title: TNFalpha blockade in human diseases: mechanisms and future directions.
abstract: Tumor necrosis factor-alpha (TNFalpha) antagonists have shown remarkable efficacy in a variety of immune-mediated inflammatory diseases (IMIDs). Therapeutic scope and limitations of these agents are reviewed in a recently published article in the Journal. In spite of their therapeutic popularity, little is known about their modes of action in vivo and factors that limit their scope of therapeutic use. Intriguingly, while all TNFalpha antagonists including blocking antibodies and soluble receptors are effective in certain IMIDs, only anti-TNFalpha antibodies are effective in other IMIDs. Early efforts at understanding how TNFalpha antagonists act in IMIDs centered on their ability to neutralize soluble TNFalpha or to block TNF receptors from binding to their ligands. Subsequent studies suggested a role of complement-mediated lysis or antibody-dependent cell cytotoxicity in their therapeutic effects. More recent models postulate that TNFalpha blockers may act by affecting intracellular signaling, with the end result being a hastened cell cycle arrest, apoptosis, suppression of cytokine production, or improved Treg cell function. TNFalpha antagonists can also modulate the functions of myofibroblasts and osteoclasts, which might explain how TNFalpha antagonists reduce tissue damage in chronic IMIDs. Focusing on the human therapeutic experience, this analytical review will review the biology of mechanisms of action, the limiting factors contributing to disease restriction in therapeutic efficacy, and the mechanism and frequency of treatment-limiting adverse responses of TNFalpha antagonists. It is hoped that the overview will address the needs of clinicians to decide on optimal use, spur clinical innovation, and incite translational researchers to set priorities for in vivo human investigations.
authors.affiliation: UCLA David Geffen School of Medicine, Los Angeles, CA 90095, USA.
authors.forename: Maida
authors.initials: M
authors.lastname: Wong
authors.forename: David
authors.initials: D
authors.lastname: Ziring
authors.forename: Yael
authors.initials: Y
authors.lastname: Korin
authors.forename: Sheetal
authors.initials: S
authors.lastname: Desai
authors.forename: Sungjin
authors.initials: S
authors.lastname: Kim
authors.forename: Jan
authors.initials: J
authors.lastname: Lin
authors.forename: David
authors.initials: D
authors.lastname: Gjertson
authors.forename: Jonathan
authors.initials: J
authors.lastname: Braun
authors.forename: Elaine
authors.initials: E
authors.lastname: Reed
authors.forename: Ram Raj
authors.initials: RR
authors.lastname: Singh
mesh_terms: D000068879:Adalimumab; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000009:adverse effects / Q000627:therapeutic use*; D000911:Antibodies, Monoclonal / Q000009:adverse effects / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized; D018501:Antirheumatic Agents / Q000009:adverse effects / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000276:immunology; D016207:Cytokines / Q000276:immunology / Q000378:metabolism*; D000068800:Etanercept; D006801:Humans; D007074:Immunoglobulin G / Q000009:adverse effects / Q000627:therapeutic use; D007249:Inflammation / Q000188:drug therapy* / Q000276:immunology; D015212:Inflammatory Bowel Diseases / Q000188:drug therapy* / Q000276:immunology; D000069285:Infliximab; D018124:Receptors, Tumor Necrosis Factor / Q000276:immunology / Q000378:metabolism / Q000627:therapeutic use; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D018501:Antirheumatic Agents; D016207:Cytokines; D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D000069285:Infliximab; D000068879:Adalimumab; D000068800:Etanercept