title: SLAMF4 Is a Negative Regulator of Expansion of Cytotoxic Intraepithelial CD8+ T Cells That Maintains Homeostasis in the Small Intestine.
abstract: OBJECTIVE
  Intraepithelial T lymphocyte cells (IEL) are the first immune cells to respond to pathogens; they help maintain the integrity of the epithelial barrier. We studied the function of the mouse glycoprotein Signaling Lymphocyte Activation Molecule Family receptor (SLAMF) 4 (encoded by Slamf4) on the surface of CD8αβ αβ T-cell receptor (TCR)(+) IELs, and the roles of these cells in homeostasis of the small intestine in mice.
  
  
  METHODS
  SLAMF4(-) CD8(+) αβTCR(+) cells isolated from spleens of OT-I Rag1(-/-) mice were induced to express gut-homing receptors and transferred to C57BL/6J mice; levels of SLAMF4(+) cells were measured in small intestine tissues. After administration of anti-CD3 or antigen, with or without anti-SLAM4, to C57BL/6J and Slamf4(-/-) mice, CD8αβ αβTCR(+) IELs were collected; cytokine production and cytotoxicity were measured. Depletion of CX3CR1(+) phagocytes was assessed in mice by live-cell confocal imaging or by cytofluorometry; small intestine tissues were analyzed by histology and inflammation was quantified.
  
  
  RESULTS
  Splenic CD8(+) αβTCR(+) cells began to express SLAMF4 only after migrating to the small intestine. Injection of C57BL/6J mice with anti-SLAMF4 and anti-CD3 increased levels of interleukin 10 and interferon gamma secretion by IEL, compared with injection of anti-CD3 only. Similarly, the number of granzyme B(+) cytotoxic CD8(+) αβTCR(+) IELs increased in Slamf4(-/-) mice after injection of anti-CD3 and anti-SLAMF4, administration of antigen, or injection of anti-CD3. Surprisingly, in vivo activation of CD8αβ(+) IELs with anti-CD3 or antigen caused transient depletion of CX3CR1(+) phagocytes, which was prolonged by co-injection with anti-SLAMF4 or in Slamf4(-/-) mice. Anti-CD3 aggravated inflammation in the small intestines of Slamf4(-/-) mice and Eat2a(-/-)Eat2b(-/-) mice, indicated by flattened villi and crypt hyperplasia.
  
  
  CONCLUSIONS
  In mice, the intestinal environment induces SLAMF4 expression and localization to the surface of CD8(+) αβTCR(+) IELs. Signaling via SLAMF4 controls expansion of cytotoxic CD8αβ(+) IELs, which regulate the reversible depletion of lamina propria phagocytes and inflammation in the small intestine.
authors: Division of Immunology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
authors: Michael S
authors: MS
authors: O'Keeffe
authors: Gastrointestinal Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Joo-Hye
authors: JH
authors: Song
authors: Division of Immunology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts. Electronic address: gliao@bidmc.harvard.edu.
authors: Gongxian
authors: G
authors: Liao
authors: Division of Immunology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
authors: Jaime
authors: J
authors: De Calisto
authors: Division of Immunology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
authors: Peter J
authors: PJ
authors: Halibozek
authors: Gastrointestinal Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: J Rodrigo
authors: JR
authors: Mora
authors: Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Atul K
authors: AK
authors: Bhan
authors: Division of Immunology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
authors: Ninghai
authors: N
authors: Wang
authors: Gastrointestinal Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors: Hans-Christian
authors: HC
authors: Reinecker
authors: Division of Immunology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts. Electronic address: cterhors@bidmc.harvard.edu.
authors: Cox
authors: C
authors: Terhorst
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000172:deficiency / Q000235:genetics; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D000073883:CX3C Chemokine Receptor 1; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis; D006965:Hyperplasia; D007413:Intestinal Mucosa / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D007421:Intestine, Small / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008213:Lymphocyte Activation; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010586:Phagocytes / Q000276:immunology / Q000378:metabolism; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology / Q000378:metabolism; D019707:Receptors, Chemokine / Q000235:genetics / Q000378:metabolism; D011971:Receptors, Immunologic / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D000071176:Signaling Lymphocytic Activation Molecule Family; D013154:Spleen / Q000276:immunology / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015703:Antigens, CD; D000073883:CX3C Chemokine Receptor 1; C490007:Cd244a protein, mouse; C471885:Cx3cr1 protein, mouse; D016207:Cytokines; C511062:Eat2a protein, mouse; C511063:Eat2b protein, mouse; D018398:Homeodomain Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D019707:Receptors, Chemokine; D011971:Receptors, Immunologic; D000071176:Signaling Lymphocytic Activation Molecule Family; C064658:RAG-1 protein; D049452:Green Fluorescent Proteins
keywords: Immune Regulation; Immunity; Intestinal Epithelium; T-Cell Development