Neutrophil Activity and Extracellular Matrix Degradation: Drivers of Lung Tissue Destruction in Fatal COVID-19 Cases and Implications for Long COVID

Pulmonary fibrosis, severe alveolitis, and the inability to restore alveolar epithelial architecture are primary causes of respiratory failure in fatal COVID-19 cases. However, the factors contributing to abnormal fibrosis in critically ill COVID-19 patients remain unclear. This study analyzed the histopathology of lung specimens from eight COVID-19 and six non-COVID-19 postmortems. We assessed the distribution and changes in extracellular matrix (ECM) proteins, including elastin and collagen, in lung alveoli through morphometric analyses. Our findings reveal the significant degradation of elastin fibers along the thin alveolar walls of the lung parenchyma, a process that precedes the onset of interstitial collagen deposition and widespread intra-alveolar fibrosis. Lungs with collapsed alveoli and organized fibrotic regions showed extensive fragmentation of elastin fibers, accompanied by alveolar epithelial cell death. Immunoblotting of lung autopsy tissue extracts confirmed elastin degradation. Importantly, we found that the loss of elastin was strongly correlated with the induction of neutrophil elastase (NE), a potent protease that degrades ECM. This study affirms the critical role of neutrophils and neutrophil enzymes in the pathogenesis of COVID-19. Consistently, we observed increased staining for peptidyl arginine deiminase, a marker for neutrophil extracellular trap release, and myeloperoxidase, an enzyme-generating reactive oxygen radical, indicating active neutrophil involvement in lung pathology. These findings place neutrophils and elastin degradation at the center of impaired alveolar function and argue that elastolysis and alveolitis trigger abnormal ECM repair and fibrosis in fatal COVID-19 cases. Importantly, this study has implications for severe COVID-19 complications, including long COVID and other chronic inflammatory and fibrotic disorders.

Low anterior resection syndrome and quality of life after intersphincteric resection for rectal cancer: a propensity score-matched study

PURPOSE

Our aim was to perform a propensity score-matched study to compare the long-term functional outcomes and quality of life following intersphincteric resection vs. low anterior resection (LAR) with very low anastomosis.

METHODS

Patients who underwent intersphincteric resection or low anterior resection with low anastomosis (≤ 4 cm from the anal verge) for rectal cancer between January 2017 and June 2020 were retrospectively included. A propensity score-matching process was performed. Functional outcomes and quality of life were assessed using the European Quality of Life 5 Dimensions 3 Level Version (EQ-5D-3L), EORC-QLQ C30, EORC-QLQ CR29, Low Anterior Resection Syndrome (LARS), Wexner, and International Prostate Symptom Score (IPSS) questionnaires. The primary outcome was the presence of LARS at least 12 months after surgery. The second outcome was the postoperative quality of life of included patients.

RESULTS

After propensity matching, 128 patients were included, including 58 males and 70 females with a median age of 59.5. Patients in the intersphincteric resection group showed a higher incidence of incontinence to flatus (32.8% versus 14.0%, p = 0.043) and stools (42.2% versus 21.9%, p = 0.046), pain/discomfort (25.0% versus 7.8%, p = 0.001), and bowel dysfunction, while the LARS scores (15.0 versus 13.2, p = 0.461) and major LARS rates (26.6% versus 14.1%, p = 0.078) were comparable in both groups.

CONCLUSION

ISR leads to increased bowel incontinence rate and increased anal pain, without affecting the grade of low anterior resection syndrome, fecal urgency, and clustering. LAR might be the preferred sphincteric-preserving approach when negative resection margins and a safe anastomosis are guaranteed. Patients should be fully informed about potential functional impairment after sphincter-preservation procedures.

