Intravenous immune globulin in multiple sclerosis: clinical and neuroradiological results and implications for possible mechanisms of action

A comprehensive review and update on the biologic treatment of adult noninfectious uveitis: part II

INTRODUCTION

Treatment of adult, noninfectious uveitis remains a major challenge for ophthalmologists around the world, especially in regard to recalcitrant cases. It is reported to comprise approximately 10% of preventable blindness in the USA. The cause of uveitis can be idiopathic or associated with infectious and systemic disorders. The era of biologic medical therapies provides new options for patients with otherwise treatment-resistant inflammatory eye disease.

AREAS COVERED

This two-part review gives a comprehensive overview of the existing medical treatment options for patients with adult, noninfectious uveitis, as well as important advances for the treatment ocular inflammation. Part I covers classic immunomodulation and latest information on corticosteroid therapy. In part II, emerging therapies are discussed, including biologic response modifiers, experimental treatments and ongoing clinical studies for uveitis.

EXPERT OPINION

The hazard of chronic corticosteroid use in the treatment of adult, noninfectious uveitis is well documented. Corticosteroid-sparing therapies, which offer a very favorable risk-benefit profile when administered properly, should be substituted. Although nothing is currently approved for on-label use in this indication, many therapies, through either translation or novel basic science research, have the potential to fill the currently exposed gaps.

Guidelines on the use of intravenous immune globulin for neurologic conditions

Canada's per capita use of intravenous immune globulin (IVIG) grew by approximately 115% between 1998 and 2006, making Canada one of the world's highest per capita users of IVIG. It is believed that most of this growth is attributable to off-label usage. To help ensure IVIG use is in keeping with an evidence-based approach to the practice of medicine, the National Advisory Committee on Blood and Blood Products (NAC) and Canadian Blood Services convened a panel of national experts to develop an evidence-based practice guideline on the use of IVIG for neurologic conditions. The mandate of the expert panel was to review evidence regarding use of IVIG for 22 neurologic conditions and formulate recommendations on IVIG use for each. A panel of 6 clinical experts, one expert in practice guideline development and 4 representatives from the NAC met to review the evidence and reach consensus on the recommendations for the use of IVIG. The primary sources used by the panel were 2 recent evidence-based reviews. Recommendations were based on interpretation of the available evidence and, where evidence was lacking, consensus of expert clinical opinion. A draft of the practice guideline was circulated to neurologists in Canada for feedback. The results of this process were reviewed by the expert panel, and modifications to the draft guideline were made where appropriate. This practice guideline will provide the NAC with a basis for making recommendations to provincial and territorial health ministries regarding IVIG use management. Recommendations for use of IVIG were made for 14 conditions, including acute disseminated encephalomyelitis, chronic inflammatory demyelinating polyneuropathy, dermatomyositis, diabetic neuropathy, Guillain-Barré syndrome, Lambert-Eaton myasthenic syndrome, multifocal motor neuropathy, multiple sclerosis, myasthenia gravis, opsoclonus-myoclonus, pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections, polymyositis, Rasmussen's encephalitis, and stiff person syndrome; IVIG was not recommended for 8 conditions including adrenoleukodystrophy, amyotropic lateral sclerosis, autism, critical illness polyneuropathy, inclusion body, myositis, intractable childhood epilepsy, paraproteinemic neuropathy (IgM variant), and POEMS syndrome. Development and dissemination of evidence-based clinical practice guidelines may help to facilitate appropriate use of IVIG.

Efficacy of intravenous immunoglobulin treatment in refractory uveitis

PURPOSE

To assess the efficacy of intravenous immunoglobulin (IVIg) therapy in patients with severe uveitis otherwise unresponsive to conventional immunomodulatory agents.

METHODS

Data on five consecutive patients treated with IVIg and followed to the present time by one of the authors (CSF) were reviewed. All patients had severe and recalcitrant uveitis of diverse etiologies. Main outcome measures were control of intraocular inflammation, steroid-sparing effect, visual acuity, and side effects.

RESULTS

The duration of IVIg therapy was 3 to 36 months (mean, 16.8 months). Treatment was effective in controlling the intraocular inflammation in 3 of 5 patients. One of those patients required maintenance of systemic steroids at a dose of 10 mg per day. Visual acuity has stabilized or improved in these three patients. No immediate or long-term side effect was observed in any of the patients.

