During my veterinary and postdoctoral training I learned the normal and abnormal histology of many organs. My research focuses on understanding immuno-pathological mechanisms generated by infectious diseases and autoimmunity using human tissue and various animal models. I have gained substantial experience working with monocytes/macrophages and their heterogeneous roles in defense against microorganisms. My Master’s studies focused on genotypic characterization of resistance/susceptibility of Colombian creole cattle to infections caused by intracellular pathogens, which often behave similar to viruses and induce similar host immune responses. I isolated primary macrophages to study their differentiation and determined various polymorphisms in the gene that encodes for the natural resistance associated macrophage protein (Nramp1). Next, I studied the hamster model of visceral leishmaniasis (VL), in which macrophages are extremely susceptible to Leishmania infection. I demonstrated that this susceptibility was related to a mutation in the promoter region of the nitric oxide (NO) gene and mutation of the transcription factor-binding element for the transcription factor CEBPβ, which accounted for the reduced expression and production of this important defense mechanism in macrophages. I then studied de novo transcriptome assembly to determine gene expression in hamster macrophages and whole spleen cells infected with Leishmania donovani, which revealed a mixed (classical and alternative) activation phenotype of macrophages. I also developed and evaluated the performance of a qualitative point of care (POC) molecular test (RPA-LF, recombinase polymerase amplification-lateral flow) for the diagnostic of different parasitic and viral pathogens. Recently, I have developed and analyzed a multiplex immunohistochemistry protocol to identify multiple macrophage biomarkers in formalin-fixed paraffin-embedded tissue sections from patients infected with Hepatitis C virus, non-alcoholic steatohepatitis (NASH) and autoimmune hepatitis (AIH). In summary, my veterinary and research training has provided me with experience in histology, molecular biology, and immunology—the tools necessary to bring the proposed project to completion.
||Doctor of Philosophy, UTHSCSA, San Antonio, TX
||Master in Sciences, Antioquia University, Medellin, Colombia
||Doctor in Veterinary Medicine, Antioquia University, Medellin, Colombia
||2020 AAI Early Career Faculty Travel Grant to attend the American Association of Immunologists annual meeting, Honolulu, Hawaii, May 2020.
||Systems and methods for spectral imaging microscopy intrahepatic macrophage profiling for predicting risk of fibrosis development in patients with chronic liver disease. Heather L. Stevenson and Omar A. Saldarriaga. US Patent App. 62/926.264
||Abstract selected as “Poster of Distinction,” (Omar Saldarriaga- First Author). American Association for the Study of Liver Diseases (AASLD). Honored at the 2018 Liver Meeting, San Francisco, CA.
||Recombinase polymerase amplification (RPA) method for Leishmania spp. and Trypanosoma cruzi. A Castellanos, B Travi, O Saldarriaga, P Melby. US Patent App. 14/993,407
||Institutional Technology Commercialization Program Award (TCP), University of Texas Medical Branch.
||James W McLaughlin Poster Travel Awardee. McLaughlin Fellowship Fund and Institute for Human Infections and Immunity- UTMB, Galveston, TX.
||McLaughlin Endowment Post-doctoral Fellowship Award, UTMB, Galveston, TX
||American Association for the Study of Liver Diseases (AASLD)
|2012 - Present
|| American Association of Immunologists (AAI)
||Society of Leukocyte Biology (SLB)
|2013 - 2017
||American Society of Tropical Medicine and Hygiene (ASTMH)
|October 2019- Present
|July 2019 – Present
|| NPJ Vaccines;
|September 2018- Present
||PLOS Neglected Tropical Diseases
|August 2018 – Present
|August 2017 – Present
- Saldarriaga OA, Freiberg B, Krishnan S, Rao Arvind, Burks J, Booth AL, Dye B, Utay N, Ferguson M, Akil A, Yi M, Beretta L and Stevenson HL. Multispectral imaging enables characterization of intrahepatic macrophages in patients with chronic liver disease. Hepatol Commun. 2020 May;4(5):708-723.
- Simoes CC, Saldarriaga OA, Utay NS, Stueck AE, Merwat SK, Merwat SN, Schiano TD, Fiel MI, Stevenson HL. Direct-Acting Antiviral Treatment of Patients with Hepatitis C Resolves Serologic and Histopathologic Features of Autoimmune Hepatitis. Hepatol Commun. 2019 Aug;3(8):1113-1123. doi: 10.1002/hep4.1388. eCollection 2019 Aug. PubMed PMID: 31388631; PubMed Central PMCID: PMC6671831.
