Biology subjects

Diamond, B.

Publications and source records attributed to Diamond, B..

At least 19 recordsLinked to original sources

bioRxiv2026

Rethinking the Benign Nature of Class II Lupus Nephritis

Introduction: Class II lupus nephritis (LN) is considered clinically benign, yet up to 50% of patients progress to more severe disease and no molecular characterization exists. We aimed to define the single-cell landscape of Class II LN and identify cellular and transcriptional features associated with kidney outcome. Methods: We performed single-cell RNA sequencing on kidney biopsies from fifteen Class II LN patients (eight de novo, seven regressed from prior proliferative or membranous disease) and six healthy controls, integrated with 155 LN and 30 healthy-control samples from the Accelerating Medicines Partnership in SLE spanning proliferative, membranous, and mixed LN. Findings were correlated with 52-week renal response and supported by urinary proteomics. Results: Despite histologically minimal changes, Class II LN exhibited marked immune cell expansion comparable to proliferative and membranous LN, including CCL3+ CCL4+ intermediate monocytes producing TNF, FOLR2+ SIGLEC1+ macrophages producing TGF{beta} and PDGF, and CD69+ CD8+ effector memory T cells producing IFN{gamma}. Fibroblasts and myofibroblasts were significantly expanded and displayed divergent transcriptional programs: pro-fibrotic and inflammatory myofibroblast modules were associated with worse 52-week outcomes, while interferon-responsive and matrix-remodeling fibroblast programs were associated with improvement. Pathogenic and protective fibroblast populations received overlapping immune-derived signals, suggesting that fibroblast transcriptional state, rather than the identity of incoming signals, shapes the stromal response. Baseline chronicity index captured this stromal heterogeneity and was the clinical parameter most associated with outcome. Urinary proteomics aligned Class II with proliferative rather than membranous disease. Conclusions: Class II LN harbors substantial molecular activity not captured by routine histology. Fibroblast transcriptional programs and baseline chronicity index are candidate correlates of kidney outcome that warrant validation in larger, prospectively followed cohorts.

genomics↗

bioRxiv2026

Mechanistic insights into B-cell activation and autoreactivity regulation in active SLE and remission.

ObjectiveTo define cellular and molecular mechanisms distinguishing active systemic lupus erythematosus (SLE) from remission by profiling autoreactive antinuclear antigen- positive (ANA+) and non-autoreactive B cells subsets in three cohorts: active disease (SLE-A), long-term, drug free remission (SLE-R), and healthy controls (HC). MethodsPeripheral blood B cells were phenotyped by flow cytometry, including ANA reactivity. Single-cell RNA sequencing (scRNA-seq) was performed on sorted ANA+ and ANA- subsets. ResultsSeven transcriptomic B cell clusters were resolved: quiescent (Naive 1, Marginal Zone B cells [MZB], IgG Memory 1) and activated (Age-Associated B cells [ABCs], Naive 2, IgM Memory, IgG Memory 2). SLE-A showed expansion of activated clusters, MZB contraction, and a higher IgG:IgM B cell ratio. SLE-R exhibited an "immunological reset," distinct from healthy homeostasis, with reduced ABCs and IgG Memory 2, persistence of Naive 2, and partial restoration of MZB and Naive 1. Interferon- (IFNa) signaling was elevated across clusters in SLE-A (SLE-A > SLE-R > HC), whereas TNF signaling was enriched in activated clusters across cohorts, with minimal differences between SLE-R and SLE-A. IFNa and TNF scores were inversely correlated. B cells predominantly expressed TNFR2, suggesting immunomodulatory TNF effects in remission. ANA+ cells in HC and SLE-R showed enriched Fc{gamma}RIIb inhibitory and IL-4/STAT6 signaling, suggesting reinstated regulatory control. DiscussionCompared to SLE-A, SLE-R was characterized by partial reversion to HC homeostasis with residual activation. These findings delineate immunologic features of remission and suggest therapeutic opportunities, including modulation of TNFR2, Fc{gamma}RIIb, and IL-4 to help sustain remission. What is already known on this topicSome patients with SLE achieve complete clinical remission without treatment, referred as immune reset; the mechanisms that underlie this state have not been well characterized. Healthy individuals and patients with Systemic Lupus Erythematosus (SLE) normally harbor similar frequencies of autoreactive B cells; the checkpoints that regulate activation of these cells are not fully defined. What this study addsB cells, stratified by their reactivity to nuclear antigens (ANA), from active SLE (SLE-A), drug-free remission (SLE-R), and healthy controls (HC) were analyzed using single cell sequencing and flow cytometry. We identified B cells states associated with disease activity; SLE-R displayed a distinct profile that differed from SLE-A and HC. TNF signaling was present in activated B cell subsets in SLE-A and SLE-R. This persistence in SLE-R may reflect an immunomodulatory function of TNF on TNFR2, which is expressed on B cells. ANA+ cells in SLE-R and HC were enriched for inhibitory Fc{gamma}RIIb and IL-4/STAT6 programs. How this study might affect research, practice or policyThe signatures identified help define the "immunological reset" state in patients with SLE-R. We also identified pathways, such as type I IFN, TNFR2, Fc{gamma}RIIb, IL-4/STAT6 as potential targets for maintaining remission.

