What we study
The Acute Respiratory Distress Syndrome (ARDS) is life-threatening and common among patients in the intensive care unit (ICU).
ARDS is common and deadly. At present, there are no targeted therapies for ARDS. Using modern techniques in molecular and cellular biology, biochemistry, and bioinformatics, we explore molecular mechanisms that govern lung injury and repair to discover novel biomarkers and therapeutic targets to help patients with critical illness.
Bednash laboratory currently focuses on the role of transfer RNAs (tRNAs) in ARDS and critical illness, which has not been previously explored. Our group employs a bedside to bench approach, meaning that we use cellular and animal models to better understand what we observe in patients with critical illness. As our research progresses, we aspire to develop diagnostic tests and novel targeted therapies for ARDS. Our research approach focuses on three pillars:
1. Leveraging human biospecimens to understand critical illness.
2. Employing modern techniques in molecular and cellular biology and biochemistry to explore mechanisms of disease.
3. Using pre-clinical models of ARDS, including genetically modified mice and human ex vivo lung samples.
The Ohio State University ICU Registry and Prospective Cohort Study (BuckICU)
BuckICU was started in 2020 by Dr. Bednash and colleagues in the pulmonary and critical care division at Ohio State. Dr. Bednash serves as the principal investigator (PI) of BuckICU, which has enrolled over 280 subjects with >12,000 samples banked. BuckICU was designed to support high throughput molecular profiling, such as RNA sequencing, proteomics, and small RNA profiling. Using banked samples from BuckICU, our group is characterizing the abundance of specific tRNAs and tRNA-derived small RNAs during critical illness.
– BuckICU is a single center, biorepository project that collects clinical data and biological samples from adult hospitalized patients with acute respiratory failure, suspicion of sepsis, or both.
– We collect longitudinal peripheral blood samples and urine on days 1, 3, 7, 10, and 21 of enrollment. An oral swab and excess respiratory samples are also collected during the study.
– Clinical and laboratory data are collected throughout the study protocol.
– Investigators may request biospecimens and clinical data to support their research.
The role of transfer RNAs in acute respiratory distress syndrome
Classically considered passive mRNA translators, tRNAs are now recognized as signaling molecules in many diseases, but their role in critical illness has not been described. tRNAs are small RNA species (~80 base pairs) that make up 10 – 15% of all cellular RNA. tRNAs are post-transcriptionally modified by methylation. During cellular stress, they may be cleaved by endonucleases to form biologically-active tRNA-dervied small RNAs that function like microRNAs.
We use a number of modern and classic molecular biology approaches to investigate tRNAs and tRNA-derived small RNAs in models of lung injury, ARDS, and critical illness. Active areas of investigation include:
– Profiling tRNAs and tRNA-derived small RNAs from BuckICU human samples, using a hybridization-based microarray.
– Characterizing the source of tRNA-derived small RNAs using multiple animal models of lung injury.
– Determining the function of tRNA-derived small RNAs with synthesized oligonucleotides that function as mimics and inhibitors.
– CRISPR / Cas9 editing of tRNA methylation sites to generate methylation deficient mutants.
Animal models of lung injury
ARDS is a complex disease that ultimately results in hypoxemic respiratory failure. The pathophysiology of ARDS encompasses multiple cell types within the lung and cytokine signaling during ARDS extends beyond the lung.
We use multiple models of experimental lung injury in mice to understand the impact of specific genetic modifications and interventions on lung injury. We currently have TRMT1 and RNase6 transgenic mice for use in our lung injury models. We also use ex vivo human lung tissue for translational of our experimental findings. Examples of pre-clinical models include:
– Sterile lung injury in mice, hydrogen peroxide, hyperoxia, and Toll-like receptor (TLR) ligands (LPS and Pam3CSK4).
– Bacterial infection as a direct lung insult, including Pseudomonas aeruginosa, Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae.
– Viral infection leading to ARDS, such as Influenza A and SARS-CoV-2.
– Transgenic mice colonies, include TRMT1 and RNase6.
– Intratracheal instillation of small RNA mimics and inhibitors.