CONCLUSIONS

Intravenous immunoglobulin therapy was an effective therapeutic modality in the treatment of three of five patients with severe uveitis that was unresponsive to conventional immunomodulatory agent(s). No adverse events were observed.

In vitro cytotoxic effects of stabilizing sugars within human intravenous immunoglobulin preparations against the human macrophage THP-1 cell-line

Intravenous immunoglobulin (IVIg) is a safe and effective therapy for the treatment of primary and secondary humoral immune deficiencies and autoimmune disorders. Both minor and more serious side effects may occur following IVIg administration in approximately 1-15% of infusions and stabilizing sugars found in IVIg preparations may contribute some of these. In this report, we aimed to determine the cytotoxic effects of IVIg as compared with four stabilizing sugars (glucose, sucrose, maltose and D-sorbitol) found in IVIg preparations on human monocyte-macrophages. The human THP-1 macrophage cell-line was used as a model to determine the effects of stabilizing sugars and IVIg preparations on cell viability and growth. The sugars differentially affected the viability of THP-1 cells. In experiments using doses of the sugars commonly found in IVIg preparations, cell viability and proliferation was unaffected when compared with doses of IVIg typically administered to patients (5 mg/ml). However, in an LDH-release cell lysis assay that measures changes in cell permeability, glucose (50 mg/ml) induced significant release of LDH as compared with complete IVIg (5 mg/ml, p<0.0001). Intranucleosomal DNA fragmentation was not detected at therapeutically relevant doses of IVIg. This suggested that THP-1 cell death was not due to apoptosis. We conclude that osmotic stress mediated by the sugars at high doses promoted THP-1 cell death. We propose that IVIg per se is not cytotoxic to the autonomously growing human THP-1 cell-line but rather, the stabilizing sugars used in the preparations are the cytotoxic factors. This observation was evident when preparations of IVIg were used at high concentrations but not at levels one would associate with clinically relevant doses of IVIg.

Impairment of the blood-nerve and blood-brain barriers in apolipoprotein e knockout mice

Apolipoprotein E (apoE) is well characterized as a plasma lipoprotein involved in lipid and cholesterol metabolism. Recent studies implicating apoE in Alzheimer's disease and successful recovery from neurological injury have stimulated much interest in the functions of apoE within the brain. To explore the functions of apoE within the nervous system, we examined apoE knockout (KO) mice. Previously, we showed that apoE KO mice have a delayed response to noxious thermal stimuli associated with a loss and abnormal morphology of unmyelinated fibers in the sciatic nerve. From these data, we hypothesized that apoE KO mice could have an impaired blood-nerve barrier (BNB). In this report, we demonstrate functionally impaired blood-nerve and blood-brain barriers (BBB) in apoE KO mice using immunofluorescent detection of serum protein leakage into nervous tissue as a diagnostic for decreased BNB and BBB integrity. Extensive extravasation of serum immunoglobulin G (IgG) is detected in the sciatic nerve, spinal cord, and cerebellum of apoE KO but not WT mice. In a subpopulation of apoE KO mice, IgG also extravasates into discrete cortical and subcortical locations, including hippocampus. Loss of BBB integrity was additionally confirmed by the ability of exogenously supplied Evans blue dye to penetrate the BBB and to colocalize with IgG immunoreactivity in CNS tissue. These observations support a role for apoE in maintaining the integrity of the BNB/BBB and suggest a novel relationship between apoE and neural injury.

Monocyte-macrophage system as targets for immunomodulation by intravenous immunoglobulin

Pooled human intravenous immunoglobulin (IVIg) has been used successfully to treat or ameliorate the clinical manifestations of humoral immune deficiencies, haematological disorders, HIV infection and many other diseases states. However, the mechanism of action of IVIg remains unclear. Several mechanisms of action of IVIg have been proposed. These include Fcy receptor blockade, accelerated clearance of endogenous pathogenic auto-antibodies, inhibition of components of the complement cascade, neutralization of super-antigens and bacterial toxins as well as anti-cytokine and anti-idiotype effects. A major contributor to host immunity and immune surveillance against infection, tissue or cell damage and malignancy is the monocyte/macrophage system. Monocyte-directed inflammation is a desirable consequence of microbiological or malignant challenge. However, monocyte hyperactivity may contribute to certain pathological conditions. These include the systemic inflammatory response syndrome (SIRS), septic shock, other dysregulated inflammatory disorders and auto-immunity. Novel therapies that can suppress the hyperactive state or correct monocyte/macrophage dysfunction without compromising normal host cell-mediated immunity are desirable. In this review, we discuss the immunomodulatory effects of IVIg focussing particularly upon the monocyte/macrophage system in pertinent disease states.

