Diosmin downregulates the expression of T cell receptors, pro-inflammatory cytokines and NF-κB activation against LPS-induced acute lung injury in mice.

Diosmin, a natural flavonoid glycoside present abundantly in the pericarp of various citrus fruits. Because of its anti-inflammatory and antioxidant properties, it can be used in many diseases. In this study, we investigated the possible protective mechanisms of the diosmin on LPS-induced lung injury through inhibition of T cell receptors, pro-inflammatory cytokines and NF-κB activation. Animals were pretreated with diosmin (50 and 100mg/kg, p.o.) for seven days prior to lipopolysaccharides (LPS) treatment. LPS administration increased neutrophils, monocytes, lymphocytes, total leukocyte count (TLC) and platelets which were decreased by diosmin. We observed that mice exposed to LPS showed increased malondialdehyde level and MPO activity whereas marked decrease in glutathione content. These changes were significantly reversed by treatment with diosmin in a dose dependent manner. Diosmin treatment showed a substantial reduction in T cell (CD4(+) and CD8(+)) receptors and pro-inflammatory (IL-2(+) and IL-17(+)) cytokines in whole blood. In addition, RT-PCR analysis revealed increased mRNA expression of IL-6, IL-17, TNF-α, and NF-κB in the LPS group, while reduced by treatment with diosmin. Western blot analysis confirmed the increased protein expression of IL-1ß, TNF-α and NF-κB p65 in the LPS group and treatment of animals with diosmin reversed these effects. The levels of cytoplasmic p-IκB-α and p-NF-κB p65 expression also were mitigated by diosmin. The histological examinations revealed protective effect of diosmin while LPS group aggravated lung injury. These results support the potential for diosmin to be investigated as a potential agent for the treatment of lung injury and inflammatory diseases.

Airway oxidative stress causes vascular and hepatic inflammation via upregulation of IL-17A in a murine model of allergic asthma.

Oxidants are generated in asthmatic airways due to infiltration of inflammatory leukocytes and resident cells in the lung. Reactive oxygen species (ROS) such as hydrogen peroxide and superoxide radical may leak into systemic circulation when generated in uncontrolled manner and may impact vasculature. Our previous studies have shown an association between airway inflammation and systemic inflammation; however so far none has investigated the impact of airway oxidative inflammation on hepatic oxidative stress and Th1/Th2/Th17 cytokine markers in liver/vasculature in a murine model of asthma. Therefore, this study investigated the contribution of oxidative stress encountered in asthmatic airways in modulation of systemic/hepatic Th1/Th2/Th17 cytokines balance and hepatic oxidative stress. Mice were sensitized intraperitoneally with cockroach extract (CE) in the presence of aluminum hydroxide followed by several intranasal (i.n.) challenges with CE. Mice were then assessed for systemic/hepatic inflammation through assessment of Th1/Th2/Th17 cytokines and oxidative stress (iNOS, protein nitrotyrosine, lipid peroxides and myeloperoxidase activity). Challenge with CE led to increased Th2/Th17 cytokines in blood/liver and hepatic oxidative stress. However, only Th17 related pro-inflammatory markers were upregulated by hydrogen peroxide (H2O2) inhalation in vasculature and liver, whereas antioxidant treatment, N-acetyl cysteine (NAC) downregulated them. Hepatic oxidative stress was also upregulated by H2O2 inhalation, whereas NAC attenuated it. Therefore, our study shows that airway oxidative inflammation may contribute to systemic inflammation through upregulation of Th17 immune responses in blood/liver and hepatic oxidative stress. This might predispose these patients to increased risk for the development of cardiovascular disorders.

Histamine 4 receptor promotes expression of costimulatory B7.1/B7.2 molecules, CD28 signaling and cytokine production in stress-induced immune responses.

Recently, the expression of histamine 4 receptor (H4R) on neurons was reported, however its function in cells within the central nervous system (CNS) remains poorly understood. To this end, we used the H4R agonist, 4-methylhistamine (4-MeH), and the H4R antagonist, JNJ77777120 (JNJ), to investigate the function of H4R signaling in immune cells in a murine model of chronic stress. Treatment of stressed mice with 4-MeH resulted in an increase in the proportion of lymphocyte subsets (CD3(+), CD8(+), CD28(+), and CD4(+)CD28(+)) and cells expressing the co-stimulatory molecules CD80(+) (B7.1) and CD86(+) (B7.2) in heparinized blood as compared to normal control (NC) and stressed control (SC) groups. We also observed that as compared to NC and SC mice, 4-MeH-treated mice showed greater production of IL-2(+), IL-6(+), IL-9(+), IL-21(+), and IL-27(+) cytokines in the spleen and by splenic CD4(+) T cells. Furthermore, 4-MeH treatment of stressed mice led to an increase in the levels of serum Th1/Th17 cytokines and corticosterone, and a decrease in Th2 cytokines. Treatment of chronically-stressed mice with 4-MeH also augmented expression of IL-6, IL-21, NF-κB p65, and STAT3 mRNA. Moreover, Western blot analyses confirmed increased protein expression of NF-κB, iNOS, and STAT3 expression following 4-MeH treatment of chronically-stressed mice as compared to controls. These proteins provide a novel relevant targets for the manipulation of chronic stress induced immune regulation. In striking contrast, treatment of stressed mice with the H4R antagonist, JNJ, resulted in a substantial reduction in all of the aforementioned effects upon immune cell percentages and cytokine production.