Intravenous immunoglobulin ameliorates experimental autoimmune encephalomyelitis and reduces neuropathological abnormalities when administered prophylactically

Immunotherapy in Autoantibody-Associated Psychiatric Syndromes in Adults

Background: Autoantibody-associated psychiatric syndromes are often distinct from, but might also be part of autoimmune encephalitis. Our article focuses on potential immunotherapy in these patients with a probable autoimmune origin of their psychiatric syndrome. Methods: We searched through PubMed for appropriate articles on immunotherapy in autoantibody-associated psychiatric syndromes between 2010 and 2020 for this narrative review. Results: In line with prior recommendations for autoimmune encephalitis and autoimmune psychosis, we suggest that in patients with a probable autoimmune-based psychiatric syndrome should be given early corticosteroids, intravenous immunoglobulins, or plasmapheresis as first line immunotherapy. If these therapeutic options fail, second-line immunotherapy should be applied within 1 month consisting of rituximab or cyclophosphamide. Maintenance therapy is best for those patients responding to steroids including mycofenolate mofetil or azathioprine. So far, there is evidence from a few retrospective cohort studies supporting the usage of first- and second-line, and maintenance immunotherapies for autoantibody-associated psychiatric syndromes. Some immunological agents are discussed that might exert an effect in autoimmune-based psychiatric syndromes, but the latest evidence is low and derived from case reports or series with autoimmune encephalitis patients. Conclusions: Taken together, the immunotherapeutic landscape for patients with autoantibody-associated psychiatric syndromes is delineated. Our suggestions rely on observational studies in autoantibody-associated psychiatric syndromes and a few placebo-controlled, randomized trials for patients with autoimmune encephalitis and psychosis. Thus, adequate powered, prospective as well as placebo-controlled clinical trials in patients with autoantibody-associated psychiatric syndromes are warranted in order to enlighten efficacy and safety aspects of current and novel therapy strategies.

High-dose intravenous immunoglobulins reduce nerve macrophage infiltration and the severity of bortezomib-induced peripheral neurotoxicity in rats

Background

Chemotherapy-induced peripheral neurotoxicity (CIPN) is a severe adverse effect in patients receiving antitumor agents, and no effective treatment is available. Although the mechanisms responsible for the development of CIPN are poorly understood, recent findings make neuroinflammation an attractive target to be investigated, particularly when neuropathic pain is a prominent feature such as after bortezomib administration.

The aim of our study was to evaluate the effect of intravenous immunoglobulins (IVIg) delivery in chronic CIPN. The related neuro-immune aspects were investigated in a well-characterized rat model of bortezomib-induced peripheral neurotoxicity (BIPN).

Methods

After determination of a suitable schedule based on a preliminary pharmacokinetic pilot study, female Wistar rats were treated with IVIg 1 g/kg every 2 weeks. IVIg treatment was started at the beginning of bortezomib administration (“preventive” schedule), or once BIPN was already ensued after 4 weeks of treatment (“therapeutic” schedule). Neurophysiological and behavioral studies were performed to assess the extent of painful peripheral neurotoxicity induced by bortezomib, and these functional assessments were completed by pathologic examination of peripheral nerves and intraepidermal nerve fiber quantification (IENF). The role of the innate immune response in BIPN was investigated by immunochemistry characterization of macrophage infiltration in peripheral nerves.

Results

Both schedules of IVIg administration were able to significantly reduce bortezomib-induced heat and mechanical allodynia. Although these changes were not evidenced at the neurophysiological examination of peripheral nerves, they behavioral effects were paralleled in the animals treated with the preventive schedule by reduced axonopathy in peripheral nerves and significant protection from loss of IENF. Moreover, IVIg administration was very effective in reducing infiltration in peripheral nerves of macrophages with the M1, pro-inflammatory phenotype.

Conclusion

Our results suggest a prominent role of neuroinflammation in BIPN and that IVIg might be considered as a possible safe and effective therapeutic option preventing M1 macrophage infiltration. However, since neuropathic pain is frequent also in other CIPN types, it also indicates the need for further investigation in other forms of CIPN.

Protection from experimental autoimmune encephalomyelitis by polyclonal IgG requires adjuvant-induced inflammation

Background

Intravenous immunoglobulin (IVIG) proved to be an efficient anti-inflammatory treatment for a growing number of neuroinflammatory diseases and protects against the development of experimental autoimmune encephalomyelitis (EAE), a widely used animal model for multiple sclerosis (MS).

