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Critical for diverse biological processes, proteases represent one of the largest families of pharmaceutical targets. To inhibit pathogenic proteases with desired selectivity, monoclonal antibodies (mAbs) hold great promise as research tools and therapeutic agents. However, identification of mAbs with inhibitory functions is challenging because current antibody discovery methods rely on binding rather than inhibition. This study developed a highly efficient selection method for protease inhibitory mAbs by coexpressing 3 recombinant proteins in the periplasmic space of Escherichia coli—an antibody clone, a protease of interest, and a β-lactamase modified by insertion of a protease cleavable peptide sequence. During functional selection, inhibitory antibodies prevent the protease from cleaving the modified β-lactamase, thereby allowing the cell to survive in the presence of ampicillin. Using this method to select from synthetic human antibody libraries, we isolated panels of mAbs inhibiting 5 targets of 4 main protease classes: matrix metalloproteinases (MMP-14, a predominant target in metastasis; MMP-9, in neuropathic pain), β-secretase 1 (BACE-1, an aspartic protease in Alzheimer’s disease), cathepsin B (a cysteine protease in cancer), and Alp2 (a serine protease in aspergillosis). Notably, 37 of 41 identified binders were inhibitory. Isolated mAb inhibitors exhibited nanomolar potency, exclusive selectivity, excellent proteolytic stability, and desired biological functions. Particularly, anti-Alp2 Fab A4A1 had a binding affinity of 11 nM and inhibition potency of 14 nM, anti-BACE1 IgG B2B2 reduced amyloid beta (Aβ40) production by 80% in cellular assays, and IgG L13 inhibited MMP-9 but not MMP-2/-12/-14 and significantly relieved neuropathic pain development in mice.

Single domain antibodies (VHHs) are potentially disruptive therapeutics, with important biological value for treatment of several diseases, including neurological disorders. However, VHHs have not been widely used in the central nervous system (CNS), largely because of their restricted blood–brain barrier (BBB) penetration. Here, we propose a gene transfer strategy based on BBB‐crossing adeno‐associated virus (AAV)‐based vectors to deliver VHH directly into the CNS. As a proof‐of‐concept, we explored the potential of AAV‐delivered VHH to inhibit BACE1, a well‐characterized target in Alzheimer’s disease. First, we generated a panel of VHHs targeting BACE1, one of which, VHH‐B9, shows high selectivity for BACE1 and efficacy in lowering BACE1 activity in vitro . We further demonstrate that a single systemic dose of AAV‐VHH‐B9 produces positive long‐term (12 months plus) effects on amyloid load, neuroinflammation, synaptic function, and cognitive performance, in the App NL‐G‐F Alzheimer’s mouse model. These results constitute a novel therapeutic approach for neurodegenerative diseases, which is applicable to a range of CNS disease targets. Synopsis VHH and blood‐brain‐barrier (BBB)‐crossing AAV‐based vectors are combined to achieve highly‐specific, long‐term BACE1 inhibition in a mouse model of Alzheimer's disease (AD). A gene transfer strategy based on BBB‐crossing AAV vectors is developed to deliver VHH single domain antibodies directly into the CNS. VHH‐B9 is generated to target BACE1, an enzyme critical to Aβ generation in AD, and incorporated into an AAV‐PHP.B‐based vector. A single dose of AAV‐VHH resulted in long‐term VHH expression in the App NL‐G‐F mouse model, with concomitant improvements in cognitive status, amyloidosis, neuroinflammation, and synaptic function. Graphical Abstract VHH and blood‐brain‐barrier (BBB)‐crossing AAV‐based vectors are combined to achieve highly‐specific, long‐term BACE1 inhibition in a mouse model of Alzheimer's disease (AD).

