Institute of Immunology

The virulence of Plasmodium falciparum is closely linked to P. falciparum erythrocyte membrane protein 1 (PfEMP1), encoded by a diverse var gene family. PfEMP1 mediates parasite immune evasion and vascular adhesion of infected red blood cells, contributing to severe disease. While expression of group A or domain cassettes (DC8 and DC13)-containing var genes have been associated with severe malaria, comparisons between the severe malaria syndromes remain limited. Furthermore, interactions between specific var gene expression and the rosetting phenotype, a known marker of severe malaria, are incompletely understood across severe malaria syndromes. We analyzed parasites and clinical data from 712 Kenyan children with non-severe and severe malaria syndromes collected over 18 years in Kilifi, Kenya. We used RT-qPCR and DBLα-tag sequencing to quantify var gene expression. We show that parasites expressing var genes containing the cys2 MFK+REY−motif or encoding DC8 domains were associated with impaired consciousness (IC), while rosetting was associated with respiratory distress (RD) and severe malarial anaemia (SMA), but not IC. These findings demonstrate that distinct PfEMP1 variants are preferentially expressed in specific severe malaria syndromes, highlighting potential targets for variant-specific future therapeutic and diagnostic strategies.

Kinetoplastids, such as Trypanosoma brucei , are eukaryotes that likely separated from the main lineage at an exceptionally early point in evolution. Consequently, many aspects of kinetoplastid biology differ significantly from other eukaryotic model systems, including yeasts, plants, worms, flies, and mammals. As in many eukaryotes, the T. brucei genome contains repetitive elements at various chromosomal locations, including centromere- and telomere-associated repeats and interspersed retrotransposon elements. T. brucei also contains intermediate-sized and mini-chromosomes that harbour abundant 177 bp repeat arrays and 70 bp repeat elements implicated in Variable Surface Glycoprotein (VSG) gene switching. In many eukaryotes, repetitive elements are assembled in specialised chromatin such as heterochromatin; however, apart from centromere- and telomere-associated repeats, little is known about chromatin-associated proteins that decorate these and other repetitive elements in kinetoplastids. Here, we utilise affinity selection of synthetic TALE DNA binding proteins designed to target specific repeat elements to identify enriched proteins by proteomics. Validating the approach, a telomere repeat binding TelR-TALE identifies many proteins previously implicated in telomere function. Furthermore, the 70R-TALE designed to bind 70 bp repeats indicates that proteins involved in DNA repair are enriched on these elements that reside adjacent to VSG genes. Interestingly, the 177 bp repeat binding 177R-TALE enriches for many kinetochore proteins, suggesting that intermediate-sized and mini-chromosomes assemble kinetochores related in composition to those located on the main megabase chromosomes. This provides a first insight into the chromatin landscape of repetitive regions of the trypanosome genome with relevance for their mechanisms of chromosome integrity, immune evasion, and cell replication.

Abstract Lysosomes and the endoplasmic reticulum (ER) are Ca 2+ stores that interact to generate Ca 2+ signals regulating fundamental cellular processes. NAADP-sensitive TPC2 channels on lysosomes induce local Ca 2+ elevations that sensitize ER Ca 2+ release channels, triggering global Ca 2+ signals. The ensuing ER Ca 2+ depletion activates STIM1-gated Orai1 channels that mediate store-operated Ca 2+ entry (SOCE) to sustain long-lasting Ca 2+ signals. How TPC2 channels interact with STIM1 to integrate distinct intra and extracellular cues is unclear. Here, we show that TPC2 activation inhibits SOCE by enforcing rapid and persistent Ca 2+ -CaM-dependent inactivation of the STIM-Orai activating region (SOAR). The TPC2 agonists NAADP and TPC2-A1-N abrogated SOCE in multiple cell lines and enhanced the slow Ca 2+ dependent inactivation (SCDI) of STIM1-gated Orai1 channels. TPC2 engagement triggered lysosomal Ca 2+ release and mobilized ER Ca2+ stores independently of inositol trisphosphate receptors but prevented RFP-STIM1 recruitment to the TIRF plane by thapsigargin and disassembled RFP-STIM1 clusters forming after store depletion, preventing and acutely reversing SOCE. These effects persisted in STIM1 mutants truncated after the SOAR and were prevented by genetic or pharmacological invalidation of TPC2, Calmodulin (CaM) inhibition, and cytosolic Ca 2+ chelation. We conclude that Ca 2+ ions released by TPC2 channels on lysosomes regulate CaM-dependent STIM1 inactivation.

Eukaryotic genomes contain numerous transposable elements (TEs), whose dysregulation threatens genome stability and may contribute to cancer. Pancreatic adenocarcinoma (PAAD) is among the deadliest cancers, marked by abundant stroma that obscures tumor-specific molecular signals, complicating bulk-tissue analyses. Here, using 71 patient-derived PAAD organoids, we show that TE activities may potentially promote tumorigenesis and provide a source of novel immunotherapeutic targets. We identify 16 new TE-derived transcripts fused with 15 known oncogenes, exhibiting potential oncogenic function and prognostic value. Notably, LTR7-PLAAT4, present in 29% of tumors, encodes a protein variant transcriptionally regulated by FOXM1 binding to the LTR7 promoter. LTR7-PLAAT4 isoform 2 is associated with increased cholesterol ester accumulation and lipid droplet formation mediated through BSCL2 coexpression, potentially fostering tumor progression. On the immunogenic front, HLA-I immunopeptidomics of AsPC-1 cells and DAC13 organoids identify over 11,000 peptides respectively. Althought mutation-derived neoantigens are rare, several peptides are originated from TE-chimeric transcripts, including four predicted by TEprof2. The peptide FLIQHLPLV, detected in 27% of organoids, exhibits robust immunogenicity, validated by T2 binding, mass spectrometry and ELISPOT assays with HLA-genotyped PBMCs. Together, these findings suggest that TE activities may contribute to PAAD progression and diversify its immunopeptidome, providing new opportunities for molecular subtyping and potential immunotherapeutic intervention.

