Association of Levels of CSF Osteopontin With Cortical Atrophy and Disability in Early Multiple Sclerosis

Abstract

Background and objectives: To evaluate CSF inflammatory markers with accumulation of cortical damage as well as disease activity in patients with early relapsing-remitting MS (RRMS).

Methods: CSF levels of osteopontin (OPN) and 66 inflammatory markers were assessed using an immune-assay multiplex technique in 107 patients with RRMS (82 F/25 M, mean age 35.7 ± 11.8 years). All patients underwent regular clinical assessment and yearly 3T MRI scans for 2 years while 39 patients had a 4-year follow-up. White matter lesion number and volume, cortical lesions (CLs) and volume, and global cortical thickness (CTh) were evaluated together with the 'no evidence of disease activity' (NEDA-3) status, defined by no relapses, no disability worsening, and no MRI activity, including CLs.

Results: The random forest algorithm selected OPN, CXCL13, TWEAK, TNF, IL19, sCD30, sTNFR1, IL35, IL16, and sCD163 as significantly associated with changes in global CTh. OPN and CXCL13 were most related to accumulation of atrophy after 2 and 4 years. In a multivariate linear regression model on CSF markers, OPN (p < 0.001), CXCL13 (p = 0.001), and sTNFR1 (p = 0.024) were increased in those patients with accumulating atrophy (adjusted R-squared 0.615). The 10 markers were added in a model that included all clinical, demographic, and MRI variables: OPN (p = 0.002) and IL19 (p = 0.022) levels were confirmed to be significantly increased in patients developing more CTh change over the follow-up (adjusted R-squared 0.619). CXCL13 and OPN also revealed the best association with NEDA-3 after 2 years, with OPN significantly linked to disability accumulation (OR 2.468 [1.46-5.034], p = 0.004) at the multivariate logistic regression model.

Discussion: These data confirm and expand our knowledge on the prognostic role of the CSF inflammatory profile in predicting changes in cortical pathology and disease activity in early MS. The data emphasize a crucial role of OPN.

Figure 1. Random Forest Approach: OPN and CXCL13 Best Associated With Cortical Thickness Change After 2 and 4 Years of Follow-Up

(A) Multiway importance plot: OPN and CXCL13 were selected as the most important variables associated with the cortical thickness change after two years of follow-up (panel on the left). (B) OPN was selected as the most important variable after 4 years. CCL22 = chemokine (C-C motif) ligand 22; CCL7 = chemokine (C-C motif) ligand 7; CXCL10 = chemokine (C-X-C motif) ligand 10; CXCL13 = chemokine (C-X-C motif) ligand 13 or B lymphocyte chemoattractant; IFNA2 = interferon alfa2; IL16 = interleukin-16; IL19 = interleukin-19; IL22 = interleukin-22; IL-35 = interleukin-35; IL8 = interleukin-8; MIF = macrophage migration inhibitory factor; OPN = osteopontin; sCD163 = soluble Cluster of Differentiation 163; sCD30 = soluble Cluster of Differentiation 30; sTNFR1 = soluble TNFRSF1A or TNF receptor superfamily member 1A; TNF = tumor necrosis factor; TWEAK = TNFSF12 or TNF superfamily member.

Figure 2. Cortical Atrophy Rates According to Osteopontin and CXCL13 Levels

(A and B) Patients with high levels of osteopontin and CXCL13 showed significantly increased rates of cortical thinning after both 2 and 4 years. (C) Having high levels of both molecules led to higher atrophy rates. High/low was defined according to median values. CTh = cortical thickness. ∆T0-T2: cortical thickness change between baseline and the end of 4 years of follow-up (T2).

Figure 3. Pathway Analysis of CSF Markers Identified as Associated With Accumulating Cortical Atrophy

Protein-protein associations between molecules detected at the RF approach (protein-protein enrichment p value = 7.93e-13). Table II lists the specific functions related to the pathway. CD163 = Cluster of Differentiation 163; CXCL13 = chemokine (C-X-C motif) ligand 13 or B lymphocyte chemoattractant; IL-16 = interleukin-16; IL-19 = interleukin-19; IL-35 = interleukin-35; SPP1 = secreted phosphoprotein 1 or osteopontin; TNF = tumor necrosis factor; TNFRSF1A = TNF receptor superfamily member 1A or TNFR1; TNFRSF8 = TNF receptor superfamily member 8 or Cluster of Differentiation 30; TNFSF12 = TNF superfamily member 12 or TWEAK.

Figure 4. Cytokines and Chemokines That Are Associated With Cortical Atrophy and Disease Activity

The molecules associated with each outcome are shown. OPN emerged as the best associated with accumulating cortical atrophy and confirmed disability worsening. CCL19 = chemokine (C-C motif) ligand 19; CDW = confirmed disability worsening; CXCL13 = chemokine (C-X-C motif) ligand 13 or B lymphocyte chemoattractant; CXCL15 = chemokine (C-X-C motif) ligand 15; IFNg = interferon gamma; IL-19: interleukin 19; IL-4 = interleukin 4; IL-6 = interleukin 6; OPN = osteopontin; sTNFR1 = soluble TNFRSF1A or TNF receptor superfamily member 1A; TNF = tumor necrosis factor. Created with BioRender.com.