Antibody response to pneumococcal polysaccharide vaccine in myasthenia gravis: effect of therapeutic plasmapheresis

Immunogenicity of SARS-CoV-2 vaccines in patients treated with chronic double filtration plasmapheresis

BACKGROUND

The impact of chronic therapeutic plasmapheresis on humoral response following COVID-19 vaccination is poorly documented, especially among patients treated with double filtration plasmapheresis (DFPP).

OBJECTIVES

This retrospective single-center study evaluated the humoral response after SARS-CoV-2 vaccination and studied anti-SPIKE seropositivity and antibody dynamics in patients with chronic DFPP at our institution.

METHOD

All patients undergoing chronic DFPP at a tertiary center in France from December 2020 to November 2022 were included. We defined one patient subgroup as Group 1 to evaluate anti-SPIKE seropositivity after vaccination, with three groups based on their anti-SPIKE titers: (Group 1A) nonresponders (<0.8 UI/mL), (Group 1B) weak responders (0.8 to <250 binding antibody unit [BAU]/mL), and (Group 1C) strong responders (>250 BAU/mL). Group 2 served to evaluate antibody dynamics with anti-SPIKE levels measured 3 months after initial vaccination, Group 2A having a sustained level and Group 2B a declining pattern.

RESULTS

The 21 patients included had a median age of 63 years, and 13 (56%) were male. The indications for chronic DFPP mainly included dysimmune pathologies (15; 71%) and familial dyslipidemia (6; 29%). For the humoral response to vaccination in Patient Group 1, the only nonresponder was a patient who had undergone kidney transplantation 30 months earlier and was on immunosuppressive medication. For Patient Group 2, the median follow-up of antibody titers was 13 months [12-13]. Two distinct patterns of anti-SPIKE dynamics were observed: a rapid decline in anti-SPIKE antibody titers within 6 months following the initial vaccination or booster dose (n = 10 [71.4%] Group 2A) and stable anti-SPIKE levels above 250 BAU/mL over >6 months (n = 4 [28.6%] Group 2B) with more patients with familial dyslipidemia in the former.

CONCLUSIONS

Humoral response to SARS-CoV-2 vaccination appears robust in patients undergoing chronic DFPP and may be linked to patients' immune status rather than DFPTP itself. Our results support current recommendations for administering three doses of vaccine with a booster every 6 months.

Therapeutic Plasma Exchange Versus FcRn Inhibition in Autoimmune Disease

Therapeutic plasma exchange (TPE or PLEX) is used in a broad range of autoimmune diseases, with the goal of removing autoantibodies from the circulation. A newer approach for the selective removal of immunoglobulin G (IgG) antibodies is the use of therapeutic molecules targeting the neonatal Fc receptor (FcRn). FcRn regulates IgG recycling, and its inhibition results in a marked decrease in circulating autoantibodies of the IgG subtype. The difference between FcRn inhibition and PLEX is often questioned. With anti-FcRn monoclonal antibodies (mAbs) and fragments only recently entering this space, limited data are available regarding long-term efficacy and safety. However, the biology of FcRn is well understood, and mounting evidence regarding the efficacy, safety, and potential differences among compounds in development is available, allowing us to compare against nonselective plasma protein depletion methods such as PLEX. FcRn inhibitors may have distinct advantages and disadvantages over PLEX in certain scenarios. Use of PLEX is preferred over FcRn inhibition where removal of antibodies other than IgG or when concomitant repletion of missing plasma proteins is needed for therapeutic benefit. Also, FcRn targeting has not yet been studied for use in acute flares or crisis states of IgG-mediated diseases. Compared with PLEX, FcRn inhibition is associated with less invasive access requirements, more specific removal of IgG versus other immunoglobulins without a broad impact on circulating proteins, and any impacts on other therapeutic drug levels are restricted to other mAbs. In addition, the degree of IgG reduction is similar with FcRn inhibitors compared with that afforded by PLEX. Here we describe the scientific literature regarding the use of PLEX and FcRn inhibitors in autoimmune diseases and provide an expert discussion around the potential benefits of these options in varying clinical conditions and scenarios.

Vaccines and myasthenia gravis: a comprehensive review and retrospective study of SARS-CoV-2 vaccination in a large cohort of myasthenic patients

Introduction

Myasthenia gravis (MG) is an autoimmune disease, for which the risk of exacerbation after vaccines is debated. The aim of this study is to review the available literature concerning safety and efficacy of vaccines in MG. In addition, we also conducted a retrospective research of MG exacerbations and new onset MG after anti-SARS-CoV-2 vaccination in a large cohort of patients.

