Chikafumi Arita

Limb allografts in rats immunosuppressed with FK506. I: Reversal of rejection and indefinite survival

We have tested the effects of FK506 (FK), a new immunosuppressive agent, on a rat limb allograft model. Histoincompatible BN limb allografts were rejected in untreated F344 hosts within 11±1 days (mean ± SD) after operation. A single injection of 2 mg/kg, 10 mg/ kg, or 50 mg/kg of FK on the day of limb transplantation (day 0) significantly prolonged graft survival in a dose-dependent manner—i.e., mean limb survival times (MST) based on gross signs of skin rejection were 16±3 days, 51 ±6 days, or 104±17 days, respectively (P < 0.01). Delayed treatment with a single injection of 10 mg/kg of FK at when early signs of rejection were visible (day 7 or day 10) reversed the ongoing rejection. The MSTs in these groups were comparable to that of those treated with the same dosage of FK on day 0. The FK-induced unresponsiveness toward limb allografts was donor-specific because limb-allografted, FK-protected rats could not accept the skin grafts from a third-party donor. In the next set of experiments, rats were given a single administration of 10 mg/kg of FK on the day of limb allograft, followed by intermittent injections of 3 mg/kg of FK once a week. This regimen produced complete graft survival for more than 200 days, though Pneumocyatis carinii pneumonia occurred in most of the recipients. These results represent the unique effects of FK in preventing or reversing the graft rejection and in inducing indefinite survival in this animal model of composite tissue allografts.

Limb allografts in rats immunosuppressed with cyclosporine: as a whole-joint allograft.

We performed limb allografts in three inbred rat strains immunosuppressed with cyclosporine. As controls, 10 autografts and 10 isografts exhibited an excellent result. In minor-mismatched allografts (Lewis to Fischer, n = 45), with the use of cyclosporine, the grafted limbs survived and the articular cartilage retained normal architecture and cell viability 52 weeks after grafting, but without cyclosporine treatment severe degeneration and destruction of articular cartilage were shown by 16 weeks after operation. In major-mismatched allografts (Brown Norway to Fischer, n = 35), the articular cartilage of cyclosporine-treated animals maintained normal architecture and cell viability 52 weeks after operation despite the gross appearance of skin rejection, while that of non-cyclosporine-treated animals was degenerated and destroyed by 6 weeks. These results suggest the possibility of whole-joint allografts in humans with the use of cyclosporine, as well as other organ transplantations.

Serum transfer of collagen arthritis to cyclosporin-treated, type II collagen-tolerant rats

Collagen arthritis has been passively transferred with a serum concentrate from immunized donors to immunologically naive recipients as well as cyclosporin-treated, type II collagen-tolerant rats. These findings point to an important role for anticollagen antibody and appear to rule out a role for cellular immunity to type II collagen in the initiation of this disease. The passively transferred arthritis was a transient lesion in the majority of naive recipients and in the cyclosporin-treated, type II collagen-tolerant rats as well when a serum concentrate was transferred after the cessation of cyclosporin treatment. When cyclosporin-treated, type II collagen-tolerant rats received transfer concentrate while cyclosporin was administered continuously, arthritis was significantly enhanced, and lasted as long as cyclosporin was administered and in the majority of rats up to 2 weeks after the cessation of cyclosporin treatment. These results, together with a rapid clearance of anticollagen antibody from the serum, suggest that anticollagen antibody is not the sole regulatory factor and that a cellular suppressor system, sensitive to cyclosporin, might participate in the regulation of this disease process.

Inhibition by FK506 of established lesions of collagen-induced arthritis in rats

We investigated the superior poteney of the immunosuppressive agent FK506 on collagen‐induced arthritis in rats. In our initial studies, we demonstrated that only one shot administration of FK506 at a dose of 10 mg/kg on the same day as type II collagen immunization suppressed the incidence of arthritis completely as well as humoral and delayed‐type hypersensitivity (DTH) skin lest responses to type II collagen. Yet no major side effects were observed in the rats treated with such a high dose of FK506. Additional studies demonstrated that pretreatment with FK506 on day — 7 or day — 3 was effective in suppressing the severity of arthritis and immune responses to type II collagen. The immunosuppressive effect of a single high‐dose administration of FK506 continued for at least 1 week in this animal model of arthritis. A single administration of FK506 at a dose of 10 mg/kg on day 12 or 15, after the clinical onset of arthritis, was also effective in suppressing the severity of arthritis and immune response to type II collagen. We conclude that FK506, in this model, possesses an important, curative action when applied therapeutically. The outlook of FK506 treatment in clinical autoimmunity is promising at present.

Suppression of collagen arthritis in rats by heterologous anti-idiotypic antisera against anticollagen antibodies

Affinity-purified rat anti-type II collagen antibodies were used to prepare anti-idiotypic antibodies in rabbits. It has been demonstrated that such anti-idiotypic antibodies are capable of binding to anti-type II collagen antibodies in vitro. Intravenous administration of heterologous anti-idiotypic antisera at the time of immunization with type II collagen resulted in a significant suppression of anti-type II collagen antibody formation and the development of arthritis, although delayed-type hypersensitivity skin test response to type II collagen was not affected. However, treatment of rats with heterologous anti-idiotypic antisera at Day 7 after immunization was ineffective in altering disease expression. On the other hand, treatment with heterologous anti-idiotypic antisera had no significant suppressive effect on the incidence or severity of adjuvant arthritis. These results indicate that the effect of heterologous anti-idiotypic antisera directed toward anti-type II collagen antibodies is disease specific and is restricted to collagen arthritis.

