Varisco Lab

Congenital diaphragmatic hernia (CDH) occurs in 1:2000-1:3000 pregnancies. In severe CDH, translocation of abdominal organs into the chest cavity cause severe pulmonary hypoplasia and high rates of perinatal mortality with severe lung dysfunction in survivors. To treat this condition, an emerging surgical therapy involves the fetoscopic placement of an endotracheal occlusion device (FETO) which prevents egress of pulmonary fluid out of the trachea causing lung growth and improved lung size. Emerging data suggests that this therapy confers a survival benefit to treated infants. However, we have little understanding of how CDH and FETO alter the normal developmental trajectory and function of different lung cell lineages. By understanding the cell-specific changes that occur after FETO, we will better understand pulmonary structure-function relationships in this new population of patients and better tailor postnatal therapies to optimize lung function.

In collaboration with the Fetal Surgical center at Cincinnati Children’s Hospital, we have shown that:

• In a rabbit model, the whole lung gene signature of CDH lung is more similar to normal lung than either CDH/FETO or FETO lung
• CDH/FETO and FETO lung have a more immature gene expression profile than control or CDH lung
• Cell proliferation is increased in CDH/FETO and FETO with a greater increase in lung epithelial cell proliferation compared to non-epithelial
• These same findings are present in a novel mouse, transuterine model of fetal tracheal occlusion with data that the Yap and Akt signaling pathways play a key role
• Proteomic analysis of fetal sheep tracheal fluid validate upregulation in these pathways after FETO and suggest that FETO may also alter the status of Th17 and Th2 pathways.

Current questions we are investigating include:

• Is the immature gene expression profile of the lung after FETO cell-type specific?
• Can cells-specific changes after FETO be reversed by activation or inhibition of affected cell signaling pathways?
• Are there defects in lung development after FETO and if so, can they be reversed?

Relevant Publications

Varisco BM, Sbragia L, Chen J, Scorletti F, Joshi R, Wong HR, Lopes-Figueira R, Oria M, Peiro J. Excessive Reversal of Epidermal Growth Factor Receptor and Ephrin Signaling Following Tracheal Occlusion in Rabbit Model of Congenital Diaphragmatic Hernia. Mol Med. 2016 Jul 19;22.

Aydin E, Joshi R, Oria M, Varisco BM, Lim FY, Peiro JL. Fetal Tracheal Occlusion in Mice: An Novel Transuterine Approach. J of Surg Res. 2018.

The human lung continues to grow and develop postnatally with the formation of new alveolar septate to increase surface area and the remodeling of existing septae to improve the efficiency of gas exchange and increase lung compliance (i.e. reduce the work of breathing). We identified a novel protease, chymotrypsin-like elastase 1 (Cela1) which is expressed in the lung and plays a role in reducing postnatal lung compliance.

In collaboration with investigators from multiple different institutions, we have shown that:

• Cela1 is expressed in regions of lung elastin remodeling
• The lungs of Cela1-/- mice are stiffer and have smaller alveoli than those of wild type mice
• Cela1 degrades immature elastin and mature elastin without substantial specificity; however, elastin crosslinking domains inhibit its elastolytic activity in mature elastin
• Among three Cela isoforms (Cela1, Cela2, and Cela3), Cela1 is the only one universally present in placental mammals and both protein and promoter sequences are unique compared to mammalian Cela2 and Cela3 which are more similar to non-mammalian Cela isoforms suggesting that Cela1 plays a unique role in placental mammals

Current questions we are investigating include:

• What cell type is responsible for Cela1 remodeling activity?
• What are the transcriptional regulators of Cela1 activity?
• Can Cela1 activity be modulated to improve lung structure and function in bronchopulmonary dysplasia?

Relevant Publications

Joshi R, Heinz A, Fan Q, Guo S, Monia B, Schmelzer CEH, Weiss AS, Batie M, Parameshwaran H, Varisco BM. Role for Cela1 in Postnatal Lung Remodeling and AAT-deficient Emphysema. Am J Respir Cell Mol Biol. 2018 Feb 8.

Joshi R, Liu S, Brown MD, Young SM, Batie M, Kofron JM, Xu Y, Weaver TE, Apsley K, Varisco BM. Stretch regulates expression and binding of chymotrypsin-like elastase 1 in the postnatal lung. FASEB J. 2016 Feb;30(2):590-600.

Liu S, Young SM, Varisco BM. Dynamic Expression of Chymotrypsin Like Elastase-1 Over the Course of Lung Development. American Journal of Lung Cell and Molecular Physiology. 2014 Jun 15;306(12):L1104-16. PMID: 24793170

Alpha-1 antitrypsin (AAT)-deficient emphysema is a disease characterized by progressive airspace destruction that is often diagnosed in the 4th and 5th decades of life and is a leading indication for lung transplantation. AAT is an anti-protease which neutralizes different serine proteases such as neutrophil elastase, cathepsin G, and protease-3. Although these three proteases have all been implicated in AAT-deficient emphysema, neither specific inhibition strategies nor AAT replacement therapy have been shown to substantially alter disease course.