Methods

A study of the available literature regarding vaccines and MG was carried out through research in the online database “Pubmed”. We also retrospectively collected data from 80 MG patients, who were followed at the Treviso Hospital and completed an anti-SARS-CoV-2 vaccination cycle. For each patient, we recorded MG exacerbations between first and second doses and within a window period of 1 day – 6 weeks after the second dose.

Results

We found 26 relevant articles about influenza, SARS-CoV-2 and other vaccines. No clear associations between most vaccines and MG exacerbations were found. Moreover, cases of new onset post-vaccine MG are mostly anecdotal, except for Japanese encephalitis virus vaccine. Concerning our cohort, 4/80 (5%) MG patients experienced an exacerbation within the post-vaccine window period. In addition, we report a case of new onset post-vaccine MG.

Discussion

Inactivated and subunit vaccines are safe and effective in MG. Although some of them, such as anti-SARS-CoV-2 vaccine, might uncommonly cause MG exacerbations, data from our review suggest that benefits still outweigh by far the potential risks, thus they should be recommended to these patients. Nevertheless, large prospective studies are needed for further investigations.

Myasthenia gravis exacerbation in association with antibody overshoot following plasmapheresis

INTRODUCTION/AIM

Antibody overshoot following therapeutic plasmapheresis (PLEX) is defined by subsequent increase in antibody to levels exceeding those prior to removal. It has been infrequently described in the past, and its influence on the clinical course of myasthenia gravis (MG) remains unclear.

METHODS

This was a retrospective analysis of five patients with generalized MG treated with PLEX.

RESULTS

All five patients possessed antibodies against acetylcholine receptor (AChR-Ab). After undergoing 3 to 12 PLEX treatment sessions, AChR-Ab titer increased to a median of 1292% of the baseline level. The median interval from the last PLEX session to peak AChR-Ab detection was 6 wk. In four patients, AChR-Ab overshoot was associated with a clinical deterioration.

DISCUSSION

The AChR-Ab overshoot may occur following PLEX. In patients who deteriorate following PLEX treatment, the presence of antibody overshoot may serve as additional guidance for treatment adjustment.

The mechanisms of action of plasma exchange

The initial description of therapeutic plasma exchange (TPE) in an animal model was published almost 100 years ago. Since that time, this treatment has been applied to a wide variety of diseases but limited research has been published examining the mechanisms of action of TPE. The therapeutic effects of TPE could include the removal of pathological substances from the blood, such as monoclonal paraproteins and autoantibodies, as well as the replacement of deficient plasma components when plasma is used as a replacement fluid. Beyond these potential mechanisms, other possible mechanisms include possible alterations in lymphocyte proliferation and function that could sensitize these cells to immunosuppressant and chemotherapeutic agents and alterations in the immune system including changes in B and T cell numbers and activation, increased T suppressor function, and alteration in T-helper cell type 1/2 (Th1/Th2) ratio. Much remains unknown about the mechanisms of action of TPE, indicating a need for basic research into this therapy.

Hepatocyte expression of soluble donor MHC class I antigen via gene transfer inhibits multiple aspects of the antidonor immune response in fully sensitized rat transplant recipients

Sensitized organ transplant recipients face an increased risk of hyperacute rejection (HAR) due to donor major histocompatibility complex (MHC) class I antigen (Ag) preexposure. We recently reported a novel donor-specific strategy to address this problem, whereby soluble donor MHC class I Ag gene therapy prevented HAR of heart allografts in passively sensitized rats. Here, we tested this same approach in presensitized rat recipients with a fully preactivated humoral and cellular immune response. Our gene therapy method involved liposomal transfection of cultured recipient (Lewis-RT1.A(1)) hepatocytes with DNA encoding secretable donor MHC class I Ag, RT1.A(a). Control-transfected or RT1.A(a)-transfected hepatocytes were implanted intrasplenically into Lewis rats presensitized with three skin transplants. Subsequently, antidonor antibody, cytotoxic T lymphocyte (CTL), and helper T lymphocyte (HTL) assays were performed. Additionally, the effectiveness of our gene therapy on the prevention of ACI (RT1(a)) heart HAR was evaluated. Results indicated that soluble MHC not only decreased cytotoxic antibody levels, but also suppressed antidonor CTL and HTL responses; furthermore, HAR of heart allografts was prevented in all recipients. Therefore, soluble donor MHC class I gene therapy can inhibit multiple aspects of the primed antidonor immune response in actively presensitized rats. Development of this strategy in presensitized humans could improve organ transplant outcome.

