Prophylactic and therapeutic effects of a humanized monoclonal antibody against the IL-2 receptor (DACLIZUMAB) on collagen-induced arthritis (CIA) in rhesus monkeys

CIA in the rhesus monkey is an autoimmune-based polyarthritis with inflammation and erosion of synovial joints that shares various features with human rheumatoid arthritis (RA). The close phylogenetic relationship between man and rhesus monkey makes the model very suitable for preclinical safety and efficacy testing of new therapeutics with exclusive reactivity in primates. In this study we have investigated the prophylactic and therapeutic effects of a humanized monoclonal antibody (Daclizumab) against the alpha-chain of the IL-2 receptor (CD25). When Daclizumab treatment was started well after immunization but before the expected onset of CIA a significant reduction of joint-inflammation and joint-erosion was observed. A therapeutic treatment, initiated as soon as the first clinical signs of CIA were observed, proved also effective since joint-degradation was abrogated. The results of this study indicate that Daclizumab has clinical potential for the treatment of RA during periods of active inflammation and suppression of the destruction of the joint tissues.

Bispecific humanized anti-IL-2 receptor alpha beta antibodies inhibitory for both IL-2- and IL-15-mediated proliferation

Humanized anti-Tac (HAT) and Mik beta1 (HuMik beta 1) Abs directed at IL-2R alpha and IL-2R beta, respectively, inhibit IL-2 binding and biological activity and together act synergistically in vitro. The Abs have been used successfully in primate models of allograft rejection, graft-vs-host disease, and autoimmunity. We produced bifunctional humanized anti-IL-2R alpha beta Abs (BF-IgG) to combine the specificity of the two Abs into one entity by fusing HAT-producing NSO cells and HuMik beta 1-producing Sp2/0 cells. BF-IgG was purified using protein G-Sepharose affinity chromatography, followed by IL-2R alpha and IL-2R beta affinity chromatography and hydrophobic interaction chromatography. BF-IgG exhibited both anti-IL-2R alpha and anti-IL-2R beta specificities in binding assays. While the Ab binds the IL-2R with intermediate affinity (Kd = 2.82 nM), it does not inhibit IL-15 binding to its high affinity IL-15R. In Kit225/K6 (IL-2R alpha beta gamma+) cells, BF-IgG was 10-fold more potent than a HAT/HuMik beta 1 equimolar mixture in blocking IL-2-induced proliferation and, unexpectedly, was at least 65-fold more active than the mixture in blocking IL-15-induced proliferation. This dual inhibitory activity may be due to cross-linking of the IL-2R alpha and IL-2R beta, thus blocking IL-2 binding and possibly impeding the association of IL-2R beta with IL-15R. BF-IgG has potent immunosuppressant activities against both IL-2- and IL-15-mediated responses, and this antagonist could be more efficacious than HAT and/or HuMik beta 1 for the treatment of autoimmunity and the prevention of allograft rejection.

Bispecific humanized anti-IL-2 receptor alpha beta antibodies inhibitory for both IL-2- and IL-15-mediated proliferation

Humanized anti-Tac (HAT) and Mik beta1 (HuMik beta 1) Abs directed at IL-2R alpha and IL-2R beta, respectively, inhibit IL-2 binding and biological activity and together act synergistically in vitro. The Abs have been used successfully in primate models of allograft rejection, graft-vs-host disease, and autoimmunity. We produced bifunctional humanized anti-IL-2R alpha beta Abs (BF-IgG) to combine the specificity of the two Abs into one entity by fusing HAT-producing NSO cells and HuMik beta 1-producing Sp2/0 cells. BF-IgG was purified using protein G-Sepharose affinity chromatography, followed by IL-2R alpha and IL-2R beta affinity chromatography and hydrophobic interaction chromatography. BF-IgG exhibited both anti-IL-2R alpha and anti-IL-2R beta specificities in binding assays. While the Ab binds the IL-2R with intermediate affinity (Kd = 2.82 nM), it does not inhibit IL-15 binding to its high affinity IL-15R. In Kit225/K6 (IL-2R alpha beta gamma+) cells, BF-IgG was 10-fold more potent than a HAT/HuMik beta 1 equimolar mixture in blocking IL-2-induced proliferation and, unexpectedly, was at least 65-fold more active than the mixture in blocking IL-15-induced proliferation. This dual inhibitory activity may be due to cross-linking of the IL-2R alpha and IL-2R beta, thus blocking IL-2 binding and possibly impeding the association of IL-2R beta with IL-15R. BF-IgG has potent immunosuppressant activities against both IL-2- and IL-15-mediated responses, and this antagonist could be more efficacious than HAT and/or HuMik beta 1 for the treatment of autoimmunity and the prevention of allograft rejection.

