Inhibition of Bruton's Tyrosine Kinase Modulates Microglial Phagocytosis: Therapeutic Implications for Alzheimer's Disease

Therapeutic treatment with Ibrutinib attenuates imiquimod-induced psoriasis-like inflammation in mice through downregulation of oxidative and inflammatory mediators in neutrophils and dendritic cells

Psoriasis is clinically characterized by well-demarcated silvery plaques which may appear on the extremities, scalp, and sacral area. The multidimensional interactions among innate immune cells [neutrophils and dendritic cells (DCs)], adaptive immune cells and skin resident cells result in characteristic features of psoriatic inflammation such as acanthosis, hyperkeratosis, and parakeratosis. Tec family kinases are involved in the pathogenesis of several inflammatory diseases. One of them is Bruton's tyrosine kinase (BTK) which is reported to carry out inflammatory and oxidative signaling in neutrophils and DCs. Effect of BTK inhibitor with regard to psoriatic inflammation has not been explored previously especially in a therapeutic setting. In the current investigation, effect of BTK inhibitor, Ibrutinib on oxidative/inflammatory signaling in dermal/splenic neutrophils [phosphorylated BTK (p-BTK), inducible nitric oxide synthase (iNOS), nitrotyrosine], CD11c + DCs (p-BTK, iNOS, nitrotyrosine, MCP-1, TNF-α) and enzymatic antioxidants [superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR)] in imiquimod (IMQ)-induced psoriatic inflammation was evaluated using therapeutic mode. Our results show that IMQ treatment led to induction of p-BTK expression along with concomitant increase in oxidative stress in neutrophils, and CD11c + DCs in skin/periphery. Therapeutic treatment with Ibrutinib caused attenuation of IMQ-induced oxidative stress in CD11c + DCs and neutrophils. Further there were dysregulations in antioxidants enzymes (SOD/GPx/GR) in the skin of IMQ-treated mice, which were corrected by Ibrutinib. In short, our study reveals that BTK signaling in neutrophils and CD11c + DCs upregulates oxidative stress which is concomitant with psoriatic inflammation in mice. Ibrutinib attenuates psoriasis inflammation through downregulation of oxidative stress in these innate immune cells.

The protective effect of Geniposide on diabetic cognitive impairment through BTK/TLR4/NF-κB pathway

The purpose of the present study was to elucidate the pharmacological effects of Geniposide (GEN) on high diet fed and streptozotocin (STZ)-caused diabetic cognitive impairment. The mice were fed with high fat diet (HFD) for 4 weeks and intraperitoneally injected with 60 mg/kg STZ for three times within 72 h. The mice with glucose level over 15 mmol/l were regarded as diabetic and selected for further studies. The animals were intragastrically treated with metformin or GEN once daily for 4 weeks. Afterwards, the animals were applied for Y maze, novel object recognition (NOR) test, step-through passive avoidance test, and Morris water maze (MWM) test. The blood glucose and body weight were examined. The SH-SY5Y cells were treated with GEN in the presence or absence of ibrutinib and stimulated with high-glucose culture medium. The tumor necrosis factor-a (TNF-α) and interleukin (IL)-6 in serum, hippocampus, and supernatant were measured using ELISA method. The protein expressions of Bruton's tyrosine kinase (BTK), Toll-like receptor 4 (TLR4), myeloid differentiating factor 88 (MyD88), nuclear factor kappa-B (NF-κB), p-NF-κB, brain-derived neurotrophic factor (BDNF), cAMP-response element binding protein (CREB), p-CREB, and glucagon-like peptide-1 receptor (GLP-1R) were detected by western blot analyses. As a result, the GEN treatment notably attenuated the body weight, blood glucose, and cognitive decline. GEN also inhibited the generations of inflammatory cytokines. Furthermore, the administrations of GEN ameliorated the alterations of BTK, TLR4, MyD88, NF-κB, and BDNF in HFD + STZ-induced mice. With the application of ibrutinib, the selective inhibitor of BTK, it was also found that BTK/TLR4/NF-κB pathway was associated with the GEN treatment in high glucose-induced SH-SY5Y cells. In summary, the results suggested that GEN exerted the protective effect on STZ-induced cognitive impairment possibly through the modulation of BTK/TLR4/NF-κB signaling.