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Intravenous immunoglobulin treatment of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis
Journal of the Neurological Sciences 233 (2005) 61 – 65 www.elsevier.com/locate/jns
Intravenous immunoglobulin treatment of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis Signe Humle Jorgensen*, Per Soelberg Sorensen Copenhagen MS Centre, Department of Neurology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark Available online 22 April 2005
Abstract Intravenous immunoglobulin (IVIG) is an established treatment of immune-mediated demyelinating neuropathy. Since IVIG possesses multiple immunomodulatory and anti-inflammatory properties, IVIG therapy may represent a way of interfering with the disease process in multiple sclerosis (MS). In the MS animal model experimental autoimmune encephalomyelitis (EAE), infusions of IVIG significantly reduced disease symptoms as well as the underlying CNS pathology. IVIG was only effective in EAE when administered in a prophylactic treatment protocol, since IVIG infusions during the established phase of EAE did not alter the disease course or the degree of inflammation found in the central nervous system. IVIG also has the potential to act through myelin repair mechanisms as evidenced by work done in the Theilers murine encephalomyelitis virus model of demyelination. Together these observations have led to certain expectations for IVIG as a treatment for MS, and have resulted in various clinical trials. Several controlled trials report beneficial effects of IVIG on relapse rate, new MRI lesions, and disease progression in relapsing – remitting MS, while a remyelinating effect of IVIG has not been documented. IVIG is, therefore, presently regarded as a second-line therapy of MS. D 2005 Elsevier B.V. All rights reserved. Keywords: Intravenous immunoglobulin; Immunoglobulin G; Experimental autoimmune encephalomyelitis; Multiple sclerosis; Controlled trials
1. Introduction The commercial preparations of immunoglobulin for intravenous administration (IVIG) consist of purified immunoglobulin obtained from several thousands healthy blood donors, and therefore contain polyclonal antibodies with a variety of specificities. The immunoglobulin in IVIG, which is mainly of the IgG subclass, represents intact antibody molecules with retained biological properties, and accordingly, IVIG has multiple possible mechanisms of actions owing to reactions of both the variable regions and the constant Fc regions of the antibody molecules (Table 1) [1,2]. IVIG was introduced several decades ago as replacement therapy for antibody deficiencies. Since then, IVIG has also established its role as a treatment of disorders where the immune system mediates peripheral demyelinating neuro-
* Corresponding author. Tel.: +45 35 45 28 88; fax: +45 35 45 67 13. E-mail address: [email protected] (S. Humle Jorgensen). 0022-510X/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jns.2005.03.005
pathy, e.g. the Guillan-Barre´ syndrome and chronic inflammatory demyelinating polyneuropathy (CIPD) [3]. In the management of autoimmunity, IVIG was initially introduced because of the capacity to suppress the activity of autoantibodies through anti-idiotypic interactions [4,5]. Later however, IVIG was also recognised as being effective in autoimmune diseases mediated by pathogenic T lymphocytes [6,7]. Furthermore, IVIG may modulate macrophage functions, interfere with the production of cytokines, and inhibit the complement system (Table 1). As a result of IVIG being able to interfere with the immune system at both the cellular and the humoral level, it is considered a potential treatment in MS, where IVIG may target multiple components in the disease pathology. This view has been advanced further by findings in the classical MS animal model experimental autoimmune encephalomyelitis (EAE), where studies have been performed to explore the IVIG mechanisms of action, and have provided supportive evidence for beneficial effects of IVIG in inflammatory CNS demyelination.