Dynamic establishment and maintenance of the human intestinal B cell population and repertoire following transplantation

It is unknown how intestinal B cell populations and B cell receptor (BCR) repertoires are established and maintained over time in humans. Following intestinal transplantation (ITx), surveillance ileal mucosal biopsies provide a unique opportunity to map the dynamic establishment of gut lymphocyte populations. Using polychromatic flow cytometry that includes HLA allele group-specific mAbs distinguishing donor from recipient cells along with high throughput BCR sequencing, we tracked the establishment of recipient B cell populations and BCR repertoire in the allograft mucosa of ITx recipients. We confirm the early presence of naïve donor B cells in the circulation and, for the first time, document the establishment of recipient B cell populations, including B resident memory cells, in the intestinal allograft mucosa. Recipient B cell repopulation of the allograft was most rapid in infant (<1 year old)-derived allografts and, unlike T cell repopulation, did not correlate with rejection rates. While recipient memory B cell populations were increased in graft mucosa compared to circulation, naïve recipient B cells remained detectable in the graft mucosa for years. Comparisons of peripheral and intra-mucosal B cell repertoires in the absence of rejection revealed increased BCR mutation rates and clonal expansion in graft mucosa compared to circulating B cells, but these parameters did not increase markedly after the first year post-transplant. Furthermore, clonal mixing between the allograft mucosa and the circulation was significantly greater in ITx recipients, even years after transplantation, than in healthy control adults. Collectively, our data demonstrate intestinal mucosal B cell repertoire establishment from a circulating pool, a process that continues for years without evidence of establishment of a stable mucosal B cell repertoire.

Multidetector CT-derived tricuspid annulus measurements predict tricuspid regurgitation reduction after transcatheter aortic valve replacement

AIM

To use multidetector row computed tomography (MDCT)-derived tricuspid annulus (TA) measurements to identify predictors for tricuspid regurgitation (TR) reduction after transcatheter aortic valve replacement (TAVR), and to investigate the impact of TR change on prognosis.

MATERIALS AND METHODS

A retrospective, single-centre study was conducted on consecutive patients who underwent TAVR with concomitant baseline mild or more severe TR from April 2012 to April 2022. TA parameters were measured using MDCT.

RESULTS

The study comprised 266 patients (mean age 74.2 ± 7.6 years, 147 men) and 45.1% had more than one grade of TR reduction at follow-up. Independent predictors of TR reduction at follow-up were distance between TA centroid and antero-septal commissure (odd ratio [OR] 0.776; 95% confidence interval [CI]: 0.672-0.896, p=0.001), baseline TR of moderate or worse (OR 4.599; 95% CI: 2.193-9.648, p<0.001), systolic pulmonary artery pressure (OR 1.018; 95% CI: 1.002-1.035, p=0.027), age (OR 0.955; 95% CI: 0.920-0.993, p=0.019), and pre-existing atrial fibrillation (OR 0.209; 95% CI: 0.101-0.433, p<0.001). Patients without TR reduction had higher rates of rehospitalisation (hazard ratio [HR] 0.642; 95% CI: 0.413-0.998, p=0.049).

CONCLUSIONS

The MDCT-derived TA parameter was predictive of TR reduction after TAVR. Persistent TR after TAVR was associated with higher rates of rehospitalisation.

SARS-CoV-2 infection and recovery in children: Distinct T cell responses in MIS-C compared to COVID-19

SARS-CoV-2 infection for most children results in mild or minimal symptoms, though in rare cases severe disease can develop, including a multisystem inflammatory syndrome (MIS-C) with myocarditis. Here, we present longitudinal profiling of immune responses during acute disease and following recovery in children who developed MIS-C, relative to children who experienced more typical symptoms of COVID-19. T cells in acute MIS-C exhibited transient signatures of activation, inflammation, and tissue residency which correlated with cardiac disease severity, while T cells in acute COVID-19 upregulated markers of follicular helper T cells for promoting antibody production. The resultant memory immune response in recovery showed increased frequencies of virus-specific memory T cells with pro-inflammatory functions in children with prior MIS-C compared to COVID-19 while both cohorts generated comparable antibody responses. Together our results reveal distinct effector and memory T cell responses in pediatric SARS-CoV-2 infection delineated by clinical syndrome, and a potential role for tissue-derived T cells in the immune pathology of systemic disease.