immunology↗

bioRxiv2026

Blood-brain barrier disrupting stimuli induce production of extracellular vesicles with distinct protein cargoes and functionality

The blood-brain barrier (BBB) protects the brain from substances in the circulation; yet, this barrier can be breached. Systemic lupus erythematosus is a disease in which over 50% of patients experience manifestations of neuropsychiatric lupus (NPSLE), with many displaying BBB dysfunction. High levels of TNF, IL-1{beta}, C5a, and epinephrine, which have all been shown to cause BBB permeability, may be present in the serum of SLE patients. Brain microvascular endothelial cells (BMVECs) are a major structural element of the BBB. We asked whether BMVECs stimulated with barrier-disrupting factors release extracellular vesicles (EVs) which might participate in autocrine signaling or might have utility as diagnostic biomarkers of BBB permeability. We analyzed proteins in EVs secreted by unstimulated and stimulated BMVECs by mass spectrometry and used secreted EVs for further BMVEC stimulation. We subjected BMVECs to bulk RNA-seq to identify response signatures to the initial stimulus and to secondary stimulation with EVs. We show that there are agent-specific EV-associated protein profiles. EVs from BMVECs subjected to BBB-breaching stimuli alter the BMVEC transcriptional program, representing a potential feed-forward mechanism. Finally, we suggest that the proteins associated with EVs might be markers of BBB disruption.

molecular biology↗

bioRxiv2025

Plasma cell identity escape drives resistance to anti-BCMA T-cell-redirecting therapy in multiple myeloma

Chimeric antigen receptor T-cell (CART) and T-cell engager (TCE) therapies targeting B-cell maturation antigen (BCMA) are transforming the treatment landscape for relapsed multiple myeloma (MM). However, despite impressive initial response rates, most patients eventually relapse. To investigate this unmet medical need, we applied whole-genome sequencing (WGS) to MM cells from cohorts of 102 relapsed patients treated with anti-BCMA CART and TCE therapies. Several genomic alterations were associated with clinical outcomes, particularly primary refractoriness, including high genomic complexity and mutations in genes regulating plasma cell identity, which predicted resistance to therapy. Single-cell RNA sequencing further revealed that MM cells from refractory patients exhibited high proliferation signatures and reduced expression of TNFRSF17 (encoding BCMA), while were less enriched for plasma cell-associated transcriptional programs, a phenomenon we term "plasma cell identity escape." This profile was strongly associated with immune dysregulation of CD8 T cells including increased activation and exhaustion. This evolution of MM toward a more proliferative and lineage-divergent state, refractory to the anti-BCMA T-cell redirecting therapies, was functionally validated in preclinical MM mouse models. Collectively, our results comprehensively define the cellular and molecular mechanisms underlying primary resistance to anti-BCMA therapies.

cancer biology↗

bioRxiv2025

Heterogeneity of anti-Caspr2 antibodies: specificity and pathogenicity

Maternal anti-Caspr2 (Contactin-associated protein-like 2) antibodies have been associated with increased risk for autism spectrum disorder (ASD). Previous studies have shown that in utero exposure to anti-Caspr2 antibodies results in a phenotype with ASD-like features in male mice. Here we ask whether four newly generated antibodies against Caspr2 are pathogenic to the developing fetal brain and whether they function through similar means. Our results show that the novel anti-Caspr2 antibodies recognize different epitopes of Caspr2. In utero exposure to these antibodies elicits differential ASD-like phenotypes in male offspring, tested in the social interaction, open field, and light-dark tasks. These results demonstrate variability in the antigenic specificity and pathogenicity of anti-Caspr2 antibodies which may have clinical implications.