62
S. Humle Jorgensen, P.S. Sorensen / Journal of the Neurological Sciences 233 (2005) 61 – 65
Table 1 Immunomodulation by IVIG Target
Regulatory effects
T lymphocytes
Regulation of cytokine production Neutralisation of T-cell superantigens Inhibition of B-cell differentiation Selective regulation of antibody production Blocking of effector cells by FcR saturation and FcR downregulation Inhibition of antibody-dependent cellular cytotoxicity Elimination of autoantibodies by increased catabolism Inhibition of pathogenic antibodies by anti-idiotypic network Modulation of mononuclear cell cytokine production Induction of anti-inflammatory cytokines Binding of complement components Attenuation of complement activation
B lymphocytes Fc Receptors
Antibodies Cytokines Complement
8 and 9 p.i. Throughout the study, animals were evaluated on a daily basis for weight loss and neurological symptoms of active disease. The symptoms of EAE were assessed according to the following scoring system: 0—no clinical signs; 1—tail paralysis; 2—mild to moderate hind limb paresis; 3—severe hind limb paresis; 4—paralysis of the limbs; 5—quadriplegia; 6—moribund state or death from EAE. The experiments were ended after 4 weeks and samples of the spinal cord and the brain were dissected and processed for histological examination. Clinical symptoms of active EAE disease were observed 1 week after the immunisation, where rats in the placebo group experienced a profound weight loss. If animals received the treatment with IVIG at days 0 – 1 p.i., the loss of body weight was significantly reduced. When IVIG was administered at days 8– 9 p.i. when the symptoms of EAE were evident, the treatment had no effect on the body weight changes. Development of the neurological EAE symptoms coincided with the observed body weight changes, and early treatment with immunoglobulin resulted in a less severe course of the disease with mild or even absent clinical symptoms of EAE (Fig. 1A). When the infusions of IVIG were given during established disease, however, no significant treatment effects could be observed (Fig. 1B). In tissue samples from the central nervous system obtained 4 weeks after the induction of EAE, the inflammatory changes and demyelination were evaluated in paraffin sections cut for histological analysis. The principal findings were a pronounced inflammatory response in both the brain and spinal cord, predominantly perivascular infiltrations, but areas with demyelination were also observed. Treatment with IVIG before the onset of EAE symptoms significantly inhibited the inflammatory response as evaluated by blinded scoring of the histological findings (Table 2). In summary, intravenous treatment with human polyclonal immunoglobulin G had significant effects on both
In recent years, focus has been set on the benefits of using IVIG in the treatment of multiple sclerosis (MS), and various clinical trials have been performed to address this.
2. IVIG treatment of experimental autoimmune encephalomyelitis In susceptible strains of rats, a protracted and relapsing type of demyelinating EAE may be induced by inoculating animals with a homogenate of incomplete Freund’s adjuvant and syngenic spinal cord tissue from healthy animals [8,9]. We induced this type of EAE in the inbred rat strain Dark Agouti (DA) and treated the animals with intravenous infusions of human IVIG (1 g/kg) or a placebo solution after the immunisation procedure [10]. The IVIG infusions were administered at two consecutive days: As prophylactic treatment at the time of EAE induction at days 0 and 1 post immunisation (p.i.), or in a therapeutic treatment protocol at the beginning at the acute EAE attack at days
A
4
B
IVIG Placebo
IVIG Placebo
3
EAE score
3
EAE score
4
2
2
1
1
0
0 0
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30
day p.i.
0
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30
day p.i.
Fig. 1. EAE score. Scoring of the neurological symptoms at day 0 – 28 after the immunisation with encephalitogenic homogenate. The values are mean SEM (n = 12 in each group). Arrows indicate the administration of placebo or IVIG. When the infusions were given in the early treatment protocol (panel A), significant effects of IVIG were observed (*p < 0.05, Mann – Whitney rank sum test).
S. Humle Jorgensen, P.S. Sorensen / Journal of the Neurological Sciences 233 (2005) 61 – 65
63
Table 2 Histological score Infusion days 0 – 1 p.i.
Brain Spinal Cord Cervical Spinal Cord Lumbar
Infusion days 8 – 9 p.i.
IVIG
Placebo
IVIG
Placebo
0.8 T 0.1* (n = 12) 1.6 T 0.3 (n = 12) 0.9 T 0.3* (n = 12)
1.4 T 0.2 (n = 11) 1.9 T 0.3 (n = 11) 1.7 T 0.3 (n = 11)
1.4 T 0.3 (n = 8) 2.1 T 0.4 (n = 8) 1.5 T 0.3 (n = 8)
1.3 T 0.3 (n = 8) 2.0 T 0.3 (n = 8) 1.9 T 0.4 (n = 8)
The average histological score evaluated in the brain, cervical, and lumbar spinal cord segments by the following scoring system: 0—no inflammation; 1— minor perivascular infiltrations; 2—several perivascular and parenchymal infiltrations; 3—maximal inflammatory response and demyelination. Prophylactic infusions of IVIG reduced the inflammatory changes in the CNS significantly (*p < 0.05, Mann – Whitney rank sum test), while administration of IVIG during established EAE disease had no apparent effects on the histological findings.
disease course and CNS inflammation in EAE, but only when administered at the time of immunisation. In addition to these anti-inflammatory actions of IVIG it is of special interest with regard to demyelinating diseases that immunoglobulin may also be implicated in myelin repair or remyelination. This effect of IVIG has been suggested by observations in a different experimental animal model, the Theiler’s murine encephalomyelitis virus (TMEV) model of demyelination.
