Integrative single-cell analysis of cardiac and pulmonary sarcoidosis using publicly available cardiac and bronchoalveolar lavage fluid sequencing datasets.

Introduction: Cardiac presentation of autoimmune sarcoidosis, known as cardiac sarcoidosis (CS), is a poorly understood disease with high mortality and low diagnosis rate. While CS is an immunological syndrome, little is known about how cardiac parenchymal and stromal cells mediate its pathogenesis. Moreover, while most current sarcoidosis research is based on research in pulmonary sarcoidosis (PS), it remains unclear how much both presentations of sarcoidosis overlap. To tackle these concerns, we leveraged publicly available sarcoidosis transcriptomic datasets. Methods: Two publicly available bronchoalveolar lavage single-cell RNA sequencing datasets were integrated to analyze PS relative to control. Additionally, two publicly available cardiac single-nucleus RNA sequencing datasets were integrated to analyze CS relative to control. Following integration, we ran cell-cell communication, transcription factor, and differential expression analyses on parenchymal, stromal, and immune subsets identified in our analysis. Results: Our analysis revealed that there was an expansion of stromal and immune cells in PS and CS. We also observed upregulation of Th17.1 and attenuated activation transcriptional profiles in the immune cells of CS and PS relative to control. Additionally, we found upregulation of pro-inflammatory and pro-fibrotic transcriptional profiles in the cardiac stromal cells of CS relative to control. We also found that cardiomyocytes exhibited upregulated cardiac stress and proliferation transcriptional profiles in CS relative to control. Conclusions: Our integrative transcriptomic analysis shows that despite tissue-specific differences, there are shared transcriptional trends between CS and PS. It also shows that stromal and parenchymal populations exhibit transcriptional trends that could explain their pathogenic role in CS.

Cross-decoration of dendritic cells by non-inherited maternal antigen-containing extracellular vesicles: Potential mechanism for PD-L1-based tolerance in cord blood and organ transplantation.

Exposure to non-inherited maternal antigens (NIMA) during the fetal period induces lifelong split tolerance to grafts expressing these allo-antigens. In adult mice, the production of extracellular vesicles (EVs) from maternal microchimeric cells causes cross-decoration (XD) of offspring dendritic cells (DC) with NIMA and upregulation of PD-L1, contributing to NIMA tolerance. To see how this may apply to humans, we tested NIMA acquisition by fetal DCS in human cord blood. The average percentage of NIMA-XD among total DCs was 2.6% for myeloid and 4.5% for Plasmacytoid DC. These cells showed higher PD-L1 expression than their non-XD counterparts (mDC: p = .0016; pDC: p = .024). We detected CD9+ EVs bearing NIMA and PD-L1 in cord blood. To determine if this immune regulatory mechanism persists beyond the pregnancy, we analyzed NIMA-expressing kidney and liver transplant recipients. We found donor antigen XD DCs in peripheral blood and graft-infiltrating DCs. As in cord blood, the pattern of donor antigen expression was punctate, and PD-L1 expression was upregulated, likely due to both protein and miRNA acquired from EV. Our findings support a mechanism for split tolerance to NIMAs that develops during pregnancy and is recapitulated in adult transplant recipients.

Donor HLA-DR Drives the Development of De Novo Autoimmunity Following Lung and Heart Transplantation.

Individuals harbor preexisting HLA-DR/DQ-restricted responses to collagen type V (ColV) mediated by Th17 cells under Treg control, both specific to peptides that bind to inherited HLA class II antigens. Yet after transplant, the donor-DR type somehow influences graft outcome. We hypothesized that, long after a lung or heart allograft, the particular HLA-DR type of the mismatched transplant donor transforms the specificity of the "anti-self" response. This could explain why, over long term, certain donor DRs could be more immunogenic than others. METHODS: We analyzed 7 HLA-DR15neg patients who had received a lung allograft from a DR15+ donor. To determine the mechanism of acquired specificity in self-reactivity, we analyzed the kinetics of DR1 (host) and DR15 (donor) peptide restriction in a heart transplant model using DR-transgenic mice. RESULTS: Beyond 1.5 years post-lung transplant, all patients tested had acquired DR15-restricted immune responses to ColV peptides. These responses were either unrestrained Th17 type (n = 4) or Th17 controlled by Treg arising early (<5 y) or late (>7 y) after transplant (n = 4). Treg suppression via conventional (transforming growth factor-ß [TGF-ß]) and extracellular vesicle-associated (IL-35) cytokines correlated with superior outcomes. Naïve DR1 and DR15 transgenic mice had preexisting DR-restricted responses, exclusively to ColV fragments containing DR1- or DR15-binding peptides. When HLA-DR1 transgenic recipients of a HLA-DR15 heart developed ColV reactivity post-transplant, mice that acutely rejected (20-25 d) responded only to the DR1-restricted ColV peptide epitope. In animals whose grafts survived long term, we could detect acquisition of DR from the transplant donor onto the surface of recipient dendritic cells, and immune responses against a donor DR15-restricted ColV peptide. CONCLUSIONS: These results might explain how certain donor HLA-DR types redirect host immune responses to novel peptides of critical self-antigens. Unless regulated, such responses may predispose the allograft to chronic rejection.

