Background and indications for protein A-based extracorporeal immunoadsorption

Efficacy of protein A immunoadsorption and therapeutic plasma exchange in ANCA-associated vasculitis with severe renal involvement: a retrospective study

BACKGROUND

Severe renal impairment is a common complication of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and is associated with poor prognosis and shorter survival. It is urgent to find effective treatments to improve the prognosis of AAV patients. This study was designed to assess the efficacy and safety of protein A immunoadsorption (PAIA) and therapeutic plasma exchange (TPE) for AAV with severe renal involvement.

METHODS

A total of 48 AAV patients with renal involvement admitted to the Second Xiangya Hospital from January 2018 to February 2021 were selected. Clinical data, myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA), remission at 6 months, and outcomes were evaluated. The primary outcomes of interest were death and renal survival as defined by the occurrence of end-stage renal disease (ESRD).

RESULTS

PAIA was effective in the removal of MPO-ANCA and IgG, and showed superior over TPE in the clearance of MPO-ANCA within 1 month after treatment. After a median follow-up of 14.5 months, PAIA therapy showed an advantage in reducing mortality over TPE. There was no difference in the development of ESRD between the two groups. Multivariate Cox regression analysis indicated that higher serum creatinine (SCr) and lower haemoglobin level were independent risks of ESRD. Age > 60, lower serum albumin (ALB), and failure to achieve remission at 6 months were independent risks of death.

CONCLUSIONS

PAIA treatment reduces MPO-ANCA and IgG as well as mortality in AAV patients, and may be beneficial for severe AAV in clinical practice. Higher SCr, lower serum ALB or haemoglobin levels, age > 60, and failure to achieve remission at 6 months independently predict the ESRD or death of AAV patients with severe renal involvement.KEY MESSAGESCompared with therapeutic plasma exchange, protein A immunoadsorption treatment eliminates myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) and IgG better and reduces mortality in ANCA-associated vasculitis (AAV) patients with severe renal involvement.Higher serum creatinine, lower serum albumin or haemoglobin levels, age > 60, and failure to achieve remission at 6 months independently predict the end-stage renal disease (ESRD) or death of AAV patients with severe renal involvement.

Performance, clinical effectiveness, and safety of immunoadsorption in a wide range of indications

Immunoadsorption is well known to selectively remove immunoglobulins and immune complexes from plasma and is applied in a variety of autoimmune diseases and for desensitization before, or at acute rejection after organ transplantation. Performance, safety, and clinical effectiveness of immunoadsorption were the aim of this study. This prospective, noninterventional, multicentre cohort study included patients treated with immunoadsorption (Immunosorba or GLOBAFFIN adsorbers) for any indication. Clinical effectiveness was assessed after termination of the patient's individual treatment schedule. Eighty‐one patients were included, 69 were treated with Immunosorba, 11 with GLOBAFFIN, one patient with both adsorbers. A majority of patients was treated for neurological indications, dilated cardiomyopathy, and before or after kidney or heart transplantation. Mean IgG reduction from pre‐ to post‐treatment was 69.9% ± 11.5% for Immunosorba and 74.1% ± 5.0% for GLOBAFFIN, respectively. The overall IgG reduction over a complete treatment block was 68%–93% with Immunosorba and 62%–90% with GLOBAFFIN depending on the duration of the overall treatment. After termination of the immunoadsorption therapy, an improvement of clinical status was observed in 63.0%, stabilization of symptoms in 29.6%, and a deterioration in 4.9% of patients. Changes in fibrinogen, thrombocytes, and albumin were mostly classified as noncritical. Overall, the treatments were well tolerated. Immunoadsorption in routine clinical practice with both GLOBAFFIN and Immunosorba has been safely performed, was well tolerated by patients, and effective in lowering immunoglobulins with an improvement or maintenance of clinical status, thus represents an additional therapeutic option for therapy refractory immune disorders.

