Ameliorative impact of sacubitril/valsartan on paraquat-induced acute lung injury: role of Nrf2 and TLR4/NF-κB signaling pathway

Abstract

Herbicides such as paraquat (PQ) are frequently utilized particularly in developing nations. The present research concentrated on the pulmonary lesions triggered by PQ and the beneficial effect of the angiotensin receptor neprilysin inhibitor (ARNI), sacubitril/valsartan, against such pulmonary damage. Five groups of rats were established: control, ARNI, PQ (10 mg/kg), ARNI 68 + PQ, and ARNI 34 + PQ. Following euthanasia, lungs were isolated and subjected to a histopathological test, and the ELISA technique was used to evaluate oxidative stress biomarkers, toll-like receptor 4 (TLR4), nuclear factor erythroid 2-related factor 2 (Nrf2), phosphatidylinositol-3-kinase (PI3K), phosphorylated protein kinase B (p-AKT), and inflammatory markers: nuclear factor kappa B p65 subunit (NF-κB p65), tumor necrosis factor α (TNFα), and interleukin 1beta (IL-1β). In conjunction with abnormally high levels of malondialdehyde (MDA) and inducible nitric oxide synthase (iNOS), the PQ group also displayed low levels of reduced glutathione (GSH) and total antioxidant capacity (TAC). Additionally, TLR4, PI3K, and p-AKT were significantly elevated together with unusually low level of Nrf2. Moreover, inflammatory biomarkers, NF-κB p65, TNFα, and IL-1β, were abnormally elevated. Meanwhile, ARNI-treated groups reversed all alterations precipitated by PQ in a dose-dependent manner. ARNI could mitigate pulmonary damage triggered by PQ via potential antioxidant anti-inflammatory qualities.

Keywords: ARNI; NF-κB; Nrf2; PQ; TLR4.

Fig. 1

Impact of ARNI on histopathological alterations in pulmonary tissues of PQ-injected rats using H&E stain (low magnifications: X: 100 and high magnifications X: 400). A, B Pulmonary tissues of control and ARNI groups showed a normal histological appearance of lung alveoli and interalveolar septa. C Pulmonary tissues of PQ group showed mild expansion of interalveolar septa by numerous coalescing aggregations of mononuclear cells and numerous aggregations of lymphocytes, macrophages, fibroblast, and admixed with RBcs expanded the interalveolar septa (thin arrow). D Pulmonary tissues of (ARNI 34 + PQ) showed few alveolar damage with moderate expansion of interalveolar septa (thin arrow). E Pulmonary tissues of (ARNI 68 + PQ) showed minimal interalveolar septa thickening (thin arrow). E, F, G Semi-quantitative scoring of intra-alveolar thickening, bronchiolar damage, and inflammation respectively. PQ, paraquat; ARNI, angiotensin receptor neprilysin inhibitor. Data are expressed as median ± interquartile range (n = 6). ^&(p < 0.05) vs. control group using Kruskal Wallis test followed by Dunn’s multiple comparison post hoc test

Fig. 2

Impact of ARNI on altered oxidant/antioxidant balance in pulmonary tissues of PQ-injected rats. A Pulmonary reduced glutathione (GSH). B Pulmonary total antioxidant capacity (TAC). C Pulmonary malondialdehyde (MDA). D Pulmonary inducible nitric oxide synthase (iNOS). PQ, paraquat; ARNI, angiotensin receptor neprilysin inhibitor. The data are expressed as mean ± SD (n = 6). ^{&, @, %}(p < 0.05) vs. control, PQ, and (ARNI 34 + PQ) groups, respectively, using one-way ANOVA followed by Tukey-Kramer multiple comparisons test

Fig. 3

Impact of ARNI on pulmonary Nrf2 and TLR4 of PQ-injected rats. A Pulmonary nuclear factor erythroid 2–related factor 2 (Nrf2). B Pulmonary toll-like receptor 4 (TLR4). PQ, paraquat; ARNI, angiotensin receptor neprilysin inhibitor. The data are expressed as mean ± SD (n = 6). ^{&, @, %}(p < 0.05) vs. control, PQ, and (ARNI 34 + PQ) groups, respectively, using one-way ANOVA followed by Tukey-Kramer multiple comparisons test

Fig. 4

Impact of ARNI on pulmonary PI3K and p-AKT of PQ-injected rats. A Pulmonary phosphatidylinositol-3-kinase (PI3K). B Pulmonary phosphorylated protein kinase B (p-AKT). PQ, paraquat; ARNI, angiotensin receptor neprilysin inhibitor. The data are expressed as mean ± SD (n = 6). ^{&, @, %}(p < 0.05) vs. control, PQ, and (ARNI 34 + PQ) groups, respectively, using one-way ANOVA followed by Tukey-Kramer multiple comparisons test

Fig. 5

Impact of ARNI on inflammatory biomarkers in pulmonary tissues of PQ-injected rats. A Pulmonary nuclear factor kappa B p65 Phospho-Ser536 subunit (NF-κB p65 (P-Ser536)). B Pulmonary tumor necrosis factor α (TNFα). C Pulmonary interleukin 1beta (IL-1β). The data are expressed as mean ± SD (n = 6). PQ, paraquat; ARNI, angiotensin receptor neprilysin inhibitor. ^{@, &, %}(p < 0.05) vs. control, PQ, and (ARNI 34 + PQ) groups, respectively, using one-way ANOVA followed by Tukey-Kramer multiple comparisons test

Fig. 6

Schematic diagram of potential mechanisms by which ARNI may attenuate pulmonary injury precipitated by PQ. PQ, paraquat; ARNI, angiotensin receptor neprilysin inhibitor; ROS, reactive oxygen species; iNOS, inducible nitric oxide synthase; MDA, malondialdehyde; GSH, reduced glutathione; TAC, total antioxidant capacity; IL-1β, interleukin 1beta; TNFα, tumor necrosis factor α; NF-κB, nuclear factor kappa B; TLR4, toll-like receptor 4; PI3K, phosphatidylinositol-3-kinase; p-AKT, phosphorylated protein kinase B; Nrf2, nuclear factor erythroid 2–related factor 2