immunology↗

bioRxiv2025

IL-21-STAT3 axis negatively regulates LAIR1 expression in B cells

LAIR1 is an inhibitory receptor broadly expressed on human immune cells, including B cells. LAIR1 has been shown to modulate BCR signaling, however, it is still unclear whether its suppressive activity can be a negative regulator for autoreactivity. In this study, we demonstrate the LAIR1 expression profile on human B cells and prove its regulatory function and relationships to B cell autoreactivity. We show that both the frequency and level of LAIR1 expression decreases during B cell differentiation. LAIR1 expressing (LAIR1+) switched memory (SWM) B cells have a transcriptional profile less differentiated toward a plasma cell (PC) phenotype, harbor more autoreactive B cells and exhibit less PC differentiation in vitro than the LAIR1 negative (LAIR1-) counterpart. These data suggests that LAIR1 functions as a B cell tolerance checkpoint. We confirm previous data showing that patients with systemic lupus erythematosus (SLE) express less LAIR1 on B cells, implying a breakdown of the checkpoint, consistent with the enhanced PC differentiation seen in SLE. We further demonstrate that LAIR1 expression is down-regulated through the IL-21/STAT3 pathway which is known to be upregulated in SLE. These data suggest therapeutic targets that might decrease the aberrant PC differentiation observed in SLE.

immunology↗

bioRxiv2025

SELECTION OF ANTI-NUCLEAR ANTIGEN (ANA) REACTIVE B CELLS IN SYSTEMIC LUPUS ERYTHEMATOSUS.

ObjectiveAutoreactive B cells that recognize nuclear antigens are normally present in healthy individuals and patients with systemic lupus erythematosus (SLE), yet their activation and the production of IgG autoantibodies is a hallmark of SLE. The selection process and regulation of these cells in patients with SLE has not been completely understood. To gain insights into tolerance checkpoints and the developmental trajectories of autoreactive clones, we studied the BCR sequences from thousands of anti-nuclear antigen binding (ANA)+ and ANA-B cells from patients with SLE. MethodsFrom a cohort of 13 patients with SLE, we identified and isolated ANA+ and ANA-B cells by flow cytometry using a method based on their binding to nuclear extracts. We sequenced B cell receptor (BCR) heavy chain variable regions and investigated the features of the IgH repertoire of ANA+ and ANA-B cells from naive, memory and age-associated B cells (ABCs), and from total plasmablasts. ResultsThe frequency of ANA+ B cells was similar in ABCs and naive B cells and higher in both than in memory B cells. We observed preferential usage of some VH (IGHV1-18, IGHV3-21, IGHV3-23|3-23D, IGHV4-34, IGHV4-39 and IGHV4-59) and VJ genes (IGHJ4 and IGHJ6) in B cells from these patients. ANA+ naive and ANA+ ABCs used different gene segments and have longer CDR3 sequences than ANA+ memory B cells and ANA-subsets. ANA+ ABCs and memory B cells have a lower frequency of somatic hypermutation (SHM) and less activation induced deaminase (AID) targeting to WRC hotspots compared with their ANA-counterparts. Patients with active disease have a lower frequency of SHM in ANA+ ABCs and memory B cells and in ANA-ABCs. ConclusionCompared to memory B cells, ABCs are enriched in autoreactivity. Our results suggest that there is an immune checkpoint that restricts the differentiation of ANA+ naive B cells into memory B cells and that ANA+ ABCs originate from ANA+ naive B cells. Lower frequencies of SHM in antigen experienced ANA+ B cells, and particularly ANA+ ABCs, suggest that these cells might be generated through an extrafollicular (EF) pathway, and that in patients with active SLE there is more EF activation.

immunology↗

bioRxiv2024

CD38 biallelic loss is a recurrent mechanism of resistance to anti-CD38 antibodies in multiple myeloma.

