IL-23) 25%, and interleukin 8 (IL-8) in 29% of studies. Some studies only found differences when differentiating between patients with long and short illness duration [9, 16].

Taking 18 per cent as a Bayesian prior, this new evidence is not shifting my belief very far at all. Cytokine detection technology has come up very fast and it makes sense for us to exploit it, but cytokine differences are proving to be very elusive in ME/CFS and may not be a good place to look for biomarkers.

Alternatively It could be that our bodies are mostly able to control our cytokines when we're not in PEM, or something like that. I'm increasingly convinced that studies looking for a biological signature without first inducing PEM are going to miss the relevant facts.