3. IVIG and remyelination The possible remyelinating potential of IVIG preparations has been based on studies in the TMEV model [11]. This experimental model of immune-mediated demyelination resembles the pattern of progressive MS with chronic CNS demyelination and a progressive loss of motor function. Originally, Rodriguez and co-workers observed that in the TMEV model of demyelination, immunisation with a spinal cord homogenate promoted remyelination [12]. Later it was discovered that the beneficial effects could be attributed to the presence of certain antibodies that were directed against myelin components. These antibodies were characterised as being able to bind to oligodendrocytes, suggesting that the remyelinating effects of the immunoglobulins were mediated by direct stimulation of the myelinproducing cells within the CNS [13]. The auto-reactive antibodies with remyelinating potential appear to occur naturally in the plasma of healthy individuals. Hence, commercial preparations of IVIG could be of therapeutic value in MS, not only due to antiinflammatory effects of the polyclonal immunoglobulins, but also by promoting myelin repair. These considerations have led to certain expectations for IVIG as a treatment for MS, since remyelination is an important therapeutic goal to prevent axonal damage following demyelination.
[14 –17]. In the controlled studies a beneficial effect of IVIG therapy on the MS disease activity could be demonstrated by a significant reduction of the relapse rate and a reduced change in the mean Kurtzke expanded disability status scale (EDSS) (Table 3). Favourable effects were also observed in the two trials that included MRI outcome measures [16,17]. In these studies treatment with IVIG reduced the number of new and total gadolinium-enhancing lesions in the brain. Since the four controlled trials have included relatively small numbers of patients, a meta-analysis was recently published in order to provide an overall evaluation of the benefits of IVIG in relapsing – remitting MS [18]. The results from the meta-analysis confirmed that IVIG significantly reduces the annual relapse rate, the proportion of relapse-free patients, and the disease progression as measured by the change in EDSS score. In the treatment of relapsing – remitting MS, the beneficial effects of IVIG on relapse rate and gadolinium-enhancing lesions were of the same magnitude as treatment with glatiramer acetate or interferon-h. Furthermore, there was a reduction in the overall progression of disease, since the proportion of patients with clinical deterioration was reduced after IVIG treatment. However, the efficacy of IVIG still needs to be confirmed in additional controlled clinical trials, as does determination of the optimal IVIG dose. Recently, the large phase 3 trial European Study on Immunoglobulin in MS, or ESIMS, has been completed
Table 3 Randomised clinical trials of IVIG in relapsing – remitting MS Study
N
Primary Beneficial effects of IVIG on: end point
Fazekas 150 EDSS et al. [14] changes Achiron et al. [15] Sorensen et al. [16]
40 Relapse rate 26 MRI lesions
Lewanska et al. [17]
49 Relapse rate
4. IVIG in clinical trials The effects of IVIG on relapsing –remitting MS have been studied in a number of open clinical trials and in four randomised, double-blind and placebo-controlled studies
Change in EDSS Mean annual relapse rate Proportion of relapse-free patients Annual relapse rate Trend towards reduced change in EDSS Number of gadolinium contrast-enhancing lesions New gadolinium-enhancing lesions Number of relapses Relapse rate Change in EDSS
Primary end points and parameters with significant beneficial results of IVIG therapy.
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S. Humle Jorgensen, P.S. Sorensen / Journal of the Neurological Sciences 233 (2005) 61 – 65
[19,20]. This study focused on IVIG in the progressive phase of MS and included 318 patients with clinically definite secondary progressive MS. The outcome of the ESIMS study was negative, as no significant differences were found in the delay of clinical progression, the primary outcome measure. The change in lesion volume by MRI was also unaffected by IVIG treatment [20]. Other clinical trials have aimed at investigating the effects of IVIG on the acute exacerbations that often occur after childbirth in MS patients with a relapsing –remitting disease course. Administration of IVIG after delivery has been found to reduce the occurrence of these relapses significantly, and in a number of cases IVIG treatment was even observed to prevent the acute exacerbations associated with childbirth [21,22]. The multicentre study, Gammaglobulins in the Post Partum Period in MS for Prevention of Exacerbations after delivery (GAMPP), was recently concluded and publication of the trial results is pending. IVIG has also been evaluated in clinical trials for a possible remyelinating effect in MS. The placebo-controlled clinical trials focused on the effects of IVIG on optic neuritis [23] or permanent motor deficits [24,25] as indirect measures of possible remyelination effects. Apart from one small open trial [26], these studies have not been able to detect a positive effect of the IVIG administration. However, it is conceivable that the permanent loss of sight or permanent muscle weakness may be a result from axonal loss rather than actual demyelination.
