Lactobacillus paracasei ATG-E1 improves particulate matter 10 plus diesel exhaust particles (PM10D)-induced airway inflammation by regulating immune responses

Abstract

Particulate matter (PM) exposure can adversely affect respiratory function. Probiotics can alleviate the inflammatory responses in respiratory diseases. We examined the protective effects of Lactobacillus paracasei ATG-E1 isolated from the feces of a newborn baby against airway inflammation in a PM₁₀ plus diesel exhaust particle (DEP) (PM₁₀D)-induced airway inflammation model. BALB/c mice were exposed to PM₁₀D by intranasal injection three times at 3-day intervals for 12 days, and L. paracasei ATG-E1 was administered orally for 12 days. Analysis of immune cell population and expression of various inflammatory mediators and gut barrier-related genes were determined in bronchoalveolar lavage fluid (BALF), lung, peyer's patch, and small intestine. A histological analysis of the lungs was performed. In addition, the in vitro safety and their safety in genomic analyses were examined. L. paracasei ATG-E1 was found to be safe in vitro and by genomic analysis. L. paracasei ATG-E1 suppressed neutrophil infiltration and the number of CD4⁺, CD4⁺CD69⁺, CD62L^-CD44^+high, CD21/35⁺B220⁺, and Gr-1⁺CD11b⁺ cells, as well as the expression of inflammatory mediators, including chemokine (C-X-C motif) ligand (CXCL)-1, macrophage inflammatory protein (MIP)-2, interleukin (IL)-17a, tumor necrosis factor (TNF)-α, and IL-6 in BALF and lungs in PM₁₀D-induced airway inflammation. It protected against histopathological damage in the lungs of mice with PM₁₀D-induced airway inflammation. L. paracasei ATG-E1 concomitantly increased the expression levels of the gut barrier function-related genes occludin, claudin-1, and IL-10 in the small intestine, with an increased number of CD4⁺ and CD4⁺CD25⁺ immune cells in the peyer's patch. L. paracasei ATG-E1 suppressed immune activation and airway inflammatory responses in the airways and lungs by restoring the lung damage by PM₁₀D. It also regulated intestinal immunity and ameliorated the gut barrier function in the ileum. These results indicate the potential of L. paracasei ATG-E1 as an protective and therapeutic agent against airway inflammation and respiratory diseases.

Keywords: Lactobacillus paracasei; airway inflammation; diesel exhaust particles; particulate matter; probiotics.

FIGURE 1

Circular genome map of L. paracasei ATG-E1.

FIGURE 2

Effects of L. paracasei ATG-E1 on cell numbers in a PM₁₀D-induced airway inflammation animal. Total number of (A) lung cells, (B) BALF cells, (C) neutrophil number in BALF cytospins, and (D) photomicrograph of BALF cytospins. The data are presented as means ± SEM (n = 8). Blue arrow represents the neutrophils. ^#p < 0.05 and ^###p < 0.005 vs. NC; **p < 0.01 and ***p < 0.005 vs. CTL. NC: normal mice; CTL: PM₁₀D-sensitized control mice; Dexa: 3 mg/kg dexamethasone-treated PM₁₀D-sensitized mice; ATG-E1: 4 × 10⁹ CFU/day of L. paracasei ATG-E1-treated PM₁₀D-sensitized mice.

FIGURE 3

Effects of L. paracasei ATG-E1 on histological analysis in a PM₁₀D-induced airway inflammation animal. (A) H&E, MT, and PAS staining of lung tissues and (B) quantitative analyses of the degree of lung tissue damage. The data are presented as means ± SEM (n = 8). ^###p < 0.001 vs. NC; ***p < 0.005 vs. CTL. NC: normal mice; CTL: PM₁₀D-sensitized control mice; Dexa: 3 mg/kg dexamethasone-treated PM₁₀D-sensitized mice; ATG-E1: 4 × 10⁹ CFU/day of L. paracasei ATG-E1-treated PM₁₀D-sensitized mice.

FIGURE 4

Effects of L. paracasei ATG-E1 on proinflammatory mediators in BALF and lung of a PM₁₀D-induced airway inflammation animal. (A) CXCL-1, (B) MIP-2, (C) IL-17a, and (D) TNF-α levels in the BALF. (E) CXCL-1, (F) MIP-2, (G) IL-6, and (H) TNF-α gene expression levels in the lung. The data are presented as means ± SEM (n = 8). ^#p < 0.05, ^##p < 0.01, and ^###p < 0.005 vs. NC; *p < 0.05, **p < 0.01 and ***p < 0.005 vs. CTL. NC: normal mice; CTL: PM₁₀D-sensitized control mice; Dexa: 3 mg/kg dexamethasone-treated PM₁₀D-sensitized mice; ATG-E1: 4 × 10⁹ CFU/day of L. paracasei ATG-E1-treated PM₁₀D-sensitized mice.

FIGURE 5

Effects of L. paracasei ATG-E1 on immune cell numbers and cytokine expression levels in the peyer’s patch and the ileum of a PM₁₀D-induced airway inflammation animal. (A) CD4⁺, (B) CD4⁺CD69⁺, (C) B220⁺CD69⁺, and (D) CD11c⁺CD69⁺ absolute cell numbers in peyer’s patch. (E) TNF-α, and (F) IL-10 mRNA expression levels in the ileum. The data are presented as means ± SEM (n = 8). ^##p < 0.01 and ^###p < 0.05 vs. NC; *p < 0.05 and **p < 0.01 vs. CTL. NC: normal mice; CTL: PM₁₀D-sensitized control mice; Dexa: 3 mg/kg dexamethasone-treated PM₁₀D-sensitized mice; ATG-E1: 4 × 10⁹ CFU/day of L. paracasei ATG-E1-treated PM₁₀D-sensitized mice.

FIGURE 6

Effects of L. paracasei ATG-E1 on the expression of tight junction-related genes in the ileum of a PM₁₀D-induced airway inflammation animal. (A) Occludin, (B) claudin-1, and (C) ZO-1 mRNA expression levels in the ileum. The data are presented as means ± SEM (n = 8). ^##p < 0.01 vs. NC; *p < 0.05 vs. CTL. NC: normal mice; CTL: PM₁₀D-sensitized control mice; Dexa: 3 mg/kg dexamethasone-treated PM₁₀D-sensitized mice; ATG-E1: 4 × 10⁹ CFU/day of L. paracasei ATG-E1-treated PM₁₀D-sensitized mice.