Mechanism of antibodies purification by protein A

Protein A, a major cell wall component of Staphylococcus aureus, is one of the first immunoglobulin-binding proteins that is discovered about 80 years ago. However, a great deal of development in both purification methods and application of antibodies in treatment have been done. There are many publications based on the untargeted (size exclusion, ion exchange and hydrophobic interactions) and targeted (affinity) methods by scientists in academic/industry groups. In this review, we have focused on the study of both native and engineered Protein A to understand its mechanism in the purification of antibodies. What domain of Protein A dose interact with antibody? Where are contact regions? What is the non-covalent interaction mechanism of Protein A and antibody? Does alkaline condition, in the washing step, influence on antibody structure and activity? On the other hand, the immobilization of Protein A on various sorbents such as agarose, silica, polysaccharide, polymers, and magnetic nanoparticles have investigated. Also, the application of Protein A as biosensor for detection of the antibody is discussed. We have tried to find interesting and stimulating answers to all these questions.

Development of a disposable micro-capillary film grafted with peptide ligands for immunoadsorption

Traditional chromatographic techniques used in downstream processes of biomolecule manufacturing are often time-consuming and expensive. In this study, a cost-effective microporous micro-capillary film (MMCF) composed of ethylenevinyl alcohol (EVOH) was evaluated for its potential application in immunoadsorption with high process efficiency. A peptide ligand Ac-Phe-Tyr-His-Glu (Ac-FYHE) was immobilized on the inner surface of MMCF for selective binding of human immunoglobulin (hIgG). The porous structure and chemical properties of the prepared MMCF were confirmed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). hIgG (2 mg/ml) adsorption studies demonstrated that the binding process followed a Langmuir isotherm with equilibrium adsorption capacities of 9.31 and 3.47 mg/ml adsorbent under static and dynamic conditions, respectively. Moreover, the membrane showed good flowrate tolerance when studied under flowrates of 0.5 ml/min to 10 ml/min. hIgG purity was 88.2% when obtained from an hIgG (2 mg/ml) and HSA (8 mg/ml) mixture and the purity remained over 80.0% when hIgG concentrations increased in the mixtures. Moreover, purity of 82.3% was achieved when removing hIgG directly from human serum. The MMCF-Ac-FYHE affinity column is expected to selectively remove hIgG from blood for the treatment of autoimmune diseases with high efficiency and cost effectiveness.

Apheresis therapies for NMOSD attacks: A retrospective study of 207 therapeutic interventions

Objective

To analyze whether 1 of the 2 apheresis techniques, therapeutic plasma exchange (PE) or immunoadsorption (IA), is superior in treating neuromyelitis optica spectrum disorder (NMOSD) attacks and to identify predictive factors for complete remission (CR).

Methods

This retrospective cohort study was based on the registry of the German Neuromyelitis Optica Study Group, a nationwide network established in 2008. It recruited patients with neuromyelitis optica diagnosed according to the 2006 Wingerchuk criteria or with aquaporin-4 (AQP4-ab)-antibody-seropositive NMOSD treated at 6 regional hospitals and 16 tertiary referral centers until March 2013. Besides descriptive data analysis of patient and attack characteristics, generalized estimation equation (GEE) analyses were applied to compare the effectiveness of the 2 apheresis techniques. A GEE model was generated to assess predictors of outcome.

Results

Two hundred and seven attacks in 105 patients (87% AQP4-ab-antibody seropositive) were treated with at least 1 apheresis therapy. Neither PE nor IA was proven superior in the therapy of NMOSD attacks. CR was only achieved with early apheresis therapy. Strong predictors for CR were the use of apheresis therapy as first-line therapy (OR 12.27, 95% CI: 1.04-144.91, p = 0.047), time from onset of attack to start of therapy in days (OR 0.94, 95% CI: 0.89-0.99, p = 0.014), the presence of AQP4-ab-antibodies (OR 33.34, 95% CI: 1.76-631.17, p = 0.019), and monofocal attack manifestation (OR 4.71, 95% CI: 1.03-21.62, p = 0.046).

Conclusions

Our findings suggest early use of an apheresis therapy in NMOSD attacks, particularly in AQP4-ab-seropositive patients. No superiority was shown for one of the 2 apheresis techniques.

