James D. Zieske, Ph.D.

Harvard Medical School

Associate Professor of Ophthalmology

Schepens Eye Research Institute of Massachusetts Eye and Ear

Senior Scientist

Research Summary

Center/Research Area Affiliations

Biography

Dr. Zieske is interested in understanding the mechanisms involved in corneal wound repair. The corneal epithelium is the outermost layer of the eye and is seven cell layers thick. It is considered the first line of defense against foreign materials and therefore, must heal quickly in order to prevent the entry of foreign materials. Currently, his laboratory is investigating how the stroma and epithelium interact during corneal fibrosis and regeneration. He has found that expression of integrin avb6 in the epithelium after wounding appears to play a major role in directing the fibrotic response in the cornea. The current focus of his laboratory is the role of exosomes on cell-cell communication and the stimulation of fibrosis.

Download his CV or biosketch [PDF] for more information.

Education

Ph.D., Biological Chemistry, University of Michigan (1981)

Postgraduate Training

Research Fellowship, Cell Surface Glycoproteins and Epidermal Differentiation, University of Michigan (1981-1982)
Research Fellowship, Cell Surface Proteins in Corneal Epithelium, Schepens Eye Research Institute of Mass. Eye and Ear (1982-1984)

His Story

With continuous support from the National Eye Institute since 1984, Dr. James Zieske’s research aims to better understand the mechanisms involved in corneal wound repair. To date, his laboratory has published more than 90 peer-reviewed articles in this area.

The Zieske laboratory is currently investigating how the stroma and epithelium interact during corneal fibrosis and regeneration. Fibrosis, or scarring, is an evolutionarily developed method to rapidly close and repair a wound. Excessive deposition of extracellular matrix and the generation of contractile fibroblasts (myofibroblasts) characterize fibrosis. In the cornea, severe wounds that damage the basement membrane heal using fibrosis. However, in contrast to other tissues where function is maintained, fibrosis in the cornea leaves an opaque cornea that can impair vision.

During the past two years, Dr. Zieske and colleagues made the exciting observation that the epithelium releases exosomes that stimulate fibrosis in human corneal fibroblasts (HCF). Exosomes are nanovesicles (30-100nm) that are released from most cells, and are part of a larger group of vesicles released from cells, termed extracellular vesicles (EVs). EVs have been the subject of intense research efforts over the past five years after the discovery that they carry “cargo” consisting of proteins, mRNA, and miRNA, which can affect the behavior of adjacent cells. Indeed, this appears to be a major mechanism in the initiation of cancer, where EVs from cancer cells invade host cells and stimulate them to secrete matrix that supports the cancer cells. While examining EVs from the cornea, Dr. Zieske and colleagues made several interesting observations: 1) All three major cell types of the cornea release EVs; 2) EVs isolated from human corneal epithelial cells stimulate the expression of α-smooth muscle actin (a marker of fibrosis) in HCF; 3) Epithelial EVs do not appear to penetrate the epithelial basement membrane; and 4) EVs from unwounded corneal epithelial cells do not appear to stimulate fibrosis, but EVs from wounded epithelium do stimulate fibrosis in HCF. These observations suggest that the cargo in EVs released by wounded epithelium is altered compared to those from unwounded.

The Zieske laboratory’s current hypothesis is as follows: EV cargo from epithelial cells is altered during wound repair to contain proteins that stimulate fibrosis in HCF.

The Zieske laboratory is also currently addressing three questions:

  1. Do epithelial EVs penetrate the epithelial basement membrane;
  2. What are the dynamics of EV penetration into the cornea
  3. Do endothelial EVs penetrate the Descemet’s membrane?

Their preliminary findings indicate that epithelial EVs interact with stromal cells and endothelial EVs do penetrate the Descemet’s membrane. Overall, their goal is to understand the interactions of EVs in the cornea. In the process, if they find that topically applied EVs can alter corneal activities, this would have great clinical potential, as EVs could be loaded with cargo that could blunt fibrosis or other corneal diseases.

Projects

Research Interests

Mechanisms involved in corneal wound repair

Cornea Wound Repair

For the past 30 years much of the research in Dr. Zieske’s laboratory has been focused on corneal wound repair, and many original findings have occurred through that research, including the following:

  1. focal contacts are formed during corneal epithelial migration;
  2. epidermal growth factor is activated during epithelial wound repair;
  3. stromal cell proliferation occurs following apoptosis of stromal cells in the wound area;
  4. local activators of TGF-β are expressed in response to corneal wounding;
  5. TGF-b1 and -b3 have differential effect on wound healing, with TGF-b1 increasing fibrosis and TGF-b3 decreasing fibrosis;
  6. p38 inhibitor decreases fibrosis in corneal wounds that would normally heal in a fibrotic manner.

This final finding led Dr. Zieske and Dr. Guo to file and obtain a patent:

P38 MAP Kinase Inhibitors for Wound Healing

US Patent Application Number PCT/US2016/057337, Publication Number WO2017066758 A1, Published April 20, 2017

Blocking the p38-signaling pathway in human corneal and skin fibroblast cells greatly decreases expression of α-smooth muscle actin with TGFβ1 stimulation. We postulate that the p38 pathway is an important mechanism driving the corneal and skin scaring. This finding may prevent/improve tissue fibrosis after wounding.

