Dr. Subash Sad

Biography

Research Interests

Inflammation touches every aspect of health and disease throughout our lives. Our laboratory studies the mechanisms that maintain a healthy immune system and prevent the development of inflammatory diseases. In particular, we are interested in the intricate mechanisms that control inflammatory cell death in immune cells. While under normal conditions, immune cells are essential to provide protection against the continuous challenge of pathogens in our environment, an imbalance in the death of immune cells can result in chronic inflammation, collateral damage to the surrounding tissue and throughout the body. In particular, we are studying cell death in macrophages, which are important cells of the innate immune system that engulf pathogens and release powerful immune signals that can have both inflammatory and anti-inflammatory effects. We have identified novel mechanisms that control a newly discovered form of programmed necrotic cell death, known as necroptosis. When macrophages die by necroptosis their cell membrane ruptures, spilling the cell contents out into extracellular milieu and leading to massive inflammation. We have identified that the production of a key inflammatory signal (interferon) is an essential upstream inducer of this inflammatory cell death. By improving the understanding of the mechanisms of necroptosis this research will lead to the development of new therapeutic approaches to treat chronic inflammatory diseases.

Our laboratory is evaluating the impact of inflammatory cell death in various diseases such as sepsis, cystic fibrosis and gut inflammation. Excessive and systemic inflammatory response results in sepsis which rapidly progresses to shock, leading to 50-60% mortality. Our laboratory is evaluating the impact of inhibiting necrotic cell death in sepsis.  We are also working on mechanisms that lead to pulmonary exacerbations in cystic fibrosis patients.  Cystic fibrosis is caused by mutation in CFTR, which results in impaired chloride transport in cells.  As a result, pathogens such as Pseudomonas aeruginosa, persist in the lungs of cystic fibrosis patients and are considered to exacerbate the disease.  Our laboratory is evaluating whether inflammatory cell death induced by lung resident pathogens results in pulmonary exacerbations in cystic fibrosis. We are also deciphering the mechanisms that lead to excessive inflammation in the gut.  We have recently reported that the transcription factor FoxO3a plays a key role in regulating inflammatory response, and we are evaluating the upstream and downstream mechanisms involved.  

We use cell biological and genomic approaches to decipher the mechanisms involved.  We have generated various recombinant pathogens in which genes have been cloned in, or key virulence genes have been deleted. Function of specific genes in cell death is evaluated using knockout mice, or by knocking down specific genes in cells.  Functional assays of cell death, cell cycling, cytokine expression and cytolytic activity are coupled with cell imaging and in vivo readouts.

Recent publications (last five years)

