Increased NLRP3 Inflammasome Activation and Pyroptosis in Patients With Multiple Sclerosis With Fingolimod Treatment Failure

by Selleckchem | Apr 23 2023

Background and objectives: Inflammasomes are involved in the pathogenesis of different neuroimmune and neurodegenerative diseases, including multiple sclerosis (MS). In a previous study by our group, the nucleotide-binding oligomerization domain, leucine-rich repeat receptor and pyrin-domain-containing 3 (NLRP3) inflammasome was reported to be associated with the response to interferon-beta in MS. Based on recent data showing the potential for the oral therapy fingolimod to inhibit NLRP3 inflammasome activation, here we investigated whether fingolimod could also be implicated in the response to this therapy in patients with MS.

Methods: NLRP3 gene expression levels were measured by real-time PCR in peripheral blood mononuclear cells at baseline and after 3, 6, and 12 months in a cohort of patients with MS treated with fingolimod (N = 23), dimethyl fumarate (N = 21), and teriflunomide (N = 21) and classified into responders and nonresponders to the treatment according to clinical and radiologic criteria. In a subgroup of fingolimod responders and nonresponders, the percentage of monocytes with an oligomer of ASC was determined by flow cytometry, and the levels of interleukin (IL)-1β, IL-18, IL-6, tumor necrosis factor (TNF)α, and galectin-3 were quantified by ELISA.

Results: NLPR3 expression levels were significantly increased in fingolimod nonresponders after 3 (p = 0.03) and 6 months (p = 0.008) of treatment compared with the baseline but remained similar in responders at all time points. These changes were not observed in nonresponders to the other oral therapies tested. The formation of an oligomer of ASC in monocytes after lipopolysaccharide and adenosine 5'-triphosphate stimulation was significantly decreased in responders (p = 0.006) but increased in nonresponders (p = 0.0003) after 6 months of fingolimod treatment compared with the baseline. Proinflammatory cytokine release from stimulated peripheral blood mononuclear cells was comparable between responders and nonresponders, but galectin-3 levels on cell supernatants, as a marker of cell damage, were significantly increased in fingolimod nonresponders (p = 0.02).

Discussion: The differential effect of fingolimod on the formation of an inflammasome-triggered ASC oligomer in monocytes between responders and nonresponders could be used as a response biomarker after 6 months of fingolimod treatment and suggests that fingolimod may exert their beneficial effects by reducing inflammasome signaling in a subset of patients with MS.

Comments：

In this study, the researchers aimed to investigate whether fingolimod, an oral therapy for multiple sclerosis (MS), could be implicated in the response to treatment through its inhibition of the nucleotide-binding oligomerization domain, leucine-rich repeat receptor and pyrin-domain-containing 3 (NLRP3) inflammasome, which has been associated with the pathogenesis of neuroimmune and neurodegenerative diseases, including MS.

The study involved measuring NLRP3 gene expression levels in peripheral blood mononuclear cells of MS patients treated with fingolimod, dimethyl fumarate, or teriflunomide, and classifying them as responders or nonresponders based on clinical and radiologic criteria. The percentage of monocytes with an oligomer of ASC, a protein involved in inflammasome activation, was also determined, as well as the levels of proinflammatory cytokines and galectin-3, a marker of cell damage.

The results showed that NLRP3 expression levels were significantly increased in fingolimod nonresponders after 3 and 6 months of treatment, but remained similar in responders at all time points. This effect was not observed in nonresponders to the other oral therapies tested. The formation of an ASC oligomer in monocytes was significantly decreased in responders, but increased in nonresponders after 6 months of fingolimod treatment compared to baseline. Proinflammatory cytokine release from stimulated peripheral blood mononuclear cells was comparable between responders and nonresponders, but galectin-3 levels were significantly increased in fingolimod nonresponders.

The authors suggest that the differential effect of fingolimod on the formation of an inflammasome-triggered ASC oligomer in monocytes between responders and nonresponders could be used as a response biomarker after 6 months of fingolimod treatment. These findings also suggest that fingolimod may exert its beneficial effects in a subset of MS patients by reducing inflammasome signaling.