Methods

The clinical efficacy of IVIG and IVIG-derived F(ab’)₂ fragments, generated using the streptococcal cysteine proteinase Ide-S, was evaluated in EAE induced by active immunization and by adoptive transfer of myelin-specific T cells. Frequency, phenotype, and functional characteristics of T cell subsets and myeloid cells were determined by flow cytometry. Antibody binding to microbial antigen and cytokine production by innate immune cells was assessed by ELISA.

Results

We report that the protective effect of IVIG is lost in the adoptive transfer model of EAE and requires prophylactic administration during disease induction. IVIG-derived Fc fragments are not required for protection against EAE, since administration of F(ab’)₂ fragments fully recapitulated the clinical efficacy of IVIG. F(ab’)₂-treated mice showed a substantial decrease in splenic effector T cell expansion and cytokine production (GM-CSF, IFN-γ, IL-17A) 9 days after immunization. Inhibition of effector T cell responses was not associated with an increase in total numbers of Tregs but with decreased activation of innate myeloid cells such as neutrophils, monocytes, and dendritic cells. Therapeutically effective IVIG-derived F(ab’)₂ fragments inhibited adjuvant-induced innate immune cell activation as determined by IL-12/23 p40 production and recognized mycobacterial antigens contained in Freund’s complete adjuvant which is required for induction of active EAE.

Conclusions

Our data indicate that F(ab’)₂-mediated neutralization of adjuvant contributes to the therapeutic efficacy of anti-inflammatory IgG. These findings might partly explain the discrepancy of IVIG efficacy in EAE and MS.

Optimal attenuation of experimental autoimmune encephalomyelitis by intravenous immunoglobulin requires an intact interleukin-11 receptor

Background

Intravenous immunoglobulin (IVIg) has been used to treat a variety of autoimmune disorders including multiple sclerosis (MS); however its mechanism of action remains elusive. Recent work has shown that interleukin-11 (IL-11) mRNAs are upregulated by IVIg in MS patient T cells. Both IVIg and IL-11 have been shown to ameliorate experimental autoimmune encephalomyelitis (EAE), an animal model of MS. The objective of this study was to determine whether the protective effects of IVIg in EAE occur through an IL-11 and IL-11 receptor (IL-11R)-dependent mechanism.

Methods

We measured IL-11 in the circulation of mice and IL-11 mRNA expression in various organs after IVIg treatment. We then followed with EAE studies to test the efficacy of IVIg in wild-type (WT) mice and in mice deficient for the IL-11 receptor (IL-11Rα^−/−). Furthermore, we evaluated myelin-specific Th1 and Th17 responses and assessed spinal cord inflammation and demyelination in WT and IL-11Rα^−/− mice, with and without IVIg treatment. We also examined the direct effects of mouse recombinant IL-11 on the production of IL-17 by lymph node mononuclear cells.

Results

IVIg treatment induced a dramatic surge (>1000-fold increase) in the levels of IL-11 in the circulation and a prominent increase of IL-11 mRNA expression in the liver. Furthermore, we found that IL-11Rα^−/− mice, unlike WT mice, although initially protected, were resistant to full protection by IVIg during EAE and developed disease with a similar incidence and severity as control-treated IL-11Rα^−/− mice, despite initially showing protection. We observed that Th17 cytokine production by myelin-reactive T cells in the draining lymph nodes was unaffected by IVIg in IL-11Rα^−/− mice, yet was downregulated in WT mice. Finally, IL-11 was shown to directly inhibit IL-17 production of lymph node cells in culture.

Conclusion

These results implicate IL-11 as an important immune effector of IVIg in the prevention of Th17-mediated autoimmune inflammation during EAE.

Role of pathogens in multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating autoimmune disease of the central nervous system (CNS). Although the etiology of MS is unknown, genetic and environmental factors play a role. Infectious pathogens are the likely environmental factors involved in the development of MS. Pathogens associated with the development or exacerbation of MS include bacteria, such as Mycoplasma pneumoniae and Chlamydia pneumoniae, the Staphylococcus aureus-produced enterotoxins that function as superantigens, viruses of the herpes virus (Epstein-Barr virus and human herpesvirus 6) and human endogenous retrovirus (HERV) families and the protozoa Acanthamoeba castellanii. Evidence, from studies with humans and animal models, supporting the association of these various pathogens with the development and/or exacerbation of MS will be discussed along with the potential mechanisms including molecular mimicry, epitope spreading and bystander activation. In contrast, infection with certain parasites such as helminthes (Schistosoma mansoni, Fasciola hepatica, Hymenolepis nana, Trichuris trichiura, Ascaris lumbricoides, Strongyloides stercolaris, Enterobius vermicularis) appears to protect against the development or exacerbation of MS. Evidence supporting the ability of parasitic infections to protect against disease will be discussed along with a brief summary of a recent Phase I clinical trial testing the ability of Trichuris suis ova treatment to improve the clinical course of MS. A complex interaction between the CNS (including the blood-brain barrier), multiple infections with various infectious agents (occurring in the periphery or within the CNS), and the immune response to those various infections may have to be deciphered before the etiology of MS can be fully understood.