Identification of PD1-mediated regulation of antitumor antigen response in patients with NSCLC using the trans vivo DTH assay.

OBJECTIVES: Emerging evidence has shown a role for tumor antigen-specific regulation in cancer. Identifying individuals with pre-existing regulatory responses may be key to understand those who are more likely to respond to Programmed Death-1 (PD-1) or PD-1 Ligand 1 (PD-L1) checkpoint blockade. We hypothesized that a functional assay could identify the role of PD-1/PD-L1 interactions on tumor-specific immune cells in the peripheral blood in patients with advanced non-small-cell lung cancer (NSCLC). METHODS: We performed the trans vivo delayed-type hypersensitivity assay to identify the role of PD-1/PD-L1-mediated tumor-specific immune regulation in ten patients with advanced NSCLC. RESULTS: The majority of patients had PD-1-mediated anergic immune responses towards their tumor antigens. Eight out of nine of these patients did not respond to their own tumor antigens but responded in the presence of anti-PD-1 antibody ('PD-1 anergy' phenotype). A minority (3/9) also had 'active' PD-1-mediated immune suppressive regulatory responses. Our results suggest that PD-1-anergy is a common feature of NSCLC immune responses, whereas PD-1-mediated immune suppression is present only in a minority of patients. The latter was associated with poor clinical outcomes in our sample. CONCLUSIONS: Overall, our results indicate that bystander suppression or the 'anergy-only' phenomenon may be novel biomarkers in NSCLC and suggest prediction value based on these phenotypes.

Treg-Cell-Derived IL-35-Coated Extracellular Vesicles Promote Infectious Tolerance.

Interleukin-35 (IL-35) is an immunosuppressive cytokine composed of Epstein-Barr-virus-induced protein 3 (Ebi3) and IL-12α chain (p35) subunits, yet the forms that IL-35 assume and its role in peripheral tolerance remain elusive. We induce CBA-specific, IL-35-producing T regulatory (Treg) cells in TregEbi3WT C57BL/6 reporter mice and identify IL-35 producers by expression of Ebi3TdTom gene reporter plus Ebi3 and p35 proteins. Curiously, both subunits of IL-35 are displayed on the surface of tolerogen-specific Foxp3+ and Foxp3neg (iTr35) T cells. Furthermore, IL-35 producers, although rare, secrete Ebi3 and p35 on extracellular vesicles (EVs) targeting a 25- to 100-fold higher number of T and B lymphocytes, causing them to acquire surface IL-35. This surface IL-35 is absent when EV production is inhibited or if Ebi3 is genetically deleted in Treg cells. The unique ability of EVs to coat bystander lymphocytes with IL-35, promoting exhaustion in, and secondary suppression by, non-Treg cells identifies a novel mechanism of infectious tolerance.

Role of exosomes in tumour and transplant immune regulation.

Exosomes are a potent means for intercellular communication. However, exosomes have received intensive research focus in immunobiology only relatively recently. Because they transport proteins, lipids and genetic material between cells, they are especially suited to amplify their parental cell's message and overcome the physical constraints of cell-to-cell contact, that is exosome release gives cells the ability to alter distant, non-contiguous cells. As progress is made in this field, it has become increasingly obvious that exosomes are involved in most biological processes. In the immune system, exosomes are fundamental tools used by every immune cell type to fulfil its function and promote inflammation or tolerance. In this review, we first summarize key aspects of immune cell-specific exosomes and their functions. Then, we describe how exosomes have been shown to be indispensable orchestrators of the immune response in two immunological scenarios, namely transplant rejection or tolerance, and tumour evasion or initiation of anti-tumour immune responses.

[Acute abdomen as initial manifestation of meningococcemia]. / Abdomen agudo como manifestación inicial de meningococemia.

