Bruton's tyrosine kinase-bearing B cells and microglia in neuromyelitis optica spectrum disorder.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory autoimmune disease of the central nervous system that involves B-cell receptor signaling as well as astrocyte-microglia interaction, which both contribute to evolution of NMOSD lesions. MAIN BODY: Through transcriptomic and flow cytometry analyses, we found that Bruton's tyrosine kinase (BTK), a crucial protein of B-cell receptor was upregulated both in the blood and cerebrospinal fluid of NMOSD patients. Blockade of BTK with zanubrutinib, a highly specific BTK inhibitor, mitigated the activation and maturation of B cells and reduced production of causal aquaporin-4 (AQP4) autoantibodies. In a mouse model of NMO, we found that both BTK and pBTK expression were significantly increased in microglia. Transmission electron microscope scan demonstrated that BTK inhibitor ameliorated demyelination, edema, and axonal injury in NMO mice. In the same mice colocalization of GFAP and Iba-1 immunofluorescence indicated a noticeable increase of astrocytes-microglia interaction, which was alleviated by zanubrutinib. The smart-seq analysis demonstrated that treatment with BTK inhibitor instigated microglial transcriptome changes including downregulation of chemokine-related genes and genes involved in the top 5 biological processes related to cell adhesion and migration, which are likely responsible for the reduced crosstalk of microglia and astrocytes. CONCLUSIONS: Our results show that BTK activity is enhanced both in B cells and microglia and BTK inhibition contributes to the amelioration of NMOSD pathology. These data collectively reveal the mechanism of action of BTK inhibition and corroborate BTK as a viable therapeutic target.

Rituximab induces a transient fluctuation of peripheral and follicular helper T cells in neuromyelitis optica spectrum disorder.

Autoreactive CD4+ helper T cells are implicated in the pathogenesis of neuromyelitis optica spectrum disorder (NMOSD). Both PD-1+CXCR5+CD4+ T follicular helper (Tfh) cells and PD-1+CXCR5-CD4+ T peripheral helper (Tph) cells can contribute to B-cell immune responses and the production of antibodies. Here we show the effect of B-cell depletion with rituximab on the homeostasis of Tfh cells, Tph cells and their subsets in patients with NMOSD. After rituximab treatment, total Tph cells, total Tfh cells, Tph17 cells, Tph17.1 cells, Tph1 cells, and Tfh1 cells tended to decrease at month 1, but gradually increased at month 6 and restored at month 12. Besides, Tph17.1 cells and Tfh17.1 cells were correlated with the proportion of CD19- antibody-secreting cells. Our data suggest that rituximab induced a fluctuation of proinflammatory Tph and Tfh subsets within one year after initiation of the treatment.

Longitudinal treatment responsiveness on plasma neurofilament light chain and glial fibrillary acidic protein levels in neuromyelitis optica spectrum disorder.

BACKGROUND: Neurofilament light chain (NfL) and glial fibrilliary acidic protein (GFAP) have been suggested to be biomarkers of the pathophysiological process of neuromyelitis optica spectrum disorders (NMOSD), but the relationship between the plasma levels of these molecules with disease activity and treatment is incompletely understood. OBJECTIVE: To investigate the treatment effects of disease-modifying drugs on plasma neurofilament light chain (pNfL) and plasma glial fibrillary acidic protein (pGFAP) and explore the predictive value of pNfL and pGFAP in the activity of NMOSD. METHODS: pNfL and pGFAP levels were measured using single-molecule arrays in 72 patients with NMOSD and 38 healthy controls (HCs). Patients with NMOSD received tocilizumab (n = 29), rituximab (n = 23), oral prednisone (n = 16), and oral azathioprine or mycophenolate mofetil (n = 4). RESULTS: NMOSD patients had significantly higher pNfL and pGFAP levels than HCs (pNfL, 18.3 (11.2-39.3) versus 11.5 (7.0-23.3) pg/mL; p = 0.001; pGFAP, 149.7 (88.6-406.5) versus 68.7 (59.4-80.8) pg/mL; p < 0.001). Multivariable regression analyses indicated that baseline pNfL concentration was associated with age (p = 0.017), Expanded Disability Status Scale (EDSS) score (p = 0.002), and recent relapses (p < 0.001). Baseline pGFAP concentration was also associated with EDSS (p < 0.001) and recent relapses (p < 0.001). Compared with prednisone, tocilizumab and rituximab significantly reduced pNfL [tocilizumab, exp(ß), 0.65; 95% confidence interval (CI), 0.56-0.75; p < 0.001; rituximab, exp(ß), 0.79; 95% CI = 0.68-0.93; p = 0.005] and pGFAP levels [tocilizumab, exp(ß), 0.64; 95% CI, 0.51-0.80; p < 0.001; rituximab, exp(ß), 0.77; 95% CI, 0.61-0.98; p = 0.041] at the end of the study. The pNfL levels in the tocilizumab and rituximab groups were reduced to those of HCs [tocilizumab, 8.5 (7.06-17.90) pg/mL; p = 0.426; rituximab, 14.0 (9.94-21.80) pg/mL; p = 0.216]. However, the pGFAP levels did not decrease to those of HCs in NMOSD patients at the end of study [tocilizumab, 88.9 (63.4-131.8) pg/mL; p = 0.012; rituximab, 141.7 (90.8-192.7) pg/mL; p < 0.001]. CONCLUSION: pNfL and pGFAP may serve as biomarkers for NMOSD disease activity and treatment effects.