Induction of bronchus-associated lymphoid tissue is an early life adaptation for promoting human B cell immunity

Infants and young children are more susceptible to common respiratory pathogens than adults but can fare better against novel pathogens like severe acute respiratory syndrome coronavirus 2. The mechanisms by which infants and young children mount effective immune responses to respiratory pathogens are unknown. Through investigation of lungs and lung-associated lymph nodes from infant and pediatric organ donors aged 0-13 years, we show that bronchus-associated lymphoid tissue (BALT), containing B cell follicles, CD4+ T cells and functionally active germinal centers, develop during infancy. BALT structures are prevalent around lung airways during the first 3 years of life, and their numbers decline through childhood coincident with the accumulation of memory T cells. Single-cell profiling and repertoire analysis reveals that early life lung B cells undergo differentiation, somatic hypermutation and immunoglobulin class switching and exhibit a more activated profile than lymph node B cells. Moreover, B cells in the lung and lung-associated lymph nodes generate biased antibody responses to multiple respiratory pathogens compared to circulating antibodies, which are mostly specific for vaccine antigens in the early years of life. Together, our findings provide evidence for BALT as an early life adaptation for mobilizing localized immune protection to the diverse respiratory challenges during this formative life stage.

[Feasibility and safety of transseptal transcatheter mitral valve replacement for severe mitral regurgitation]

A prospective, single-center, single-arm, and open-design study was performed to evaluate the feasibility and safety of transseptal transcatheter mitral valve replacement in the treatment of severe mitral regurgitation. Patients with symptomatic moderate-severe or severe mitral regurgitation at high-surgical risk and anatomically appropriate for the HighLife transseptal mitral valve replacement (TSMVR) system in West China Hospital, Sichuan University from December 2021 to August 2022 were enrolled. Four patients (1 male and 3 females) with severe mitral regurgitation were included, with a median age of 68.5 (64.0-77.0) years and a median Society of Thoracic Surgeons (STS) score of 8.1% (6.4%-8.9%). Technical success was achieved in all the patients. There was no residual mitral regurgitation, paravalvular leakage, or left ventricular outflow tract obstruction. Three major cardiovascular and cerebrovascular adverse events occurred within 30 days after the procedure, including ventricular tachycardia, iatrogenic atrial septal defect closure, and heart failure readmission. The current study preliminarily demonstrates that transcatheter mitral valve replacement using the HighLife system via the transseptal approach for severe mitral regurgitation is feasible and relatively safe.

Children with Multi-System Inflammatory Syndrome (MIS-C) develop functionally competent T cell memory against SARS-CoV-2 following recovery

While pediatric SARS-CoV-2 infection is largely spared from severe COVID-19, a small fraction of children develop a life-threatening condition known as MIS-C, which is associated with an aberrant peripheral blood immunophenotype; namely within adaptive immune cell populations. Little is known about how MIS-C impacts memory generation that would be imperative for future SARS-CoV-2 responses. Here, we used high dimensional flow cytometry and TCR sequencing to assess the peripheral blood T cell profile during acute MIS-C (n=17), following recovery (MIS-C-R) up to 9 months post-MIS-C (n=9), and relative to age-matched convalescent, mild pediatric COVID-19 (non-MIS-C; n=5) and uninfected controls (n=3). We also applied antigen-specific analyses to determine the magnitude and functional capacity of SARS-CoV-2-specific T cells in MIS-C-R (n=10) and non-MIS-C children (n=16). Flow cytometry showed unique T cell composition in MIS-C which resolved in recovery: lacking persistence of exhausted CD8+ T cells observed during MIS-C, and reestablishment of the naïve T cell pool. TCR sequencing showed decreased clonal diversity and distinct TCR Vβ usage in acute MIS-C compared to MIS-C-R. Results from antigen-specific analyses show that while T cell memory is similar phenotypically, MIS-C-R children have greater frequencies of SARS-CoV-2-specific CD4+ T cells than non-MIS-C up to 9 months since diagnosis. Meanwhile, SARS-CoV-2-specific CD8+ T cells in MIS-C children were more cytokine-producing, while more cytotoxic in non-MIS-C children. Together, these results reveal a restoration in global T cell phenotype in MIS-C-R children, as well as the robust production of functionally competent SARS-CoV-2 specific T cell memory.