5. Conclusions In summary, prophylactic treatment with IVIG is effective in EAE if administered at the time of induction, and significantly reduces the symptoms of disease as well as the underlying CNS pathology. Therapeutic IVIG treatment of established EAE has not proven effective. The effects of IVIG may be brought about by immunological specificity at the variable regions of the antibody molecules and by the effector properties mediated by conserved antibody Fc regions. Moreover, IVIG has the potential to act through myelin repair mechanism as evidenced by the studies in experimental TMEV demyelination. Beneficial effects of IVIG on relapses, disability, and MRI changes in MS have been reported in the relapsing – remitting type of the disease, the effects being of a magnitude comparable to that of interferon-h and glatiramer acetate. Clinical trials have not been able to establish an effect of IVIG on the progressive phase of MS or confirm the presence of a remyelinating effect of IVIG. Therefore, IVIG is at present regarded as a valuable second-line alternative in the treatment of relapsing – remitting MS, and may be offered to patients that are unwilling to receive frequent injections or have contraindications to first-line therapies. Moreover, the large dose-finding study still needs
to be completed in order to determine the most effective dose of IVIG in relapsing – remitting MS.
References [1] Kazatchkine MD, Kaveri SV. Immunomodulation of autoimmune and inflammatory diseases with intravenous immune globulin. N Engl J Med 2001;345:747 – 55. [2] Stangel M, Toyka KV, Gold R. Mechanisms of high-dose intravenous immunoglobulins in demyelinating diseases. Arch Neurol 1999; 56:661 – 3. [3] Dalakas MC. Intravenous immune globulin therapy for neurologic diseases. Ann Intern Med 1997;126:721 – 30. [4] Kaveri S, Prasad N, Vassilev T, Hurez V, Pashov A, Lacroix-Desmazes S, et al. Modulation of autoimmune responses by intravenous immunoglobulin (IVIg). Mult Scler 1997;3:121 – 8. [5] Rossi F, Dietrich G, Kazatchkine M. Anti-idiotypes against autoantibodies in normal immunoglobulins: evidence for network regulation of human autoimmune responses. Immunol Rev 1989;110:135 – 49. [6] Amran D, Renz H, Lack G, Bradley K, Gelfand EW. Suppression of cytokine-dependent human T-cell proliferation by intravenous immunoglobulin. Clin Immunol Immunopathol 1994;73:180 – 6. [7] Aktas O, Waiczies S, Grieger U, Wendling U, Zschenderlein R, Zipp F. Polyspecific immunoglobulins (IVIg) suppress proliferation of human (auto)antigen-specific T cells without inducing apoptosis. J Neuroimmunol 2001;114:160 – 7. [8] Lorentzen JC, Issazadeh S, Storch M, Mustafa MI, Lassmann H, Linington C, et al. Protracted, relapsing and demyelinating experimental autoimmune encephalomyelitis in DA rats immunized with syngeneic spinal cord and incomplete Freund’s adjuvant. J Neuroimmunol 1995;63:193 – 205. [9] Tanuma N, Shin T, Matsumoto Y. Characterization of acute versus chronic relapsing autoimmune encephalomyelitis in DA rats. J Neuroimmunol 2000;108:171 – 80. [10] Humle Jorgensen S, Jensen PEH, Laursen H, Sorensen PS. Intravenous immunoglobulin ameliorates experimental autoimmune encephalomyelitis and reduces neuropathological abnormalities when administered prophylactically. Neurol Res 2005 (in press). [11] Bieber AJ, Warrington A, Pease LR, Rodriguez M. Humoral autoimmunity as a mediator of CNS repair. Trends Neurosci 2001;24: S39 – 44. [12] Rodriguez M, Lennon VA. Immunoglobulins promote remyelination in the central nervous system. Ann Neurol 1990;27:12 – 7. [13] Warrington AE, Asakura K, Bieber AJ, Ciric B, Keulen V, Kaveri SV, et al. Human monoclonal antibodies reactive to oligodendrocytes promote remyelination in a model of multiple sclerosis. Proc Natl Acad Sci U S A 2000;97:6820 – 5. [14] Fazekas F, Deisenhammer F, Strasser Fuchs S, Nahler G, Mamoli B. Randomised placebo-controlled trial of monthly intravenous immunoglobulin therapy in relapsing – remitting multiple sclerosis. Austrian Immunoglobulin in Multiple Sclerosis Study Group. Lancet 1997; 349:589 – 93. [15] Achiron A, Gabbay U, Gilad R, Hassin BS, Barak Y, Gornish M, et al. Intravenous immunoglobulin treatment in multiple sclerosis. Effect on relapses. Neurology 1998;50:398 – 402. [16] Sorensen PS, Wanscher B, Jensen CV, Schreiber K, Blinkenberg M, Ravnborg M, et al. Intravenous immunoglobulin G reduces MRI activity in relapsing multiple sclerosis. Neurology 1998;50: 1273 – 1281. [17] Lewanska M, Zajdel MS, Selmaj K. Low dose of intravenous immunoglobulins is equally effective in multiple sclerosis as high dose. Clinical and MRI assessment. Eur J Neurol 2002;9:565 – 72. [18] Sorensen PS, Fazekas F, Lee M. Intravenous immunoglobulin G for the treatment of relapsing – remitting multiple sclerosis: a metaanalysis. Eur J Neurol 2002;9:557 – 63.