Effective use of donor MHC class I gene therapy in organ transplantation: prevention of antibody-mediated hyperacute heart allograft rejection in highly sensitized rat recipients

Immunologically sensitized recipients present one of the most critical problems in clinical organ transplantation today, since preformed antibodies rapidly destroy donor tissue expressing specific MHC class I antigens (Ag). Therefore, sensitized patients are either unable to receive a compatible organ, or experience a prolonged waiting period. In this study we examined the effectiveness of donor MHC class I gene therapy in preventing hyperacute rejection (HR) of rat heart allografts in passively sensitized recipients. Our gene therapy strategy to address this problem is based on the phenomenon that liver transplants, which resist antibody-mediated HR, produce soluble MHC class I Ag capable of neutralizing preformed antibodies and suppressing the immune response. To mimic this "liver effect," we used liposomes to transfect cultured recipient (Lewis-RT1.Al) hepatocytes with plasmid DNA encoding the soluble donor MHC class I Ag, RT1.Aa. Control or RT1.Aa-transfected hepatocytes were implanted intrasplenically into Lewis recipients 1 day prior to heterotopic ACI (RT1.Aa) heart transplantation and injection of 6 ml of anti-ACI hyperimmune serum (HIS). Results showed that nearly all recipients receiving ACI-specific HIS and control hepatocytes experienced HR, while none of the recipients receiving HIS and hepatocytes expressing soluble RT1.Aa developed HR. Furthermore, active immunosuppression by soluble RT1.Aa was evidenced by prolongation of allograft survival, compared with controls not receiving HIS. In summary, soluble donor-MHC class I Ag gene therapy can prevent antibody-mediated destruction associated with HR. Future development of a similar strategy in humans may significantly improve the results of clinical organ transplantation in immunologically sensitized recipients.

Immunologic rebound

Evidence for accelerated specific antibody (Ab) rebound or overshoot after single or multiple therapeutic plasmapheresis (TP) is fragmentary but suggested by both clinical and experimental evidence. In vitro studies showing increased peripheral blood lymphocyte turnover and total immunoglobulin production after a series of TP without immunosuppression may signify a generalized immunostimulation through removal of regulatory molecules by TP. It is known that IgG class Ab can down regulate B cells by cross linkage of their Ag and Fc receptors. Cyclophosphamide and other cytotoxic immunosuppressive agents effectively delete proliferating lymphocytes. TP could particularly foster deletion of lymphocytes actively mediating autoimmunity, since they would be more readily stimulated to proliferation by removal of Ab or other inhibitory factors than the generally resting normal immune system. This is supported by a relatively greater reduction of autoantibody levels than total immunoglobulin after treatment with TP and cytotoxic immunosuppressives.

Treatment-free remission in severe systemic lupus erythematosus following synchronization of plasmapheresis with subsequent pulse cyclophosphamide

OBJECTIVE

To investigate the effect of an intensified treatment protocol synchronizing plasmapheresis with subsequent pulse cyclophosphamide for severe systemic lupus erythematosus (SLE).

METHODS

A protocol of plasmapheresis (3 x 60 ml/kg) and subsequent high-dose pulse cyclophosphamide (36 mg/kg) followed by 6 months of peroral immunosuppression was used to treat 14 patients with severe SLE.

RESULTS

Rapid improvement was achieved in all patients. Immunosuppressants, including corticosteroids, were withdrawn at month 6 in 12 patients. Eight patients continued without treatment for a mean observation period of 5.6 years (46-91 months).

CONCLUSION

The results demonstrate that treatment-free clinical remission can be achieved in some patients with severe SLE.

Effect of antigen-specific immunoadsorption on antibody kinetics in a rat model

The investigation of antibody kinetics following antigen-specific immunoadsorption in alkaline phosphatase immunized rats revealed significantly lower antibody levels than in untreated controls over a follow-up period of 6 weeks. A rebounding antibody synthesis as a result of specific depletion was not observed. Non-adsorption of specific antiidiotypic antibodies may explain these findings.

Plasmapheresis and subsequent pulse cyclophosphamide versus pulse cyclophosphamide alone in severe lupus: design of the LPSG trial. Lupus Plasmapheresis Study Group (LPSG)

A group of clinics are collaborating in the Lupus Plasmapheresis Study Group (LPSG) to investigate whether repeated plasmapheresis prior to pulse cyclophosphamide improves the therapeutical results in severe systemic lupus erythematosus (SLE). The underlying rationale is the hypothesis that plasmapheresis 1) eliminates pathogenic autoantibodies and immune complexes and 2) induces compensatory lymphocyte activation via feedback mechanisms between circulating antibodies and their respective clones ("antibody rebound"). It should be possible to utilize this enhanced activity for increased clonal deletion if pulse cyclophosphamide is applied shortly after plasmapheresis. Accordingly, in a randomized study, the LPSG will be comparing the repeated application of pulse cyclophosphamide alone with a treatment involving repeated plasmapheresis prior to the cyclophosphamide pulses in severe SLE. A third arm of the study will be gathering experience with a more intensified procedure. This overview summarizes the most important details of the planned study.