Abstract Introduction: B1a lymphocytes are components of the innate immune response that maintain their population through self-renewal, a process that declines with age. Objective To evaluate the effect of Biomodulina T® (BT) on B1a lymphocyte subpopulations in older Cuban adults. Methods In this non-randomized clinical trial, 30 institutionalized adults aged ≥ 60 years received intramuscular BT (3 mg) twice weekly for six weeks. B1a lymphocyte subpopulations (CD19⁺CD5⁺, CD20⁺CD5⁺, and CD19⁺CD20⁺) were quantified by flow cytometry at baseline, six weeks, and six months post-treatment. Results The median percentages and absolute counts of B1a CD5⁺CD20⁺ lymphocytes increased after six weeks of treatment with BT (0.96 vs. 2.11, SD 6.02 vs. 2.38) and (17.02 vs. 40.58, SD 80.09 vs. 39.70), with statistical significance (p = 0.026 and p = 0.014, respectively). In contrast, the percentage and absolute count of lymphocytes coexpressing CD19⁺ and CD20⁺ antigens decreased after six weeks of BT treatment (4.87 vs. 1.94, SD 4.69 vs. 4.57) and (88.48 vs. 31.03, SD 62.14 vs. 65.54), with statistical significance (p = 0.014 and p = 0.018, respectively). Six months after completing the treatment, both the percentage and absolute count of these cells continued to increase (4.87 vs. 8.47, SD 4.69 vs. 26.69) and (88.48 vs. 173.5, SD 62.14 vs. 323.8), reaching statistical significance (p = 0.012 and p = 0.011, respectively). Conclusions BT exerts an immunomodulatory effect on B1a lymphocytes in older adults, with partial persistence six months after treatment, suggesting potential benefits in preventing age-related immune decline.

Virus infections elicit long-term IgG antibody and memory responses. Human cytomegalovirus (HCMV) is widespread in humans and disseminates despite the presence of virus-specific antibodies. Here, we report that the HCMV Fcγ-binding glycoprotein 34 modulates humoral immunity by binding to IgG⁺ memory B cells. gp34–B cell receptor (BCR) interaction initiates activation of the PDK1/AKT/mTOR/S6 pathway and BCR internalization in a SYK-independent manner. Prolonged stimulation also induces B-cell activation via upregulation of CD69 and CD86. In a T-cell-dependent response, however, interaction with gp34 blocks B-cell proliferation, differentiation into plasmablasts, and soluble IgG production, while stimulating TNF-α secretion. Through gp34 stimulation on IgG⁺ B cells, neighboring IgM⁺ and IgA⁺ B cells are likewise impaired in proliferation, plasmablast formation, and immunoglobulin secretion. In summary, gp34 specifically interacts with IgG⁺ memory B cells, inducing a hyporesponsive state across the B-cell compartment through direct and indirect regulation. This reveals a novel mode of viral evasion from B-cell responses by suppressing secondary immunity.

Metabolomics studies in oncology provide a deeper understanding of the biochemical processes associated with tumor growth and the body's response to treatment. In patients with lymphoma, systemic metabolic changes remain poorly understood despite their high clinical significance. To evaluate changes in the metabolomic profile of blood plasma in patients with lymphoma at various stages of polychemotherapy (PCT) and compare them to those of healthy volunteers. The study included 18 patients with lymphoma from whom blood was collected before treatment and after the first and third courses of PCT. The control group included 30 healthy volunteers. The analysis was performed by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) and included measurements of amino acids, tryptophan and arginine derivatives, and acylcarnitines. Statistical processing was performed using analysis of variance and principal component analysis. Prior to therapy, patients showed characteristic metabolic disorders: activation of the kynurenine pathway of tryptophan metabolism, a decrease in arginine, and an increase in its methylated derivatives, as well as shifts in the amino acid and acylcarnitine profiles. During PCT, partial normalization of these indicators was observed, especially for the serotonin-melatonin cascade and kynurenine metabolites. Metabolomics analysis revealed characteristic biochemical changes in patients with lymphoma and their changes over time during treatment. The data obtained emphasize the potential of metabolomics as a tool for monitoring treatment effectiveness and patient condition in oncology.

Abstract Background & aims Intestinal epithelial cells rely on a complex array of signals from the stromal microenvironment to determine their fate and function along the crypt-villus axis, but the precise cellular sources and combinations of signals regulating each position remain poorly defined. Methods Here, we present a high-resolution atlas of a unique mesenchymal cell type previously identified as telocytes, mapped along the crypt-villus axis using single-cell RNA sequencing integrated with in-situ approaches and reporter mouse models. Results We identify four spatially distinct telocyte subtypes: crypt, villus base, villus mid and villus tip, each with a unique gene expression profile. Crypt telocytes are enriched for canonical Wnt signaling components that support stem and progenitor cell maintenance, while villus base telocytes are a source of Bmps (bone morphogenic proteins) and express contractility-associated genes, suggesting a role in tissue architecture. Villus mid telocytes display signatures of immune regulation and inflammation, while villus tip telocytes are specialized for the regulation of ribonucleoprotein complexes and nutrient sensing. Conclusions This atlas provides a foundational resource for understanding how diverse telocyte populations coordinate signaling environments and shape intestinal homeostasis through both epithelial interactions and extensive crosstalk among themselves.