Biology subjects

Sundling, C.

Publications and source records attributed to Sundling, C..

14 recordsLinked to original sources

bioRxiv2026

PIM6 Induces Tolerance and Confers Protection against Mycobacterium tuberculosis in Primary Macrophages

Glycolipids are major components of the mycobacterial cell envelope and play critical roles in host-pathogen interactions. Here we investigate the capacity of the mycobacterial glycolipid phosphatidyl-myo-inositol hexamannosides (PIM6) to modulate innate responsiveness in naive primary human monocytes and monocyte-derived macrophages (MDMs). Monocytes and MDMs prestimulated with PIM6, followed by 5 days of rest, secreted attenuated levels of tumor necrosis factor alpha (TNF-), interleukin 6 (IL-6), and interleukin 10 (IL-10) following LPS challenge. PIM6 pretreatment significantly altered pattern recognition receptor expression through the experimental time course and programmed a tolerized phenotype in myeloid cells independent of TLR2 activity. In an infection challenge with H37Rv Mycobacterium tuberculosis (M.tb), MDMs pretreated with PIM6 secreted decreased levels of TNF- and IL-10 and exhibited early increased bacterial control. Together, these data reveal PIM6 as a complex immunomodulator that tolerizes myeloid cells to subsequent stimuli and exerts direct effects on the control of M.tb infection.

immunology↗

bioRxiv2025

CD11c+ Memory B Cell Differentiation Across Blood and Tonsil Follows Origin-Specific Routes Revealed by CD24/CD27 Profiling

Atypical B cells (ABCs) are observed across infections, yet their ontogeny and differentiation remain unclear. Using high-dimensional flow cytometry, single-cell transcriptomics, V(D)J sequencing, and functional assays in human malaria and healthy donors, we identified markers of cellular origin while tracking ABC differentiation. Early ABCs express CD11c and arise predominantly from memory B cells. Two intermediate states originate from germinal center-derived and marginal zone-like B cells. Pseudotime and lineage analyses reveal trajectories marked by progressive CD24 and CD27 loss, recapitulated in vitro, defining bona fide differentiation programs. Differentiation culminates in late ABCs lacking CD24, CD27, and CD21, with high CD11c, T-bet, and NKG7, partly overlapping with double-negative 2 cells. Early- and intermediate stages show greater plasma-cell differentiation potential and cytokine production capacity, whereas later stages acquire antigen-presentation transcriptomic signatures and microbial-particle association, defining stage-dependent functions that reconcile conflicting ABC roles. Comparable ABC populations occur in healthy blood and tonsils, with tissue-associated class switching and CD86 expression consistent with recent T-cell interaction. This framework consolidates ABC definitions onto a single differentiation axis and clarifies cellular origins. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/676235v2_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@140364corg.highwire.dtl.DTLVardef@accbb5org.highwire.dtl.DTLVardef@720dc3org.highwire.dtl.DTLVardef@1e591f3_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

Previous malaria exposure attenuates monocyte-driven inflammation and shapes B cell immunity

Clinical immunity to malaria develops after repeated malaria episodes. In this process, the inflammatory response is modulated to respond less vigorously upon reinfection. Monocytes are a major source of pro-inflammatory mediators during blood-stage infection and are known to adapt to repeated pathogen exposure. Here, we investigated the impact of previous malaria exposure on monocytes during blood-stage malaria by comparing the response in previously exposed and primary infected individuals. We observed reduced levels of the proinflammatory chemokine CXCL10 in previously exposed individuals, linked to changes in CD16+ monocytes. Similarly, BAFF levels were lower in these individuals and associated with modulation of monocyte and dendritic cells. This affected the BAFF-BAFF-R axis, crucial for B cell responses, correlating with increasing parasite-specific antibody levels. Collectively, we present novel insights into how previous malaria exposure shapes monocyte responses during acute malaria and how these in turn correlate with modulation of the B cell compartment and humoral immune response.

immunology↗

bioRxiv2025

Human IGH germline gene diversity and allele frequencies in 2486 individuals from 25 global populations delineated by ultra-high throughput genotyping

The extraordinary diversity of human immunoglobulin (IG) genes underpins effective antibody responses, yet the full scope and functional impact of germline-encoded IG variation across populations is largely unknown. Here, we present ImmuneDiscover, an ultra-high-throughput sequencing platform enabling individualized IG genotyping from nanogram-scale DNA and simultaneous analysis of over 1,000 individuals. Using ImmuneDiscover, we generated high-resolution IG genotypes for 2,486 individuals from the 1000 Genomes Project, spanning diverse ancestries, and built KIARVA, an open-access atlas of IG gene variation. Cross-validation with SNP data from over one million genomes confirmed the accuracy and novelty of discovered alleles. Our analysis reveals striking population-specific patterns, including a multigene IGHD segment deletion found in up to 30% of East Asian individuals, and haplotypic differences linked to disease-associated loci. These findings illuminate the evolutionary forces shaping IG diversity and provide a foundational resource for investigating the immunogenetic basis of pathogen susceptibility and vaccine responsiveness worldwide.

immunology↗

bioRxiv2024

Antibody-Fab and -Fc features promote Mycobacterium tuberculosis restriction.