Comparative studies of the effects of FK506 and cyclosporin A on passively transferred collagen-induced arthritis in rats

We investigated the effect of a novel immunosuppressive agent, FK506, in comparison with cyclosporin A (CsA) on the development of passive arthritis induced by anti-type II collagen (CII) antisera in rats. FK506 pretreatment shortly before serum transfer markedly suppressed the incidence and the severity of passive arthritis, while CsA pretreatment had no observable effects on this disease when used in doses sufficient to suppress the development of active arthritis induced by CII immunization. In an additional study, we examined whether these agents affect antibody-mediated tolerance induction. CII-specific immunological tolerance was induced by serum transfer, but was unaffected by either FK506 or CsA pretreatment in our regimen. While its precise mechanism of the immunosuppressive activity remains to be elucidated, FK506 can act on the antibody-mediated effector phase of arthritis and may offer new insights into the possible role of potential therapeutic utility in human autoimmune diseases.

Reversal of antigen-induced resistance to collagen arthritis by cyclophosphamide

Treatment of rats with intravenous injection of 1 mg of soluble native type II collagen induced resistance against the subsequent induction of active arthritis by type II collagen immunization. This resistant state was accompanied by suppressed antibody response and delayed-type hypersensitivity (DTH) skin reaction to type II collagen. However, pretreatment of rats with 20 mg/kg of cyclophosphamide (CY), an agent reputed to damage suppressor T-cell function, 2 days before intravenous injection of soluble type II collagen abrogated the antigen-induced resistance against the subsequent induction of active arthritis. The DTH skin reaction to type II collagen was completely restored and the antibody response to type II collagen was significantly though not completely restored by CY pretreatment. These results provide evidence that antigen-induced resistance to collagen arthritis is mediated, at least in part, under the control of CY-sensitive events.

Effect of cyclophosphamide and its analogs on collagen arthritis in rats

The effects of cyclophosphamide (CY) and its structurally related analogs, ifosfamide (Ifo), sufosfamide (Sufo), and mafosfamide (Mafo), on collagen arthritis in Sprague-Dawley rats were examined. Prophylactic treatment with 7.5-10 mg/kg/day of CY. 15 mg/kg/day of Ifo, and 10-15 mg/kg/day of Sufo for the first 10 days starting on the same day as the type II collagen immunization suppressed arthritis induction as well as humoral immune response to type II collagen. Prophylactic treatment with Mafo at doses ranging from 10 to 40 mg/kg/day for 10 days was ineffective in suppressing the disease development. When drug treatment was started only during the immediate preclinical phase of arthritis, the development of arthritis was suppressed in the animals treated with 10 mg/kg/day of CY and 15 mg/kg/day of Ifo from Day 5 to Day 14. Additional studies demonstrated that treatment with 10 mg/kg/day of CY and 15 mg/kg/day of Ifo started at the time of disease onset significantly suppressed the severity of arthritis compared with the control group. These results show the effectiveness of Ifo and CY on this animal model of polyarthritis and suggest the possibility of clinical use of Ifo for the treatment of human arthritides similar to CY.

High‐density proteoglycan induces specific suppression of adjuvant‐induced arthritis in rats

In vitro data support the view that T cells in adjuvant‐induced arthritis (AIA) respond to the proteoglycan (PG) component of articular cartilage; however, an in vivo role for PG in AIA has yet to be shown. To do so. we examined the effects of pretreatment with bovine cartilage high density PG (HDPG) on AIA induced by heat‐killed Mycobacterium butyricum in Lewis rats. Purified bovine cartilage HDPG emulsified in Freunds incomplete adjuvant (FIA) was injected intradermally into rats 7 days before challenge with Myco. butyricum. The severity of arthritis was significantly suppressed in rats pretreated with as little as 0.75 mg of HDPG, and the arthritis was completely suppressed in rats pretreated with 3.0 mg of HDPG. This suppression was specific, as the same treatment did not protect against type II collagen‐induced arthritis. Suppression of AIA is primarily a property of the HDPG, as suppression of the arthritis was significantly less with pretreatment with 3.0 mg of middle density fractions of PG, and no suppression was observed with pretreatment with the lowest density fraction of PG. Thus we report that pretreatment with cartilage HDPG, but not lower density PG, can induce specific suppression of AIA. These in vivo results support the view that immunity to cartilage HDPG plays a major role in the pathogenesis of AIA, and can induce specific tolerance to this type of arthritis.

Enhancing effects of tilorone on collagen arthritis and humoral immune response to type II collagen

The effect of tilorone, which is known to suppress adjuvant arthritis, on the induction of collagen arthritis in rats was investigated. Combined data of the present experiments show that all of the tilorone-treated rats except one in the lowest dosage group developed arthritis but that the incidence of arthritis in the tilorone-treated groups was not significantly different from that of the control group. The results also show that the two higher dosages (12.5 and 25 mg/kg/day) of tilorone caused a significant increase in the severity of collagen arthritis. Humoral immune response to type II collagen was significantly augmented in these two higher dosage groups; however, delayed-type hypersensitivity response to type II collagen was suppressed while tilorone was administered continuously. In addition, treatment with tilorone caused a significant increase in the concentration of anticollagen IgG extractable from the joint tissue. Anticollagen IgG subclass analysis revealed that the major subclass was IgG2a in both the serum and paw extract, with minor amounts of IgG2b, IgG2c, and IgG1. The response of all these subclasses was almost equally activated by tilorone treatment.