Targeting Aspergillus fumigatus Crf Transglycosylases With Neutralizing Antibody Is Relevant but Not Sufficient to Erase Fungal Burden in a Neutropenic Rat Model

Aspergillus fumigatus is an airborne opportunistic fungal pathogen responsible for severe infections. Among them, invasive pulmonary aspergillosis has become a major concern as mortality rates exceed 50% in immunocompromised hosts. In parallel, allergic bronchopulmonary aspergillosis frequently encountered in cystic fibrosis patients, is also a comorbidity factor. Current treatments suffer from high toxicity which prevents their use in weakened subjects, resulting in impaired prognostic. Because of their low toxicity and high specificity, anti-infectious therapeutic antibodies could be a new alternative to conventional therapeutics. In this study, we investigated the potential of Chitin Ring Formation cell wall transglycosylases of A. fumigatus to be therapeutic targets for therapeutic antibodies. We demonstrated that the Crf target was highly conserved, regardless of the pathophysiological context; whereas the CRF1 gene was found to be 100% conserved in 92% of the isolates studied, Crf proteins were expressed in 98% of the strains. In addition, we highlighted the role of Crf proteins in fungal growth, using a deletion mutant for CRF1 gene, for which a growth decrease of 23.6% was observed after 48 h. It was demonstrated that anti-Crf antibodies neutralized the enzymatic activity of recombinant Crf protein, and delayed fungal growth by 12.3% in vitro when added to spores. In a neutropenic rat model of invasive pulmonary aspergillosis, anti-Crf antibodies elicited a significant recruitment of neutrophils, macrophages and T CD4 lymphocytes but it was not correlated with a decrease of fungal burden in lungs and improvement in survival. Overall, our study highlighted the potential relevance of targeting Crf cell wall protein (CWP) with therapeutic antibodies

Alternative Routes of Administration for Therapeutic Antibodies -State of the Art

International audienceBackground: For the past two decades, there has been a huge expansion in the development of therapeutic antibodies, with 6 to 10 novel entities approved each year. Around 70% of these Abs are delivered through IV injection, a mode of administration allowing rapid and systemic delivery of the drug. However, according to the evidence presented in the literature, beyond the reduction of invasiveness, a better efficac can be achieved with local delivery. Consequently, efforts have been made toward the development of innovative methods of administration, and in the formulation and engineering of novel Abs to improve their therapeutic index.Objective: This review presents an overview of the routes of administration used to deliver Abs, different from the IV route, whether approved or in the clinical evaluation stage. We provide a description of the physical and biological fundamentals for each route of administration, highlighting their relevance with examples of clinically-relevant Abs, and discussing their strengths and limitations.Methods: We reviewed and analyzed the current literature, published as of the 1 April 2022 using MEDLINE and EMBASE databases, as well as the FDA and EMA websites. Ongoing trials were identified using clinicaltrials.gov. Publications and data were identified using a list of general keywords.Conclusions: Apart from the most commonly used IV route, topical delivery of Abs has shown clinical successes, improving drug bioavailability and efficacy while reducing side-effects. However, additional research is necessary to understand the consequences of biological barriers associated with local delivery for Ab partitioning, in order to optimize delivery methods and devices, and to adapt Ab formulation to local delivery. Novel modes of administration for Abs might in fine allow a better support to patients, especially in the context of chronic diseases, as well as a reduction of the treatment cost

Pneumocystis pneumonia: pitfalls and hindrances to establish a reliable animal model

International audiencePneumocystis pneumonia is a severe lung infection that occurs primarily in largely immunocompromised patients. Few treatment options exist and the mortality remains substantial. To develop new strategies in the fields of diagnosis and treatment, it appears critical to improve the scientific knowledge about the biology of the Pneumocystis agent and the course of the disease. In the absence of in vitro continuous culture system, in vivo animal studies represent a crucial cornerstone for addressing Pneumocystis pneumonia in laboratories. These models constitute an essential complement to clinical studies. Here, we provide an overview of the animal models of Pneumocystis pneumonia that were reported in the literature over the last 60 years. It summarizes the various technical parameters to consider in the preparation of the model and the interpretation of the limits / results of such studies. Overall, this review highlights the great heterogeneity of the variables studied: the choice of the host species and its genetics, the different immunosuppressive regimens to render animal susceptible, the experimental challenge, and the different validation methods of the model

