ILT2 and ILT4 Drive Myeloid Suppression via Both Overlapping and Distinct Mechanisms.

Solid tumors are dense three-dimensional (3D) multicellular structures that enable efficient receptor-ligand trans interactions via close cell-cell contact. Immunoglobulin-like transcript (ILT)2 and ILT4 are related immune-suppressive receptors that play a role in the inhibition of myeloid cells within the tumor microenvironment. The relative contribution of ILT2 and ILT4 to immune inhibition in the context of solid tumor tissue has not been fully explored.

Oral mucosal breaks trigger anti-citrullinated bacterial and human protein antibody responses in rheumatoid arthritis.

Periodontal disease is more common in individuals with rheumatoid arthritis (RA) who have detectable anti-citrullinated protein antibodies (ACPAs), implicating oral mucosal inflammation in RA pathogenesis. Here, we performed paired analysis of human and bacterial transcriptomics in longitudinal blood samples from RA patients. We found that patients with RA and periodontal disease experienced repeated oral bacteremias associated with transcriptional signatures of ISG15HLADR and CD48S100A2 monocytes, recently identified in inflamed RA synovia and blood of those with RA flares.

Immune-stimulating antibody conjugates elicit robust myeloid activation and durable antitumor immunity.

Innate pattern recognition receptor agonists, including Toll-like receptors (TLRs), alter the tumor microenvironment and prime adaptive antitumor immunity. However, TLR agonists present toxicities associated with widespread immune activation after systemic administration. To design a TLR-based therapeutic suitable for systemic delivery and capable of safely eliciting tumor-targeted responses, we developed immune-stimulating antibody conjugates (ISACs) comprising a TLR7/8 dual agonist conjugated to tumor-targeting antibodies.

Impact of long-term ibrutinib treatment on circulating immune cells in previously untreated chronic lymphocytic leukemia.

This study evaluated long-term immunophenotypic changes in circulating levels of 24 immune cell subsets through 4 years of continuous treatment with first-line ibrutinib (420 mg once daily) in 31 patients with chronic lymphocytic leukemia (CLL) from the RESONATE-2 study, and compared them with untreated age-matched healthy donors (n = 20). Ibrutinib progressively decreased total B-cell counts and preferentially targeted malignant CLL B cells over normal B cells. Elevated counts of chronically activated, exhausted, and effector memory T cells were normalized within 6-16 months, while naive T cells remained mostly within healthy donor range (HDR).

Modeling human adaptive immune responses with tonsil organoids.

Most of what we know about adaptive immunity has come from inbred mouse studies, using methods that are often difficult or impossible to confirm in humans. In addition, vaccine responses in mice are often poorly predictive of responses to those same vaccines in humans. Here we use human tonsils, readily available lymphoid organs, to develop a functional organotypic system that recapitulates key germinal center features in vitro, including the production of antigen-specific antibodies, somatic hypermutation and affinity maturation, plasmablast differentiation and class-switch recombination.

Ibrutinib restores immune cell numbers and function in first-line and relapsed/refractory chronic lymphocytic leukemia.

Ibrutinib positively modulates many T-cell subsets in chronic lymphocytic leukemia (CLL). To understand ibrutinib's effects on the broader landscape of immune cell populations, we comprehensively characterized changes in circulating counts of 21 immune blood cell subsets throughout the first year of treatment in patients with relapsed/refractory (R/R) CLL (n = 55, RESONATE) and previously untreated CLL (n = 50, RESONATE-2) compared with untreated age-matched healthy donors (n = 20). Ibrutinib normalized abnormal immune cell counts to levels similar to those of age-matched healthy donors.

Affinity Maturation of the Anti-Citrullinated Protein Antibody Paratope Drives Epitope Spreading and Polyreactivity in Rheumatoid Arthritis.

Objective: Anti-citrullinated protein antibodies (ACPAs) are a hallmark of rheumatoid arthritis (RA). While epitope spreading of the serum ACPA response is believed to contribute to RA pathogenesis, little is understood regarding how this phenomenon occurs. This study was undertaken to analyze the antibody repertoires of individuals with RA to gain insight into the mechanisms leading to epitope spreading of the serum ACPA response in RA.

Discovery of Distinct Immune Phenotypes Using Machine Learning in Pulmonary Arterial Hypertension.

Rationale: Accumulating evidence implicates inflammation in pulmonary arterial hypertension (PAH) and therapies targeting immunity are under investigation, although it remains unknown if distinct immune phenotypes exist.

Objective: Identify PAH immune phenotypes based on unsupervised analysis of blood proteomic profiles.

Methods And Results: In a prospective observational study of group 1 PAH patients evaluated at Stanford University (discovery cohort; n=281) and University of Sheffield (validation cohort; n=104) between 2008 and 2014, we measured a circulating proteomic panel of 48 cytokines, chemokines, and factors using multiplex immunoassay.

Robust B Cell Responses Predict Rapid Resolution of Lyme Disease.

Lyme disease ( infection) is increasingly recognized as a significant source of morbidity worldwide. Here, we show that blood plasmablasts and CD27 memory B cells are elevated in untreated Lyme disease, with higher plasmablast levels associated with more rapid resolution of clinical symptoms. Stronger serum reactivity to surface proteins and peptides from was also associated with faster resolution of clinical symptoms.