Monoclonal antibodies targeting CD38 are a therapeutic mainstay in multiple myeloma (MM). While they have contributed to improved outcomes, most patients still experience disease relapse, and little is known about tumor-intrinsic mechanisms of resistance to these drugs. Antigen escape has been implicated as a mechanism of tumor cell evasion in immunotherapy. Yet, it is unknown whether MM cells can develop permanent resistance to anti-CD38 antibodies by acquiring genomic events leading to biallelic disruption of the CD38 gene locus. Here, by using whole genome and whole exome sequencing data from 701 newly diagnosed patients, 67 patients at relapse with naivety to anti-CD38 antibodies, and 50 patients collected at relapse following anti-CD38 antibodies. We report a loss of CD38 in 20% (10/50) of patients post-CD38 therapy, three of which exhibited a loss of both copies. Two of these cases showed convergent evolution where distinct subclones independently acquired similar advantageous variants. Functional studies on missense mutations involved in biallelic CD38 events revealed that two variants, L153H and C275Y, decreased binding affinity and antibody-dependent cellular cytotoxicity of the commercial antibodies Daratumumab and Isatuximab. However, a third mutation, R140G, conferred selective resistance to Daratumumab, while retaining sensitivity to Isatuximab. Clinically, patients with MM are often rechallenged with CD38 antibodies following disease progression and these data support a role for next generation sequencing to guide treatment selection.

cancer biology↗

bioRxiv2024

IFN-associated B cell hyperactivity is highly enriched in SLE patients harboring Sm/RNP antibodies

Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by an array of autoantibodies, in particular anti-nuclear antibodies (ANA). The disease is also hallmarked by an expansion of plasmablasts (PB) in peripheral blood. How these relate to autoantibody production is not clear. Here, we aimed to understand B cell alterations in SLE and their relationship to immunoglobulin levels and autoantibody production. We demonstrate that a subgroup of SLE patients is characterized by a high frequency of PB relative to memory B cells (high PB/M). Patients with this phenotype more frequently had high disease activity. Despite low overall frequencies of memory B cells, these patients exhibited an increased activation in the switched CD27+ memory compartment and a strong IFN signature in PB. Repertoire analysis revealed a highly polyclonal expansion and enrichment for IgG1 expressing PB in patients with a high PB/M ratio which was reflected in increased serum IgG levels. Importantly, the hyperactive B cell phenotype was highly enriched in patients harboring Sm/RNP autoantibodies (OR: 9.17 (2.97-26.0)). In summary, we show for the first time a direct relationship between IFN and PB expansion in a subgroup of SLE patients, highly enriched in those harboring Sm/RNP antibodies. These results provide insight into the pathways leading to B cell hyperactivity and autoantibody production which may guide the tailoring of B cell- and IFN-targeted therapies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=156 SRC="FIGDIR/small/624119v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1f74053org.highwire.dtl.DTLVardef@1a01da4org.highwire.dtl.DTLVardef@fa27f4org.highwire.dtl.DTLVardef@155140f_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2024

Mutagenic impact and evolutionary influence of radiotherapy in hematologic malignancies

Ionizing radiotherapy (RT) is a widely used palliative and curative treatment strategy for malignancies. In solid tumors, RT-induced double strand breaks lead to the accumulation of indels, and their repair by non-homologous end-joining has been linked to the ID8 mutational signature in resistant cells. However, the extent of RT-induced DNA damage in hematologic malignancies and its impact on their evolution and interplay with commonly used chemotherapies has not yet been explored. Here, we interrogated 580 whole genome sequencing (WGS) from patients with large B-cell lymphoma, multiple myeloma, and myeloid neoplasms and identified ID8 only in relapsed disease. Yet, it was detected after exposure to both RT and mutagenic chemotherapy (i.e., platinum). Using WGS of single-cell colonies derived from treated lymphoma cells, we revealed a dose-response relationship between RT and platinum and ID8. Finally, using ID8 as a genomic barcode we demonstrate that a single RT-resistant cell may seed systemic relapse.