Abdominal pain as an initial symptom of meningococcemia is an infrequent entity, rarely described in literature. We present a case of a 4 year-old, male, previously healthy child with a 24 hour history of fever and abdominal pain. He is admitted in a surgical unit with a diagnosis of acute abdomen for surgical resolution. The clinical course turns unfavorably, and patient presents signs of severe sepsis. Urgent laparotomy is performed, observing little brownish fluid and mesenteric adenitis. He then exhibits palpable purpuric rapidly progressive lesions in lower extremities, progressing to septic shock. Later, Neisseria meningitidis serogroup B is isolated from blood cultures. The aim of this article is drawing attention to a nontypical form of manifestation of meningococcemia, as a delayed diagnosis and treatment has an impact on morbidity and mortality among the pediatric population.

Abdomen agudo como manifestación inicial de meningococemia / Acute abdomen as initial manifestation of menincococcemia

El abdomen agudo como síntoma inicial de meningococemia es una entidad muy poco frecuente y raramente descripta en la bibliografía. Presentamos el caso de un paciente de 4 años de edad, sexo masculino, previamente sano, que consulta por síndrome febril y dolor abdominal de 24 h de evolución. Seinterna en unidad clínico-quirúrgica con diagnóstico de abdomen agudo quirúrgico. El paciente evoluciona desfavorablemente y súbitamente presenta signos compatibles con sepsis grave. Se realiza laparotomía de urgencia; se observa escasa cantidad de líquido citrino libre en cavidad con adenitis mesentérica. Desarrolla luego lesiones purpúricas palpables de rápida progresión en miembros inferiores y evolución al shock séptico. Se aísla en hemocultivos periféricos Neisseria meningitidis serogrupo B. El objetivo de esta publicación es exponer y alertar sobre una modalidad de presentación clínica poco frecuente de la meningococemia, pues el retraso en su diagnóstico y tratamiento impactan sobre la morbimortalidad en la población pediátrica.

Abdominal pain as an initial symptom of meningococcemia is an infrequent entity, rarely described in literature. We present a case of a 4 year-old, male, previously healthy child with a 24 hour history of fever and abdominal pain. He is admitted in a surgical unit with a diagnosis of acute abdomen for surgical resolution. The clinical course turns unfavorably, and patient presents signs of severe sepsis. Urgent laparotomy is performed, observing little brownish fluid and mesenteric adenitis. He then exhibits palpable purpuric rapidly progressive lesions in lower extremities, progressing to septic shock. Later, Neisseria meningitidis serogroup B is isolated from blood cultures.The aim of this article is drawing attention to a nontypical form of manifestation of meningococcemia, as a delayeddiagnosis and treatment has an impact on morbidity and mortality among the pediatric population.

Abdomen agudo como manifestación inicial de meningococemia / Acute abdomen as initial manifestation of menincococcemia

El abdomen agudo como síntoma inicial de meningococemia es una entidad muy poco frecuente y raramente descripta en la bibliografía. Presentamos el caso de un paciente de 4 años de edad, sexo masculino, previamente sano, que consulta por síndrome febril y dolor abdominal de 24 h de evolución. Seinterna en unidad clínico-quirúrgica con diagnóstico de abdomen agudo quirúrgico. El paciente evoluciona desfavorablemente y súbitamente presenta signos compatibles con sepsis grave. Se realiza laparotomía de urgencia; se observa escasa cantidad de líquido citrino libre en cavidad con adenitis mesentérica. Desarrolla luego lesiones purpúricas palpables de rápida progresión en miembros inferiores y evolución al shock séptico. Se aísla en hemocultivos periféricos Neisseria meningitidis serogrupo B. El objetivo de esta publicación es exponer y alertar sobre una modalidad de presentación clínica poco frecuente de la meningococemia, pues el retraso en su diagnóstico y tratamiento impactan sobre la morbimortalidad en la población pediátrica. (AU)

Abdominal pain as an initial symptom of meningococcemia is an infrequent entity, rarely described in literature. We present a case of a 4 year-old, male, previously healthy child with a 24 hour history of fever and abdominal pain. He is admitted in a surgical unit with a diagnosis of acute abdomen for surgical resolution. The clinical course turns unfavorably, and patient presents signs of severe sepsis. Urgent laparotomy is performed, observing little brownish fluid and mesenteric adenitis. He then exhibits palpable purpuric rapidly progressive lesions in lower extremities, progressing to septic shock. Later, Neisseria meningitidis serogroup B is isolated from blood cultures.The aim of this article is drawing attention to a nontypical form of manifestation of meningococcemia, as a delayeddiagnosis and treatment has an impact on morbidity and mortality among the pediatric population.(AU)