S. Humle Jorgensen, P.S. Sorensen / Journal of the Neurological Sciences 233 (2005) 61 – 65 [19] Sorensen PS. The role of intravenous immunoglobulin in the treatment of multiple sclerosis. J Neurol Sci 2003;206:123 – 30. [20] Hommes OR, Sorensen PS, Fazekas F, Enriquez MM, Koelmel HW, Fernandez O, et al. Intravenous immunoglobulin in secondary progressive multiple sclerosis: randomised placebo-controlled trial. Lancet 2004;364:1149 – 56. [21] Orvieto R, Achiron R, Rotstein Z, Noy S, Bar-Hava I, Achiron A. Pregnancy and multiple sclerosis: a 2-year experience. Eur J Obstet Gynecol Reprod Biol 1999;82:191 – 4. [22] Haas J. High dose IVIG in the post partum period for prevention of exacerbations in MS. Mult Scler 2000;6(suppl. 2):18 – 20. [23] Noseworthy JH, O’Brien PC, Petterson TM, Weis J, Stevens L, Peterson WK, et al. A randomized trial of intravenous immunoglobu-
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lin in inflammatory demyelinating optic neuritis. Neurology 2001;56: 1514 – 1522. [24] Noseworthy JH, O’Brien PC, Weinshenker BG, Weis JA, Petterson TM, Erickson BJ, et al. IV immunoglobulin does not reverse established weakness in MS. Neurology 2000;55:1135 – 43. [25] Stangel M, Boegner F, Klatt CH, Hofmeister C, Seyfert S. Placebo controlled pilot trial to study the remyelinating potential of intravenous immunoglobulins in multiple sclerosis. J Neurol Neurosurg Psychiatry 2000;68:89 – 92. [26] van Engelen BG, Hommes OR, Pinckers A, Cruysberg JR, Barkhof F, Rodriguez M. Improved vision after intravenous immunoglobulin in stable demyelinating optic neuritis. Ann Neurol 1992;32:834 – 45.