This work is supported by grants from NIH (K23 AI141686, 3U01 AI100119-10S1)

Human T cells in barrier sites exhibit site-specific characteristics and clonal compartmentalization

The skin, gut, and lung are critical physical and immune barriers that protect from pathogen entry. Within these sites, T cell memory is largely maintained by populations of tissue resident memory T cells (TRMs), capable of rapid protective responses. The degree of interconnection between these TRMs from various sites of residence is poorly understood, particularly in humans. Here, we analyze how tissue specificity affects transcriptional heterogeneity and the T cell receptor (TCR) repertoire across 9 tissue sites within individual donors, including barrier sites (skin, gut, and lung) and associated lymph nodes, as well as blood and lymphoid organs (blood, bone marrow, spleen). Cytometry by time-of-flight (CyTOF) and single cell RNA sequencing reveal phenotypic and transcriptomic features unique to skin or gut T cells, which are distinct from T cells in lymphoid sites or blood. These results were reflected in both bulk sequencing of TRBV gene rearrangement and single cell TCR sequencing, where skin and gut T cells exhibited site-specific clonal expansions that were not present in other sites. Conversely, lung T cells showed clonal overlap and transcriptional similarity to T cells in lymphoid and blood rich sites. Site-specific expansions were mediated by TRMs, while clones disseminated across tissues exhibit large clonal expansions and a CD8 terminal effector (TEMRA) phenotype. Together, these results reveal that TRMs in barrier sites are maintained in situ, while memory T cells in the lung, blood-rich and lymphoid sites are more interconnected. Blood T cells are not representative of barrier T cell clonal space. These results have important implications for monitoring and promoting barrier immunity through site-specific targeting.

Supported by grants from NIH (P01 AI106697)

Aberrant methylation-mediated downregulation of the LINC01554 gene accelerates the malignant progression and regulates the chemosensitivity of laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) is diagnosed as a malignant tumor with a poor prognosis, the associated mechanisms still need to be further investigated. The LINC01554 gene is confirmed to participate in the tumorigenesis of hepatocellular carcinoma, but its role in LSCC has not been investigated. The aim of this study was to investigate the function and the potential mechanism of LINC01554 in LSCC, LINC01554 further was used as a molecular target for the diagnosis and molecular targeted therapy of LSCC. The microarray-based gene expression profiling of LSCC and its adjacent non-tumor tissue were used to identify the differentially expressed long non-coding RNAs (lncRNAs). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was applied to verify the expression levels of LINC01554 in tissue and LSCC cell lines. The DNA methylation level of the LINC01554 promoter was detected by the application of bisulfite genomic sequencing (BGS), and the bisulfite conversion-specific/methylation-specific polymerase chain reaction (BS-MSP) method. The effect of LINC01554 on the proliferation, migration, and invasion of squamous cell carcinoma was assessed by MTS, wound healing, transwell, RT-qPCR, Western blot in vitro-cultured TU177 cells, and AMC-HN-8 cells. The microarray-based gene expression profiling identified the differentially expressed lncRNAs, including LINC01554, with downregulation in the LSCC tissue vs. normal tissue. The RT-qPCR verified the downregulation of LINC01554 in the LSCC tissue (P=0.0049) and LSCC cell (P=0.0020). The BGS and BS-MSP exhibited the hypermethylation level of the LINC01554 promoter, which mediated the downregulation of LINC01554. A gain-of-function experiment showed that LINC01554 inhibited the proliferation, migration, and invasion of TU177 and AMC-HN-8. Subsequently, LINC01554 overexpression was shown to decrease cell viability in TU177 and AMC-HN-8 cells treated with cisplatin. Our findings indicated that the aberrant methylation-mediated downregulation of LINC01554 promoted malignant progression and cisplatin resistance in LSCC, and LINC01554 may serve as a potential diagnostic biomarker and a novel therapeutic target for LSCC.

[Preliminary clinical experience of the novel transcatheter aortic valve system Prizvalve® for the treatment of severe aortic stenosis]