Intravenous immunoglobulin therapy for ocular cicatricial pemphigoid: a preliminary study

OBJECTIVE

To report the effects of intravenous immunoglobulin treatment of ten patients with progressive ocular cicatricial pemphigoid who did not respond to conventional immunomodulatory regimens.

DESIGN

Noncomparative, interventional case series.

PARTICIPANTS

Ten patients with biopsy-proven progressive cicatricial pemphigoid affecting the eyes who did not respond adequately to other local and systemic immunosuppressive treatment regimens.

INTERVENTION

Intravenous infusions of pooled human immunoglobulin, 2 to 3 g/kg body weight/cycle, divided over 3 days, and repeated every 2 to 6 weeks.

MAIN OUTCOME MEASURES

Reduction in conjunctival inflammation, prevention of progression of subepithelial conjunctival fibrosis, improvement in ocular symptoms (discomfort, photophobia), improved visual acuity, reduction in extraocular mucosal lesions.

RESULTS

Clinical deterioration was arrested and resolution of chronic conjunctivitis was documented in all ten patients. Maximum therapeutic effect was observed and maintained after a minimum of 4 cycles of therapy; three patients required 12 cycles before disease control. The duration of therapy in these ten patients has been 16 to 23 months (mean, 19.3 months) with no treatment-induced side effects. Extraocular mucosal lesion resolution has occurred in all but one patient, Visual acuity has stabilized or improved in all ten patients, and subjective complaints of discomfort and photophobia have decreased in all patients.

CONCLUSIONS

Intravenous immunoglobulin immunomodulatory therapy can be a safe and effective therapy for otherwise treatment-resistant ocular cicatricial pemphigoid.

Recent developments in drug therapy for multiple sclerosis

Symptomatic treatment of multiple sclerosis (MS) includes a diverse range of drugs intended to relieve the specific symptoms with which a patient may present at a particular point in the progression of the disease. These drugs, not specifically designed for the treatment of MS, may include antispastic agents (e.g. baclofen), drugs to reduce tremor (e.g. clonazepam), anticholinergics (e.g. oxybutynin) which relieve urinary symptoms, anti-epileptics (e.g. carbamazepine) to control neuralgia, stimulants to reduce fatigue (e.g. amantadine), and antidepressants (e.g. fluoxetine) to treat depression. The treatment of acute relapses or exacerbations is dominated by corticosteroids such as methylprednisolone. The most active area of current investigation is the development of drugs which will inhibit the progression of the disease process itself, and in this category the beta- and alpha-interferons are the most effective drugs currently available, although many new treatments are currently in trials, including immunoglobulin, copolymer-1. bovine myelin, T-cell receptor (TCR) peptide vaccines, platelet activating factor (PAF) antagonists, matrix metallo-proteinase inhibitors, campath-1, and insulin-like growth factor (IGF).

Imaging of remyelination

Now that the concept of remyelination is gaining acceptance in MS, there is a need for a paraclinical marker to monitor remyelination in MS, for example to study the effect of therapeutical interventions. At present there is no known imaging marker for remyelination. While positron emission tomography (PET) has ample sensitivity and specificity, an appropriate tracer is locking and spatial resolution is poor. Magnetic resonance (MR) imaging has superior sensitivity and spatial resolution, but the standard techniques lack specificity. Conventional T2-weighted images will most probably still appear abnormal in an area of remyelination. Among several newer MR techniques that are more specific, magnetization transfer contrast is the best candidate with regards to imaging remyelination. There is a strong need for an appropriate animal model and for histopathological confirmation to be able to further develop both PET and MR.