Affinity Maturation Drives Epitope Spreading and Generation of Proinflammatory Anti-Citrullinated Protein Antibodies in Rheumatoid Arthritis.

Objective: Rheumatoid arthritis (RA) is characterized by the presence of anti-citrullinated protein antibodies (ACPAs); nevertheless, the origin, specificity, and functional properties of ACPAs remain poorly understood. The aim of this study was to characterize the evolution of ACPAs by sequencing the plasmablast antibody repertoire at serial time points in patients with established RA.

Methods: Blood samples were obtained at up to 4 serial time points from 8 individuals with established RA who were positive for ACPAs by the anti-cyclic citrullinated peptide test.

Plasmablast antibody repertoires in elderly influenza vaccine responders exhibit restricted diversity but increased breadth of binding across influenza strains.

Seasonal influenza vaccines elicit antibody responses that can prevent infection, but their efficacy is reduced in the elderly. While a subset of elderly individuals can still mount sufficient vaccine-induced antibody responses, little is known about the properties of the vaccine-induced antibody repertoires in elderly as compared to young responders. To gain insights into the effects of aging on influenza vaccine-induced antibody responses, we used flow cytometry and a cell-barcoding method to sequence antibody heavy and light chain gene pairs expressed by individual blood plasmablasts generated in response to influenza vaccination in elderly (aged 70-89) and young (aged 20-29) responders.

Circulating plasmablasts are elevated and produce pathogenic anti-endothelial cell autoantibodies in idiopathic pulmonary arterial hypertension.

Idiopathic pulmonary arterial hypertension (IPAH) is a devastating pulmonary vascular disease in which autoimmune and inflammatory phenomena are implicated. B cells and autoantibodies have been associated with IPAH and identified as potential therapeutic targets. However, the specific populations of B cells involved and their roles in disease pathogenesis are not clearly defined.

VP4- and VP7-specific antibodies mediate heterotypic immunity to rotavirus in humans.

Human rotaviruses (RVs) are the leading cause of severe diarrhea in young children worldwide. The molecular mechanisms underlying the rapid induction of heterotypic protective immunity to RV, which provides the basis for the efficacy of licensed monovalent RV vaccines, have remained unknown for more than 30 years. We used RV-specific single cell-sorted intestinal B cells from human adults, barcode-based deep sequencing of antibody repertoires, monoclonal antibody expression, and serologic and functional characterization to demonstrate that infection-induced heterotypic immunoglobulins (Igs) primarily directed to VP5*, the stalk region of the RV attachment protein, VP4, are able to mediate heterotypic protective immunity.

Elevated IgA Plasmablast Levels in Subjects at Risk of Developing Rheumatoid Arthritis.

Objective: The disease process in rheumatoid arthritis (RA) starts years before the clinical diagnosis is made, and elevated levels of disease-specific autoantibodies can be detected during this period. Early responses to known or novel autoantigens likely drive the eventual production of pathogenic autoimmunity. Importantly, the presence of disease-specific autoantibodies can identify individuals who are at high risk of developing RA but who do not currently have arthritis.

Barcode-enabled sequencing of plasmablast antibody repertoires in rheumatoid arthritis.

Objective: A hallmark of rheumatoid arthritis (RA) is the production of autoantibodies, including anti-citrullinated protein antibodies (ACPAs). Nevertheless, the specific targets of these autoantibodies remain incompletely defined. During an immune response, B cells specific for the inciting antigen(s) are activated and differentiate into plasmablasts, which are released into the blood.

High-throughput sequencing of natively paired antibody chains provides evidence for original antigenic sin shaping the antibody response to influenza vaccination.

We developed a DNA barcoding method to enable high-throughput sequencing of the cognate heavy- and light-chain pairs of the antibodies expressed by individual B cells. We used this approach to elucidate the plasmablast antibody response to influenza vaccination. We show that >75% of the rationally selected plasmablast antibodies bind and neutralize influenza, and that antibodies from clonal families, defined by sharing both heavy-chain VJ and light-chain VJ sequence usage, do so most effectively.

Expulsion of secondary Trichinella spiralis infection in rats occurs independently of mucosal mast cell release of mast cell protease II.

Our aim was to elucidate the contribution of mucosal mast cells to the effector phase of a secondary immune response to Trichinella spiralis. During secondary infection, rats expel 90-99% of T. spiralis first-stage larvae from the intestine in a matter of hours.

TLR9 traffics through the Golgi complex to localize to endolysosomes and respond to CpG DNA.

Toll-like receptor 9 (TLR9) promiscuously binds self- and microbial DNA, but only microbial DNA elicits an inflammatory response. How TLR9 discriminates between self- and foreign DNA is unclear, but inappropriate localization of TLR9 permits response to self-DNA, suggesting that TLR9 localization and trafficking are critical components. The molecular mechanisms controlling the movement of TLR9 may provide new insight into the recognition of DNA in normal and in pathological conditions such as autoimmune systemic lupus erythematosus.