Intravenous immunoglobulin treatment of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis Signe Humle Jorgensen*, Per Soelberg Sorensen Copenhagen MS Centre, Department of Neurology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark Available online 22 April 2005
Abstract Intravenous immunoglobulin (IVIG) is an established treatment of immune-mediated demyelinating neuropathy. Since IVIG possesses multiple immunomodulatory and anti-inflammatory properties, IVIG therapy may represent a way of interfering with the disease process in multiple sclerosis (MS). In the MS animal model experimental autoimmune encephalomyelitis (EAE), infusions of IVIG significantly reduced disease symptoms as well as the underlying CNS pathology. IVIG was only effective in EAE when administered in a prophylactic treatment protocol, since IVIG infusions during the established phase of EAE did not alter the disease course or the degree of inflammation found in the central nervous system. IVIG also has the potential to act through myelin repair mechanisms as evidenced by work done in the Theilers murine encephalomyelitis virus model of demyelination. Together these observations have led to certain expectations for IVIG as a treatment for MS, and have resulted in various clinical trials. Several controlled trials report beneficial effects of IVIG on relapse rate, new MRI lesions, and disease progression in relapsing – remitting MS, while a remyelinating effect of IVIG has not been documented. IVIG is, therefore, presently regarded as a second-line therapy of MS. D 2005 Elsevier B.V. All rights reserved. Keywords: Intravenous immunoglobulin; Immunoglobulin G; Experimental autoimmune encephalomyelitis; Multiple sclerosis; Controlled trials
1. Introduction The commercial preparations of immunoglobulin for intravenous administration (IVIG) consist of purified immunoglobulin obtained from several thousands healthy blood donors, and therefore contain polyclonal antibodies with a variety of specificities. The immunoglobulin in IVIG, which is mainly of the IgG subclass, represents intact antibody molecules with retained biological properties, and accordingly, IVIG has multiple possible mechanisms of actions owing to reactions of both the variable regions and the constant Fc regions of the antibody molecules (Table 1) [1,2]. IVIG was introduced several decades ago as replacement therapy for antibody deficiencies. Since then, IVIG has also established its role as a treatment of disorders where the immune system mediates peripheral demyelinating neuro-
* Corresponding author. Tel.: +45 35 45 28 88; fax: +45 35 45 67 13. E-mail address: [email protected] (S. Humle Jorgensen). 0022-510X/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jns.2005.03.005
pathy, e.g. the Guillan-Barre´ syndrome and chronic inflammatory demyelinating polyneuropathy (CIPD) [3]. In the management of autoimmunity, IVIG was initially introduced because of the capacity to suppress the activity of autoantibodies through anti-idiotypic interactions [4,5]. Later however, IVIG was also recognised as being effective in autoimmune diseases mediated by pathogenic T lymphocytes [6,7]. Furthermore, IVIG may modulate macrophage functions, interfere with the production of cytokines, and inhibit the complement system (Table 1). As a result of IVIG being able to interfere with the immune system at both the cellular and the humoral level, it is considered a potential treatment in MS, where IVIG may target multiple components in the disease pathology. This view has been advanced further by findings in the classical MS animal model experimental autoimmune encephalomyelitis (EAE), where studies have been performed to explore the IVIG mechanisms of action, and have provided supportive evidence for beneficial effects of IVIG in inflammatory CNS demyelination.
62
S. Humle Jorgensen, P.S. Sorensen / Journal of the Neurological Sciences 233 (2005) 61 – 65
Table 1 Immunomodulation by IVIG Target
Regulatory effects
T lymphocytes
Regulation of cytokine production Neutralisation of T-cell superantigens Inhibition of B-cell differentiation Selective regulation of antibody production Blocking of effector cells by FcR saturation and FcR downregulation Inhibition of antibody-dependent cellular cytotoxicity Elimination of autoantibodies by increased catabolism Inhibition of pathogenic antibodies by anti-idiotypic network Modulation of mononuclear cell cytokine production Induction of anti-inflammatory cytokines Binding of complement components Attenuation of complement activation
B lymphocytes Fc Receptors
Antibodies Cytokines Complement
8 and 9 p.i. Throughout the study, animals were evaluated on a daily basis for weight loss and neurological symptoms of active disease. The symptoms of EAE were assessed according to the following scoring system: 0—no clinical signs; 1—tail paralysis; 2—mild to moderate hind limb paresis; 3—severe hind limb paresis; 4—paralysis of the limbs; 5—quadriplegia; 6—moribund state or death from EAE. The experiments were ended after 4 weeks and samples of the spinal cord and the brain were dissected and processed for histological examination. Clinical symptoms of active EAE disease were observed 1 week after the immunisation, where rats in the placebo group experienced a profound weight loss. If animals received the treatment with IVIG at days 0 – 1 p.i., the loss of body weight was significantly reduced. When IVIG was administered at days 8– 9 p.i. when the symptoms of EAE were evident, the treatment had no effect on the body weight changes. Development of the neurological EAE symptoms coincided with the observed body weight changes, and early treatment with immunoglobulin resulted in a less severe course of the disease with mild or even absent clinical symptoms of EAE (Fig. 1A). When the infusions of IVIG were given during established disease, however, no significant treatment effects could be observed (Fig. 1B). In tissue samples from the central nervous system obtained 4 weeks after the induction of EAE, the inflammatory changes and demyelination were evaluated in paraffin sections cut for histological analysis. The principal findings were a pronounced inflammatory response in both the brain and spinal cord, predominantly perivascular infiltrations, but areas with demyelination were also observed. Treatment with IVIG before the onset of EAE symptoms significantly inhibited the inflammatory response as evaluated by blinded scoring of the histological findings (Table 2). In summary, intravenous treatment with human polyclonal immunoglobulin G had significant effects on both
In recent years, focus has been set on the benefits of using IVIG in the treatment of multiple sclerosis (MS), and various clinical trials have been performed to address this.