Chymotrypsin-like elastase 1 (Cela1) is a protease that is expressed in the lung in response to lung tissue stretch. Cela1 is covalently neutralized by α1-antytrypsin (AAT) in vitro and in vivo.

We have shown that:

• After knockdown of AAT in vivo, there is a corresponding reduction on the quantity of ~70kDa AAT-neutralized Cela1 in the lung
• AAT knockdown triggers emphysema development in mice from which Cela1-/- mice are completely protected
• Cela1 is increased in human AAT-deficient and AAT-sufficient emphysema

Current questions we are investigating include:

• What cells synthesize and secrete Cela1 in emphysema?
• Can inhibition of Cela1 prevent emphysema in AAT-deficiency?
• Is Cela1 important in AAT-sufficient emphysema?

Relevant Publications

Young SM, Liu S, Joshi R, Batie MR, Kofron M, Guo J, Woods JC, Varisco BM. Localization and stretch-dependence of lung elastase activity in development and compensatory growth. J Appl Physiol (1985). 2015 Apr 1;118(7):921-31. 

Joshi R, Heinz A, Fan Q, Guo S, Monia B, Schmelzer CEH, Weiss AS, Batie M, Parameshwaran H, Varisco BM. Role for Cela1 in Postnatal Lung Remodeling and AAT-deficient Emphysema. Am J Respir Cell Mol Biol. 2018 Feb 8.

Given the biology of Cela1 in lung development and its interaction with AAT, we seek to characterize the molecular biology of this interaction. Confounding this analysis is the fact that Cela1 is:

• While Cela1 mRNA-containing cells also contain Cela1 protein, there are also several strongly-protein positive but mRNA negative cells in the lung

Current questions we are investigating include:

• Does Cela1 interact with AAT at its reactive center loop as do other serine proteases? If so, at what specific amino acids?
• What cells take up the AAT-Cela1 neutralization product in the lung?

Relevant Publications

Joshi R, Heinz A, Fan Q, Guo S, Monia B, Schmelzer CEH, Weiss AS, Batie M, Parameshwaran H, Varisco BM. Role for Cela1 in Postnatal Lung Remodeling and AAT-deficient Emphysema. Am J Respir Cell Mol Biol. 2018 Feb 8.

Adolescent idiopathic scoliosis is a curvature of the spine that manifests after puberty and affects 1-2% of all adolescents. Ten percent of these patients will need surgical correction of the spinal defect. Scoliosis results in a concave and a convex lung, and although the impact of scoliosis on pulmonary function is debatable, patients report improvements in pulmonary status after spinal fusion.

In collaboration with the Center for Pulmonary Imaging Research and the Division of Orthopaedic Surgery at Cincinnati Children’s, we have used hyperpolarized helium MRI imaging to show that:

• The lungs of patients with scoliosis tend to have fewer and larger alveoli than control
• One year after posterior spinal fusion, the size of alveoli tends to decrease while in control subjects, it increases slightly; although, this change in size is not accompanied by a corresponding increase in alveolar number.

Current questions we are investigating include:

• Are the alveoli of patients with scoliosis consistently larger, or are there a subset of patients in which this is true?
• What are the characteristics of posterior spinal fusion patients that have a reduction in alveolar size and number that differentiate them from scoliosis patients that undergo posterior spinal fusion without this reduction in alveolar size?

Acute respiratory distress syndrome (ARDS) is a multifactorial condition that causes substantial morbidity and mortality in the pediatric intensive care unit (PICU). Often, the underlying cause of ARDS is unknown, and we possess at best modest prognostic tools. While many ARDS therapies show promise in small, single-center trials, most have failed when subjected to larger, multi-site trials. The premise of this project is that by using respiratory epithelial cell gene expression profiling, we can better identify ARDS endotypes which will improve diagnosis of underlying etiology and improve prognostication.

We have shown that:

• Respiratory epithelial cell RNA can be collected, stored, and processed with sufficient quality to permit gene expression analysis
• Bronchial epithelial cell RNA can be collected using a bronchoscopic brush and blind bronchial brushing.

Current questions we are investigating include:

• Can we detect a difference in gene expression profile in the bronchial epithelial cells of ARDS versus non-ARDS patients?
• If so, are there identifiable profiles with ARDS, and do they correlate with suspected etiology?
• Is there a gene expression profile that correlates with recovery or non-recovery from ARDS?
• Does nasal epithelial cell gene expression correlate with bronchial as it does in other respiratory diseases?