Repeated short-term intranasal instillation of lupus-prone mice with to crystalline silica (cSiO2) induces inflammatory gene expression and ectopic lymphoid neogenesis in the lung, leading to early onset of systemic autoimmunity and rapid progression to glomerulonephritis. These responses are suppressed by dietary supplementation with the ω-3 polyunsaturated fatty acid docosahexaenoic acid (DHA). Here, we tested the hypothesis that dietary DHA supplementation suppresses cSiO2-induced inflammatory proteins in bronchoalveolar alveolar lavage fluid (BALF) and plasma of lupus-prone mice. Archived tissue fluid samples were used from a prior investigation in which 6 wk-old lupus-prone female NZBWF1 mice were fed isocaloric diets containing 0 or 10 g/kg DHA for 2 wk and then intranasally instilled with 1 mg cSiO2 or vehicle once weekly for 4 wks. Cohorts were terminated at 1, 5, 9 or 13 wk post-instillation (PI). BALF and plasma from each cohort were analyzed by high density multiplex array profiling of 200 inflammatory proteins. cSiO2 time-dependently induced increases in the BALF protein signatures that were highly reflective of unresolved lung inflammation, although responses in the plasma were much less robust. Induced proteins in BALF included chemokines (e.g., MIP-2, MCP-5), enzymes (e.g., MMP-10, granzyme B), adhesion molecules (e.g., sE-selectin, sVCAM-1), co-stimulatory molecules (e.g., sCD40L, sCD48), TNF superfamily proteins (e.g., sTNFRI, sBAFF-R), growth factors (e.g., IGF-1, IGFBP-3), and signal transduction proteins (e.g., MFG-E8, FcgRIIB) - many of which were blocked or delayed by DHA supplementation. The BALF inflammatory proteome correlated positively with prior measurements of gene expression, pulmonary ectopic lymphoid neogenesis, and induction of autoantibodies in the lungs of the control and treatment groups. Ingenuity Pathway Analysis (IPA) revealed that IL-1β, TNF-α, and IL-6 were among the top upstream regulators of the cSiO2- induced protein response. Furthermore, DHA’s effects were associated with downregulation of cSiO2- induced pathways involving i) ARE-mediated mRNA decay, ii) bacterial and viral pattern recognition receptor activation, or iii) TREM1, STAT3, NF-κB, and VEGF signaling and upregulation of PPAR, LXR/RXR and PPARα/RXRα signaling. Taken together, these preclinical findings further support the contention that dietary DHA supplementation could be applicable as an intervention against inflammation-driven autoimmune triggering by cSiO2 or potentially other environmental agents.
Author ORCID Identifier
James Pestka https://orcid.org/0000-0003-4689-2756
Lichchavi D. Rajasinghe https://orcid.org/0000-0002-5136-7422
Abby D. Benninghoff https://orcid.org/0000-0002-7993-0117
Lupus Foundation of America;
USDA, National Institute of Food and Agriculture (NIFA)
Utah State University
NIH ES027353 Lupus Foundation of America; USDA, National Institute of Food and Agriculture (NIFA) 1020129
Dietary Lipids and Silica-Triggered Autoimmunity.
Mouse bronchoalveolar lavage fluid and plasma samples were collected as described in a prior publication (Bates, et al. 2019 Front Immunol. DOI: 10.3389/fimmu.2018.02002) and processed to determine protein expression using the Quantibody Array Q40000 (catalog QAM-CAA-4000, RayBiotech, Norcross, GA) per manufactureÕs protocol. A GenePix 4000B Microarray Scanner (Molecular Devices, Sunnyvale, CA) was used for fluorescent image acquisition. Resultant images were then digitized using GenePix software (Molecular Devices). Fluorescent intensities were acquired in quadruplicate for each sample and readings averaged to obtain mean fluorescence intensity (MFI). Signal-to-noise ratios (SNRs) were determined by comparing MFI to background signal for a specified analyte. SNRs greater than 2.0 were deemed positive for analyte signal above background.
BALF, bronchoalveolar lavage fluid
DHA, docosahexaenoic acid
cSiO2, crystalized silica dioxide
VEH, vehicle treatment
CON, control treatment
MFI, mean fluorescence intensity
SNR, signal-to-noise ratio
This work is licensed under a Creative Commons Attribution 4.0 License.
Pestka, J., Rajasinghe, L., & Benninghoff, A. (2021). Data for: Silica Induction of Diverse Inflammatory Proteome in Lungs of Lupus-prone Mice Quelled by Dietary Docosahexaenoic Acid Supplementation [Data set]. Utah State University. https://doi.org/10.26078/W1G0-KB31
Available for download on Wednesday, January 05, 2022