Gene Expression Profile Reveals Hematopoietic-Related Molecule Changes in Response to Hypoxic Exposure

Transcriptomic evidence of erythropoietic adaptation from the International Space Station and from an Earth-based space analog

Space anemia affects astronauts and the underlying molecular alterations remain unknown. We evaluated the response of erythropoiesis-modulating genes to spaceflight through the analysis of leukocyte transcriptomes from astronauts during long-duration spaceflight and from an Earth model of microgravity. Differential expression analysis identified 50 genes encoding ribosomal proteins with reduced expression at the transition to bed rest and increased during the bed rest phase; a similar trend was observed in astronauts. Additional genes associated with anemia (15 genes), erythrocyte maturation (3 genes), and hemoglobin (6 genes) were down-regulated during bed rest and increased during reambulation. Transcript levels of the erythropoiesis transcription factor GATA1 and nine of most enriched erythrocyte proteins increased at reambulation after bed rest and at return to Earth from space. Dynamic changes of the leukocyte transcriptome composition while in microgravity and during reambulation supported an erythropoietic modulation accompanying the hemolysis of space anemia and of immobility-induced anemia.

Microarray-Based Prediction of Polycythemia after Exposure to High Altitudes

In high-altitude environments, the prevalence of high-altitude polycythemia (HAPC) ranges between 5 and 18 percent. However, there is currently no effective treatment for this condition. Therefore, disease prevention has emerged as a critical strategy against this disease. Here, we looked into the microarray profiles of GSE135109 and GSE29977, linked to either short- or long-term exposure to the Qinghai Tibet Plateau (QTP). The results revealed inhibition in the adaptive immune response during 30 days of exposure to QTP. Following a gene set enrichment analysis (GSEA) discovered that genes associated with HAPC were enriched in Cluster1, which showed a dramatic upregulation on the third day after arriving at the QTP. We then used GeneLogit to construct a logistic prediction model, which allowed us to identify 50 genes that classify HAPC patients. In these genes, LRRC18 and HCAR3 were also significantly altered following early QTP exposure, suggesting that they may serve as hub genes for HAPC development. The in-depth study of a combination of the datasets of transcriptomic changes during exposure to a high altitude and whether diseases occur after long-term exposure in Hans can give us some inspiration about genes associated with HAPC development during adaption to high altitudes.

Crosstalk between E-Cadherin/β-Catenin and NF-κB Signaling Pathways: The Regulation of Host-Pathogen Interaction during Leptospirosis

Approximately 1 million cases of leptospirosis, an emerging infectious zoonotic disease, are reported each year. Pathogenic Leptospira species express leucine-rich repeat (LRR) proteins that are rarely expressed in non-pathogenic Leptospira species. The LRR domain-containing protein family is vital for the virulence of pathogenic Leptospira species. In this study, the biological mechanisms of an essential LRR domain protein from pathogenic Leptospira were examined. The effects of Leptospira and recombinant LRR20 (rLRR20) on the expression levels of factors involved in signal transduction were examined using microarray, quantitative real-time polymerase chain reaction, and western blotting. The secreted biomarkers were measured using an enzyme-linked immunosorbent assay. rLRR20 colocalized with E-cadherin on the cell surface and activated the downstream transcription factor β-catenin, which subsequently promoted the expression of MMP7, a kidney injury biomarker. Additionally, MMP7 inhibitors were used to demonstrate that the secreted MMP7 degrades surface E-cadherin. This feedback inhibition mechanism downregulated surface E-cadherin expression and inhibited the colonization of Leptospira. The degradation of surface E-cadherin activated the NF-κB signal transduction pathway. Leptospirosis-associated acute kidney injury is associated with the secretion of NGAL, a downstream upregulated biomarker of the NF-κB signal transduction pathway. A working model was proposed to illustrate the crosstalk between E-cadherin/β-catenin and NF-κB signal transduction pathways during Leptospira infection. Thus, rLRR20 of Leptospira induces kidney injury in host cells and inhibits the adhesion and invasion of Leptospira through the upregulation of MMP7 and NGAL.