Polyvalent immunoglobulin preparations inhibit pneumolysin-induced platelet destruction

Platelets play an important role in the development and progression of respiratory distress. Functional platelets are known to seal inflammatory endothelial gaps and loss of platelet function has been shown to result in loss of integrity of pulmonary vessels. This leads to fluid accumulation in the pulmonary interstitium, eventually resulting in respiratory distress. Streptococcus pneumoniae is one of the major pathogens causing community-acquired pneumonia. Previously, we have shown that its major toxin pneumolysin forms pores in platelet membranes and renders them non-functional. In vitro, this process was inhibited by polyvalent intravenous immunoglobulins (IVIG). In this study, we compared the efficacy of a standard intravenous immunoglobulin preparation (IVIG, 98% IgG; Privigen, CSL Behring, USA) and an IgM/IgA-enriched immunoglobulin preparation (21% IgA, 23% IgM, 56% IgG; trimodulin, Biotest AG, Germany) to inhibit pneumolysin-induced platelet destruction. Platelet destruction and functionality were assessed by flow cytometry, intracellular calcium release, aggregometry, platelet viability, transwell, and flow chamber assays. Overall, both immunoglobulin preparations efficiently inhibited pneumolysin-induced platelet destruction. The capacity to antagonize pneumolysin mainly depended on the final IgG content. As both polyvalent immunoglobulin preparations efficiently prevent pneumolysin-induced platelet destruction and maintain platelet function in vitro, they represent promising candidates for clinical studies on supportive treatment of pneumococcal pneumonia to reduce progression of respiratory distress.

Guillain-Barré syndrome: diagnosis and treatment guidelines

GuillainBarr syndrome is an acute, rapidly progressive immune-mediated disease of the peripheral nervous system, combining several variants and subtypes with various clinical, pathophysiological and electrophysiological signs. GuillainBarr syndrome usually develops 13 weeks after the viral or bacterial infection, which acts as the trigger triggering autoimmune mechanisms, leading to demyelination and axonal damage. The disease is getting more acute due to the emergence of a new coronavirus infection. Behind the diseases dipathophysiology there is the activation of cellular and humoral immunity with the production of autoantibodies to specific gangliosides and glycolipids and the formation of circulating immune complexes that attack peripheral nerves and roots (the phenomenon of molecular mimicry). The examination of patients requires an integrated approach, including, along with clinical and anamnestic data, the results of laboratory and neurophysiological examination. The treatment of patients with GuillainBarr syndrome is carried out in an intensive care unit and includes both pathogenetic therapy and nonspecific measures aimed to correct dysfunctions of vital organs, prevent complications and provide symptomatic therapy. Currently, the main direction of pathogenetic therapy of this disease is the use of high-dose intravenous immunotherapy with human normal immunoglobulin preparations or high-volume therapeutic plasmapheresis. Taking into account the absence of data about differences in the effectiveness of these methods, the choice of direction is determined taking into account the contraindications and possible development of adverse events, as well as the capabilities of the medical institution (2 tables, bibliography: 15 refs)

The Functional Role of IgA in the IgM/IgA-Enriched Immunoglobulin Preparation Trimodulin

In comparison to human immunoglobulin (Ig) G, antibodies of IgA class are not well investigated. In line with this, the functional role of the IgA component in IgM/IgA-enriched immunoglobulin preparations is also largely unknown. In recent years, powerful anti-pathogenic and immunomodulatory properties of human serum IgA especially on neutrophil function were unraveled. Therefore, the aim of our work is to investigate functional aspects of the trimodulin IgA component, a new plasma-derived polyvalent immunoglobulin preparation containing ~56% IgG, ~23% IgM and ~21% IgA. The functional role of IgA was investigated by analyzing the interaction of IgA with FcαRI, comparing trimodulin with standard intravenous IgG (IVIG) preparation and investigating Fc receptor (FcR)-dependent functions by excluding IgM-mediated effects. Trimodulin demonstrated potent immunomodulatory, as well as anti-pathogenic effects in our neutrophil model (neutrophil-like HL-60 cells). The IgA component of trimodulin was shown to induce a strong FcαRI-dependent inhibitory immunoreceptor tyrosine-based activation motif (ITAMi) signaling, counteract lipopolysaccharide-induced inflammation and mediate phagocytosis of Staphylococcus aureus. The fine-tuned balance between immunomodulatory and anti-pathogenic effects of trimodulin were shown to be dose-dependent. Summarized, our data demonstrate the functional role of IgA in trimodulin, highlighting the importance of this immunoglobulin class in immunoglobulin therapy.

