Genome Wide Expression Analysis Suggests Perturbation of Vascular Homeostasis during High Altitude Pulmonary Edema

<div><p>Background</p><p>High altitude pulmonary edema (HAPE) is a life-threatening form of non-cardiogenic edema which occurs in unacclimatized but otherwise normal individuals within two to four days after rapid ascent to altitude beyond 3000 m. The precise pathoetiology and inciting mechanisms regulating HAPE remain unclear.</p><p>Methodology/Principle findings</p><p>We performed global gene expression profiling in individuals with established HAPE compared to acclimatized individuals. Our data suggests concurrent modulation of multiple pathways which regulate vascular homeostasis and consequently lung fluid dynamics. These pathways included those which regulate vasoconstriction through smooth muscle contraction, cellular actin cytoskeleton rearrangements and endothelial permeability/dysfunction. Some notable genes within these pathways included <i>MYLK</i>; rho family members <i>ARGEF11</i>, <i>ARHGAP24</i>; cell adhesion molecules such as <i>CLDN6</i>, <i>CLDN23</i>, <i>PXN</i> and <i>VCAM1</i> besides other signaling intermediates. Further, several important regulators of systemic/pulmonary hypertension including <i>ADRA1D, ECE1,</i> and <i>EDNRA</i> were upregulated in HAPE. We also observed significant upregulation of genes involved in paracrine signaling through chemokines and lymphocyte activation pathways during HAPE represented by transcripts of <i>TNF</i>, <i>JAK2, MAP2K2, MAP2K7, MAPK10</i>, <i>PLCB1</i>, <i>ARAF</i>, <i>SOS1</i>, <i>PAK3</i> and <i>RELA</i> amongst others. Perturbation of such pathways can potentially skew vascular homeostatic equilibrium towards altered vascular permeability. Additionally, differential regulation of hypoxia-sensing, hypoxia-response and OXPHOS pathway genes in individuals with HAPE were also observed.</p><p>Conclusions/Significance</p><p>Our data reveals specific components of the complex molecular circuitry underlying HAPE. We show concurrent perturbation of multiple pathways regulating vascular homeostasis and suggest multi-genic nature of regulation of HAPE.</p></div

Work flow of gene expression analysis.

<p>The figure represents scheme of extraction of differentially expressed genes (up regulated: 420, down regulated: 308) from the raw microarray data.</p

KEGG Pathway-specific gene transcripts in HAPE data set (Extracted from DAVID Bioinformatics Resource).

<p>List of key KEGG Pathways extracted from differentially expressed genes utilizing DAVID Bioinformatic Resource. Specific pathways are arranged in order of their p-value. Gene names and Fold changes for individual genes were added from the original data set.</p

Schematic representation of possible events occurring during HAPE.

<p>The pathways suggested by the current data set have been integrated with established phenomenon such as pulmonary vasoconstriction, elevated pulmonary artery pressure which are known to precede HAPE. Perturbation of pathways such as those regulating vasoconstriction, inflammation, gap junctions and adhesion molecules can dysregulate vascular homeostasis leading to fluid leak and edema formation.</p

Clustering of GO terms related to biological processes.

<p>GO terms were clustered utilizing software BINGO and individual clusters indicated as shown in the figure.</p

Comparison of relative expression (log2 values) of selected genes obtained by microarray and real time PCR experiments (TLDA).

<p>17 out of 20 genes show similarity of trend on both the platforms.</p

Hierarchical clustering of gene expression data obtained from acclimatized controls (CN) and HAPE (PE) individuals.

<p>Hierarchical clustering distinctly separated the two groups of individuals (CN and PE) indicating unique gene expression signatures. Expression values of specific genes are represented by color intensities shown in the reference color key.</p

Photobiomodulation with Pulsed and Continuous Wave Near-Infrared Laser (810 nm, Al-Ga-As) Augments Dermal Wound Healing in Immunosuppressed Rats

<div><p>Chronic non-healing cutaneous wounds are often vulnerable in one or more repair phases that prevent normal healing and pose challenges to the use of conventional wound care modalities. In immunosuppressed subject, the sequential stages of healing get hampered, which may be the consequences of dysregulated or stagnant wound inflammation. Photobiomodulation (PBM) or low-level laser (light) therapy (LLLT) emerges as a promising drug-free, non-invasive biophysical approach for promoting wound healing, reduction of inflammation, pain and restoration of functions. The present study was therefore undertaken to evaluate the photobiomodulatory effects of 810 nm diode laser (40 mW/cm²; 22.6 J/cm²) with pulsed (10 and 100 Hz, 50% duty cycle) and continuous wave on full-thickness excision-type dermal wound healing in hydrocortisone-induced immunosuppressed rats. Results clearly delineated that 810 nm PBM at 10 Hz was more effective over continuous and 100 Hz frequency in accelerating wound healing by attenuating the pro-inflammatory markers (NF-kB, TNF-α), augmenting wound contraction (α-SM actin), enhancing cellular proliferation, ECM deposition, neovascularization (HIF-1α, VEGF), re-epithelialization along with up-regulated protein expression of FGFR-1, Fibronectin, HSP-90 and TGF-β2 as compared to the non-irradiated controls. Additionally, 810 nm laser irradiation significantly increased CCO activity and cellular ATP contents. Overall, the findings from this study might broaden the current biological mechanism that could be responsible for photobiomodulatory effect mediated through pulsed NIR 810 nm laser (10 Hz) for promoting dermal wound healing in immunosuppressed subjects.</p></div

Protein expression of MMP-2 and 9 by gelatin zymography in 810 nm laser irradiated and non-irradiated control wound tissues after 7 days post-wounding.

<p>Densitometric analysis using Fiji software. Change in expression expressed as net intensity (% control). Values are mean ± SEM, n = 6 animals per group. *<i>p</i> < 0.05 compared to the non-irradiated control.</p

Effect of 810 nm laser on wound contraction rate (% change) in immunosuppressed rats.

<p>At days 4 through 8, the 810 nm LLLT (40 mw/ cm², 22.6 J/ cm²) 10 Hz group shows a smaller wound area than CW and 100 Hz groups compared to the control. Values are mean ± SEM, n = 6 animals per group. *<i>p</i> < 0.05 compared to the non-irradiated control.</p