3D Stroma-like Culture System

Dr. Zieske’s laboratory has developed a 3D stroma-like culture system, which is comprised of human corneal stromal fibroblasts that when stimulated with Vitamin C, self-assemble their own extracellular matrix, and has been shown to mimic the in situ stroma. Dr. Zieske’s laboratory has utilized this 3D culture system to observe and examine cell-cell interactions by co-culturing human epithelial and endothelial cells on the 3D construct. This system has been used in numerous publications and shared with other laboratories. Dr. Zieske’s laboratory will continue to use this system in their current studies with exosomes.

Role of Exosomes in Corneal Wound Repair

Dr. Zieske’s laboratory is currently examining corneal cell-cell communication during wound repair via exosomes, both in 2D culture and their 3D culture system. Exosomes are nanovesicles (30-100nm) that are released from most cells, and are part of a larger group of vesicles released from cells, termed extracellular vesicles (EVs). EVs have been the subject of intense research efforts over the past five years after the discovery that they carry “cargo” consisting of proteins, mRNA, and miRNA, which can affect the behavior of adjacent cells. Indeed, this appears to be a major mechanism in the initiation of cancer, where EVs from cancer cells invade host cells and stimulate them to secrete matrix that supports the cancer cells. While examining EVs from the cornea, Dr. Zieske and colleagues made several interesting observations:

  1. All three major cell types in the human cornea release EVs: epithelium, fibroblasts, and endothelium.
  2. EVs isolated from human corneal epithelial cells stimulate the expression of alpha-smooth muscle actin (a marker of fibrosis) in HCF;
  3. Epithelial EVs do not appear to penetrate the epithelial basement membrane, but either fibroblast and/or endothelial EVs do appear to penetrate the Descemet’s membrane.
  4. EVs from unwounded corneal epithelial cells do not appear to stimulate fibrosis, but EVs from wounded epithelium do stimulate fibrosis in HCF, suggesting that the cargo in EVs released by wounded epithelium is altered compared to those that are not wounded.

These observations led to Dr. Zieske’s current hypothesis that EV cargo from epithelial cells is altered during wound repair to contain proteins that stimulate fibrosis in corneal fibroblasts, and over the course of the next few years, Dr. Zieske’s laboratory will examine several aspects of EV biology in the cornea:

  1. Compare proteins, and possibly mRNA and/or miRNA, in the cargo of EVs isolated from wounded and unwounded corneal epithelial cells, as well as examine the effect of matrix their 3D culture system.
  2. Examine if EV cargo is altered in keratocytes compared to myofibroblasts, and if the EVs from myofibroblasts contain cargo that enhance the fibrotic response
  3. Use time-lapse microscopy to examine migration characteristics of the EVs in the cornea.

During this time, several questions will be examined, including:

  1. Do epithelial EVs penetrate the epithelial basement membrane?
  2. What are the dynamics of EV penetration into the cornea?
  3. Do endothelial EVs penetrate the Descemet’s membrane?

The overall goal of this project is to understand the interactions of EVs in the cornea, and if Dr. Zieske and colleagues find that topically applied EVs alter corneal activities, this would have great clinical potential, as EVs could be loaded with cargo that could blunt fibrosis or other corneal diseases.

Current Research Funding

1984-present

NIH/NEI R01 EY005665: Principal Investigator
Corneal epithelial-stromal interactions during regeneration and fibrosis
$1 million: total direct costs for current funding cycle, beginning in 2018

The major goal of this project is to demonstrate the role of extracellular vesicles in corneal wound healing, and to determine if they can be “loaded” with certain “cargo” (i.e. growth factors, cytokines, or drugs) that would be useful as therapeutics to promote healing with minimal generation of myofibroblasts.


Publications

H-index

40 (Google Scholar, as of September 2017)

Selected Publications

Dr. Zieske has published more than 100 peer-reviewed articles, reviews and chapters. Below is a list of selected publications. View his publications on PubMed.

  1. Guo X, Sriram S, Tran JA, Hutcheon AEK, and Zieske JD. Inhibition of Human Corneal Myofibroblast Formation. Invest Ophthalmol Vis Sci. 2018 Jul 2;59(8):3511-3520. 
  2. Guo X, Hutcheon AE, Tran JA, Zieske JD. TGF-beta-target genes are differentially regulated in corneal epithelial cells and fibroblast. New Front in Ophthalmol. 2017;3(1). Epub 2017 Jan 30.:1-8. 
  3. Han KY, Tran JA, Chang JH, Azar DT, Zieske JD. Potential role of corneal epithelial cell-derived exosomes in corneal wound healing and neovascularization. Sci Rep. 2017 Feb 6;7:40548. 
  4. Sriram S, Tran JA, Guo X, Hutcheon AE, Lei H, Kazlauskas A, Zieske JD. PDGFRα is a Key Regulator of T1 and T3’s Differential Effect on SMA Expression in Human Corneal Fibroblasts. Invest Ophthalmol Vis Sci. 2017 Feb 1;58(2):1179-1186.
  5. Guo X, Hutcheon AE, Zieske JD. Molecular insights on the effect of TGF-β1/-β3 in human corneal fibroblasts. Exp Eye Res. 2016 May;146:233-41. Epub 2016 Mar 16. 

Laboratory

Current Members of Dr. Zieske’s Laboratory

Instructor
Xiaoqing Guo, Ph.D.

Senior Research Assistant/Laboratory Manager
Audrey E.K. Hutcheon, B.S.

Post-Doctoral Fellow
Tina McKay, Ph.D.

Alumni

More than 15 trainees have worked in Dr. James Zieske’s laboratory. To view the complete list of alumni, download his CV [PDF].