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1.  Essential Role for the C5a Receptor in Regulating the Effector Phase of Synovial Infiltration and Joint Destruction in Experimental Arthritis 
The Journal of Experimental Medicine  2002;196(11):1461-1471.
A characteristic feature of rheumatoid arthritis is the abundance of inflammatory cells in the diseased joint. Two major components of this infiltrate are neutrophils in the synovial fluid and macrophages in the synovial tissue. These cells produce cytokines including tumor necrosis factor α and other proinflammatory mediators that likely drive the disease through its effector phases. To investigate what mechanisms underlie the recruitment of these cells into the synovial fluid and tissue, we performed expression analyses of chemoattractant receptors in a related family that includes the anaphylatoxin receptors and the formyl-MetLeuPhe receptor. We then examined the effect of targeted disruption of two abundantly expressed chemoattractant receptors, the receptors for C3a and C5a, on arthritogenesis in a mouse model of disease. We report that genetic ablation of C5a receptor expression completely protects mice from arthritis.
PMCID: PMC2194257  PMID: 12461081
arthritis; C5a receptors; granulocytes; chemoattractants; monocytes
2.  CCR2 and CXCR4 regulate peripheral blood monocyte pharmacodynamics and link to efficacy in experimental autoimmune encephalomyelitis 
CCR2 plays a key role in regulating monocyte trafficking to sites of inflammation and therefore has been the focus of much interest as a target for inflammatory disease.
Here we examined the effects of CCR2 blockade with a potent small molecule antagonist to determine the pharmacodynamic consequences on the peripheral blood monocyte compartment in the context of acute and chronic inflammatory processes.
We demonstrate that CCR2 antagonism in vivo led to a rapid decrease in the number of circulating Ly6Chi monocytes and that this decrease was largely due to the CXCR4-dependent sequestration of these cells in the bone marrow, providing pharmacological evidence for a mechanism by which monocyte dynamics are regulated in vivo. CCR2 antagonism led to an accumulation of circulating CCL2 and CCL7 levels in the blood, indicating a role for CCR2 in regulating the levels of its ligands under homeostatic conditions. Finally, we show that the pharmacodynamic changes due to CCR2 antagonism were apparent after chronic dosing in mouse experimental autoimmune encephalomyelitis, a model in which CCR2 blockade demonstrated a dramatic reduction in disease severity, manifest in a reduced accumulation of monocytes and other cells in the CNS.
CCR2 antagonism in vivo has tractable pharmacodynamic effects that can be used to align target engagement with biologic effects on disease activity.
PMCID: PMC2777898  PMID: 19906300
3.  Role of the caspase-1 inflammasome in Salmonella typhimurium pathogenesis 
The Journal of Experimental Medicine  2006;203(6):1407-1412.
Caspase-1 is activated by a variety of stimuli after the assembly of the “inflammasome,” an activating platform made up of a complex of the NOD-LRR family of proteins. Caspase-1 is required for the secretion of proinflammatory cytokines, such as interleukin (IL)-1β and IL-18, and is involved in the control of many bacterial infections. Paradoxically, however, its absence has been reported to confer resistance to oral infection by Salmonella typhimurium. We show here that absence of caspase-1 or components of the inflammasome does not result in resistance to oral infection by S. typhimurium, but rather, leads to increased susceptibility to infection.
PMCID: PMC2118315  PMID: 16717117
4.  Self-Recognition of Cd1 by γ/δ T Cells 
The specificity of immunoglobulins and α/β T cell receptors (TCRs) provides a framework for the molecular basis of antigen recognition. Yet, evolution has preserved a separate lineage of γ/δ antigen receptors that share characteristics of both immunoglobulins and α/β TCRs but whose antigens remain poorly understood. We now show that T cells of the major tissue γ/δ T cell subset recognize nonpolymorphic CD1c molecules. These T cells proliferated in response to CD1+ presenter cells, lysed CD1c+ targets, and released T helper type 1 (Th1) cytokines. The CD1c-reactive γ/δ T cells were cytotoxic and used both perforin- and Fas-mediated cytotoxicity. Moreover, they produced granulysin, an important antimicrobial protein. Recognition of CD1c was TCR mediated, as recognition was transferred by transfection of the γ/δ TCR. Importantly, all CD1c-reactive γ/δ T cells express Vδ1 TCRs, the TCR expressed by most tissue γ/δ T cells. Recognition by this tissue pool of γ/δ T cells provides the human immune system with the capacity to respond rapidly to nonpolymorphic molecules on professional antigen presenting cells (APCs) in the absence of foreign antigens that may activate or eliminate the APCs. The presence of bactericidal granulysin suggests these cells may directly mediate host defense even before foreign antigen-specific T cells have differentiated.
PMCID: PMC2193122  PMID: 10727456
T lymphocytes; T cell antigen receptors γ/δ; CD1; cytolysis; granulysin
5.  Molecular Recognition of Lipid Antigens by T Cell Receptors  
The T cell antigen receptor (TCR) mediates recognition of peptide antigens bound in the groove of major histocompatibility complex (MHC) molecules. This dual recognition is mediated by the complementarity-determining residue (CDR) loops of the α and β chains of a single TCR which contact exposed residues of the peptide antigen and amino acids along the MHC α helices. The recent description of T cells that recognize hydrophobic microbial lipid antigens has challenged immunologists to explain, in molecular terms, the nature of this interaction. Structural studies on the murine CD1d1 molecule revealed an electrostatically neutral putative antigen-binding groove beneath the CD1 α helices. Here, we demonstrate that α/β TCRs, when transferred into TCR-deficient recipient cells, confer specificity for both the foreign lipid antigen and CD1 isoform. Sequence analysis of a panel of CD1-restricted, lipid-specific TCRs reveals the incorporation of template-independent N nucleotides that encode diverse sequences and frequent charged basic residues at the V(D)J junctions. These sequences permit a model for recognition in which the TCR CDR3 loops containing charged residues project between the CD1 α helices, contacting the lipid antigen hydrophilic head moieties as well as adjacent CD1 residues in a manner that explains antigen specificity and CD1 restriction.
PMCID: PMC1887682  PMID: 9874576
CD1; antigen presentation; T cell receptor; Mycobacterium tuberculosis; mycolic acid

Results 1-5 (5)