The Hydroalcoholic Extract of Nasturtium officinale Reduces Lung Inflammation and Oxidative Stress in an Ovalbumin-Induced Rat Model of Asthma

Abstract

Background: Asthma is known as a disease that causes breathing problems in children and adults and is also associated with chronic inflammation and oxidative stress of the airways. Nasturtium officinale (NO) possesses a wide range of pharmacological properties, particularly anti-inflammation and antioxidant potentials. Thus, this study for the first time was aimed to investigate anti-inflammatory and antioxidative activities of NO extract (NOE) in an ovalbumin-induced rat model of asthma.

Materials and methods: Forty-four male Wistar rats were sensitized with ovalbumin (OVA) to induce asthma symptoms. The animals were allocated into five groups: control (C), asthmatic (A), A + NOE (500 mg/kg), NOE (500 mg/kg), and A + dexamethasone (DX, 2.5 mg/kg). After 7 days, blood and tissue samples were taken from the rats. Then, the level of inflammatory markers, oxidative stress parameters, and antioxidant enzymes activity were measured.

Results: The obtained results showed that OVA-sensitive rats significantly increased the levels of pro-inflammatory cytokines IL-1B, TGF-β, and SMA-α compared to the control group (p < 0.05), while treatment with NOE remarkably reduced the SMA-α gene expression compared to the asthma group (p < 0.05). Furthermore, it decreased the expression of IL-1B and TNF-α genes, although it was not statistically significant. The level of glutathione peroxidase (GPX) significantly reduced in A group compared to the C group (p < 0.05), whereas NOE administration significantly increased this marker (p < 0.05). Moreover, NOE attenuated inflammation and alveolar injury in the lungs of OVA-sensitive rat compared to the nontreated A group.

Conclusions: Overall, our findings demonstrated that NOE somewhat is able to reduce airway inflammation by reducing inflammatory and increasing GPX activity. Indeed, further experiments investigating the impact of different extract doses are needed to confirm the antioxidant and anti-inflammatory effects of NOE.

Figure 1

The effect of NOE on serum oxidative stress markers in OVA-induced rats. FRAP: ferric reducing antioxidant power; TSH: total thiol group; MDA: malondialdehyde; C: control; A: asthma; NOE: 500 mg hydroalcoholic extract of Nasturtium officinale; DTX: 2.5 mg dexamethasone. Data are expressed as mean ± SEM; ^∗significant difference compared to the C group. #significant difference compared to the A group (p < 0.05).

Figure 2

The effect of NOE on the FRAP (a) and nitric oxide metabolite (b) levels in the bronchoalveolar lavage fluid (BALF) in OVA-induced rats. FRAP: ferric reducing antioxidant power; NO metabolite: nitric oxide metabolite; C control; A asthma; NOE: 500 mg hydroalcoholic extract of Nasturtium officinale; DTX: 2.5 mg dexamethasone. Data are expressed as mean ± SEM; ^∗significant difference compared to the C group (p < 0.05), ^#significant difference compared to the A group (p < 0.05).

Figure 3

The effect of NOE on the antioxidant enzymes activity of SOD (a) and GPX (b) in the lung tissue in ovalbumin-induced rats. SOD: superoxide dismutase; GPX: glutathione peroxidase. C: control; A: asthma; NOE: 500 mg hydroalcoholic extract of Nasturtium officinale; DTX: 2.5 mg dexamethasone. Data are expressed as mean ± SEM; ^∗significant difference compared to the C group (p < 0.05), ^#significant difference compared to the A group (p < 0.05).

Figure 4

The effect of NOE on the mRNA levels of TNF-α, IL-1, TGF-β, and α-SMA in ovalbumin-induced asthmatic rats. Data are expressed as mean ± SEM; ^∗significant difference compared to the C group (p < 0.05), ^#significant difference compared to the A group (p < 0.05). C: control; A: asthma; NOE: 500 mg hydroalcoholic extract of Nasturtium officinale; DTX: 2.5 mg dexamethasone.

Figure 5

The effects of NOE on histopathological changes in a rat model of OVA-induced asthma. (a) Photomicrograph of the lung stained with haematoxylin and eosin (10x); (a): control; (b) asthma; (c) control group treated with 500 mg/kg of NOE; (d) asthmatic group treated with 2.5 mg/kg of dexamethasone; (e) asthmatic group treated with 500 mg/kg of NOE.