Teriflunomide attenuates immunopathological changes in the dark agouti rat model of experimental autoimmune encephalomyelitis

Teriflunomide is an oral disease-modifying therapy recently approved in several locations for relapsing-remitting multiple sclerosis. To gain insight into the effects of teriflunomide, immunocyte population changes were measured during progression of experimental autoimmune encephalomyelitis in Dark Agouti rats. Treatment with teriflunomide attenuated levels of spinal cord-infiltrating T cells, natural killer cells, macrophages, and neutrophils. Teriflunomide also mitigated the disease-induced changes in immune cell populations in the blood and spleen suggesting an inhibitory effect on pathogenic immune responses.

Essential role of NK cells in IgG therapy for experimental autoimmune encephalomyelitis

Intravenous immunoglobulin has long been used in treating autoimmune diseases, although mechanisms remain uncertain. Activating Fcγ receptors are receptors of IgG and reported to be essential in intravenous immunoglobulin (IVIG) therapy. Therefore, we hypothesized natural killer (NK) cells, which express abundant activating Fcγ receptors, are the potential cellular target. In experimental autoimmune encephalomyelitis (EAE), we demonstrated that IgG suppressed disease development in intact, but not in NK cell depleted mice. Adoptive transfer of IgG-treated NK cell could protect mice against EAE, and suppressed interferon γ and interleukin 17 production. The percentage of CD4⁺Foxp3⁺ regulatory T cells was significantly increased. The increase of regulatory T cells was also observed in IgG-treated EAE mice but not in NK cell depleted mice. In vitro experiments confirmed that IgG-treated NK cells enhanced regulatory T cell induction from naïve CD4⁺ T cells. Interestingly, cells from draining lymph nodes produced more interleukin 2 after the adoptive transfer of IgG-treated NK cells. We neutralized interleukin 2 and the induction of CD4⁺Foxp3⁺ T cells by IgG-treated NK cells was significantly reduced. To our knowledge, we identified for the first time the critical role of NK cells in the mechanism of IgG-induced induction of Treg cells in treatment of autoimmunity.

Intravenous immunoglobulin therapy prevents development of autoimmune encephalomyelitis and suppresses activation of matrix metalloproteinases

Although intravenous immunoglobulin (IVIG) has been reported to improve the status of expanded disability status scale (EDSS) of multiple sclerosis (MS) patients and reduce the annual relapse rate, some studies did not find its beneficial effects. In the present study, using an animal model for MS, we found that prophylactic, but not therapeutic, treatment successfully suppressed the disease development. During the search for factors involved in the disease suppression by IVIG, we obtained evidence suggesting that IVIG exerts its function, at least in part, by suppressing activation of matrix metalloproteinases (MMP)-2 and -9. Gelatin zymography revealed that gelatinase activities were suppressed by IVIG treatment in the spinal cord, but not in plasma. This finding raises the possibility that IVIG blocks MMP activities at the interface between the blood stream and CNS. With in situ zymography, we also observed that gelatinase activities were expressed mainly in astrocytes in the inflamed spinal cord of control rats and that this expression was attenuated by the treatment. These findings provide useful information to set optimal conditions for IVIG treatment of MS and to obtain more beneficial effects.

Treatment of neurodegenerative CNS disease in Langerhans cell histiocytosis with a combination of intravenous immunoglobulin and chemotherapy

BACKGROUND

In rare cases, patients with Langerhans cell histiocytosis (LCH) develop neurodegenerative CNS disease (ND-CNS-LCH). Management of ND-CNS-LCH has not been established.

METHODS

We treated five pediatric patients with a combination of intravenous immunoglobulin (IVIG) and chemotherapy (steroid +/- vinblastine +/- 6-mercaptopurine +/- methotrexate). Prior to the therapy, three of the five patients had cerebellar ataxia while the remaining two had abnormal MRI findings without apparent neurological deficits. IVIG was given monthly or twice monthly at the dosage of 250-400 mg/kg/dose.

RESULTS

The four patients administered more than 23 doses of IVIG and chemotherapy remained in a stable condition and did not show significant progression signs in neurological deficits or brain MRI findings during the 30-month follow-up period (median; range: 19+ to 38+) following the initiation of therapy for ND-CNS-LCH.