genomics↗

bioRxiv2024

Temporal Genomic Dynamics Shape Clinical Trajectory in Multiple Myeloma

To comprehensively unravel the temporal relationship between initiating and driver events and its impact on clinical outcomes, we analyzed 421 whole-genome sequencing profiles from 382 patients. Using clock-like mutational signatures, we estimated a time lag of 2-4 decades between initiating events and diagnosis. In patients with hyperdiploidy, we demonstrate that trisomies of odd-numbered chromosomes can be acquired simultaneously with other chromosomal gains, such as 1q gain. We provide evidence that hyperdiploidy is acquired after canonical IGH translocation when both events are present. Finally, patients with early 1q gain had adverse outcomes similar to those with 1q amplification (>1 extra-copies), but faring worse than those with late 1q gain. This underscores that the prognostic impact of 1q gain/amp depends more on the timing of acquisition than on the number of extra copies gained. Overall, this study contributes to a better understanding of the life history of MM and may have prognostic implications.

cancer biology↗

bioRxiv2024

Timing antigenic escape in multiple myeloma treated with T-cell redirecting immunotherapies

Recent data highlight genomic events driving antigen escape as a recurring cause of chimeric antigen receptor T-cell (CAR-T) and bispecific T-cell engager (TCE) resistance in multiple myeloma (MM). Yet, it remains unclear if these events, leading to clonal dominance at progression, result from acquisition under treatment selection or selection of pre-existing undetectable clones. This differentiation gains importance as these immunotherapies progress to earlier lines of treatment, prompting the need for innovative diagnostic testing to detect these events early on. By reconstructing phylogenetic trees and exploring chemotherapy mutational signatures as temporal barcodes in 11 relapsed refractory MM patients with available whole genome sequencing data before and after CART/TCE treatment, we demonstrated that somatic antigen escape mechanisms for BCMA- and GPRC5D-targeting therapies are acquired post-diagnosis, likely during CART/TCE treatment. Longitudinal tracking of these mutations using digital PCR in 4 patients consistently showed that genomic events promoting antigen escape were not detectable during the initial months of therapy but began to emerge nearly 1 year post therapy initiation. This finding reduces the necessity for a diagnostic panel to identify these events before CART/TCE. Instead, it underscores the importance of surveillance and identifying patients at higher risk of acquiring these events. KEY POINTSO_LIGenomic events driving antigen escape are recurrent mechanisms of resistance to CART and T-cell engagers in multiple myeloma. C_LIO_LIUsing chemotherapy mutational signatures, we demonstrated that these events are most likely acquired during treatment. C_LI

genomics↗

bioRxiv2023

Vagus nerve stimulation limits the germinal center B cell response via CD4+ T cell-derived acetylcholine

Neural signals are known to contribute to immune regulation and modulation of the innate immune response downstream of the vagus nerve has been well studied. The effects of vagus nerve activity on antibody production, however, have been largely unexplored. Here we use a chronic vagus nerve stimulation (VNS) mouse model to study the effect of vagal activation on T-dependent B cell responses. We observed lower titers of high-affinity serum IgG and fewer antigen-specific germinal center (GC) B cells in the spleen. GC B cells from chronic VNS mice expressed more active caspase-3 and exhibited an altered gene expression profile suggesting increased susceptibility to apoptosis and impaired maturation. Follicular dendritic cell (FDC) cluster dispersal and altered FDC gene expression suggested poor FDC function. These alterations were diminished in the absence of a subset of acetylcholine-producing CD4+ T cells. In vitro studies revealed that 7 and 9 nicotinic acetylcholine receptors (nAChRs) directly regulated B cell production of TNF, a cytokine crucial to FDC clustering. Engagement of the 4 nAChR subunit on B cells impaired Akt phosphorylation, presumably decreasing B cell survival. Thus, VNS-induced GC impairment can be attributed, at least in part, to the effect of acetylcholine on B cell intrinsic pathways, resulting in hindered B cell survival and maturation and leading to an alteration in FDC function. Our findings identify a potential therapeutic target to prevent immunosuppression in conditions associated with increased vagal activity.

immunology↗

bioRxiv2023

Intrarenal myeloid subsets associated with kidney injury are comparable in mice and patients with lupus nephritis