Objective: To evaluate the safety and efficacy of transcatheter aortic valve implantation (TAVI) with the novel Prizvalve^® system in treating severe aortic stenosis. Methods: This is a single-center, prospective, single-arm, observational study. A total of 11 patients with severe aortic stenosis with high risk or inappropriate for conventional surgical aortic valve replacement (SAVR) were included, and TAVI was achieved with the Prizvalve^® system between March 2021 and May 2021 in West China Hospital. Transthoracic echocardiography (TTE) was performed immediately after prosthesis implantation to evaluate mean transaortic gradient and maximal transaortic velocity. The device success rate was calculated, which was defined as (1) the device being delivered via the access, deployed, implanted and withdrawn, (2) mean transaortic gradient<20 mmHg (1 mmHg=0.133 kPa) or a maximal transaortic velocity<3 m/s post TAVI, and without severe aortic regurgitation or paravalvular leak post TAVI. TTE was performed at 30 days after the surgery, and all-cause mortality as well as the major cardiovascular adverse events (including acute myocardial infarction, disabling hemorrhagic or ischemic stroke) up to 30 days post TAVI were analyzed. Results: The age of 11 included patients were (78.1±6.3) years, with 8 males. A total of 10 patients were with NYHA functional class Ⅲ or Ⅳ. Devices were delivered via the access, deployed, implanted and withdrawn successfully in all patients. Post-implant mean transaortic gradient was (7.55±4.08) mmHg and maximal transaortic velocity was (1.78±0.44) m/s, and both decreased significantly as compared to baseline levels (both P<0.05). No severe aortic regurgitation or paravalvular leak was observed post TAVI. Device success was achieved in all the 11 patients. No patient died or experienced major cardiovascular adverse events up to 30 days post TAVI. Mean transaortic gradient was (9.45±5.07) mmHg and maximal transaortic velocity was (2.05±0.42) m/s at 30 days post TAVI, which were similar as the values measured immediately post TAVI (both P>0.05). Conclusions: TAVI with the Prizvalve^® system is a feasible and relatively safe procedure for patients with severe aortic stenosis and at high risk or inappropriate for SAVR. Further clinical studies could be launched to obtain more clinical experience with Prizvalve^® system.

IgA Plasma Cells Are Long-Lived Residents of Gut and Bone Marrow That Express Isotype- and Tissue-Specific Gene Expression Patterns

Antibody secreting plasma cells are made in response to a variety of pathogenic and commensal microbes. While all plasma cells express a core gene transcription program that allows them to secrete large quantities of immunoglobulin, unique transcriptional profiles are linked to plasma cells expressing different antibody isotypes. IgA expressing plasma cells are generally thought of as short-lived in mucosal tissues and they have been understudied in systemic sites like the bone marrow. We find that IgA+ plasma cells in both the small intestine lamina propria and the bone marrow are long-lived and transcriptionally related compared to IgG and IgM expressing bone marrow plasma cells. IgA+ plasma cells show signs of shared clonality between the gut and bone marrow, but they do not recirculate at a significant rate and are found within bone marrow plasma cells niches. These data suggest that systemic and mucosal IgA+ plasma cells are from a common source, but they do not migrate between tissues. However, comparison of the plasma cells from the small intestine lamina propria to the bone marrow demonstrate a tissue specific gene transcription program. Understanding how these tissue specific gene networks are regulated in plasma cells could lead to increased understanding of the induction of mucosal versus systemic antibody responses and improve vaccine design.

Lipid nanoparticles enhance the efficacy of mRNA and protein subunit vaccines by inducing robust T follicular helper cell and humoral responses

Adjuvants are critical for improving the quality and magnitude of adaptive immune responses to vaccination. Lipid nanoparticle (LNP)-encapsulated nucleoside-modified mRNA vaccines have shown great efficacy against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but the mechanism of action of this vaccine platform is not well-characterized. Using influenza virus and SARS-CoV-2 mRNA and protein subunit vaccines, we demonstrated that our LNP formulation has intrinsic adjuvant activity that promotes induction of strong T follicular helper cell, germinal center B cell, long-lived plasma cell, and memory B cell responses that are associated with durable and protective antibodies in mice. Comparative experiments demonstrated that this LNP formulation outperformed a widely used MF59-like adjuvant, AddaVax. The adjuvant activity of the LNP relies on the ionizable lipid component and on IL-6 cytokine induction but not on MyD88- or MAVS-dependent sensing of LNPs. Our study identified LNPs as a versatile adjuvant that enhances the efficacy of traditional and next-generation vaccine platforms.

mRNA vaccines induce durable immune memory to SARS-CoV-2 and variants of concern

The durability of immune memory after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccination remains unclear. In this study, we longitudinally profiled vaccine responses in SARS-CoV-2–naïve and –recovered individuals for 6 months after vaccination. Antibodies declined from peak levels but remained detectable in most subjects at 6 months. By contrast, mRNA vaccines generated functional memory B cells that increased from 3 to 6 months postvaccination, with the majority of these cells cross-binding the Alpha, Beta, and Delta variants. mRNA vaccination further induced antigen-specific CD4+ and CD8+ T cells, and early CD4+ T cell responses correlated with long-term humoral immunity. Recall responses to vaccination in individuals with preexisting immunity primarily increased antibody levels without substantially altering antibody decay rates. Together, these findings demonstrate robust cellular immune memory to SARS-CoV-2 and its variants for at least 6 months after mRNA vaccination.