Classification of evidence

This study provides Class IV evidence that for patients with NMOSD, neither PE nor IA is superior in the treatment of attacks.

Low rate of infectious complications following immunoadsorption therapy without regular substitution of intravenous immunoglobulins

INTRODUCTION

Immunoadsorption (IA) is increasingly used instead of plasma exchange due to lower risk of side effects and a higher selectivity. As a consequence of the reduction of immunoglobulins (Ig), the rate of infectious complications might increase in those patients. We therefore aimed to investigate the infection rate following IA without intravenous IG (IVIG) substitution in our apheresis center, where patients do not receive IVIG on a regular basis.

MATERIAL AND METHODS

We conducted a retrospective analysis of the IA treatments performed between 2010 and 2015 without IVIG substitution and collected data on patient age, diagnosis, number of IA treatments, serum levels of Ig, total protein, albumin, C-reactive protein (CRP) and infectious complications that occurred within 2 months after the IA treatment cycle.

RESULTS

A total number of 52 patients (27 females) received at least 5 IA sessions using the following adsorbers: TheraSorb™-Ig (n = 3), TheraSorb™-Ig flex (n = 44), TheraSorb™ Ig pro (n = 1) and TheraSorb™-IgE (n = 5). The median number of treatment sessions was 8.8 [range 5-16], the median IgG reduction was 82 [11-99] %. Serum albumin was decreased by 8%. The median CRP levels remained normal until the end of therapy and within 2 months after that (3.10 and 4.30 mg/L respectively). Only 4 patients had infections (7.7%). Three of them received additional immunosuppressive therapy.

CONCLUSIONS

Immunoadsorption leads to a significant reduction of IgG. CRP as inflammatory marker is not affected. Even without substitution of IVIG the complication rate directly linked with IA is low and questionable.

Antigen-specific apheresis of autoantibodies in myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disorder affecting the neuromuscular junction, usually caused by autoantibodies against the acetylcholine receptor (AChR) or the muscle-specific kinase (MuSK). Our aim is the development of a therapy based on the selective extracorporeal elimination of anti-AChR or anti-MuSK antibodies. To this end, the extracellular domains of the AChR subunits and MuSK have been expressed in yeast to be used as adsorbents, after optimization, and to obtain large quantities of proteins with near-native structure. We have characterized these proteins with respect to their use as specific immunoadsorbents for MG autoantibodies, and have begun large-scale experiments in order to verify the feasibility of application of the method for therapy. Furthermore, we have initiated animal studies to test possible toxicity and safety issues of the adsorbents or the procedure itself. The successful completion of the scale-up and safety tests will allow the initiation of clinical trials.

Immunoadsorption (IAS) for systemic lupus erythematosus

Immunoadsorption (IAS) is used as a rescue therapy in severely ill SLE patients who are refractory to conventional therapies. This extracorporeal method aims at the rapid and extensive removal of pathogenic immunocomplexes (ICs) and (auto-)antibodies (Abs). Although past data have shown short- to mid-term efficacy and biocompatibility of IAS in (renal) SLE, it is still an experimental and rather expensive procedure – and evidence from randomized controlled trials (RCTs) is lacking. Nevertheless, IAS is successfully used in life-threatening situations because of its fast mode of action and its acceptable safety profile.

Community-acquired methicillin-resistant Staphylococcus aureus: community transmission, pathogenesis, and drug resistance