Immunomodulatory effects of different intravenous immunoglobulin preparations in chronic lymphocytic leukemia

Hypogammaglobulinemia is the most frequently observed immune defect in chronic lymphocytic leukemia (CLL). Although CLL patients usually have low serum levels of all isotypes (IgG, IgM and IgA), standard immunoglobulin (Ig) preparations for replacement therapy administrated to these patients contain more than 95% of IgG. Pentaglobin is an Ig preparation of intravenous application (IVIg) enriched with IgM and IgA (IVIgGMA), with the potential benefit to restore the Ig levels of all isotypes. Because IVIg preparations at high doses have well-documented anti-inflammatory and immunomodulatory effects, we aimed to evaluate the capacity of Pentaglobin and a standard IVIg preparation to affect leukemic and T cells from CLL patients. In contrast to standard IVIg, we found that IVIgGMA did not modify T cell activation and had a lower inhibitory effect on T cell proliferation. Regarding the activation of leukemic B cells through BCR, it was similarly reduced by both IVIgGMA and IVIgG. None of these IVIg preparations modified spontaneous apoptosis of T or leukemic B cells. However, the addition of IVIgGMA on in vitro cultures decreased the apoptosis of T cells induced by the BCL-2 inhibitor, venetoclax. Importantly, IVIgGMA did not impair venetoclax-induced apoptosis of leukemic B cells. Overall, our results add new data on the effects of different preparations of IVIg in CLL, and show that the IgM/IgA enriched preparation not only affects relevant mechanisms involved in CLL pathogenesis but also has a particular profile of immunomodulatory effects on T cells that deserves further investigation.

Immunomodulation: Immunoglobulin Preparations Suppress Hyperinflammation in a COVID-19 Model via FcγRIIA and FcαRI

The rapid spread of SARS-CoV-2 has induced a global pandemic. Severe forms of COVID-19 are characterized by dysregulated immune response and “cytokine storm”. The role of IgG and IgM antibodies in COVID-19 pathology is reasonably well studied, whereas IgA is neglected. To improve clinical outcome of patients, immune modulatory drugs appear to be beneficial. Such drugs include intravenous immunoglobulin preparations, which were successfully tested in severe COVID-19 patients. Here we established a versatile in vitro model to study inflammatory as well as anti-inflammatory processes by therapeutic human immunoglobulins. We dissect the inflammatory activation on neutrophil-like HL60 cells, using an immune complex consisting of latex beads coated with spike protein of SARS-CoV-2 and opsonized with specific immunoglobulins from convalescent plasma. Our data clarifies the role of Fc-receptor-dependent phagocytosis via IgA-FcαRI and IgG-FcγR for COVID-19 disease followed by cytokine release. We show that COVID-19 associated inflammation could be reduced by addition of human immunoglobulin preparations (IVIG and trimodulin), while trimodulin elicits stronger immune modulation by more powerful ITAMi signaling. Besides IgG, the IgA component of trimodulin in particular, is of functional relevance for immune modulation in this assay setup, highlighting the need to study IgA mediated immune response.

