Neel K. Krishna, Ph.D.

 ‌

Associate Professor

Department of Microbiology and Molecular Cell Biology

Lewis Hall, Room 3184
700 W. Olney Road
Norfolk, Virginia 23508
Office: (757) 446- 5677
Lab: (757) 446- 5645
Email: krishnnk@evms.edu

Teaching:

Biomedical Graduate Students

Introduction to the Research Literature
Biomedical Sciences Seminar (Journal Club)
Concepts in Research Design Research Techniques
Advanced Molecular and Cellular Techniques, Course Director
Current Topics in Molecular Biology
Animal Virology
Advanced Cell Biology
Advanced Proteomics
Biomedical Sciences Program Track: Molecular Integrative Biosciences (MIB)

Medical Students

Medical Microbiology and Immunology, Course Director

Medical Masters Students

Medical Masters Library Thesis Research Paper

Education

• PhD, Pennsylvania State University School of Medicine, Hershey, PA
• Postdoctoral Fellow, The Scripps Research Institute, La Jolla, CA

Academic Positions

2011 – Present

• Associate Professor
• Eastern Virginia Medical School
• Department of Microbiology & Molecular Cell Biology
• Department of Pediatrics

2003 – 2011

• Assistant Professor
• Eastern Virginia Medical School
• Department of Microbiology & Molecular Cell Biology
• Department of Pediatrics

Lab Members

		Julia A. Sharp, Ph.D. Postdoctoral Fellow Ph.D., EVMS Norfolk, VA Phone: (757) 446-5645 Email: sharpja@evms.edu
‌		Cody A. Phelps Biotechnology Masters Student Phone: (757) 446-5645 Email: phelpsca@evms.edu
		Tricia Railling Biotechnology Masters Student Phone: (757) 446-5645 Email: raillip@evms.edu
‌		Haree K. Pallera Undergraduate Student Phone: (757) 446-5645 Email: Pallera@evms.edu

Research Interests

Keywords:  astrovirus, capsid/coat protein, peptide, inhibitor, complement, classical pathway, lectin pathway, C1q, MBL, Peptide Inhibitor of Complement C1 (PIC1).

I. Mechanistic study of astrovirus peptide inhibition of the complement system

My laboratory has traditionally studied the human astroviruses (HAstVs), a family of non-enveloped, icosahedral RNA viruses that cause gastroenteritis, predominantly in infants. Eight HAstV serotypes have been identified with a worldwide distribution. While the HAstVs represent a significant public health concern, very little is known about the pathogenesis and host immune response to this virus. Our research group, along with the laboratory of our collaborator Dr. Kenji Cunnion in the Department of Pediatrics, has demonstrated that HAstV-1 virions, specifically the viral capsid protein, suppress the complement system, a fundamental component of the innate immune response against pathogens in vertebrates. This is achieved by the capsid protein binding to the first component of the complement pathway, C1q and the related molecule MBL. Binding of C1q/MBL by capsid protein inhibits complement activation and its downstream effects (e.g., inflammation, cell lysis, phagocytosis, etc.). Our laboratory has recently isolated a highly potent peptide of 15 amino acid residues derived from the astrovirus capsid protein that mediates this complement suppressing activity. This peptide is termed Peptide Inhibitor of Complement C1 (PIC1). We are interested in determining the precise mechanism whereby PIC1 inhibits complement activation. Our working hypothesis of PIC1 inhibition of C1/MBL is illustrated below. Additionally, we are analyzing the role PIC1 may play in blocking the interaction of C1q/MBL with its cell surface ligands cC1qR (calreticulin) and gC1qR and the functional consequence of this activity on immune cell signaling.
 

Figure 1. A working model of PIC1 inhibition of C1q/MBL activation. In serum, C1q/MBL are associated with their cognate serine proteases (C1r₂C1s₂/MASPs respectively, shown as yellow sphere). Under normal conditions, C1q/MBL binds to an activator (aggregated antibody or directly to certain pathogens) via the globular heads (blue spheres) activating the serine proteases which leads to downstream activation of the complement system. PIC1 binds tightly to C1q/MBL conformationally altering the interaction of C1q/MBL with its respective serine proteases, thus preventing their activation.

II. Therapeutic development of PIC1

A second area of interest for our laboratory is the development PIC1 as a therapeutic for complement-mediated disease. Whilst the human complement system represents a front-line defense against pathogens such as bacteria and viruses, its uncontrolled activation can lead to severe pathology in many different inflammatory and autoimmune disorders with an immune component such as systemic lupus erythematosis, rheumatoid arthritis, inflammatory bowel disease, ischemia-reperfusion injury (myocardial infarct, stroke), glomerulonephritis, adult respiratory distress syndrome, transplant rejection, graft versus host disease and burn injuries.

Figure 2. Complement is an extremely powerful immunological amplification cascade (avalanche) for killing infectious microbes. However, disregulated complement activity can also severely damage the host and is responsible for many inflammatory and autoimmune diseases in humans. PIC1 is a synthesized peptide designed to stop complement activation at the first step in the cascade.

Currently there are only two complement inhibitors on the market. Given the very potent inhibition of the astrovirus derived peptides on the complement system, we are currently interested in developing PIC1 into a therapeutic compound as a method for regulating aberrant complement activity. Recently published data from the Cunnion and Krishna labs demonstrates that this peptide can block ABO incompatibility in vitro (a classical pathway mediated disease) and inhibit complement activation in vivo. We are currently evaluating the efficacy of PIC1 in pre-clinical models of complement-mediated disease such as acute intravascular hemolytic transfusion reaction (ABO incompatibility) as a proof of concept for eventual therapeutic development for conditions such as hemolytic anemia of the newborn (fetal hydrops, newborn jaundice), sickle cell crisis, and generalized acute intravascular transfusion reactions.

Figure 3. PIC1 inhibits human red blood cell (RBC) lysis in vitro. Top panel: ABO incompatible destruction of RBCs by the classical pathway of complement. In this example, transfused cells expressing A antigen have been exposed to incompatible recipient serum containing anti-A IgM. The bound IgM molecule is then recognized by serum complement C1 complex (C1q + C1r₂C1s₂). Upon binding IgM, C1 activates the classical pathway resulting in complement deposition on the donor cell and eventual clearance or lysis of host RBCs by the membrane attack complex (MAC). For clarity, only C1 binding and MAC formation are illustrated here. We hypothesized that PIC1 would bind to C1 and inhibit classical pathway mediated destruction of the target RBCs. Bottom panel: PIC1 inhibits complement activity in vitro. Human O serum was incubated with increasing concentrations of PIC1 or a buffer control and then added to human AB erythrocytes.  PIC1 blocked complement mediated hemolysis of the RBCs in a dose dependent manner. Values are the means of three independent experiments.  Error bars represent the SEM. Adapted from Mauriello et al., 2013.

In the News

Inducted into Alpha Omega Alpha (AOA) Honor Society, May 2013

Virginia Innovation Partnership U.S. Department of Commerce iP6 Challenge grant award recipient, April 2013:http://www.virginia.edu/vpr/i6/fundedprojects.html

Hampton Roads Community Foundation Yearbook, 2012
http://content.yudu.com/Library/A1xkbd/HamptonRoadsCommunit/resources/7.htm

ScienceDaily.com article: Researchers Closer to Development of Drug to Prevent Deadly Immune Response, August 27, 2010
http://www.sciencedaily.com/releases/2010/08/100826182508.htm

Original Research Articles (peer-reviewed)

Selected Book Chapters (out of 5)

Patent Applications

Patents Granted