1. Tomlinson J.J., Shutinoski B., Dong L., Meng F., Elleithy D., Lengacher N.A., Nguyen A.P., Cron G.O., Jiang Q., Roberson E.D., Nussbaum R.L., Majbour N.K., El-Agnaf O.M., Bennett S.A., Lagace D.C., Woulfe J.M., Sad S, Brown E.G., Schlossmacher M.G. (2017) Holocranohistochemistry enables the visualization of α-synuclein expression in the murine olfactory system and discovery of its systemic anti-microbial effects. J Neural Transm. Jun;124(6):721-738. doi: 10.1007/s00702-017-1726-7.
2. Deguise M.O., De Repentigny Y., McFall E., Auclair N, Sad S. and Kothary R. (2017). Immune dysregulation may contribute to disease pathogenesis in spinal muscular atrophy mice. Hum Mol Genet. Jan 19. pii: ddw434. doi: 10.1093/hmg/ddw434
3. Joseph J., Ametepe E.S., Haribabu N., Agbayani G., Krishnan LK., Blais A. and Sad S. (2016). Inhibition of ROS and upregulation of inflammatory cytokines by FoxO3a promotes survival against Salmonella typhimurium. Nature Commun. Sep 7;7:12748.
4. Karunakaran D, Geoffrion M, Wei L, Gan W, Richards L, Shangari P, DeKemp EM, Beanlands RA, Perisic L, Maegdefessel L, Hedin U, Sad S, Guo L, Kolodgie FD, Virmani R, Ruddy T, Rayner KJ. (2016) Targeting macrophage necroptosis for therapeutic and diagnostic interventions in atherosclerosis. Science Advances, Jul 22;2(7):e1600224.
5. Shutinoski B., Alturki N.A., Rijal D., Bertin J., Gough P.J., Schlossmacher M.G. and Sad S. (2016). K45A mutation of RIPK1 results in poor necroptosis and cytokine signaling in macrophages which impacts inflammatory responses in vivo. Cell death and differentiation. Oct;23(10):1628-37.
6. Huus K.E., Joseph J., Zhang L., Wong A., Aaron S.D., Mah T-F. and Sad S. (2016). Clinical isolates of Pseudomonas aeruginosa from chronically infected cystic fibrosis patients fail to activate the inflammasome during both stable infection and pulmonary exacerbation. J. Immunol. Apr. 1; 196(7): 3097-108.
7. Patel R. and Sad S. (2015). Transcription Batf3 is important for the development of CD8+ T cell response against a phagosomal bacterium regardless of the location of antigen. Immunol. Cell Biol. Apr; 94(4): 378-87.
8. Ferreira R.B., Valdez Y., Coombes B.K., Sad S., Gouw J.W., Brown E.M., Li Y., Grassl G.A., Antunes L.C., Gill N., Truong M., Scholz R., Reynolds L.A., Krishnan L., Zafer A.A., Sal-Man N., Lowden M.J., Auweter S.D., Foster L.J. and Finlay B.B. (2015). A Highly Effective Component Vaccine against Nontyphoidal Salmonella enterica Infections. MBio. Sep 22;6(5):e01421-15.
9. Arulanandam R., Batenchuk C., Angarita F.A., Ottolino-Perry K., Cousineau S., Mottashed A., Burgess E., Falls T.J., De Silva N., Tsang J., Howe G.A., Bourgeois-Daigneault M.C., Conrad D.P., Daneshmand M., Breitbach C.J., Kirn D.H., Raptis L., Sad S., Atkins H., Huh M.S., Diallo J.S., Lichty B.D., Ilkow C.S., Le Boeuf F., Addison C.L., McCart J.A. and Bell J.C. (2015). VEGF-mediated induction of PRD1-BF1/Blimp1 expression sensitizes tumor vasculature to oncolytic virus infection. Cancer Cell. Aug 10;28(2):210-24.
10. Cote S., Matte J., Sad S., Angel J.B. and Crawley A.M. (2015). Complexed soluble IL-7 receptor a and IL-7 increase IL-7-mediated proliferation and viability of CD8⁺ T-cells in vitro. Cell Immunol. Feb;293(2):122-5.
11. McComb S, Cessford E, Alturki NA, Joseph J, Shutinoski B, Startek JB, Gamero AM, Mossman KL, Sad S. (2014). Type-I interferon signaling through ISGF3 complex is required for sustained Rip3 activation and necroptosis in macrophages. Proc. Natl. Acad. Sci. (USA). Aug 5; 111(31): E3206-13.
12. McComb S., Shutinoski B., Thurston S., Cessford E., Kumar K. and Sad S. (2014). Cathepsins limit macrophage necroptosis through cleavage of Rip1 kinase. J. Immunol. Jun 15;192(12):5671-8. 
13. Tai L.H., Zhang J., Scott K.J., de Souza C.T., Alkayyal A.A., Ananth A.A., Sahi S., Adair R.A., Mahmoud A.B., Sad S., Bell J.C., Makrigiannis A.P., Melcher A.A., Auer R.C. (2013). Perioperative influenza vaccination reduces postoperative metastatic disease by reversing surgery-induced dysfunction in natural killer cells. Clin. Cancer Res. Sep 15;19(18):5104-15.
14. Nguyen T, Robinson N., Allison S.E., Coombes B.K., Sad S., Krishnan L. (2013). IL-10 produced by trophoblast cells inhibits phagosome maturation leading to profound intracellular proliferation of Salmonella enterica Typhimurium. Placenta. 2013 Sep;34(9):765-74.
15. Tzelepis F., Haddad H.K., MacLean S., Dudani R., Agenes F., Peng S.L., Sekaly R-P. and Sad S. (2013). Intrinsic role of FoxO3a in the development of CD8+ T cell memory. J. Immunol. February 1, 190( 3): 1066-1075.
16. Tzelepis F., Alcon V., Young K.G., Gurnani K., Everson E.S., Rüssmann H., Krishnan L. and Sad S. (2012). Modulation of antigenic location converts chronic into acute infection by forcing CD8+ T cell recognition. Cell Reports: Dec 27;2(6):1710-21.
17. Hussack G., Keklikian A., Alsughavvir J., Hanifi-Moghaddam P., Arbabi-Ghahroudi, M., Van Faassen H., Hou ST, Sad S., MacKenzie R. and Tanha J. (2012). A VL single-domain antibody library shows a high-propensity to yield non-aggregating binders. Protein Engineering, Design and Selection, 25(6); 313-318.
18. McComb S, Cheung HH, Korneluk RG, Wang W., Krishnan L. and Sad S. (2012) cIAP1 and cIAP2 limit macrophage necroptosis by inhibiting RIP1 and RIP3 activation.Cell death and differentiation, Nov;19(11):1791-1801.
19. Robinson N., McComb S., Mulligan R., Dudani R., Krishnan L. and Sad S., (2012) Type I interferon induces necroptosis in macrophages during Salmonella Typhimurium infection. Nature Immunol., Oct;13(10):954-962.
20. Stark FC, Gurnani K, Sad S, Krishnan L (2012). Lack of functional selectin ligand interactions compromises long term tumor protection by CD8 T cells. PLoS One. Feb; 7(2): e32211.