The profile of autoantibodies is dysregulated in patients with Alzheimer’s disease (AD). Autoantibodies to beta-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) are present in human blood. This study aims to investigate the clinical relevance and pathophysiological roles of autoantibodies to BACE1 in AD. Clinical investigations were conducted in two independent cohorts, the Chongqing cohort, and the Australian Imaging, Biomarkers, and Lifestyle (AIBL) cohort. The Chongqing cohort included 55 AD patients, 28 patients with non-AD dementia, and 70 cognitively normal subjects (CN). The AIBL cohort included 162 Aβ-PET − CN, 169 Aβ-PET + cognitively normal subjects (preclinical AD), and 31 Aβ-PET + cognitively impaired subjects (Clinical AD). Plasma autoantibodies to BACE1 were determined by one-site Elisa. The associations of plasma autoantibodies to BACE1 with brain Aβ load and cognitive trajectory were investigated. The effects of autoantibodies to BACE1 on AD-type pathologies and underlying mechanisms were investigated in APP/PS1 mice and SH/APPswe/PS1wt cell lines. In the Chongqing cohort, plasma autoantibodies to BACE1 were higher in AD patients, in comparison with CN and non-AD dementia patients. In the AIBL cohort, plasma autoantibodies to BACE1 were highest in clinical AD patients, followed by preclinical AD and CN subjects. Higher autoantibodies to BACE1 were associated with an increased incidence of brain amyloid positivity conversion during follow-up. Autoantibodies to BACE1 exacerbated brain amyloid deposition and subsequent AD-type pathologies, including Tau hyperphosphorylation, neuroinflammation, and neurodegeneration in APP/PS1 mice. Autoantibodies to BACE1 increased Aβ production by promoting BACE1 expression through inhibiting PPARγ signaling. These findings suggest that autoantibodies to BACE1 are pathogenic in AD and the upregulation of these autoantibodies may promote the development of the disease. This study offers new insights into the mechanism of AD from an autoimmune perspective.

To look deep inside tissues, traditional histological methods cut specimens into thin slices. Providing access to the intricate anatomy of intact organs, tissue clearing offers neuroscientists unbiased and complete views of brain anatomy and function. One area where these methods have particular utility is in the development of CNS therapeutics where they can be used to examine the regional distribution of the therapeutics in the brain. We have developed a pipeline that provides unbiased and complete cellular resolution measurements of brain-wide therapeutic biodistribution in pre-clinical rodent brains. Using our iDISCO-based tissue clearing method and a light sheet microscope, we can image micron-scale resolution immunoreactivity across entire intact mouse brains. Here we explore the use of our technology to detect antibody therapeutics crossing the blood-brain barrier (BBB) and engaging with targets. In initial studies, we used a bispecific antibody engineered to bind to the Alzheimer's Disease target, BACE1, as well as the transferrin receptor (TfR1), which helps shuttle the antibody across the brain endothelium and into the brain parenchyma. The IV-dosed monospecific antibody could not be detected in the brain, but the bispecific Brainshuttle antibody was detected in the brain vasculature, presumably bound to TfR1, but also in the parenchyma, enriched in brain regions with high BACE1 expression, indicating that the bispecific antibody crosses the BBB and engages the target. To quantify the effective parenchymal levels of the bispecific antibody, we have extended our AI-powered quantification pipeline to segment the staining in the vasculature and measure only the therapeutically relevant bispecific antibody signal in the brain parenchyma. Interestingly, the Brainshuttle mechanism is not always necessary. IV-dosing of a Donanemab (Kisunla™) biosimilar was not detected in WT mice, but it accumulated in the brain of ARTE10 AD model mice, crossing the BBB and colocalizing with Amyloid plaques. Using our whole-brain quantification tools, we segmented and quantified Donanemab biosimilar aggregates throughout the brain. These data provide a clear demonstration of the utility of tissue clearing methods for quantitative brain-wide monitoring of Alzheimer's Disease therapeutic antibody biodistribution.

► We describe the first formulation of a virosomal fungal vaccine. ► Immunogenicity, protection and safety profile are reported for this new vaccine. ► This new formulation was highly effective against experimental candidal vaginitis. ► We significantly progressed in the perspective of a human anticandidal vaccine.1Current address: CSL Behring AG, CH-3014 Bern, Switzerland.2Current address: Lonza AG, CH-3930 Visp, Switzerland. A novel vaccine (PEV7) consisting of a truncated, recombinant aspartyl proteinase-2 of Candida albicans incorporated into influenza virosomes was studied. This vaccine candidate generated a potent serum antibody response in mouse and rat following intramuscular immunization. Anti-Sap2 IgG and IgA were also detected in the vaginal fluid of rats following intravaginal or intramuscular plus intravaginal administration. In a rat model of candidal vaginitis, PEV7 induced significant, long-lasting, likely antibody-mediated, protection following intravaginal route of immunization. PEV7 was also found to be safe in a repeated-dose toxicological study in rats. Overall, these data provide a sound basis to envisage the clinical development of this new candidate vaccine against candidal vaginitis.