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is a leading cause of death by an infectious disease globally, with no efficacious vaccine. Antibodies are implicated in Mtb control, but the mechanisms of antibody action remain poorly understood. We assembled a library of TB monoclonal antibodies (mAb) and screened for the ability to restrict Mtb in mice, identifying protective antibodies targeting known and novel antigens. To dissect the mechanism of mAb-mediated Mtb restriction, we optimized a protective lipoarabinomannan-specific mAb through Fc-swapping. In vivo analysis of these Fc-variants revealed a critical role for Fc-effector function in Mtb restriction. Restrictive Fc-variants altered distribution of Mtb across innate immune cells. Single-cell transcriptomics highlighted distinctly activated molecular circuitry within innate immune cell subpopulations, highlighting early activation of neutrophils as a key signature of mAb-mediated Mtb restriction. Therefore, improved antibody-mediated restriction of Mtb is associated with reorganization of the tissue-level immune response to infection and depends on the collaboration of antibody Fab and Fc.

immunology↗

bioRxiv2024

Naturally acquired IgG responses to Plasmodium falciparum do not target the conserved termini of the malaria vaccine candidate merozoite surface protein 2

Malaria remains a significant burden, and a fully protective vaccine against Plasmodium falciparum is critical for reducing morbidity and mortality. Antibody responses against the blood-stage antigen merozoite surface protein 2 (MSP2) are associated with protection from P. falciparum malaria, but its extensive polymorphism is a barrier to its development as a vaccine candidate. New tools, such as long-read sequencing and accurate protein structure modelling allow us to more easily study the genetic diversity and immune responses towards antigens from clinical isolates. This study sought to better understand naturally acquired MSP2-specific antibody responses. IgG responses against recombinantly expressed full- length, central polymorphic regions, and peptides derived from the conserved termini of MSP2 variants sequenced from patient isolates, were tested in plasma from travelers with recent, acute malaria and from individuals living in an endemic area of Tanzania. IgG responses towards full MSP2 and truncated MSP2 antigens were variant specific. IgG antibodies in the plasma of first-time infected or previously exposed travelers did not recognize the conserved termini of expressed MSP2 variants by ELISA, but they bound 13- amino acid long linear epitopes from the termini in a custom-made peptide array. Alphafold3 modelling suggests extensive structural heterogeneity in the conserved termini upon antigen oligomerization. IgG from individuals living in an endemic region, many who were asymptomatically infected, did not recognize the conserved termini by ELISA. Our results suggest that responses to the variable regions are important for the development of naturally acquired immunity towards MSP2.

immunology↗

bioRxiv2024

IMMUNOPHENOTYPING AND FUNCTIONAL ANALYSIS OF NK CELL SUBSETS IN Mycobacterium tuberculosis-INFECTED INDIVIDUALS

Infection with Mycobacterium tuberculosis remains a global health challenge, with diverse clinical outcomes ranging from latent TB (LTB) infection to active TB disease (ATB). We conducted a comprehensive analysis of NK cell subsets and function in individuals with LTB, ATB, and healthy controls to elucidate their potential association with TB pathogenesis. Peripheral blood mononuclear cells (PBMCs) were isolated from Mtb-infected individuals and analyzed by mass cytometry and flow cytometry. We identified distinct NK cell subsets and evaluated their functional responses to stimulation. Our findings revealed comparable frequencies of total and NK cell subsets across LTB, ATB, and controls. Functional assays demonstrated similar degranulation, cytokine production, and proliferation capabilities among NK cell subsets across the three groups. This study provides insights into the heterogeneity of NK cell responses in TB and highlights the need for standardized methodologies with well-characterized cohorts controlling for donor background. Further investigations are warranted to delineate the specific roles of NK cells in TB immunity and pathogenesis.

immunology↗

bioRxiv2023

Regulation of B cell function and expression of CD11c, T-bet, and FcLR5 after infection and in response to different activation pathways