Humanized antibodies against the alpha-chain of the IL-2 receptor and against the beta-chain shared by the IL-2 and IL-15 receptors in a monkey uveitis model of autoimmune diseases

We studied the efficacy and tolerance of humanized Ab interfering with the signal of the IL-2 and IL-15 receptors in a primate model of experimental autoimmune uveoretinitis. The inhibitory effects of humanized anti-Tac (HAT), an anti-IL-2R alpha-chain Ab, and HuMik beta1, an Ab directed at the beta-chain shared by the receptors of IL-2 and IL-15, were tested in culture on the proliferative response of monkey Con A-blast lymphocytes stimulated with IL-2 or IL-15. Uveitis was induced in cynomolgus monkeys by immunization with human recombinant retinal S-antigen. Treatment was initiated at the first sign of disease and consisted of HAT and HuMik beta1, alone or in combination, or vehicle control given by i.v. injection twice a week for 4 wk. Disease was evaluated by ocular funduscopy. The results in culture showed a significant dose-dependent inhibition of the IL-2-driven proliferation of lymphocytes by HAT. HuMik beta1 alone was ineffective against IL-2 stimulation, but had a marked potentiating effect in combination with HAT, independent of IL-15 signaling. IL-15-driven proliferation was inhibited by HuMik beta1, but not by HAT alone or in combination. In monkeys, experimental autoimmune uveoretinitis evolution was significantly inhibited by HAT treatment. HuMik beta1 alone had no effect on the disease. However, when used in combination, the two Ab markedly reduced the severity of ocular inflammation. The Ab were well tolerated. Only three monkeys, treated with HAT alone, made an Ab response against the injected Ab.

Humanized antibodies against the alpha-chain of the IL-2 receptor and against the beta-chain shared by the IL-2 and IL-15 receptors in a monkey uveitis model of autoimmune diseases

We studied the efficacy and tolerance of humanized Ab interfering with the signal of the IL-2 and IL-15 receptors in a primate model of experimental autoimmune uveoretinitis. The inhibitory effects of humanized anti-Tac (HAT), an anti-IL-2R alpha-chain Ab, and HuMik beta1, an Ab directed at the beta-chain shared by the receptors of IL-2 and IL-15, were tested in culture on the proliferative response of monkey Con A-blast lymphocytes stimulated with IL-2 or IL-15. Uveitis was induced in cynomolgus monkeys by immunization with human recombinant retinal S-antigen. Treatment was initiated at the first sign of disease and consisted of HAT and HuMik beta1, alone or in combination, or vehicle control given by i.v. injection twice a week for 4 wk. Disease was evaluated by ocular funduscopy. The results in culture showed a significant dose-dependent inhibition of the IL-2-driven proliferation of lymphocytes by HAT. HuMik beta1 alone was ineffective against IL-2 stimulation, but had a marked potentiating effect in combination with HAT, independent of IL-15 signaling. IL-15-driven proliferation was inhibited by HuMik beta1, but not by HAT alone or in combination. In monkeys, experimental autoimmune uveoretinitis evolution was significantly inhibited by HAT treatment. HuMik beta1 alone had no effect on the disease. However, when used in combination, the two Ab markedly reduced the severity of ocular inflammation. The Ab were well tolerated. Only three monkeys, treated with HAT alone, made an Ab response against the injected Ab.

Regional patterns of cholinergic and glutamate activity in the developing and aging human brain

The levels of choline acetyltransferase (ChAT) and the binding activity of N-methyl-D-aspartate (NMDA) and non-NMDA receptors have been measured in the hippocampus, entorhinal cortex, frontal cortex and cerebellum, in a series of human brains from 24 weeks gestation to 100 years. The patterns of ChAT and glutamate receptor activity during aging and development were strikingly different in the different brain areas. In the hippocampus and associated cortex, ChAT activity did not reach a peak until middle age, when it almost immediately started to decline by 50-60% to the 10th decade, whereas in the frontal cortex ChAT peaked transiently in the infant and then stayed constant during aging. In the cerebellum ChAT activity was very high in the foetus and fell in the neonate to maintain a constant level more in line with the concentrations found in the other brain areas through the rest of life. The high levels of ChAT in the foetal cerebellum were not associated with high acetylcholinesterase (AChE) content, which tended to increase during development, and was present initially in Purkinje cells (foetus and neonate) and the molecular layer in the adult. In the hippocampus and entorhinal cortex, autoradiographic [3H]MK-801 binding was relatively constant throughout life, however, [3H]CNQX binding rose from the perinatal period up to a peak in the 1st or 2nd decade and then tended to fall with age. In the cerebellum, autoradiographic binding of both ligands rose from the foetal period to reach a plateau by the age of 10 years and there was no apparent further change during aging. These data on cholinergic and glutamatergic phenotypic changes during development and senescence reflect marked variations in regional plasticity and aging within and between the two transmitter systems and are likely to contribute to our understanding of their role in the different brain areas investigated.