Heterogeneity of human anti-viral immunity shaped by virus, tissue, age, and sex

The persistence of anti-viral immunity is essential for protection and exhibits profound heterogeneity across individuals. Here, we elucidate the factors that shape maintenance and function of anti-viral T cell immunity in the body by comprehensive profiling of virus-specific T cells across blood, lymphoid organs, and mucosal tissues of organ donors. We use flow cytometry, T cell receptor sequencing, single-cell transcriptomics, and cytokine analysis to profile virus-specific CD8⁺ T cells recognizing the ubiquitous pathogens influenza and cytomegalovirus. Our results reveal that virus specificity determines overall magnitude, tissue distribution, differentiation, and clonal repertoire of virus-specific T cells. Age and sex influence T cell differentiation and dissemination in tissues, while T cell tissue residence and functionality are highly correlated with the site. Together, our results demonstrate how the covariates of virus, tissue, age, and sex impact the anti-viral immune response, which is important for targeting, monitoring, and predicting immune responses to existing and emerging viruses.

Malignant acanthosis nigricans and diseases with extensive oral papillary hyperplasia

Oral papillary lesions represent a variety of developmental and neoplastic conditions. Early diagnoses of different papillary lesions are challenging for oral medicine specialists. Malignant acanthosis nigricans (MAN) is a rare cutaneous disorder and a potential marker of underlying hidden tumours. It is characterized by papillary lesions that always involve the oral mucosa. In oral medicine specialities, MAN is not well understood. When the early signs of MAN are extensive oral lesions and slight cutaneous pigmentation without obvious florid cutaneous papillomatosis, the diagnosis can be incorrect or delayed. Oral medicine specialists should ask affected patients to provide details of their medical history and conduct a timely systemic examination.

Impact of nodular calcification on the outcomes of patients with acute coronary syndrome (ACS) treated with primary percutaneous coronary intervention (PCI)

Background

Calcified plaque is thought to adversely impact clinical outcomes but the impact of nodular calcification after percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS) remains unclear.

Purpose

This study sought to explore the impact of nodular calcification on the outcomes of patients undergoing percutaneous coronary intervention for acute coronary syndromes.

Methods

Five-hundred culprit plaque with calcification were analysed from 495 ACS patients in whom PCI was performed. Plaques were divided into nodular calcification group (n=238) and non-nodular calcification group (n=262). Calcification is defined as an area with low back-scattering signal and a sharp border. Nodular calcification was defined as a protruding mass with an irregular surface, high backscattering, and signal attenuation on optical coherence tomography (OCT).

Results

Patients with nodular calcification were older (p&lt;0.001) and had lower left ventricular ejection fraction (p=0.006) compared to patients with non-nodular calcification. Lesion length (31 (25.2, 38.5) vs. 29 (22.8, 34.1), p&lt;0.001) was longer in plaques with nodular calcification. A higher prevalence of superficial calcium (p&lt;0.001) was observed in plaques with nodular calcification compared with non-nodular calcification group. Minimum stent area (MSA) (5.0 (3.9, 6.3) vs. 5.4 (4.2, 6.7), p=0.011) and stent expansion (70 (62.7, 81.8) vs. 75 (65.2, 86.6), p=0.004) were significantly smaller in the nodular calcification group than in the non-nodular calcification group. Independent predictors of nodular calcification were age (p&lt;0.001) lesion length (p=0.002) and calcium depth (p&lt;0.001).

Conclusion

This study demonstrated that the presence of nodular calcification is associated with unfavourable outcomes with smaller minimum stent area and higher incidence of stent under expansion in patients with ACS treated with primary PCI.

Funding Acknowledgement

Type of funding sources: None.

Gender-specific difference of clinical and plaque characteristics in myocardial infarction with non-obstructive artery (MINOCA): insights from optical coherence tomography

Background

To date, sparse data are available with regard to gender differences in coronary plaque morphology and composition as underlying mechanism of MINOCA.

