Characterization of tonsillar IL10 secreting B cells and their role in the pathophysiology of tonsillar hypertrophy

Role of germinal center and CD39highCD73+ B cells in the age-related tonsillar involution

BACKGROUND

The tonsils operate as a protection ring of mucosa at the gates of the upper aero-digestive tract. They show similarities with lymph nodes and participate as inductive organs of systemic and mucosal immunity. Based on the reduction of their size since puberty, they are thought to experience involution in adulthood. In this context, we have used tonsillar mononuclear cells (TMC) isolated from patients at different stages of life, to study the effect of ageing and the concomitant persistent inflammation on these immune cells.

RESULTS

We found an age-dependent reduction in the proportion of germinal center B cell population (BGC) and its T cell counterpart (T follicular helper germinal center cells, TfhGC). Also, we demonstrated an increment in the percentage of local memory B cells and mantle zone T follicular helper cells (mTfh). Furthermore, younger tonsils rendered higher proportion of proliferative immune cells within the freshly isolated TMC fraction than those from older ones. We demonstrated the accumulation of a B cell subset (CD20+CD39highCD73+ cells) metabolically adapted to catabolize adenosine triphosphate (ATP) as patients get older. To finish, tonsillar B cells from patients at different ages did not show differences in their proliferative response to stimulation ex vivo, in bulk TMC cultures.

CONCLUSIONS

This paper sheds light on the changing aspects of the immune cellular landscape, over the course of time and constant exposure, at the entrance of the respiratory and digestive systems. Our findings support the notion that there is a re-modelling of the immune functionality of the excised tonsils over time. They are indicative of a transition from an effector type of immune response, typically oriented to reduce pathogen burden early in life, to the development of an immunosuppressive microenvironment at later stages, when tissue damage control gets critical provided the time passed under immune attack. Noteworthy, when isolated from such histologic microenvironment, older tonsillar B cells seem to level their proliferation capacity with the younger ones. Understanding these features will not only contribute to comprehend the differences in susceptibility to pathogens among children and adults but would also impact on vaccine developments intended to target these relevant mucosal sites.

Reproducibility of low-level residual myeloma immunoglobulin detection using ultra-deep sequencing

Multiple myeloma, a mature B-cell neoplasm, is the second most common hematologic malignancy. Despite advancements in treatment, the disease remains incurable, with more than 100,000 annual deaths worldwide. As recommended by the International Myeloma Working Group, measurable residual disease (MRD) should be addressed at a 10^-5 sensitivity level or beyond for practical purposes. Next-generation sequencing (NGS) has provided new opportunities with deep sequencing of clonal rearrangements of the immunoglobulin heavy chain (IGH) locus in B-cell malignancies. Although the ability to resolve one cancerous cell in a million other B cells is becoming attractive as a prognostic indicator in sustained patients who are MRD-negative, reaching consistent sensitivity levels is challenging because of sample stochasticity and the substantial amount of deoxyribonucleic acid (DNA) required for library preparation. Thus, in the presented study, we implemented ultra-deep sequencing of rearranged IGH to investigate the reproducibility and consistency aimed at the 10^-5 sensitivity level. In this controlled setup, our data provided stable MRD detection of 1.2 clonal cells per 100,000 analyzed cells and longitudinal reproducibility. We also demonstrated a low false-negative rate using 4-5 replicates and 700-800 ng DNA per sequencing replicate. In conclusion, adding an internal control to the replicates enabled clonal cell normalization for MRD evaluation as a stable reference. These findings may guide MRD-level reporting and comparisons between laboratories.

