Lippia javanica (Zumbani) herbal tea infusion attenuates allergic airway inflammation via inhibition of Th2 cell activation and suppression of oxidative stress

Abstract

Background Lippia javanica (lemon bush) is commonly used in the treatment of respiratory ailments, including asthma in southern African countries but there is no scientific evidence to support this claim. This study investigated the anti-inflammatory, antioxidant and anti-asthmatic effects of L. javanica using a rat model of asthma. Methods A 5% w/v L. javanica tea infusion was prepared and characterised by liquid chromatography–mass spectrometer (LC-MS). Animals were intraperitoneally sensitized with ovalbumin (OVA) and subsequently challenged intranasal with OVA on day 15 except the control group. Animals were grouped (n = 5/group) for treatment: unsensitised control, sensitised control, sensitised + prednisolone and sensitised + L. javanica at 50 mg/kg/day and 100 mg/kg/day – equivalent to 1 and 2 cups of tea per day, respectively. After 2 weeks of treatment, bronchoalveolar lavage fluid (BALF) was collected for total and differential white blood cell (WBC) count. Nitric oxide (NO), lipid peroxidation and antioxidants were also assessed in BALF. Ovalbumin specific IgE antibody and inflammatory cytokines: IL-4, IL-5, IL-13 and TNF-alpha were measured in serum. Lung and muscle tissues were histological examined. Results L. javanica was rich in phenolic compounds. OVA sensitisation resulted in development of allergic asthma in rats. L. javanica treatment resulted in a reduction in total WBC count as well as eosinophils, lymphocytes and neutrophils in BALF. L. javanica inhibited Th2-mediated immune response, which was evident by a decrease in serum IgE and inflammatory cytokines: IL-4, IL-5, IL-13 and TNF-α. L. javanica treatment also reduced malondialdehyde (MDA) and NO, and increased superoxide dismutase, glutathione and total antioxidant capacity. Histology showed significant attenuation of lung infiltration of inflammatory cells, alveolar thickening, and bronchiole smooth muscle thickening. Conclusion L. javanica suppressed allergic airway inflammation by reducing Th2-mediated immune response and oxidative stress in OVA-sensitized rats which may be attributed to the presence of phenolic compound in the plant. This finding validates the traditional use of L. javanica in the treatment of respiratory disorders.

Neuroprotective effects of Lippia javanica (Burm.F.) Spreng. Herbal tea infusion on Lead-induced oxidative brain damage in Wistar rats

“…The supernatant was transferred into vials for LC-MS analysis. The extract was analysed in an ultra-performance liquid chromatography (UPLC) (Waters, Milford, MA, USA) connected to a Waters Synapt G2 Quadrupole time-of-flight (QTOF) mass spectrometer (MS) as previously reported by us [ 35 ]. Polyalanine was used for calibration and calculations according to Rautenbach et al [ 36 ].…”

Screening of Q-markers for the wine-steamed Schisandra chinensis decoction pieces in improving allergic asthma

“…The level of IFN-γ decreased and the levels of IL-4 and IgE increased in the model group. The overexpression of Th2 cytokines, such as IL-4, and the reduced expression of Th1 cytokines, such as IFN-γ, are the main manifestations of a Th1/Th2 imbalance, which is the key mechanism of an asthma attack [ 37 , 38 ]. Therefore, it is speculated that the model group had a Th1/Th2 imbalance.…”

Screening of Q-markers for the wine-steamed Schisandra chinensis decoction pieces in improving allergic asthma

“…The results showed that the level of IFN-γ decreased and the level of IL-4 and IgE increased in the model group. Among them, the overexpression of Th 2 cytokines such as IL-4 and the decrease of Th 1 cytokines such as IFN-γ are the main manifestations of Th1/Th2 imbalance, which is also the key mechanism of mediating asthma attack [42,43]. Therefore, it is speculated that the model group has Th1/Th2 imbalance.…”