image_1_Innate Immunity Induced by the Major Allergen Alt a 1 From the Fungus Alternaria Is Dependent Upon Toll-Like Receptors 2/4 in Human Lung Epithelial Cells.jpeg

<p>Allergens are molecules that elicit a hypersensitive inflammatory response in sensitized individuals and are derived from a variety of sources. Alt a 1 is the most clinically important secreted allergen of the ubiquitous fungus, Alternaria. It has been shown to be a major allergen causing IgE-mediated allergic response in the vast majority of Alternaria-sensitized individuals. However, no studies have been conducted in regards to the innate immune eliciting activities of this clinically relevant protein. In this study, recombinant Alt a 1 was produced, purified, labeled, and incubated with BEAS-2B, NHBE, and DHBE human lung epithelial cells. Alt a 1 elicited strong induction of IL-8, MCP-1, and Gro-a/b/g. Using gene-specific siRNAs, blocking antibodies, and chemical inhibitors such as LPS-RS, it was determined that Alt a 1-induced immune responses were dependent upon toll-like receptors (TLRs) 2 and 4, and the adaptor proteins MYD88 and TIRAP. Studies utilizing human embryonic kidney cells engineered to express single receptors on the cell surface such as TLRs, further confirmed that Alt a 1-induced innate immunity is dependent upon TLR4 and to a lesser extent TLR2.</p

image_2_Innate Immunity Induced by the Major Allergen Alt a 1 From the Fungus Alternaria Is Dependent Upon Toll-Like Receptors 2/4 in Human Lung Epithelial Cells.jpeg

<p>Allergens are molecules that elicit a hypersensitive inflammatory response in sensitized individuals and are derived from a variety of sources. Alt a 1 is the most clinically important secreted allergen of the ubiquitous fungus, Alternaria. It has been shown to be a major allergen causing IgE-mediated allergic response in the vast majority of Alternaria-sensitized individuals. However, no studies have been conducted in regards to the innate immune eliciting activities of this clinically relevant protein. In this study, recombinant Alt a 1 was produced, purified, labeled, and incubated with BEAS-2B, NHBE, and DHBE human lung epithelial cells. Alt a 1 elicited strong induction of IL-8, MCP-1, and Gro-a/b/g. Using gene-specific siRNAs, blocking antibodies, and chemical inhibitors such as LPS-RS, it was determined that Alt a 1-induced immune responses were dependent upon toll-like receptors (TLRs) 2 and 4, and the adaptor proteins MYD88 and TIRAP. Studies utilizing human embryonic kidney cells engineered to express single receptors on the cell surface such as TLRs, further confirmed that Alt a 1-induced innate immunity is dependent upon TLR4 and to a lesser extent TLR2.</p

Binding of eleostearic acid (ESA) with cNLRX1 wildtype and mutant.

<p>A) Chemical structure of ESA. B) Interactions between ESA and NLRX1 predicted by molecular docking. ESA is in green ball-and-stick representation surrounded by molecular surface of the binding site with coloring by element. The free energy of binding is -6.2 kcal/mol. C) SPR sensograms for the binding of varying concentrations of ESA (40.0, 20.0, 10.0, 5.0, 2.5, 1.25 and 0.0 μM) to immobilized cNLRX1 (WT) and ASP677, PHE680, PHE681, and GLU684 to alanine mutant (Mutant). The equilibrium constant of dissociation, K_D, of ESA is 1.33 × 10⁻⁵ M for WT and 1.70 × 10⁻⁴ M for Mutant. D) Strength of association plot showing maximum response units for captured cNLRX1 WT or Mutant for a given concentration of ESA.</p

Binding of punicic acid (PUA) with cNLRX1 wildtype and mutant.

<p>A) Chemical structure of PUA. B) Interactions between PUA and cNLRX1 predicted by molecular docking. PUA is in cyan ball-and-stick representation surrounded by molecular surface of the binding site with coloring by element. The free energy of binding is -6.2 kcal/mol. C) SPR sensograms for the binding of varying concentrations of PUA (40.0, 20.0, 10.0, 5.0, 2.5, 1.25 and 0.0 μM) to immobilized cNLRX1 wildtype (WT) and ASP677, PHE680, PHE681, and GLU684 to alanine mutant (Mutant). The equilibrium constant of dissociation, K_D, of PUA is 1.46 × 10⁻⁵ M for WT and 3.38 × 10⁻⁴ M for Mutant. D) Strength of association plot showing maximum response units for captured cNLRX1 WT or Mutant for a given concentration of PUA</p

Effect of NLRX1 disruption on NF-κB activation in Bone marrow derived macrophage (BMDM).

<p>BMDMs were isolated from hind legs obtained fromm wild type and <i>Nlrx1-/-</i> in sterile conditions and cultured for 7 days After stimulated with LPS (1μg/ml) for 12 hours, cells were treated with control (medium), 40 μM PUA, and 40 μM DHA for 12 hours. Nuclear extraction was performed on colon homogenates using the Active Motif Nuclear Extraction Kit (Carlsbad, CA). ELISA was performed on both cytoplasmic and nuclear fractions using the Active Motif TransAM^® NF-κB p65 kit according to the manufacturer’s instructions. Letter superscripts indicate significant (P-value < 0.05) differences by ANOVA.</p

Expression of fatty acid metabolism related genes altered by absence of NLRX1.

<p>A) RNA-seq expression data was gathered after 7 day exposure to DSS in wild-type and <i>Nlrx1-/-</i> mice. Interactions of genes significantly altered in comparison of <i>Nlrx1-/-</i> treated with DSS to wild-type treated with DSS. Red indicates an up-regulation and green indicates a down-regulation. Image was generated using Ingenuity Pathway Analysis. B) Expression profile of genes encoding for enzymes and transporters in fatty acid metabolism pathways.</p

Effect of PUA on WT and <i>Nlrx1-/-</i> mice in DSS-induced colitis (10 mice per group).

<p>A) Average disease activity of treatment groups scored 0–4 daily for six days. B) mRNA expression of TNFα in whole colon on day six of DSS treatment. C) Histopathological assessment of colons by epithelial erosion (EE), leukocytic infiltration (LI), and mucosal thickening (MT). Asterisk indicates P-value < 0.05 by ANOVA.</p

Binding of docosahexaenoic acid (DHA) with cNLRX1 wildtype and mutant.

<p>A) Chemical structure of DHA. B) Interactions between DHA and cNLRX1 predicted by molecular docking. DHA is in orange ball-and-stick representation surrounded by molecular surface of the binding site with coloring by element. The free energy of binding is -8.0 kcal/mol. C) SPR sensograms for the binding of varying concentrations of DHA (100.0, 50.0, 25.0, 12.5, 6.23, and 3.125 μM) to immobilized cNLRX1 wild-type (WT) and ASP677, PHE680, PHE681, and GLU684 to alanine mutant (Mutant). The equilibrium constant of dissociation, KD, of DHA is 2.3 × 10–6 M for WT and 75.9 × 10–6 M for Mutant. D) Strength of association plot showing maximum response units for captured cNLRX1 WT or Mutant for a given concentration of DHA.</p