- Akil A, Endsley M, Shanmugam S, Saldarriaga O, Somasunderam A, Spratt H, Stevenson HL, Utay NS, Ferguson M, Yi M. Fibrogenic Gene Expression in Hepatic Stellate Cells Induced by HCV and HIV Replication in a Three Cell Co-Culture Model System. Sci Rep. 2019 Jan 24;9(1):568. doi: 10.1038/s41598-018-37071-y. PubMed PMID: 30679661; PubMed Central PMCID: PMC6345841.
- Kong F*, Saldarriaga OA*, Spratt H, Osorio EY, Travi BL, Luxon BA, Melby PC. Transcriptional Profiling in Experimental Visceral Leishmaniasis Reveals a Broad Splenic Inflammatory Environment that Conditions Macrophages toward a Disease-Promoting Phenotype. PLoS Pathog. 2017 Jan;13(1):e1006165. doi: 10.1371/journal.ppat.1006165. eCollection 2017 Jan. PubMed PMID: 28141856; PubMed Central PMCID: PMC5283737. *Shared first authorship.
- Saldarriaga OA, Castellanos-Gonzalez A, Porrozzi R, Baldeviano GC, Lescano AG, de Los Santos MB, Fernandez OL, Saravia NG, Costa E, Melby PC, Travi BL. An Innovative Field-Applicable Molecular Test to Diagnose Cutaneous Leishmania Viannia spp. Infections. PLoS Negl Trop Dis. 2016 Apr;10(4):e0004638. doi: 10.1371/journal.pntd.0004638. eCollection 2016 Apr. PubMed PMID: 27115155; PubMed Central PMCID: PMC4845993.
- Castellanos-Gonzalez A*, Saldarriaga OA*, Tartaglino L, Gacek R, Temple E, Sparks H, Melby PC, Travi BL. A Novel Molecular Test to Diagnose Canine Visceral Leishmaniasis at the Point of Care. Am J Trop Med Hyg. 2015 Nov;93(5):970-5. doi: 10.4269/ajtmh.15-0145. Epub 2015 Aug 3. PubMed PMID: 26240156; PubMed Central PMCID: PMC4703275.*Shared first authorship.
- Espitia CM, Saldarriaga OA, Travi BL, Osorio EY, Hernandez A, Band M, Patel MJ, Medina AA, Cappello M, Pekosz A, Melby PC. Transcriptional profiling of the spleen in progressive visceral leishmaniasis reveals mixed expression of type 1 and type 2 cytokine-responsive genes. BMC Immunol. 2014 Nov 26;15:38. doi: 10.1186/s12865-014-0038-z. PubMed PMID: 25424735; PubMed Central PMCID: PMC4253007.
- Osorio EY, Travi BL, da Cruz AM, Saldarriaga OA, Medina AA, Melby PC. Growth factor and Th2 cytokine signaling pathways converge at STAT6 to promote arginase expression in progressive experimental visceral leishmaniasis. PLoS Pathog. 2014 Jun;10(6):e1004165. doi: 10.1371/journal.ppat.1004165. eCollection 2014 Jun. PubMed PMID: 24967908; PubMed Central PMCID: PMC4072777.
- Saldarriaga OA, Travi BL, Choudhury GG, Melby PC. Identification of hamster inducible nitric oxide synthase (iNOS) promoter sequences that influence basal and inducible iNOS expression. J Leukoc Biol. 2012 Jul;92(1):205-18. doi: 10.1189/jlb.1010568. Epub 2012 Apr 18. PubMed PMID: 22517919; PubMed Central PMCID: PMC3382312.
- Perez LE, Chandrasekar B, Saldarriaga OA, Zhao W, Arteaga LT, Travi BL, Melby PC. Reduced nitric oxide synthase 2 (NOS2) promoter activity in the Syrian hamster renders the animal functionally deficient in NOS2 activity and unable to control an intracellular pathogen. J Immunol. 2006 May 1;176(9):5519-28. doi: 10.4049/jimmunol.176.9.5519. PubMed PMID: 16622021.
- Saldarriaga OA, Perez LE, Travi BL, Melby PC. Selective enhancement of the type 1 cytokine response by expression of a canine interleukin (IL)-12 fused heterodimeric DNA. Vet Immunol Immunopathol. 2006 Apr 15;110(3-4):377-88. doi: 10.1016/j.vetimm.2005.11.003. Epub 2005 Dec 28. PubMed PMID: 16386313.
- Saldarriaga OA, Travi BL, Park W, Perez LE, Melby PC. Immunogenicity of a multicomponent DNA vaccine against visceral leishmaniasis in dogs. Vaccine. 2006 Mar 10;24(11):1928-40. doi: 10.1016/j.vaccine.2005.10.052. Epub 2005 Nov 9. PubMed PMID: 16310897.