CONCLUSION

The IVIG-containing treatment may be promising for ND-CNS-LCH; however, its effectiveness remains to be further tested in more patients as well as in a randomized trial.

Monoclonal antibody against T-cell receptor alphabeta induces self-tolerance in chronic experimental autoimmune encephalomyelitis

The therapeutic effect of monoclonal antibody (H57-597 MoAb) against T-cell receptor (TCR) alphabeta has been investigated on MOG(35-55)-induced experimental autoimmune encephalomyelitis (EAE), as a model system for T-cell-mediated chronic inflammation in the central nervous system (CNS). Short-term administration of the anti-TCR alphabeta immediately after immunization protected the mice from EAE. Furthermore, anti-TCR alphabeta treatment on an established disease restored the self-tolerance which led to a complete remission of EAE and a dramatic reduction of inflammatory cells in the CNS, while treatment with control antibody (hamster IgG) was ineffective. The remission was durable and not associated with disappearance of autoreactive T cells as measured by persistence of MOG-reactive T-cell proliferation in vitro. However, MOG-reactive T cells from anti-TCR-treated animals produced significantly lower amounts of inflammatory TNF-alpha and IFN-gamma. In addition, while a transient deletion of CD4(+) and CD8(+) T cells was observed, a population of T cells expressing CD3, NK1.1 and CD69 (NKT cells) were expanding. By transfer of spleen cells from anti-TCR MoAb-treated animals, we could show that the tolerogenic capacity can be transferred to untreated recipients with EAE. The data indicate therapeutic effect of anti-TCR alphabeta MoAb (H57-597), which represents a promising approach in treatment of T-cell-mediated autoimmune diseases.

IVIG enters the central nervous system during treatment of experimental autoimmune encephalomyelitis and is localised to inflammatory lesions

Intravenous immunoglobulin (IVIG) treatment reduces the relapse rate in relapsing-remitting multiple sclerosis (MS) and may interfere with MS pathology through its various anti-inflammatory and immunomodulatory properties. It is presently unknown whether IVIG enters the central nervous system (CNS) in sufficient amounts to influence the local immune response within the brain and spinal cord, or if the treatment effects are entirely due to peripheral actions of IVIG. The purpose of the present study was to evaluate if IVIG radiolabeled with 99mTc enters the CNS during treatment of experimental autoimmune encephalomyelitis (EAE) in the susceptible rat strain Dark Agouti. After in vivo administration of 99mTc-IVIG we observed significantly increased accumulation in the brain and spinal cord from rats with EAE. Accumulation of 99mTc-IVIG was not detectable in CNS tissue from control animals. In peripheral tissue samples minor increases in 99mTc-IVIG organ binding were observed in the liver and kidney during EAE. Localisation of 99mTc-IVIG in the brain tissue was visualised by autoradiography and revealed significant accumulation of IVIG only in areas also affected by perivascular inflammation and leakage of serum proteins. In conclusion, the results indicate that significant extravasation of IVIG to the CNS only occurs when blood-brain barrier function is compromised during EAE.

IVIg attenuates T cell-mediated killing of human neurons

Beneficial effects of intravenous immunoglobulin (IVIg) in relapsing-remitting multiple sclerosis (MS) have been described, including a decrease of brain atrophy. We have previously shown that activated T cells kill neurons in culture. In this manuscript, we show that the pretreatment of activated T cells with IVIg attenuates T cell neurotoxicity. This is attributed to the ability of IVIg to decrease the adhesion of T cells onto neurons, possibly through an effect on LFA-1, and by lowering the levels of Fas and FasL on T cells. Our results are relevant to understanding how therapies affect the MS disease process.

Future of multiple sclerosis therapy: combining antigen-specific immunotherapy with strategies to promote myelin repair

Persistent CNS inflammation and the failure of myelin repair during multiple sclerosis (MS) trigger a progressive deterioration in neurophysiological function and permanent clinical debilitation. Current treatment consists of immunosuppressive therapies targeted against the immune response, which have only been moderately successful in ameliorating disease relapses and have little or no benefit in slowing disease progression or enhancing remyelination. Recent breakthroughs have revealed new targets and more selective techniques for inhibiting autoreactive T-cell responses and promoting lesion repair in animal models of MS. In light of these new findings and the limitations of current treatments, the authors hypothesize that the future of MS therapy will progress towards the development of a combinatorial therapeutic strategy that consists of specific tolerance of autoreactive T cells, myelin repair and axonal protection.