CD11c, FcRL5, or T-bet are commonly expressed by B cells expanding during inflammation, where they can make up >30% of mature B cells. However, the association between the proteins and differentiation and function in the host response remain largely unclear. We have assessed the co-expression of CD11c, T-bet and FcRL5 in an in vitro B cell culture system to determine how stimulation via the B cell receptor (BCR), toll-like receptor 9 (TLR9), and different cytokines influence CD11c, T-bet, and FcRL5 expression. We observed different expression dynamics for all markers, but a largely overlapping regulation of CD11c and FcRL5 in response to BCR and TLR9 activation, while T-bet was strongly dependent on IFN-{gamma} signalling. Investigating plasma cell differentiation and antigen-presenting cell (APC) functions, there was no association between marker expression and antibody secretion or T cell help. Rather the functions were associated with TLR9-signalling and B cell-derived IL-6 production, respectively. These results suggest that the expression of CD11c, FcRL5, and T-bet and plasma cell differentiation and improved APC functions occur in parallel and are regulated by similar activation signals, but that they are not interdependent.

immunology↗

bioRxiv2022

Archaic humans have contributed to large-scale variation in modern human T cell receptor genes

The human T cell receptor (TCR) genes are critical for mediating immune responses to pathogens, tumors and regulating self-antigen recognition. A detailed analysis and validation of expressed TCR alpha, beta, gamma, and delta genes in 45 donors from 4 human populations: African, East Asian, South Asian, and European, revealed a total of 175 novel TCR variable and junctional alleles. The majority of novel alleles contained coding changes and were present at widely differing frequencies in the populations, a finding confirmed using DNA samples and sequences from the 1000 Genomes Project. Importantly, we identified three Neanderthal-derived, introgressed TCR regions, including a highly divergent novel TRGV4 variant, present in all archaic assemblies, that was frequent in all modern Eurasian population groups. Our results demonstrate significant variation in TCR genes at both individual and population levels, providing a strong incentive for including allelic variation in studies of TCR function in human biology.

immunology↗

bioRxiv2022

A genomic platform for surveillance and antigen discovery in Plasmodium spp. using long-read amplicon sequencing

Many vaccine candidate proteins are under strong selective pressure to diversify in terms of antigenicity. We present a sequencing and data analysis platform for epidemiological surveillance and discovery of indel-rich vaccine antigens by long-read circular consensus sequencing (CCS) in multiclonal pathogen isolates. Our platform uses 40 PCR primers to asymmetrically barcode and identify multiclonal infections in pools of up to 384 samples. We validated the method using 235 mock infections combining 10 synthetic variants of the indel-rich gene merozoite surface protein 2 of Plasmodium falciparum at different concentrations and infection complexities, as well as 95 isolates from P. falciparum-infected residents of Nyamisati, Tanzania. We also constructed a fully automated analysis pipeline that streamlines the processing and interpretation of epidemiological and antigenic diversity data from demultiplexed FASTQ files. This platform can be easily adapted to other polymorphic antigens of interest in Plasmodium and other human pathogens.

genomics↗

bioRxiv2022

Performance of novel antibodies for lipoarabinomannan to develop diagnostic tests for Mycobacterium tuberculosis

Lipoarabinomannan (LAM), a component of the Mycobacterium tuberculosis (MTB) cell wall, is detectable in the urine of MTB infected patients with active tuberculosis (TB). LAM-specific antibodies (Igs) have been developed by a variety of traditional and recombinant methods for potential use in a rapid diagnostic test (RDT). We evaluated the analytical performance of the TB LAM Igs to identify pairs that offer superior performance over existing urine LAM tests. We assessed 25 new and 4 existing Igs in a matrixed format using a multiplex electrochemiluminescence-based liquid immunoassay. A total of 841 paired Ig combinations were challenged with in vitro cultured LAM (cLAM) derived from MTB strains representing diverse phylogenetic lineages, alongside urinary LAM (uLAM) from the urine of adults with active pulmonary TB. Analytical sensitivity of down-selected Ig pairs was determined using MTB Aoyama-B cLAM, while diagnostic accuracy was determined using clinical samples. When testing cLAM, the reactivity of Ig pairs was similar across MTB lineages 1-4 but lineage 5:6 had significantly more reactivity among Ig pairs. Overall, 41 Ig pairs had a strong binding affinity to cLAM, as compared to the reference pair of S4-20/A194-01, and 28 Ig pairs therein exhibited a strong affinity for both cLAM and uLAM. Retrospective testing on clinical urine specimens demonstrated varying sensitivities (12-80%) and specificities (14-100%). The five top pairs had a similar analytical limit of detection to the reference pair but in four instances, the sensitivity and specificity with clinical uLAM samples was poor. Overall, epitopes presented by uLAM are different from cLAM, which may affect antibody performance when testing uLAM in patient samples. Several new Ig pairs had similar ranges of high sensitivity to cLAM but overall, there were no new candidate Ig pairs identified in this round of screening with increased performance with uLAM as compared to an existing optimal pair.