Methicillin-resistant Staphylococcus aureus (MRSA) is able to persist not only in hospitals (with a high level of antimicrobial agent use) but also in the community (with a low level of antimicrobial agent use). The former is called hospital-acquired MRSA (HA-MRSA) and the latter community-acquired MRSA (CA-MRSA). It is believed MRSA clones are generated from S. aureus through insertion of the staphylococcal cassette chromosome mec (SCCmec), and outbreaks occur as they spread. Several worldwide and regional clones have been identified, and their epidemiological, clinical, and genetic characteristics have been described. CA-MRSA is likely able to survive in the community because of suitable SCCmec types (type IV or V), a clone-specific colonization/infection nature, toxin profiles (including Pantone-Valentine leucocidin, PVL), and narrow drug resistance patterns. CA-MRSA infections are generally seen in healthy children or young athletes, with unexpected cases of diseases, and also in elderly inpatients, occasionally surprising clinicians used to HA-MRSA infections. CA-MRSA spreads within families and close-contact groups or even through public transport, demonstrating transmission cores. Re-infection (including multifocal infection) frequently occurs, if the cores are not sought out and properly eradicated. Recently, attention has been given to CA-MRSA (USA300), which originated in the US, and is growing as HA-MRSA and also as a worldwide clone. CA-MRSA infection in influenza season has increasingly been noted as well. MRSA is also found in farm and companion animals, and has occasionally transferred to humans. As such, the epidemiological, clinical, and genetic behavior of CA-MRSA, a growing threat, is focused on in this study.

Extracellular domains of the β, γ and ε subunits of the human acetylcholine receptor as immunoadsorbents for myasthenic autoantibodies: A combination of immunoadsorbents results in increased efficiency

Myasthenia gravis (MG) is usually caused by autoantibodies against the human muscle acetylcholine receptor (AChR). Plasmapheresis offers a therapeutic option, but, as well as removing the pathogenic anti-AChR autoantibodies, it non-specifically removes indispensable immunoglobulins. An attractive alternative to plasmapheresis would be the extracorporeal specific removal of the autoantibodies using AChR-based immunoadsorbents. Previously, we used the N-terminal extracellular domain (ECD) of the AChR alpha subunit to immunoadsorb anti-alpha subunit autoantibodies from MG sera. In this study, we immobilised the beta -, gamma- and epsilon-AChR ECDs on Sepharose and tested them as immunoadsorbents on 50 MG sera. A given ECD removed a different percentage of autoantibodies from different sera and different ECDs removed different percentages from the same serum; on average, the beta-, gamma- and epsilon-ECDs removed 22%, 20% and 15.5% of the autoantibodies, respectively. Immunoadsorption was completed in 3 min, 1 mug of ECD removed approximately 2 pmol of autoantibodies, and the immunoadsorbent could be recycled approximately 4 times. The combined use of two (alpha+gamma) or four (alpha+beta+gamma+epsilon) ECDs in a single immunoadsorbent resulted in much higher (often additive) immunoadsorption. These results show that MG sera have autoantibodies against several AChR subunits, and suggest that the combined use of all AChR ECDs could provide the basis for a novel, antigen-specific therapy for MG.

Recommendations for the use of immunoapheresis in the treatment of autoimmune bullous diseases

Despite the use of high-dose systemic corticosteroids in combination with other immunosuppressants, in some patients with autoimmune bullous diseases only insufficient improvement is achieved. In these cases and in acute severe disease, adjuvant immunoapheresis has been increasingly used. A consensus meeting was held in mid-2005 in Hamburg, aiming at developing guidelines for the use of immunoapheresis in the treatment of autoimmune bullous diseases. This paper summarizes the experts' recommendations.

Removal of Pathogenic Autoantibodies by Immunoadsorption

Autoimmune diseases result from disrupted tolerance to self-antigens and subsequent damage to tissues and organs. In several diseases, specific autoantibodies have been either proved or suspected to play a role in this process. Consequently, several strategies have been devised in an attempt to discard the destructive immunoglobulins. Currently, both nonselective and epitope-specific methods are applied in several diseases. In this review, we provide a summary of the available data on elimination of pathogenic autoantibodies and discuss the advantages and pitfalls of the different approaches.

Immunoadsorption of factor VIII inhibitors

PURPOSE OF REVIEW

Extracorporeal immunoadsorption is being increasingly applied in a variety of disorders. This approach is particularly suited to removal of antibodies or inhibitors to coagulation factor VIII and may be particularly useful before the administration of large amounts of expensive replacement or bypass therapy for patients with hemophilia who are bleeding, or patients undergoing immune tolerance therapy.