Character of β-lymphocytes differentiation in women with hypertensive disorders during pregnancy

The aim of the work was to identify the features of B-lymphocyte differentiation in women with hypertensive disorders of various origins, to establish their relationship with indicators of the elastic properties of the vascular wall, and to develop additional diagnostic criteria for the severity of preeclampsia. We examined 193 women at 24-40 weeks of gestation. Of these, 39 women with chronic arterial hypertension, 35 women with preeclampsia that developed against the background of chronic arterial hypertension, 55 with preeclampsia. The control group consisted of 64 women without hypertensive disorders. To assess the elastic properties of the vascular wall, a sphygmographic attachment of the "Poly-Spectrum-8" hardware-software complex ("Neurosoft" Ivanovo) was used. The relative content of B-lymphocytes (CD19 + and CD20 +), regulatory B-cells (CD20 + IL-10 +), switched (CD19 + CD27 + IgD-) and non-switched (CD19 + CD27 + IgD +) memory cells, plasma cells (CD19 + CD20-CD38 +) in the general population of B-lymphocytes was assessed by flow cytometry on a FACSCantoII flow cytometer using the FACS Diva program. Statistical analysis was carried out using the programs "Statistica for Windows 6.0", "Microsoft Excel 2010" and "MedCals". All subjects with hypertensive disorders showed an increase in the stiffness of the arteries of the muscular and elastic types, the most pronounced in the groups of patients with PE, the maximum in women with CAH and associated PE. An increased level of B1-lymphocytes in the peripheral blood is also noted in all hypertensive disorders. There were revealed positive correlations of high strength between: the level of CD20 + cells and the velocity of pulse wave propagation through the arteries of the muscular type (PWVm) in all groups with hypertensive disorders; the content of B1 cells and PWVM in moderate preeclampsia; level emory B-cells and PWV in elastic-type arteries in women with CAH and associated PE. The ROC analysis of the relative content of B1 cells in the general population of B lymphocytes and the content of IL-10-producing cells in the population of CD20 + lymphocytes (Breg) in women with moderate and severe PE revealed criteria for the differential diagnosis of preeclampsia of varying severity. The presence of hypertensive disorders of various origins is accompanied by a decrease in the elasticity of the arterial vascular wall, which is most pronounced in patients with CAH and associated PE. These changes are largely correlated with the level of B cells. As additional criteria for determining the severity of PE, the relative content of B1 cells and IL-10-producing cells in the population of Breg CD20 + lymphocytes can be used.

Spatially visualized single-cell pathology of highly multiplexed protein profiles in health and disease

Deep molecular profiling of biological tissues is an indicator of health and disease. We used imaging mass cytometry (IMC) to acquire spatially resolved 20-plex protein data in tissue sections from normal and chronic tonsillitis cases. We present SpatialViz, a suite of algorithms to explore spatial relationships in multiplexed tissue images by visualizing and quantifying single-cell granularity and anatomical complexity in diverse multiplexed tissue imaging data. Single-cell and spatial maps confirmed that CD68+ cells were correlated with the enhanced Granzyme B expression and CD3+ cells exhibited enrichment of CD4+ phenotype in chronic tonsillitis. SpatialViz revealed morphological distributions of cellular organizations in distinct anatomical areas, spatially resolved single-cell associations across anatomical categories, and distance maps between the markers. Spatial topographic maps showed the unique organization of different tissue layers. The spatial reference framework generated network-based comparisons of multiplex data from healthy and diseased tonsils. SpatialViz is broadly applicable to multiplexed tissue biology.

Role of Tonsillar Chronic Inflammation and Commensal Bacteria in the Pathogenesis of Pediatric OSA

Immune responses at the boundary between the host and the world beyond are complex and mucosal tissue homeostasis relies on them. Obstructive sleep apnea (OSA) is a syndrome suffered by children with hypertrophied tonsils. We have previously demonstrated that these tonsils present a defective regulatory B cell (Breg) compartment. Here, we extend those findings by uncovering the crucial role of resident pro-inflammatory B and T cells in sustaining tonsillar hypertrophy and hyperplasia by producing TNFα and IL17, respectively, in ex vivo cultures. Additionally, we detected prominent levels of expression of CD1d by tonsillar stratified as well as reticular epithelium, which have not previously been reported. Furthermore, we evidenced the hypertrophy of germinal centers (GC) and the general hyperplasia of B lymphocytes within the tissue and the lumen of the crypts. Of note, such B cells resulted mainly (IgG/IgM)⁺ cells, with some IgA⁺ cells located marginally in the follicles. Finally, by combining bacterial culture from the tonsillar core and subsequent identification of the respective isolates, we determined the most prevalent species within the cohort of OSA patients. Although the isolated species are considered normal oropharyngeal commensals in children, we confirmed their capacity to breach the epithelial barrier. Our work sheds light on the pathological mechanism underlying OSA, highlighting the relevance taken by the host immune system when defining infection versus colonization, and opening alternatives of treatment.

