Molecular characterization of public anti-PfCSP antibodies in human malaria

Plasmodium falciparum is a unicellular parasite that throughout its complex lifecycle infects Anopheles mosquitos and humans. The parasite stages injected into the human by the mosquito are called sporozoites and can be neutralized by antibodies generated by the human immune system. The present study investigates the humoral immune response, i.e. the antibody response, to the major antigen on the sporozoite surface, circumsporozoite protein (CSP). A recently published study describes high-affine anti-CSP antibodies, which are generated upon repeated controlled human malaria infection of European donors, who were never exposed to the parasite before. The present work on the one hand describes the molecular characteristics that determine the binding of such antibodies. On the other hand, it investigates whether African donors from an endemic malaria region exhibited similar antibodies. In the repertoire of the European donors, several groups of antibodies were identified that share highly similar amino acid sequences and binding behaviours. It is shown that these antibodies can only bind to the antigen if very specific sequence characteristics are conserved. This probably restricts the number of potential B cell precursors that can lead to the generation of such antibodies. The most important result of this study is the observation that antibodies binding the repetitive region of CSP directly interact with each other. The antibodies even show signs of anti-idiotope affinity maturation directed against the antigen binding site of neighbouring antibodies. Surprisingly in none of the three probed African donors antibodies with measurable anti-CSP reactivity could be found. The present work suggests that this is due to the low frequency of B cell precursors, but also due to the specific binding mode that is induced by the repetitive CSP structure

IGLV3-21*01 is an inherited risk factor for CLL through the acquisition of a single-point mutation enabling autonomous BCR signaling

The prognosis of chronic lymphocytic leukemia (CLL) depends on different markers, including cytogenetic aberrations, oncogenic mutations, and mutational status of the immunoglobulin (Ig) heavy-chain variable (IGHV) gene. The number of IGHV mutations distinguishes mutated (M) CLL with a markedly superior prognosis from unmutated (UM) CLL cases. In addition, B cell antigen receptor (BCR) stereotypes as defined by IGHV usage and complementarity-determining regions (CDRs) classify ∼30% of CLL cases into prognostically important subsets. Subset 2 expresses a BCR with the combination of IGHV3-21-derived heavy chains (HCs) with IGLV3-21-derived light chains (LCs), and is associated with an unfavorable prognosis. Importantly, the subset 2 LC carries a single-point mutation, termed R110, at the junction between the variable and constant LC regions. By analyzing 4 independent clinical cohorts through BCR sequencing and by immunophenotyping with antibodies specifically recognizing wild-type IGLV3-21 and R110-mutated IGLV3-21 (IGLV3-21R110), we show that IGLV3-21R110-expressing CLL represents a distinct subset with poor prognosis independent of IGHV mutations. Compared with other alleles, only IGLV3-21*01 facilitates effective homotypic BCR-BCR interaction that results in autonomous, oncogenic BCR signaling after acquiring R110 as a single-point mutation. Presumably, this mutation acts as a standalone driver that transforms IGLV3-21*01-expressing B cells to develop CLL. Thus, we propose to expand the conventional definition of CLL subset 2 to subset 2L by including all IGLV3-21R110-expressing CLL cases regardless of IGHV mutational status. Moreover, the generation of monoclonal antibodies recognizing IGLV3-21 or mutated IGLV3-21R110 facilitates the recognition of B cells carrying this mutation in CLL patients or healthy donors

Metabolic balance in colorectal cancer is maintained by optimal Wnt signaling levels

Abstract Wnt pathways are important for the modulation of tissue homeostasis, and their deregulation is linked to cancer development. Canonical Wnt signaling is hyperactivated in many human colorectal cancers due to genetic alterations of the negative Wnt regulator APC. However, the expression levels of Wnt‐dependent targets vary between tumors, and the mechanisms of carcinogenesis concomitant with this Wnt signaling dosage have not been understood. In this study, we integrate whole‐genome CRISPR/Cas9 screens with large‐scale multi‐omic data to delineate functional subtypes of cancer. We engineer APC loss‐of‐function mutations and thereby hyperactivate Wnt signaling in cells with low endogenous Wnt activity and find that the resulting engineered cells have an unfavorable metabolic equilibrium compared with cells which naturally acquired Wnt hyperactivation. We show that the dosage level of oncogenic Wnt hyperactivation impacts the metabolic equilibrium and the mitochondrial phenotype of a given cell type in a context‐dependent manner. These findings illustrate the impact of context‐dependent genetic interactions on cellular phenotypes of a central cancer driver mutation and expand our understanding of quantitative modulation of oncogenic signaling in tumorigenesis

Additional file 1 of sciReptor: analysis of single-cell level immunoglobulin repertoires

Database structure and quality control. Visual representation of the relational database used by sciReptor. Quality control output showing the read length distribution, the statistics for sequence tag identification and the reads per cell statistics. (PDF 369 kb