The 3-dimensional structure of an allergen defines the accessible parts on the surface of the molecule or epitopes that interact with antibodies. Mapping the antigenic determinants for IgE antibody binding has been pursued through strategies based on the use of overlapping synthetic peptides, recombinant allergenic fragments or unfolded allergens. These approaches led to the identification of mostly linear epitopes and are useful for food allergens that undergo digestion or food processing. For inhaled allergens, conformational epitopes appear to be the primary targets of IgE responses. Knowledge of the molecular structure of allergens alone and in complex with antibodies that interfere with IgE antibody binding is important to understand the immune recognition of B cell-antigenic determinants on allergens and the design of recombinant allergens for immunotherapy. Starting with the molecular cloning and expression of allergens, and with the advent of X-ray crystallography and nuclear magnetic resonance techniques, we have been able to visualize conformational epitopes on allergens.

Background Plasmodium invasion of the mosquito midgut is a population bottleneck in the parasite lifecycle. Interference with molecular mechanisms by which the ookinete invades the mosquito midgut is one potential approach to developing malaria transmission-blocking strategies. Plasmodium aspartic proteases are one such class of potential targets: plasmepsin IV (known to be present in the asexual stage food vacuole) was previously shown to be involved in Plasmodium gallinaceum infection of the mosquito midgut, and plasmepsins VII and plasmepsin X (not known to be present in the asexual stage food vacuole) are upregulated in Plasmodium falciparum mosquito stages. These (and other) parasite-derived enzymes that play essential roles during ookinete midgut invasion are prime candidates for transmission-blocking vaccines. Methods Reverse transcriptase PCR (RT-PCR) was used to determine timing of P. falciparum plasmepsin VII (PfPM VII) and plasmepsin X (PfPM X) mRNA transcripts in parasite mosquito midgut stages. Protein expression was confirmed by western immunoblot and immunofluorescence assays (IFA) using anti-peptide monoclonal antibodies (mAbs) against immunogenic regions of PfPM VII and PfPM X. These antibodies were also used in standard membrane feeding assays (SMFA) to determine whether inhibition of these proteases would affect parasite transmission to mosquitoes. The Mann–Whitney U test was used to analyse mosquito transmission assay results. Results RT-PCR, western immunoblot and immunofluorescence assay confirmed expression of PfPM VII and PfPM X in mosquito stages. Whereas PfPM VII was expressed in zygotes and ookinetes, PfPM X was expressed in gametes, zygotes, and ookinetes. Antibodies against PfPM VII and PfPM X decreased P. falciparum invasion of the mosquito midgut when used at high concentrations, indicating that these proteases play a role in Plasmodium mosquito midgut invasion. Failure to generate genetic knockouts of these genes limited determination of the precise role of these proteases in parasite transmission but suggests that they are essential during the intraerythrocytic life cycle. Conclusions PfPM VII and PfPM X are present in the mosquito-infective stages of P. falciparum. Standard membrane feeding assays demonstrate that antibodies against these proteins reduce the infectivity of P. falciparum for mosquitoes, suggesting their viability as transmission-blocking vaccine candidates. Further study of the role of these plasmepsins in P. falciparum biology is warranted.

