PHYTOCHEMICAL MODULATION OF SYSTEMIC LUPUS ERYTHEMATOSUS THROUGH TLR7-INTERFERON, BAFF B-CELL, NLRP3 AND NRF2 PATHWAYS: AN INTEGRATED IN-SILICO AND IN-VIVO STUDY

Abstract

Background: Systemic lupus erythematosus (SLE) is a complex autoimmune disease of multiple organs characterized by an interplay of various factors, including the activation of the innate immune system, production of autoantibodies, inflammatory signaling, oxidative imbalance, and renal damage, which orchestrate disease progression. There is growing evidence that coordinated modulation of the signaling pathways that are associated with TLR7, the Type-I interferon pathways, BAFF-mediated activation of B-cells, NF-κB/NLRP3 inflammatory signaling pathways, and endogenous antioxidant defenses could be a promising multi-target modulation approach. Phytochemicals from plants provide a rich source of molecules that have the capacity to act in multiple of these pathways. Objective: This study aimed to establish an integrated approach, using phytochemicals as the basis for identifying the potential compounds that can be used for the treatment of SLE from Moringa oleifera, Achillea millefolium, and Doronicum hookeri, with the main phytochemicals, morin, luteolin, and quercetin, as the main molecules of the plant. Materials and Methods: Potential compounds were selected based on their occurrence in plants, their pharmacological activity, and their predicted interactions with some of the targets involved in SLE. Mechanistic framework involved TLR7, TLR9, MyD88, IRF5, JAK1, TYK2, STAT1, BAFF, NF-κB p65, NLRP3 and Nrf2. Selected phytochemicals were then tested in an experimental rat model of SLE. The proteinuria, anti-dsDNA, anti-ANA, and complement C3/C4 were used to define disease activity. Systemic inflammatory responses were assessed by measuring the levels of TNF-α, IL-6, IL-1β, IL-17A, IFN-α and BAFF, and oxidative status was assessed by measuring the levels of MDA, ROS, SOD and GSH. The immune-signaling pathway changes and renal histopathological injury were also investigated to set an integrated response profile. Results: The SLE model had significant autoimmune, inflammatory, oxidative, and renal abnormalities. Phytochemical treatment resulted in an improvement in several aspects of the disease when compared to the untreated model. Luteolin showed a consistent efficacy among all the phytochemicals evaluated, reducing proteinuria, anti-dsDNA, TNF-α, and MDA by 42.67–14.83 mg/24 h, 126.42 to 49.63 IU/mL, 86.73 to 42.12 pg/mL, and 8.92 to 4.21 nmol/mL, respectively. Luteolin also enhanced the levels of SOD and GSH and decreased ROS; it also restored Nrf2 and suppressed the activity of the TLR7-, NF-κB-, and NLRP3-associated signaling. Luteolin decreased renal histopathological injury to a score of 3.65 in the SLE model compared to 9.44. The integrated therapeutic-response index (ITRI) for luteolin was 57.87%, whereas that for quercetin and morin were 52.91% and 47.90%, respectively. Conclusions: The results indicate that an immune-recognition, interferon-associated, B-cell activation, inflammatory inflammasome, and antioxidant defense pathway phytochemical approach might work synergistically to reduce SLE-associated pathology. Luteolin had the most uniform results in serological, inflammatory, oxidative, molecular, and renal endpoints, followed by quercetin and moringin. Although in this study, luteolin proved to be a good lead compound, it has to be validated using independently replicated experiments, single-patient statistical analysis, pharmacokinetic studies, dose optimization, and a thorough safety evaluation before therapeutic efficacy is established.