Inhaled antibodies: formulations require specific development to overcome instability due to nebulization

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Crucial Role for Immune Complexes but Not FcRn in Immunization against Anti–TNF-α Antibodies after a Single Injection in Mice

International audienceThe immunogenicity of infliximab and adalimumab is a major concern because patients may develop Abs also called antidrug Abs (ADA), directed against these anti–TNF-α Abs after just a few weeks of treatment. These ADAs can lead to a decrease in biologic concentration, which is associated with lower treatment efficacy. Our aim was to study the involvement of immune complexes and neonatal Fc receptor (FcRn) in the emergence of ADAs in the case of anti–TNF-α Abs. Wild type and FcRn knockout mice were injected once with either infliximab or adalimumab, alone or preincubated with TNF-α. Adalimumab cross-reacts with murine TNF-α whereas infliximab is species specific. When injected alone, only adalimumab elicited a humoral response. By preforming immune complexes with TNF-α, an anti-infliximab response was elicited. Surprisingly, both wild type and FcRn knockout mice were able to mount an immune response against anti–TNF-α Abs, suggesting that immune complexes are a major determinant of this immunization

Mucosal administration of anti-bacterial antibody (Ab) provides long-term cross-protection against Pseudomonas aeruginosa respiratory infection

International audienceRespiratory infections are a major threat for global human health. The epidemic increase in antimicrobial resistance and seasonal virus outbreaks have severely complicated the management of respiratory infections. Airway administration of therapeutic antibodies demonstrated remarkable preclinical achievements against both viral and bacterial respiratory infections. The primary mode of action of antiinfective Ab is pathogen neutralization. However, using a mouse model of acute pneumonia induced by Pseudomonas aeruginosa lung infection, a versatile bacterium frequently associated with nosocomial infection and multidrug resistance, we also demonstrated immunomodulatory properties associated with anti-bacterial Ab. A single pulmonary administration of Ab efficiently contained the primary infection while being also able to trigger adaptive immunity providing a protecting long-term response against a secondary infection. This effect was specific and dependent on the dose of the antibody, the size of the inoculum and the presence of the cognate antigen. Thanks to adoptive transfer experiments, we showed that this long-term response was attributable to a sustained and protective humoral immunity. Remarkably, the long-lasting response mediated by a pulmonary-administered Ab allowed protection against secondary infections due to heterologous P. aeruginosa strains, expressing or not the cognate antigen. Overall, our findings suggest that mucosal delivery of Ab through the airways affords a rapid pathogen containment, while promoting long-term protection against secondary infections. This novel modality associated with anti-infective antibody opens new perspectives for the treatment of respiratory infections

Aggregates Associated with Instability of Antibodies during Aerosolization Induce Adverse Immunological Effects

International audienceBackground: Immunogenicity refers to the inherent ability of a molecule to stimulate an immune response. Aggregates are one of the major risk factors for the undesired immunogenicity of therapeutic antibodies (Ab) and may ultimately result in immune-mediated adverse effects. For Ab delivered by inhalation, it is necessary to consider the interaction between aggregates resulting from the instability of the Ab during aerosolization and the lung mucosa. The aim of this study was to determine the impact of aggregates produced during aerosolization of therapeutic Ab on the immune system.Methods: Human and murine immunoglobulin G (IgG) were aerosolized using a clinically-relevant nebulizer and their immunogenic potency was assessed, both in vitro using a standard human monocyte-derived dendritic cell (MoDC) reporter assay and in vivo in immune cells in the airway compartment, lung parenchyma and spleen of healthy C57BL/6 mice after pulmonary administration.Results: IgG aggregates, produced during nebulization, induced a dose-dependent activation of MoDC characterized by the enhanced production of cytokines and expression of co-stimulatory markers. Interestingly, in vivo administration of high amounts of nebulization-mediated IgG aggregates resulted in a profound and sustained local and systemic depletion of immune cells, which was attributable to cell death. This cytotoxic effect was observed when nebulized IgG was administered locally in the airways as compared to a systemic administration but was mitigated by improving IgG stability during nebulization, through the addition of polysorbates to the formulation.Conclusion: Although inhalation delivery represents an attractive alternative route for delivering Ab to treat respiratory infections, our findings indicate that it is critical to prevent IgG aggregation during the nebulization process to avoid pro-inflammatory and cytotoxic effects. The optimization of Ab formulation can mitigate adverse effects induced by nebulization