Baseline Inflammatory Status Reveals Dichotomic Immune Mechanisms Involved In Primary-Progressive Multiple Sclerosis Pathology

To ascertain the role of inflammation in the response to ocrelizumab in primary-progressive multiple sclerosis (PPMS).Multicenter prospective study including 69 patients with PPMS who initiated ocrelizumab treatment, classified according to baseline presence [Gd+, n=16] or absence [Gd-, n=53] of gadolinium-enhancing lesions in brain MRI. Ten Gd+ (62.5%) and 41 Gd- patients (77.4%) showed non-evidence of disease activity (NEDA) defined as no disability progression or new MRI lesions after 1 year of treatment. Blood immune cell subsets were characterized by flow cytometry, serum immunoglobulins by nephelometry, and serum neurofilament light-chains (sNfL) by SIMOA. Statistical analyses were corrected with the Bonferroni formula.More than 60% of patients reached NEDA after a year of treatment, regardless of their baseline characteristics. In Gd+ patients, it associated with a low repopulation rate of inflammatory B cells accompanied by a reduction of sNfL values 6 months after their first ocrelizumab dose. Patients in Gd- group also had low B cell numbers and sNfL values 6 months after initiating treatment, independent of their treatment response. In these patients, NEDA status was associated with a tolerogenic remodeling of the T and innate immune cell compartments, and with a clear increase of serum IgA levels.Baseline inflammation influences which immunological pathways predominate in patients with PPMS. Inflammatory B cells played a pivotal role in the Gd+ group and inflammatory T and innate immune cells in Gd- patients. B cell depletion can modulate both mechanisms.Copyright © 2022 Fernández-Velasco, Monreal, Kuhle, Meca-Lallana, Meca-Lallana, Izquierdo, Oreja-Guevara, Gascón-Giménez, Sainz de la Maza, Walo-Delgado, Lapuente-Suanzes, Maceski, Rodríguez-Martín, Roldán, Villarrubia, Saiz, Blanco, Diaz-Pérez, Valero-López, Diaz-Diaz, Aladro, Brieva, Íñiguez, González-Suárez, Rodríguez de Antonio, García-Domínguez, Sabin, Llufriu, Masjuan, Costa-Frossard and Villar.