Resident macrophages and infiltrating monocytes in kidneys of patients with lupus nephritis are altered both in frequency and function relative to their counterparts in healthy kidneys. The extent to which mouse models might be useful in developing approaches to target these cells for treating lupus nephritis is poorly understood. Here, we studied four common lupus mouse models that share clinical, serologic, and histopathologic kidney changes with humans. Using single-cell profiling and multiplex spatial imaging to analyze the intrarenal myeloid compartment with the onset of clinical disease in these models, we identified monocyte and macrophage subsets that expand or contract in kidneys with clinical nephritis. A unique subset of classical monocytes expanded with the onset of disease and expressed genes such as CD9, Spp1, Ctsd, Cd63, Apoe, and Trem2 that were previously shown to be induced by tissue injury and play a role in inflammation, lipid metabolism and tissue repair in other organs. Resident macrophages transitioned from a pro-inflammatory to a similar injury-associated state with onset of disease. To test whether these findings in mouse models were also observed in humans, we re-analyzed monocytes and macrophages in a single-cell RNAseq dataset of kidney biopsies from 155 patients with lupus nephritis and 30 healthy donors, collected by the NIH AMP RA/SLE consortium. Human monocytes and macrophages showed conserved changes in gene expression programs associated with lupus nephritis disease indices, and localized to similar kidney microenvironments as in mice. By identifying myeloid subsets and disease-associated alterations in biological processes that are conserved across species, we provide a strong rationale for functional studies of these cells and pathways in mice to uncover mechanisms and find targets relevant to human lupus nephritis. One sentence summaryThis study characterizes intrarenal myeloid cells from four lupus mouse models and 155 patients with lupus nephritis using single-cell RNA-seq and imaging, and identifies novel infiltrating and resident myeloid subsets that are conserved between mouse and human lupus nephritis, thus providing a map and strong rationale for functional studies in mice with relevance to human disease.

immunology↗

bioRxiv2023

Anti-nuclear antibody (ANA) detection in culture supernatant of cloned B cells

Anti-nuclear antibodies (ANA) of individuals with SLE contribute to disease pathogenesis and tissue injury. Systematic analysis of the fine specificity of ANA produced by individual B cells has been limited, in part, to the low concentration of immunoglobulin in single B cell cultures. We modified single B cell culture methods and developed an ANA ELISA to detect ANA at very low levels (15.0 ng/ml) of IgM in the supernatant of clonally expanded B cell cultures. This approach allows for the analysis of ANA reactivity of the IgM produced by approximately 60% of the single sorted naive B cells expanded in culture and permits a relatively high throughput evaluation at the single cell level of the ANA reactivity of naive B cells of healthy individuals and patients with autoimmune diseases.

immunology↗

bioRxiv2023

Lupus autoantibodies initiate a maladaptive equilibrium sustained by HMGB1:RAGE signaling and reversed by LAIR-1:C1q signaling

Cognitive impairment is a frequent manifestation of neuropsychiatric systemic lupus erythematosus (NPSLE), present in up to 80% of patients and leading to a diminished quality of life. We have developed a model of lupus-like cognitive impairment which is initiated when anti-DNA, anti-N-methyl D-aspartate receptor (NMDAR) cross-reactive antibodies, which are present in 30% of SLE patients, penetrate the hippocampus. This leads to immediate, self-limited excitotoxic death of CA1 pyramidal neurons followed by a significant loss of dendritic arborization in the remaining CA1 neurons and impaired spatial memory. Both microglia and C1q are required for dendritic loss. Here we show that this pattern of hippocampal injury creates a maladaptive equilibrium that is sustained for at least one year. It requires HMGB1 secretion by neurons to bind RAGE, a receptor for HMGB1 expressed on microglia, and leads to decreased expression of microglial LAIR-1, an inhibitory receptor for C1q. The angiotensin converting enzyme (ACE) inhibitor captopril, which can restore a healthy equilibrium, microglial quiescence, and intact spatial memory, leads to upregulation of LAIR-1. This paradigm highlights HMGB1:RAGE and C1q:LAIR-1 interactions as pivotal pathways in the microglial-neuronal interplay that defines a physiologic versus a maladaptive equilibrium.

immunology↗

bioRxiv2023

Ultrasound neuromodulation of an anti-inflammatory pathway at the spleen produces sustained improvement of experimental pulmonary hypertension