Effects of Tocilizumab Therapy on Circulating B Cells and T Helper Cells in Patients With Neuromyelitis Optica Spectrum Disorder.

Tocilizumab, a humanized anti-IL-6 receptor monoclonal antibody, showed its therapeutic efficacy on neuromyelitis optica spectrum disorder (NMOSD). To assess the immunological effects of this drug on B cells, follicular T helper (Tfh) cells, and peripheral T helper (Tph) cells in patients with NMOSD, peripheral B cell and Tfh cell phenotypes were evaluated in 26 patients with NMOSD before and after tocilizumab treatment by nine-color flow cytometry, as well as the expression of costimulatory and co-inhibitory molecules on B cells. Results showed that the frequency of CD27+IgD- switched memory B cells, CD27-IgD- double-negative B cells, and CD27highCD38high antibody-secreting cells was increased in patients with NMOSD. Tocilizumab treatment led to a significant shift of B cells to naïve B cells from memory B cells after 3 months. Three markers on B cells associated with T-cell activation (i.e., CD86 CD69, and HLA-DR) were downregulated after tocilizumab treatment. The frequencies of total Tfh and Tph cells were decreased, whereas that of follicular regulatory T cells tended to increase. Intrinsic increased PD-L1 and PD-L2 expression was characteristic of B cells in patients with NMOSD. Tocilizumab selectively restored PD-L1 on B-cell subsets. These results provided evidence that tocilizumab enhanced B- and T-cell homoeostasis by regulating B-cell differentiation and inhibiting lymphocyte activation in patients with NMOSD.

Cronkhite-Canada syndrome with steroid dependency: A case report.

BACKGROUND: Cronkhite-Canada syndrome (CCS) is a rare nonhereditary disease characterized by chronic diarrhoea, diffuse gastrointestinal polyposis and ectodermal manifestations. The lethality of CCS can be up to 50% if it is untreated or if treatment is delayed or inadequate. More than 35% of the patients do not achieve long-term clinical remission after corticosteroid administration, with relapse occurring during or after the cessation of glucocorticoid use. The optimal strategy of maintenance therapy of this disease is controversial. CASE SUMMARY: A 47-year-old man presented to the hospital with a 3-mo history of frequent watery diarrhoea, accompanied by macular skin pigmentation that included the palms and soles, and onychodystrophy of the fingernails and toenails. Gastroscopy and colonoscopy revealed numerous polyps in the stomach and colon. After other possibilities were ruled out by a series of examinations, CCS was diagnosed and treated with prednisone. The patient took prednisone for more than 1 year before achieving complete resolution of his symptoms and endoscopic findings. The patient was then given prednisone 5 mg/d for 6 mo of maintenance therapy. With clinical improvement and polyp regression, prednisone was discontinued. Eight mo after the discontinuation of prednisone, the diarrhoea and gastrointestinal polyps relapsed. Therefore, the patient was given the same dose of prednisone, and complete remission was achieved again. CONCLUSION: It is necessary to extend the duration of prednisone maintenance therapy for CCS. Prednisone is still effective when readministered after relapse. Surveillance endoscopy at intervals of 1 year or less is recommended to assess mucosal disease activity.

Low-dose rituximab treatment for new-onset generalized myasthenia gravis.

The aim of this retrospective case series study was to evaluate the response and durability of rituximab in patients with new-onset acetylcholine receptor positive (AChR +) generalized myasthenia gravis (MG). Patients were initiated with low-dose rituximab treatment within 3.5 months of onset without concomitant oral immunosuppressants. Seventeen patients (89%) remained relapse-free with a mean follow-up of 51.3 months. Clinical improvement was observed in parallel with the maintenance of low-dose corticosteroids or the complete discontinuation of corticosteroids. Long-term depletion of B cells with low-dose rituximab treatment has shown favorable efficacy and tolerance in reducing disease activity for AChR+ generalized MG.