Roman Dziarski

Roman Dziarski (Polish pronunciation: IPA: /ˈrɔ.man//ˈd͡ʑar.ski/ born December 11, 1949) is a Polish-born American immunologist and microbiologist. He is best known for his research on innate immunity and bacterial peptidoglycan, for discovering the family of human peptidoglycan recognition proteins, which comprises PGLYRP1, PGLYRP2, PGLYRP3, and PGLYRP4, and for defining the functions of these proteins.

Dziarski is currently Professor Emeritus of Microbiology and Immunology at Indiana University School of Medicine. in Warsaw, Poland, under the tutelage of the revered pedagogue. From 1967 to 1972, Dziarski attended the University of Warsaw with a major in Biology and Microbiology, which he studied under . He received his Bachelor of Sciences (BS) degree in 1971, and Master of Science (MS) degree in 1972. and a polyclonal activator of B lymphocytes. He determined the role of DNA synthesis, intracellular calcium, protein kinase C, and inhibitory G proteins in peptidoglycan-induced polyclonal B lymphocyte activation. He also established the role of peptidoglycan and other polyclonal B cell activators in the induction of autoantibody responses in various models of autoimmunity.

Peptidoglycan receptors and cell activation pathways In his subsequent research, Dziarski set out to identify peptidoglycan receptors on immune cells that mediate the cell-activating and immunomodulating effects of peptidoglycan. His early attempts using biochemical methods were not successful, as they were prone to nonspecific interactions and technical artifacts. He also showed that similar problems and artifacts plagued the early attempts to identify the cell receptors for bacterial lipopolysaccharide and other cell activators. Furthermore, Dziarski's and Gupta's groups identified the involvement of several signal transduction molecules and pathways in peptidoglycan-induced cell activation. Dziarski also established that chemokines are the main pro-inflammatory mediators in human monocytes activated by peptidoglycan and other bacterial cell activators.

Using similar molecular biology approach the research groups of Carsten J. Kirschning (at Tularik Inc.) and Douglas Golenbock (at Boston University School of Medicine) in collaboration with Dziarski, discovered that TLR2 is the cell-activating receptor for peptidoglycan and other components of Gram-positive bacteria. In the follow-up studies, Dziarski's and Gupta's groups identified the signal transduction pathway activated by peptidoglycan through TLR2 and verified that TLR2 is indeed the peptidoglycan cell-activating receptor.

Discovery of peptidoglycan recognition proteins Dziarski's best known contribution to innate immunity is his research on mammalian peptidoglycan recognition proteins (PGRPs). In 2001, Dziarski's and Gupta's groups discovered and cloned three human PGRPs, which they named PGRP-L, PGRP-Iα, and PGRP-Iβ (for long and intermediate size transcripts).

Functions of peptidoglycan recognition proteins Dziarski and his collaborators established that all mammalian PGRPs bind bacterial peptidoglycan. and PGLYRP1, PGLYRP3, and PGLYRP4 are directly bactericidal for both Gram-positive and Gram-negative bacteria.

In further research, Dziarski's group established the mechanism of bacterial killing by human PGRPs. They showed that human PGRPs kill bacteria by simultaneously inducing three synergistic stress responses: oxidative stress, thiol stress, and metal stress, by interfering with the function of the bacterial respiratory electron transport chain. Dziarski also showed that bacterial killing by these PGRPs does not involve cell membrane permeabilization, cell wall hydrolysis, or osmotic shock, They further showed that these PGRPs have both peptidoglycan-lytic amidase and bactericidal activities and are essential for defense against bacterial infections and survival of the developing zebrafish embryos. and PGLYRP1-deficient mice are more sensitive to systemic infections with non-pathogenic bacteria (Micrococcus luteus and Bacillus subtilis).

Dziarski's group further showed that mouse PGRPs play a role in maintaining healthy microbiome, because PGLYRP1-, PGLYRP2-, PGLYRP3-, and PGLYRP4-deficient mice have significant changes in the composition of their intestinal microbiomes. PGLYRP1-deficient mice also have changes in their lung microbiome. They showed that PGLYRP3 and PGLYRP4 are anti-inflammatory and protect mice from experimentally induced atopic dermatitis, and PGLYRP2 is also anti-inflammatory and protects mice from experimentally induced psoriasis-like inflammation. They also showed that some PGRPs have opposite effects, i.e., PGLYRP2 also has a pro-inflammatory effect, as it promotes the development of experimental arthritis, and PGLYRP1 is pro-inflammatory and promotes experimentally induced asthma and skin inflammation These results suggest that PGRPs may protect humans from these inflammatory diseases, and that mutations in PGLYRP genes may be among the genetic factors predisposing to these diseases. From 1979 to 2020, Dziarski was a Principal Investigator on more than 20 research grants, including 10 awards from the National Institutes of Health. and a chapter on peptidoglycan in Molecular Medical Microbiology textbook. which received positive reviews. Polish translation was published in 2025.

Awards and honors Stanford University List of World's Top 2% Scientists, ranked in the top 0.5% to 0.7% of world's scientists (2018-2024) Indiana University Trustees' Teaching Awards (2001, 2012, and 2018) Dziarski has three children: Matthew Dziarski, Alisha Dziarski, and Anjali Dziarski.