Antagonizing the α4β1 Integrin, but Not α4β7, Inhibits Leukocytic Infiltration of the Central Nervous System in Rhesus Monkey Experimental Autoimmune Encephalomyelitis

Abstract

The immune system is characterized by the preferential migration of lymphocytes through specific tissues (i.e., tissue tropism). Tissue tropism is mediated, in part, by the α4 integrins expressed by T lymphocytes. The α4β1 integrin mediates migration of memory T lymphocytes into the CNS, whereas the α4β7 integrin mediates migration preferentially into gastrointestinal tissue. This paradigm was established primarily from investigations in rodents; thus, the objective of this investigation was to determine if blocking the α4β7 integrin exclusively would affect migration of T lymphocytes into the CNS of primates. The effects of the dual α4β1 and α4β7 antagonist natalizumab were compared with those of the α4β7 antagonist vedolizumab on experimental autoimmune encephalomyelitis in the rhesus monkey. Animals received an initial i.v. bolus of placebo, natalizumab (30 mg/kg), or vedolizumab (30 mg/kg) before intracutaneous immunization with recombinant human myelin oligodendrocyte glycoprotein and then Ab once weekly thereafter. Natalizumab prevented CNS inflammation and demyelination significantly (p < 0.05), compared with time-matched placebo control animals, whereas vedolizumab did not inhibit these effects, despite saturating the α4β7 integrin in each animal for the duration of the investigation. These results demonstrate that blocking α4β7 exclusively does not inhibit immune surveillance of the CNS in primates.