The concentrations of interleukin 8 (IL-8) in the CSF (CSF) differentiated the acute inflammatory demyelinating polyneuropathy (AIDP) variant of Guillain-Barré syndrome (GBS) from the chronic inflammatory demyelinating polyneuropathy (CIDP), according to those in Neurology published study results: Neuroimmunology & Neuroinflammation. The study researchers suggested that CSF IL-8 levels could therefore be used to improve early treatment initiation and better outcomes in patients with GBS.
The diagnostic strategies for both GBS and CIDP depend heavily on clinical, electroneuromyography (ENMG), and CSF findings. While CIDP can be differentiated from GBS in terms of course, disease duration, prognosis and response to steroids, there is currently no specific blood or CSF biomarker that can differentiate the diseases. Clinical and paraclinical features of the diseases can also overlap, particularly in acute CIDP, where the disease mimics early stages of GBS.
Some studies have shown that CSF IL-8 is higher in GBS than in CIDP. To investigate the role of IL-8 in differentiating the diseases, the study researchers performed a retrospective immunoassay of the IL-8 CSF concentrations obtained from Geneva University Hospitals between 2010 and 2018. The samples were from patients with GBS (n = 45) and CIDP (n = 30).
Patients with GBS had a significantly higher median IL-8 concentration in the CSF than patients with CIDP (83.9 pg / ml vs. 41.0 pg / ml; p <0.001). The median concentrations of IL-8 were also higher in the AIDP variant than in CIDP in the acute phase (101.8 pg / ml vs. 53.7 pg / ml in each case). In contrast, lower IL-8 levels were observed in the variants of acute motor axonal neuropathy / acute motor and sensitive axonal neuropathy / Miller-Fischer syndrome variants (median 53.7 pg / ml).
The optimal IL-8 cutoff value was 70 pg / ml according to the analyzes of the recipient’s operating characteristics. Above this cutoff value, the patients had AIDP more frequently than other GBS phenotypes (P <0.001; specificity 75.0%; sensitivity 78.8%; positive predictive value [PPV], 89.7%; negative predictive value [NPV], 56.3%) or CIDP (P <0.0001; specificity 96.7%; sensitivity 78.8%; PPV 96.3%; NPV 80.5%). The IL-8 level in the CSF with this cutoff value was positive in 78.8% of the patients with AIDP compared to 3.3% in the patients with CIDP.
The limitations of this study were the retrospective design and the small sample size. Given these results, the study researchers suggested that the results must be validated in other studies before CSF IL-8 is used as a routine test in clinical care.
If validated, the study researchers found that “CSF-IL-8 tests could be performed during the acute phase of the investigation to allow for a faster discriminatory diagnosis in combination with the clinical and paraclinical parameters.” Ultimately, this can lead to improvements in the initial differentiation of GBS and CIDP and “could allow medical treatment to be better tailored and prevent disease progression”.
Breville G, Lascano AM, Roux-Lombard P, Vuilleumier N, Lalive PH. Interleukin 8, a biomarker used to distinguish Guillain-Barré syndrome from CIDP. Neurol Neuroimmunol Neuroinflamm. 2021; 8 (5): e1031. doi: 10.1212 / NXI.0000000000001031