Atkins, H. M. | bioRxiv Science

bioRxiv2021

Disruption of the surfactant protein A receptor SP-R210L (CD245α/MYO18Aα) alters respiratory function and iron sequestration in alveolar macrophages of aged mice

Previous studies demonstrated that the host defense collectins, surfactant protein A and complement component 1q, modulate tissue-dependent macrophage activation, pathogen clearance, and regulatory macrophage functions through the receptor SP-R210, which consists of two isoforms SP-R210L and SP-R210S. These isoforms are encoded by alternatively spliced mRNAs of the Myo18a MYO18A gene in mice and humans. The present study in conditional transgenic mice revealed novel age-related functions of the SP-R210L isoform in modulating pulmonary mechanics, iron sequestration in alveolar macrophages (AMs), and life-long maintenance of the alveolar macrophage population. Our findings support the novel idea that SP-R210L-deficient AMs undergo bi-directional epigenetic adaptation that results in chronic dysregulation of broncho-alveolar function, immune homeostasis, and maintenance of oncotic balance at the airway-capillary interface. Disruption of SP-R210L increases the risk for development of severe interstitial lung disease during development and aging.

physiology↗

bioRxiv2021

Dynamic expression of smRNA from fecal exosome in disease progression of an inflammatory bowel disorder mouse model.

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract affecting over 3 million adults in the United States. Despite being widespread, reliable early diagnostic tests are not available. We examined exosomal small RNA (smRNA), specifically targeting microRNA (miRNA) and piRNA from the stool samples of IBD model mice, interleukin 10 knockout mice (IL-10 KO), as a potential diagnostic marker. Stool samples were specifically chosen because they are readily available, and collection is noninvasive. At the end of the experimental period, the gastrointestinal (GI) tract was collected, and disease severity was scored. Histopathology showed a significant increase in inflammation and proliferation within the proximal and distal large intestines. smRNA profiles were examined upon conventional housing (start-point) which is a determinant factor of spontaneous IBD progression in the IL-10 KO mice, terminal illness (end-point), and 6 weeks before the end-point (mid-point), when the mice were still phenotypically healthy. We found 504 smRNA that were significantly differentially expressed between before symptom onset and terminal sedation. These changes were not detected in wild-type samples. Moreover, clustering analysis of expression changes over the disease progression identified a unique set of smRNAs that primarily target pro-inflammatory or anti-inflammatory genes. The expression of smRNAs that suppresses pro-inflammatory genes was higher at 6 weeks before terminal sedation, suggesting the downregulation of the pro-inflammatory genes advances the terminal illness of the IBD. In summary, our study proposes that fecal exosomal smRNA profiling offers a new opportunity to monitor the inflammatory status of the gut with a capability of detecting its pro-inflammatory (asymptomatic) status. Our next step is to understand the spatiotemporal interplay of these exosomes and the host cells in the gut as well as the complete biochemical makeup of fecal exosomes, such as mRNA, DNA, protein, and lipids. This will lead to an exciting development of reengineered exosomes that can be utilized to treat or even prevent the pro-inflammatory colonic lesion while the host is still clinically asymptomatic.

genomics↗