RECENT FINDINGS

In patients with inhibitors to factor VIII, several types of immunoadsorption therapy have been used, although reports are mainly anecdotal, consisting of relatively small numbers of persons. Nonetheless, the findings suggest that immunoadsorption may be clinically effective and cost-effective and should be considered early in the treatment of appropriate patients. New immunoadsorption technologies are being described for a variety of disorders, including hemophilia, and a new synthetic matrix of polystyrene beads functionalized with sulfonate and tyrosyl methylester groups for immunoadsorption removal of factor VIII inhibitors is intriguing.

SUMMARY

Although immunoadsorption was shown to be clinically effective in patients with inhibitors to factor VIII more than two decades ago, recent papers have emphasized the desirability of early implementation of the modality in the treatment plan. Immunoadsorption is relatively easy to perform with few adverse effects, but specialized equipment is required, and it should be performed in an experienced setting. Although potentially less costly than other (bypass) therapies, immunoadsorption is itself not inexpensive, and its comparative effectiveness with plasmapheresis and other management options for the dangerously bleeding patient with antibodies to factor VIII should be determined by multicenter randomized controlled trials. Interesting recent novel technical developments in the field may facilitate increased use of the procedure.

Successful removal of pathogenic autoantibodies in pemphigus by immunoadsorption with a tryptophan-linked polyvinylalcohol adsorber

BACKGROUND

Autoantibodies against the glycoproteins desmogleins 1 and 3 which are components of the desmosomal adhesion complex have been shown to be responsible for the loss of epidermal adhesion characteristic of pemphigus. Elimination of these antibodies should clinically improve the pathology of this group of severe autoimmune blistering skin disorders.

OBJECTIVES

To gather information about the efficacy of immunoadsorption in the reduction of pathogenic serum autoantibodies against desmogleins 1 and 3 and to evaluate the clinical benefit of immunoadsorption in the treatment of pemphigus.

PATIENTS AND METHODS

Nine patients with pemphigus and detectable circulating desmoglein antibodies were included in this open trial. Two immunoadsorption treatments separated by a 48-h interval were performed per patient. Anti-desmoglein 1 and 3 antibodies in the patients' sera were monitored by enzyme-linked immunosorbent assay and indirect immunofluorescence before and following each immunoadsorption. In addition, the efficacy of the tryptophan-linked polyvinylalcohol adsorber in removing antidesmoglein antibodies was directly evaluated.

RESULTS

IgG antibodies against desmogleins 1 and 3 were effectively eliminated from the patients' plasma upon passage through the adsorber and levels of serum autoantibodies were significantly reduced by immunoadsorption. A single immunoadsorption treatment led to a reduction of antidesmoglein autoantibodies of about 30%. Clinically, mucosal and cutaneous lesions improved allowing for a reduction of the systemic immunosuppressive treatment with glucocorticoids.

CONCLUSIONS

Immunoadsorption with tryptophan-linked polyvinylalcohol adsorbers holds promise as a highly effective and safe adjuvant therapeutic regimen in pemphigus.

A forward look at therapy for pediatric movement disorders

The mainstay of current therapy for pediatric movement disorders is oral symptomatic medication, unless a reversible etiology can be found. However, this approach is apt to pale in comparison with innovative strategies on the clinical forefront. Classical pharmacotherapy is restricted by the blood-brain barrier, which prevents access to the brain of potentially therapeutic molecules. Recent developments in molecular biotechnology include antibody-mediated drug release, feedback-responsive delivery systems, carrier-mediated transport, microspheres composed of polymers and liposomes, permeabilizers, and selective delivery to localized sites and vectors. Neuroprotective strategies for delivering neurotrophic factors and antiapoptotic and antioxidant molecules in neurodegenerative disorders are currently under study in clinical trials. Stem cell transplantation has great potential for tissue engineering and also as a carrier for gene therapy, although its use raises complex societal issues. These approaches, together with a plethora of transgenic knockout animal models of neurodegenerative disorders, offer real promise for a previously untreatable group of movement disorders.