Robert C. Alaniz, PhD
Research Assistant Professor
Director College of Medicine Cell Analysis Facility (COM-CAF)
Reynolds Medical Building, Room. 417B
College Station, TX 77843-1114
Fax : 979.436.0843
College of Medicine Cell Analysis Facility (COM-CAF)
Core for Integrated Microbiota Research
Education and Post-Graduate Training
BS, Texas A&M University (1991)
PhD, University of Washington – Immunology (2002)
Post-Doc, University of Washington – Microbial Pathogenesis (2007)
The overarching research goals of the lab are directed toward understanding important host and microbial mechanisms that instruct the development of pathogen-specific effector, memory, and protective T-cell immunity after infection with intracellular bacteria.
As our primary model, we use murine infection with Salmonella enterica Serovar typhimurium. Salmonellae are naturally acquired by the oral route and invade early after infection from the intestinal lumen through M-cells into the Peyer’s Patches. Afterward, Salmonella disseminates systemically to colonize peripheral tissues (e.g., the spleen). Protective host defenses initiate in the gut and later at peripheral sites where ultimately a combination of innate (macrophages) and humoral (B-cells, antibody) and cellular (T-cells) immunity work in concert to resolve infection. The production of the cytokine IFNγ throughout the host response (Th1-type) is absolutely required for protective immunity.
Bacteria that infect via the enteral route encounter a qualitatively different environment than pathogens that colonize through parenteral routes. Salmonella must navigate through and may take advantage of the unique immunobiology of the gut mucosa in order to efficiently colonize and establish infection. In addition, the gut mucosal immune system has evolved several mechanisms that serve to maintain immune homeostasis under a continuous onslaught of potential inflammatory and immunogenic exposure from nominal food antigens and the enormous biomass of the commensal microbiota. It is in this complex environment, that host defenses must distinguish “friend or foe”. Understanding mechanisms in this environment, under homeostatic or dysregulated states, that influence the development of Salmonella-specific CD4+ T-cells is one goal of our research.
An additional area of research aims to understand the compartmentalization of host defenses as Salmonella effectively exists as a mucosal and at later times a systemic pathogen. For instance, Salmonellae that colonize the gut and those that subsequently transition to colonize peripheral sites have different antigenic mosaics (e.g., flagellin expression). Recognizing the host and microbial differences in these compartments, we aim to determine the relative importance of CD4+ T-cells primed in the mucosa versus T-cells primed at systemic sites for overall host protective immunity. After activation, lymphocytes are instructed to progress through several possible fates and T-cells develop into an effector (TEFF) and/or memory (TCM and TEM) T-cell subsets, each with unique and important properties for immunity. CD4+ T-cells are further classified by their mucosal or peripheral imprinting status based on the expression of specific molecules on the T-cell surface. In particular, the integrin α4β7 is highly expressed on T-cells activated/imprinted in Peyer’s Patches and α4β7 mediates T-cell migration to the gut. Using flow cytometry and multiple cellular immunological techniques, we aim to isolate several populations of Salmonella-specific T-cells based on their memory and imprinting phenotypes to determine the functional roles of each subset towards protective host defense against oral Salmonella infection.
Another research theme in the lab focuses on membrane vesicles (MVs): discrete spherical nano-assemblies produced from the outer membrane by Gram-negative bacteria. Although described in the literature for decades, the mechanism of production and MV function(s) have only begun to be clarified. In preliminary studies using Salmonella, we demonstrated MVs have potent adjuvant and immunogenic properties for pathogen-specific humoral and cell-mediated host defense stimulation in vivo. After vaccination, MVs induce protective immunity in mice against subsequent live Salmonella challenge, unlike that reported for heat-inactivated bacteria. In a partly translational research approach, we aim to determine the immunogenic and proinflammatory properties of MVs that promote the induction protective immunity. In one approach to accomplish this goal, we will determine the capacity of MVs to activate dendritic cells (DCs), the critical antigen presenting cell for inducing host adaptive immunity in vivo. In addition, we will determine the immunogenic potential of MVs produced by Salmonella using in vivo immunization models as well as in vitro proteomic techniques.
- Alaniz RC, Deatherage BL, Trent MS, Beasely AS, Cotter RJ, Cookson BT. "Gram-negative bacterial membrane vesicles have malleable pro-inflammatory and antigen delivery properties and are attractive new generation vaccine candidates for pathogens." In preparation.
- Bansal T, Alaniz RC, Wood TK, Jayaraman A. The bacterial signal indole increases epithelial-cell tight-junction resistance and attenuates indicators of inflammation. Proc Natl Acad Sci U S A. 107 : 228-33 (2010) PMID 19966295.
- Alaniz RC, Deatherage BL, Lara JC, Cookson BT. "Membrane vesicles are immunogenic facsimiles of Salmonella typhimurium that potently activate dendritic cells, prime B and T cell responses, and stimulate protective immunity in vivo." J Immunol. 2007 Dec 1;179(11): 7692-701. PMID : 18025215
- Alaniz RC, Cummings LA, Bergman MA, Rassoulian-Barrett SL, Cookson BT. "Salmonella typhimurium coordinately regulates FliC location and reduces dendritic cell activation and antigen presentation to CD4+ T cells." J Immunol. 2006 Sep 15;177(6): 3983-93. PMID : 16951361
- Bergman MA, Cummings LA, Alaniz RC, Mayeda L, Fellnerova I, Cookson BT. "CD4+-T-cell responses generated during murine Salmonella enterica serovar Typhimurium infection are directed towards multiple epitopes within the natural antigen FliC." Infect Immun. 2005 Nov;73(11): 7226-35. PMID : 16239517
- Alaniz RC, Sandall S, Thomas EK, Wilson CB. "Increased dendritic cell numbers impair protective immunity to intracellular bacteria despite augmenting antigen-specific CD8+ T lymphocyte responses." J Immunol. 2004 Mar 15;172(6) : 3725-35. PMID : 15004177
- Alaniz RC, Thomas SA, Perez-Melgosa M, Mueller K, Farr AG, Palmiter RD, Wilson CB. "Dopamine beta-hydroxylase deficiency impairs cellular immunity."Proc Natl Acad Sci U S A. 1999 Mar 2: 96(5): 2274-8. PMID: 10051631