2. IVIG treatment of experimental autoimmune encephalomyelitis In susceptible strains of rats, a protracted and relapsing type of demyelinating EAE may be induced by inoculating animals with a homogenate of incomplete Freund’s adjuvant and syngenic spinal cord tissue from healthy animals [8,9]. We induced this type of EAE in the inbred rat strain Dark Agouti (DA) and treated the animals with intravenous infusions of human IVIG (1 g/kg) or a placebo solution after the immunisation procedure [10]. The IVIG infusions were administered at two consecutive days: As prophylactic treatment at the time of EAE induction at days 0 and 1 post immunisation (p.i.), or in a therapeutic treatment protocol at the beginning at the acute EAE attack at days
A
4
B
IVIG Placebo
IVIG Placebo
3
EAE score
3
EAE score
4
2
2
1
1
0
0 0
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30
day p.i.
0
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30
day p.i.
Fig. 1. EAE score. Scoring of the neurological symptoms at day 0 – 28 after the immunisation with encephalitogenic homogenate. The values are mean SEM (n = 12 in each group). Arrows indicate the administration of placebo or IVIG. When the infusions were given in the early treatment protocol (panel A), significant effects of IVIG were observed (*p < 0.05, Mann – Whitney rank sum test).
S. Humle Jorgensen, P.S. Sorensen / Journal of the Neurological Sciences 233 (2005) 61 – 65
63
Table 2 Histological score Infusion days 0 – 1 p.i.
Brain Spinal Cord Cervical Spinal Cord Lumbar
Infusion days 8 – 9 p.i.
IVIG
Placebo
IVIG
Placebo
0.8 T 0.1* (n = 12) 1.6 T 0.3 (n = 12) 0.9 T 0.3* (n = 12)
1.4 T 0.2 (n = 11) 1.9 T 0.3 (n = 11) 1.7 T 0.3 (n = 11)
1.4 T 0.3 (n = 8) 2.1 T 0.4 (n = 8) 1.5 T 0.3 (n = 8)
1.3 T 0.3 (n = 8) 2.0 T 0.3 (n = 8) 1.9 T 0.4 (n = 8)
The average histological score evaluated in the brain, cervical, and lumbar spinal cord segments by the following scoring system: 0—no inflammation; 1— minor perivascular infiltrations; 2—several perivascular and parenchymal infiltrations; 3—maximal inflammatory response and demyelination. Prophylactic infusions of IVIG reduced the inflammatory changes in the CNS significantly (*p < 0.05, Mann – Whitney rank sum test), while administration of IVIG during established EAE disease had no apparent effects on the histological findings.
disease course and CNS inflammation in EAE, but only when administered at the time of immunisation. In addition to these anti-inflammatory actions of IVIG it is of special interest with regard to demyelinating diseases that immunoglobulin may also be implicated in myelin repair or remyelination. This effect of IVIG has been suggested by observations in a different experimental animal model, the Theiler’s murine encephalomyelitis virus (TMEV) model of demyelination.
3. IVIG and remyelination The possible remyelinating potential of IVIG preparations has been based on studies in the TMEV model [11]. This experimental model of immune-mediated demyelination resembles the pattern of progressive MS with chronic CNS demyelination and a progressive loss of motor function. Originally, Rodriguez and co-workers observed that in the TMEV model of demyelination, immunisation with a spinal cord homogenate promoted remyelination [12]. Later it was discovered that the beneficial effects could be attributed to the presence of certain antibodies that were directed against myelin components. These antibodies were characterised as being able to bind to oligodendrocytes, suggesting that the remyelinating effects of the immunoglobulins were mediated by direct stimulation of the myelinproducing cells within the CNS [13]. The auto-reactive antibodies with remyelinating potential appear to occur naturally in the plasma of healthy individuals. Hence, commercial preparations of IVIG could be of therapeutic value in MS, not only due to antiinflammatory effects of the polyclonal immunoglobulins, but also by promoting myelin repair. These considerations have led to certain expectations for IVIG as a treatment for MS, since remyelination is an important therapeutic goal to prevent axonal damage following demyelination.