Adjunctive IgM-enriched immunoglobulin therapy with a personalised dose based on serum IgM-titres versus standard dose in the treatment of septic shock: a randomised controlled trial (IgM-fat trial)

IntroductionIn patients with septic shock, low levels of circulating immunoglobulins are common and their kinetics appear to be related to clinical outcome. The pivotal role of immunoglobulins in the host immune response to infection suggests that additional therapy with polyclonal intravenous immunoglobulins may be a promising option in patients with septic shock. Immunoglobulin preparations enriched with the IgM component have largely been used in sepsis, mostly at standard dosages (250 mg/kg per day), regardless of clinical severity and without any dose adjustment based on immunoglobulin serum titres or other biomarkers. We hypothesised that a personalised dose of IgM enriched preparation based on patient IgM titres and aimed to achieve a specific threshold of IgM titre is more effective in decreasing mortality than a standard dose.Methods and analysisThe study is designed as a multicentre, interventional, randomised, single-blinded, prospective, investigator sponsored, two-armed study. Patients with septic shock and IgM titres <60 mg/dL will be randomly assigned to an IgM titre-based treatment or a standard treatment group in a ratio of 1:1. The study will involve 12 Italian intensive care units and 356 patients will be enrolled. Patients assigned to the IgM titre-based treatment will receive a personalised daily dose based on an IgM serum titre aimed at achieving serum titres above 100 mg/dL up to discontinuation of vasoactive drugs or day 7 after enrolment. Patients assigned to the IgM standard treatment group will receive IgM enriched preparation daily for three consecutive days at the standard dose of 250 mg/kg. The primary endpoint will be all-cause mortality at 28 days.Ethics and disseminationThe study protocol was approved by the ethics committees of the coordinating centre (Comitato Etico dell’Area Vasta Emilia Nord) and collaborating centres. The results of the trial will be published within 12 months from the end of the study and the steering committee has the right to present them at public symposia and conferences.Trial registration detailsThe trial protocol and information documents have received a favourable opinion from the Area Vasta Emilia Nord Ethical Committee on 12 September 2019. The trial protocol has been registered on EudraCT (2018-001613-33) on 18 April 2018 and on ClinicalTrials.gov (NCT04182737) on 2 December 2019.

Pneumolysin induces platelet destruction, not platelet activation, which can be prevented by immunoglobulin preparations in vitro

Community-acquired pneumonia by primary or superinfections with Streptococcus pneumoniae can lead to acute respiratory distress requiring mechanical ventilation. The pore-forming toxin pneumolysin alters the alveolar-capillary barrier and causes extravasation of protein-rich fluid into the interstitial pulmonary tissue, which impairs gas exchange. Platelets usually prevent endothelial leakage in inflamed pulmonary tissue by sealing inflammation-induced endothelial gaps. We not only confirm that S pneumoniae induces CD62P expression in platelets, but we also show that, in the presence of pneumolysin, CD62P expression is not associated with platelet activation. Pneumolysin induces pores in the platelet membrane, which allow anti-CD62P antibodies to stain the intracellular CD62P without platelet activation. Pneumolysin treatment also results in calcium efflux, increase in light transmission by platelet lysis (not aggregation), loss of platelet thrombus formation in the flow chamber, and loss of pore-sealing capacity of platelets in the Boyden chamber. Specific anti-pneumolysin monoclonal and polyclonal antibodies inhibit these effects of pneumolysin on platelets as do polyvalent human immunoglobulins. In a post hoc analysis of the prospective randomized phase 2 CIGMA trial, we show that administration of a polyvalent immunoglobulin preparation was associated with a nominally higher platelet count and nominally improved survival in patients with severe S pneumoniae–related community-acquired pneumonia. Although, due to the low number of patients, no definitive conclusion can be made, our findings provide a rationale for investigation of pharmacologic immunoglobulin preparations to target pneumolysin by polyvalent immunoglobulin preparations in severe community-acquired pneumococcal pneumonia, to counteract the risk of these patients becoming ventilation dependent. This trial was registered at www.clinicaltrials.gov as #NCT01420744.