microbiology↗

bioRxiv2021

Systems-level analysis of patients treated for acute P. falciparum malaria reveals a role for the humoral response and cytokine milieu in limiting γδ T cell expansion

The mechanism of acquisition and maintenance of natural immunity against Plasmodium falciparum malaria remains unclear. Although, clinical immunity develops over time with repeated malaria episodes, disease tolerance is more rapidly acquired compared to protective immunity. It remains unclear, how pre-existing immune responses impacts the mechanism responsible for disease tolerance. Here, we investigated a cohort of returning travelers treated for acute symptomatic P. falciparum malaria, either infected for the first time, or with a previous history of malaria. Through repeated sampling over one year in a malaria free setting, we were able to study the acute and longitudinal effects of the infection. We combined comprehensive immune cell and plasma protein profiling with integrated and data driven analysis, describing the immune landscape from acute disease to one year after infection. We identified a strong association between pro-inflammatory signatures and {gamma}{delta} T cell expansion. The association was significantly impacted by previous exposure to malaria, resulting in a dampened pro-inflammatory response, which translated to reduced V{delta}2+ {gamma}{delta} T cell expansion compared to primary infected individuals. The dampened inflammatory signal was associated with early expansion of Fc{gamma}RIII+ monocytes and parasite-specific antibodies of IgG1 and IgG3 isotypes. Our data suggest that the interplay of Fc{gamma}RIII+ monocytes and a cytophilic parasite-specific IgG during the early blood stage infection lead to lower parasitemia and a dampened pro-inflammatory response with reduced {gamma}{delta} T cell expansion. This enhanced control and reduced inflammation points to a potential mechanism on how tolerance is established following repeated malaria exposure. One Sentence SummaryA systems immunology analysis on natural malaria sheds light on disease tolerance mechanism associated with gamma delta T cell expansion

immunology↗

bioRxiv2021

Stimulation with mycobacterial glycolipids and PPD reveals different innate immune response profiles in active and latent TB

Upon infection with Mycobacterium tuberculosis (Mtb) the host immune response might clear the bacteria, control its growth leading to latent tuberculosis (LTB), or fail to control its growth resulting in active TB (ATB). There is however no clear understanding of the features underlying a more or less effective response. Mtb glycolipids are abundant in the bacterial cell envelope and modulate the immune response to Mtb, but the patterns of response to glycolipids are still underexplored. To identify the CD45+ leukocyte activation landscape induced by Mtb glycolipids in peripheral blood of ATB and LTB, we performed a detailed assessment of the immune response of PBMCs to the Mtb glycolipids lipoarabinomannan (LAM) and its biosynthetic precursor phosphatidyl-inositol mannoside (PIM), and PPD. At 24 h and 5 days of stimulation, cell profiling and secretome analysis was done using mass cytometry and high-multiplex immunoassay. PIM mainly affected antigen-presenting cells to produce both proinflammatory (IL-2, IL-6, IL-17A, TNF- and GM-CSF), and IL-4 and IL-10 cytokines, but not IFN-{gamma}. LAM triggered a similar, albeit weaker, response. By contrast, PPD induced an increase in IFN-{gamma}-producing cells. Moreover, PPD also led to increased numbers of IL-2, IL-6, IL-10, IL-17A, TNF- and GrzB-producing cells. Treatment with an anti-TLR2 antibody led to partial inhibition of PIM-induced IL-6 production in myeloid cells, suggesting that PIM induces IL-6 production through TLR2. Expansion of monocyte subsets in response to PIM or LAM was reduced in both ATB and LTB as compared to healthy controls, suggesting a hyporesponsive/tolerance pattern in Mtb-infected individuals.

immunology↗

bioRxiv2019

The generation of plasma cells and CD27-IgD- B cells during Hantavirus infection are associated with distinct pathological findings

Human hantavirus infections can cause hemorrhagic fever with renal syndrome (HFRS), major signs of the disease being thrombocytopenia and transient kidney dysfunction. By a comprehensive and longitudinal study of circulating B cells, we demonstrate that these two pathologies associate with distinct effects on the humoral immune system during HFRS. Low thrombocyte counts strongly associated with an abnormal frequency of plasmablasts in circulation, whereas kidney dysfunction was indicative of an accumulation of CD27- B cells and plasmablasts. Finally, we provide evidence that high levels of extracellular ATP in circulation during HFRS correlates with shedding of surface CD27 on B cells via a metallomatrix proteinase-8-mediated mechanism. Since extracellular ATP is known to regulate kidney function, our study reveals a link between kidney dysfunction and the generation of CD27-IgD- B cells, and a potential molecular target for treatment of the symptomatic phase of HFRS.

immunology↗