[14 –17]. In the controlled studies a beneficial effect of IVIG therapy on the MS disease activity could be demonstrated by a significant reduction of the relapse rate and a reduced change in the mean Kurtzke expanded disability status scale (EDSS) (Table 3). Favourable effects were also observed in the two trials that included MRI outcome measures [16,17]. In these studies treatment with IVIG reduced the number of new and total gadolinium-enhancing lesions in the brain. Since the four controlled trials have included relatively small numbers of patients, a meta-analysis was recently published in order to provide an overall evaluation of the benefits of IVIG in relapsing – remitting MS [18]. The results from the meta-analysis confirmed that IVIG significantly reduces the annual relapse rate, the proportion of relapse-free patients, and the disease progression as measured by the change in EDSS score. In the treatment of relapsing – remitting MS, the beneficial effects of IVIG on relapse rate and gadolinium-enhancing lesions were of the same magnitude as treatment with glatiramer acetate or interferon-h. Furthermore, there was a reduction in the overall progression of disease, since the proportion of patients with clinical deterioration was reduced after IVIG treatment. However, the efficacy of IVIG still needs to be confirmed in additional controlled clinical trials, as does determination of the optimal IVIG dose. Recently, the large phase 3 trial European Study on Immunoglobulin in MS, or ESIMS, has been completed
Table 3 Randomised clinical trials of IVIG in relapsing – remitting MS Study
N
Primary Beneficial effects of IVIG on: end point
Fazekas 150 EDSS et al. [14] changes Achiron et al. [15] Sorensen et al. [16]
40 Relapse rate 26 MRI lesions
Lewanska et al. [17]
49 Relapse rate
4. IVIG in clinical trials The effects of IVIG on relapsing –remitting MS have been studied in a number of open clinical trials and in four randomised, double-blind and placebo-controlled studies
Change in EDSS Mean annual relapse rate Proportion of relapse-free patients Annual relapse rate Trend towards reduced change in EDSS Number of gadolinium contrast-enhancing lesions New gadolinium-enhancing lesions Number of relapses Relapse rate Change in EDSS
Primary end points and parameters with significant beneficial results of IVIG therapy.
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[19,20]. This study focused on IVIG in the progressive phase of MS and included 318 patients with clinically definite secondary progressive MS. The outcome of the ESIMS study was negative, as no significant differences were found in the delay of clinical progression, the primary outcome measure. The change in lesion volume by MRI was also unaffected by IVIG treatment [20]. Other clinical trials have aimed at investigating the effects of IVIG on the acute exacerbations that often occur after childbirth in MS patients with a relapsing –remitting disease course. Administration of IVIG after delivery has been found to reduce the occurrence of these relapses significantly, and in a number of cases IVIG treatment was even observed to prevent the acute exacerbations associated with childbirth [21,22]. The multicentre study, Gammaglobulins in the Post Partum Period in MS for Prevention of Exacerbations after delivery (GAMPP), was recently concluded and publication of the trial results is pending. IVIG has also been evaluated in clinical trials for a possible remyelinating effect in MS. The placebo-controlled clinical trials focused on the effects of IVIG on optic neuritis [23] or permanent motor deficits [24,25] as indirect measures of possible remyelination effects. Apart from one small open trial [26], these studies have not been able to detect a positive effect of the IVIG administration. However, it is conceivable that the permanent loss of sight or permanent muscle weakness may be a result from axonal loss rather than actual demyelination.
5. Conclusions In summary, prophylactic treatment with IVIG is effective in EAE if administered at the time of induction, and significantly reduces the symptoms of disease as well as the underlying CNS pathology. Therapeutic IVIG treatment of established EAE has not proven effective. The effects of IVIG may be brought about by immunological specificity at the variable regions of the antibody molecules and by the effector properties mediated by conserved antibody Fc regions. Moreover, IVIG has the potential to act through myelin repair mechanism as evidenced by the studies in experimental TMEV demyelination. Beneficial effects of IVIG on relapses, disability, and MRI changes in MS have been reported in the relapsing – remitting type of the disease, the effects being of a magnitude comparable to that of interferon-h and glatiramer acetate. Clinical trials have not been able to establish an effect of IVIG on the progressive phase of MS or confirm the presence of a remyelinating effect of IVIG. Therefore, IVIG is at present regarded as a valuable second-line alternative in the treatment of relapsing – remitting MS, and may be offered to patients that are unwilling to receive frequent injections or have contraindications to first-line therapies. Moreover, the large dose-finding study still needs
to be completed in order to determine the most effective dose of IVIG in relapsing – remitting MS.
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