BackgroundNapsin A is normally expressed in human lung pneumocytes and is a highly expressed cancer antigen in lung adenocarcinoma. We examined whether T cells specific for Napsin A may play a role in immune checkpoint inhibitor (ICI)-mediated responses. We used bulk T-cell receptor (TCR) repertoire data to assess whether the presence of Napsin A-specific clonotypes in the peripheral blood was associated with improved clinical responses to ICI.MethodsPatients with metastatic non-small cell lung cancer (NSCLC) receiving anti-programmed cell death protein 1 (PD-1) and/or programmed death-ligand 1 (PD-L1) were enrolled at Fred Hutchinson Cancer Center and Stanford University Medical Center (n=62; histology of adenocarcinoma n=48, squamous n=9, NSCLC/other n=5). Peripheral blood mononuclear cells were collected for genomic DNA isolation at one pretreatment and one post-treatment time point (range 3 weeks to 3 months). TCRβ was bulk sequenced via the immunoSEQ platform (Adaptive Biotechnologies). Napsin A-specific TCRβ sequences were identified from publicly available data and their frequencies were quantified in each patient sample. We examined whether overall survival (OS) and progression-free survival (PFS) outcomes differed in patients with or without detectable Napsin A-specific TCRs (herein Napsin TCRs). We used Cox proportional hazards regression to assess the association between detectable Napsin TCRs and PFS or OS in univariable and multivariable analyses.ResultsNapsin TCRs were detectable in the blood in a large fraction of our cohort (n=25/62 (40%) pretreatment; n=21/42 (50%) post-treatment). Patients with detectable Napsin TCRs had a significant improvement in OS compared with patients without these TCRs (median OS 45.4 vs 14.8 months, p=0.0043 pretreatment; median OS 55.4 vs 18.9 months, p=0.0066 post-treatment). Among 27 HLA-A*02 carriers of 55 human leukocyte antigen-typed patients (49%), patients with detectable pretreatment Napsin TCRs had a significant improvement in OS (median 60.2 vs 16.5 months, p=0.0054) and PFS (median 21.5 vs 7.2 months, p=0.031) compared with patients without these TCRs. In univariate and multivariate analysis, the presence of Napsin TCRs pretreatment was associated with improved OS (p=0.0057, HR 0.40, 95% CI 0.21 to 0.76 univariate; p=0.033, HR 0.45, 95% CI 0.23 to 0.91 multivariate).ConclusionsNapsin TCRs are frequently detected in patients with NSCLC and are associated with improved OS in patients with NSCLC receiving ICI.

There is a high prevalence of aeroallergen sensitivity in asthmatic populations, and seroreactivity to aeroallergens early in infancy is associated with increased risk of developing asthma later in life. In addition to allergen sensitivity, asthma development has been associated with differential microbial exposure and infection in early life. We have previously shown that cord blood mononuclear cells respond to common aeroallergens (i.e., house dust mite [Der f1] and cockroach [Bla g2]) as assayed by lymphoproliferation and cytokine (IL-13 and IFN-γ) production. We hypothesized that there is a relationship between perinatal microbial exposure and response to specific aeroallergens. To test this hypothesis, we isolated DNA from cord blood serum samples with known lymphoproliferative and cytokine responses to Bla g2 and Der f1. Bacterial 16S ribosomal DNA amplicon libraries were generated and analyzed using high throughput sequencing of cord blood serum samples. In our analysis, we identified major compositional differences, including diversity and abundance of specific taxa, between groups whose IL-13 response to Der f1 and Bla g2 differed. We demonstrate a strong association between the ratio of Acinetobacter to Proteobacteria and IL-13 production and the probability of IL-13 production after allergen exposure. IL-13 concentrations in serum were also significantly correlated with the diversity of bacterial DNA. Together, these results underscore the relationship between immune responses to allergens and bacterial exposure during perinatal development.

BACKGROUND: Toxoplasma gondii is an obligate intracellular parasite that can pose a serious threat to human health by causing toxoplasmosis. There are no drugs that target the chronic cyst stage of this infection; therefore, development of an effective vaccine would be an important advance. Aspartic proteases play essential roles in the T. gondii lifecycle. The parasite has four aspartic protease encoding genes, which are called toxomepsin 1, 2, 3 and 5 (TgASP1, 2, 3 and 5, respectively). METHODS: Bioinformatics approaches have enabled us to identify several promising linear-B cell epitopes and potential Th-cell epitopes on TgASP1, thus supporting its potential as a DNA vaccine against toxoplasmosis. We expressed TgASP1 in Escherichia coli and used the purified protein to immunize BALB/c mice. The antibodies obtained were used to determine where TgASP1 was localized in the parasite. We also made a TgASP1 DNA vaccine construct and evaluated it for the level of protection conferred to mice against infection with the virulent RH strain of T. gondii. RESULTS: TgASP1 appears to be a membrane protein located primarily at the tip of the T. gondii tachyzoite. Investigation of its potential as a DNA vaccine showed that it elicited strong humoral and cellular immune responses in mice, and that these responses were mediated by Th-1 cells. Mice immunized with the vaccine had greater levels of protection against mortality following challenge with T. gondii RH tachyzoites than did those immunized with PBS or the empty vector control. CONCLUSIONS: TgASP1 is a novel candidate DNA vaccine that merits further investigation.