Black cumin seed oil and its nano-form ameliorate lipopolysaccharide-induced brain inflammatory injury in mice

Microglia play a regulatory role in central nervous system inflammatory diseases, such as Alzheimer’s, Parkinson’s, and multiple sclerosis. Natural remedies like black cumin seeds (Nigella sativa) are rich in bioactive compounds that potentially can modulate inflammatory processes in the brain. In the current work, we studied the protective and anti-inflammatory properties of black cumin seed oil (BCSO) and its nano-form on lipopolysaccharide (LPS)-induced neurotoxicity in mice. Forty-eight mice were divided randomly into eight groups (n=6), three control groups (negative control, BCSO control, nano-BCSO control), LPS group, and four treatment groups [BCSO+LPS, nano-BCSO+LPS, indomethacin (5 mg/kg)+LPS, BCSO+indomethacin(2.5 mg/kg)+LPS]. At the end of the experiment, the brain tissues were removed for histopathological and biochemical assessments. Malondialdehyde and interleukin (IL)-10 were assessed using enzyme-linked immunosorbent assay while the gene expression of IL-6, toll-like receptor-4, brain-derived neurotrophic factor, nerve growth factor, cyclooxygenase-2, and B-cell lymphoma-2 were assessed by real-time PCR. IL-1β was quantified immunohistochemically along with the histopathological studies of the cerebral cortex of mice brains. In our study, BCSO and its nano-form demonstrated a reduction in LPS-induced neurotoxicity, exhibiting comparable or better anti-inflammatory effects to indomethacin. These treatments significantly elevated the gene expression levels of neuroprotective factors brain-derived neurotrophic factor and nerve growth factor in LPS-treated mice. Pretreatment with BCSO and its nano-form reduced the malondialdehyde levels, in addition to gene expressions of cyclooxygenase-2, toll-like receptor-4, IL-6, and B-cell lymphoma-2. Immunohistochemical analysis indicated a decrease in IL-1β with BCSO and the lowering effect of the nano-form was superior. The histopathological studies corroborated with biochemical and molecular findings, suggesting that BCSO and its nano-form attenuated the inflammation and enhanced the microglial antioxidative and anti-inflammatory status. BCSO could enhance the anti-inflammatory activity of indomethacin, so lower doses of indomethacin with BCSO may be suggested for protecting against the adverse effects of high doses of NSAIDs as gastritis. Consequently, BCSO can serve a potential stimulatory supplement of the immunity for neurodegenerative conditions.