BackgroundInflammation is pathogenically implicated in pulmonary arterial hypertension (PAH); however, it has not been adequately targeted therapeutically. We investigated whether neuromodulation of an anti-inflammatory neuroimmune pathway involving the splenic nerve using noninvasive, focused ultrasound stimulation of the spleen (sFUS) can improve experimental pulmonary hypertension (PH). MethodsPH was induced in rats either by SU5416 (20 mg/kg SQ) injection, followed by 21 (or 35) days of hypoxia (SuHx model), or by monocrotaline (60 mg/kg IP) injection (MCT model). Animals were randomized to receive either daily, 12-min-long sessions of sFUS or sham stimulation, for 14 days. Catheterizations, echocardiography, indices of autonomic function, lung and heart histology and immunohistochemistry, spleen flow cytometry and lung single-cell-RNA sequencing were performed after treatment to assess the effects of sFUS. ResultsSplenic denervation right before induction of PH results in a more severe phenotype. In both SuHx and MCT models of PH, sFUS treatment reduces right ventricular (RV) systolic pressure by 25-30% compared to sham therapy, without affecting systemic pressure, and improves RV function and autonomic indices. sFUS reduces wall thickness, apoptosis, and proliferation in small pulmonary arterioles, suppresses CD3+ and CD68+ cell infiltration in lungs and RV fibrosis and hypertrophy and lowers brain natriuretic peptide. Beneficial effects persist for weeks after sFUS discontinuation and are more robust with early and longer treatment. Splenic denervation abolishes sFUS therapeutic benefits. sFUS partially normalizes CD68+ and CD8+ T-cells cell counts in the spleen and downregulates several inflammatory genes and pathways in nonclassical and classical monocytes, and macrophages in the lung. Differentially expressed genes in those cell types are significantly enriched for human PAH-associated genes. ConclusionssFUS causes dose-dependent, sustained improvement of hemodynamic, autonomic, laboratory and pathological manifestations in two models of experimental PH. Mechanistically, sFUS normalizes immune cell populations in the spleen and downregulates inflammatory genes and pathways in the lung, many of which are relevant in human disease.

neuroscience↗

bioRxiv2022

B lymphocytes in Treatment-Naive Pediatric Lupus Patients are Epigenetically Distinct from Healthy Children

BackgroundSystemic lupus erythematosus (SLE) is a complex disease likely triggered by gene-environment interactions. We have shown that most of the SLE-associated haplotypes encompass genomic regions enriched for epigenetic marks associated with enhancer function in neutrophils, and T and B cells, suggesting that genetic risk is exerted through altered gene regulation. Data remain scarce on how epigenetic variance contributes to disease risk in pediatric SLE (pSLE). We aim to identify differences in epigenetically-regulated chromatin architecture in treatment-naive pSLE patients compared to healthy children. MethodsUsing the assay for transposase-accessible chromatin with sequencing (ATACseq), we surveyed open chromatin in 8 treatment-naive pSLE patients, with at least moderate disease severity, and 5 healthy children. We investigated whether regions of open chromatin unique to pSLE patients demonstrate enrichment for specific transcriptional regulators, using standard computational approaches to identify unique peaks and a false discovery rate of <0.05. Further analyses for differential transcription factor binding, histone modification enrichment, and variant calling were performed using multiple bioinformatics packages in R and Linux. ResultsThere were 30,139 differentially accessible regions (DAR) identified unique to pSLE B cells, of which 64.3% are more accessible in pSLE than B cells from healthy children. Many of these DAR are found in distal, intergenic regions, and are enriched for enhancer histone marks (p=0.027). When we compared B cells from pSLE patients to those of untreated adults, we found more regions of inaccessible chromatin, and fewer DAR within 10-100kb of known SLE haplotypes. In pSLE B cells, 65.2% of the DAR are located within or near known SLE haplotypes. Further analysis revealed enrichment of several transcription factor binding motifs within these DAR that may regulate genes involved in the pro-inflammatory responses and cellular adhesion. ConclusionsThis is the first report describing differences in chromatin architecture between pSLE patients and healthy children. We demonstrate an epigenetically-distinct profile in pSLE B cells when compared to those from healthy children and adults with lupus, indicating that pSLE B cells are predisposed for disease onset and development. Increased chromatin accessibility in non-coding genomic regions controlling activation of inflammation and the immune response suggest that transcriptional dysregulation by regulatory elements that control B cell activation plays an important role in the pathogenesis of pSLE.

genomics↗