Analysis of KSHV B lymphocyte lineage tropism in human tonsil reveals efficient infection of CD138+ plasma cells

Despite 25 years of research, the basic virology of Kaposi Sarcoma Herpesviruses (KSHV) in B lymphocytes remains poorly understood. This study seeks to fill critical gaps in our understanding by characterizing the B lymphocyte lineage-specific tropism of KSHV. Here, we use lymphocytes derived from 40 human tonsil specimens to determine the B lymphocyte lineages targeted by KSHV early during de novo infection in our ex vivo model system. We characterize the immunological diversity of our tonsil specimens and determine that overall susceptibility of tonsil lymphocytes to KSHV infection varies substantially between donors. We demonstrate that a variety of B lymphocyte subtypes are susceptible to KSHV infection and identify CD138+ plasma cells as a highly targeted cell type for de novo KSHV infection. We determine that infection of tonsil B cell lineages is primarily latent with few lineages contributing to lytic replication. We explore the use of CD138 and heparin sulfate proteoglycans as attachment factors for the infection of B lymphocytes and conclude that they do not play a substantial role. Finally, we determine that the host T cell microenvironment influences the course of de novo infection in B lymphocytes. These results improve our understanding of KSHV transmission and the biology of early KSHV infection in a naïve human host, and lay a foundation for further characterization of KSHV molecular virology in B lymphocyte lineages.

KSHV infection is associated with cancer in B cells and endothelial cells, particularly in the context of immune suppression. Very little is known about how KSHV is transmitted and how it initially establishes infection in a new host. Saliva is thought to be the primary route of person-to-person transmission for KSHV, making the tonsil a likely first site for KSHV replication in a new human host. Our study examines KSHV infection in B cells extracted from the tonsils of 40 human donors in order to determine what types of B cells are initially targeted for infection and examine how the presence (or absence) of other immune cells influence the initial stages of KSHV infection. We found that a variety of B cell subtypes derived from tonsils can be infected with KSHV. Interestingly, plasma cells (mature antibody-secreting B cells) were a highly targeted cell type. These results lay the foundation for further studies into the specific biology of KSHV in different types of B cells, an effort that may help us ultimately discover how to prevent the establishment of infection in these cells or reveal new ways to halt the progression of B cell cancers associated with KSHV infection.

Differential cellular composition of human palatine and pharyngeal tonsils

OBJECTIVE

The goal of this study was to gain a better understanding of the potential functional specialization of palatine and pharyngeal tonsils, by comparing their cellular composition in paired specimens from a large cohort of adenotonsillectomy patients.

DESIGN

Resident B cell, T cell, dendritic cell, and stromal cell subsets were characterized using multicolor flow cytometry in palatine and pharyngeal tonsil specimens from 27 patients, age 2-34 years.

RESULTS

Paired comparisons showed highly significant intra-individual differences in resident cell subsets of palatine and pharyngeal tonsils. Palatine tonsils harbored higher fractions of germinal center B cells/plasmablasts and IgD- CD27- double-negative B cells, and conversely lower fractions of IgD + CD38- resting naïve B cells compared to pharyngeal tonsils. Palatine tonsils also showed lower fractions of plasmacytoid dendritic cells, and higher percentages of two subsets of stromal cells - fibroblastic reticular cells and lymphatic endothelial cells - compared to pharyngeal tonsils from the same individual.

CONCLUSIONS

Despite their physical proximity and histological similarities, palatine and pharyngeal tonsils display marked intra-individual differences in their cellular composition with regard to functionally important immune and stromal subsets. These differences are likely to have immunologic, pathologic, and physiologic significance.