Purpose

To assess the differences in coronary plaque morphology in culprit lesion between women and men with MINOCA using intravascular optical coherence tomography.

Methods

Totally, 7404 consecutives acute myocardial infarction patients who underwent emergency coronary angiography between 2016 and 2019 were screened. MINOCA were identified in 292 patients (mean age: 72.6% male, 54.1% with ST-segment elevation). Optical coherence tomography was performed in 190 patients (men, n=142).

Results

Women with MINOCA were older (62.5±10.6 vs. 54.0±11.5, P&lt;0.001) and more over 55 years (75.3% vs. 43.6%, P&lt;0.001). Although women with MINOCA more frequently presented with NSTEMI (56.8% vs. 41.7%, P=0.025) and prior coronary artery disease (CAD) (33.3% vs. 6.3%, P&lt;0.001), they were less likely smoker (27.2% vs. 58.8%, P&lt;0.001). There was no significant difference in incidence of plaque rupture, erosion and calcified nodule between men and women. However, women were more likely to have thin-cap fibroatheroma (TCFA) (39.6% vs. 22.5%, P=0.025).

Conclusion

Women with MINOCA were older, more frequently presented with NSTEMI and less smoking compared to men. Besides, more TCFA were observed in women.

Funding Acknowledgement

Type of funding sources: None. Clinical and OCT plaque profilesProportion of clinical and OCT profiles

Sulforaphane overcomes T790M-mediated gefitinib resistance in vitro through epithelial-mesenchymal transition

The purpose of the present study was to investigate the effects of sulforaphane (SFN) on gefitinib-resistant cell lines with a T790 mutation (PC-9/AB11). The PC-9 and PC-9/AB11 cells were stained with H&E and visualized with a light microscope. The CCK-8 assay method was used to evaluate the antiproliferative activity of gefitinib and SFN on the cells. Cell cycle arrest and apoptosis were analyzed via flow cytometry. The cytotoxic interaction between the two drugs was evaluated in vitro using the combination index method, and epithelial-mesenchymal transition (EMT)-related proteins and alterations in the signaling pathways were determined by Western blot analysis. Compared to the PC-9 cells, the gefitinib-resistant PC-9/AB11 cells acquired a T790M mutation and had characteristics in accordance with EMT. The combination of gefitinib and SFN induced dose-dependent antiproliferative effects in the PC-9 and PC-9/AB11 cells, while both induced cell cycle arrest and cell apoptosis only in the PC-9/AB11 cells. The synergistic effect in the PC-9/AB11 cells was associated with this drug combination, as it caused an expression change of the epithelial (E-cadherin, claudin-1) and matrix proteins (vimentin, N-cadherin) in the cells, related to the reversal of EMT, as well as an expression change of the epidermal growth factor receptor (EGFR), p-EGFR, p-AKT, and p-ERK proteins. In this study, SFN overcame T790M-mediated gefitinib resistance in vitro through EMT. Thus, a combination of gefitinib and SFN may be a beneficial treatment strategy for lung cancer patients with acquired resistance due to T790M mutation.

Prospective evaluation of first-trimester screening strategy for preterm pre-eclampsia and its clinical applicability in China

OBJECTIVES

To evaluate, in a Chinese population, the performance of a screening strategy for preterm pre-eclampsia (PE) using The Fetal Medicine Foundation (FMF)'s competing-risks model and to explore its clinical applicability in mainland China.

METHODS

This was a prospective, multicenter, observational cohort study including 10 899 women with singleton pregnancy who sought prenatal care at one of 13 hospitals, located in seven cities in mainland China, between 1 December 2017 and 30 December 2019. Mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and maternal serum levels of placental growth factor (PlGF) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 to 13 + 6 weeks' gestation were measured and converted into multiples of the median using Chinese reference ranges. Individualized risk for preterm PE was calculated using the FMF algorithm. Prior risk was calculated based on maternal demographic characteristics and obstetric history. We evaluated the efficiency of the screening strategy using various combinations of biomarkers and analyzed its predictive performance for a composite of placenta-associated adverse pregnancy outcomes, including PE, placental abruption, small-for-gestational age (SGA) and preterm birth, at fixed false-positive rates for preterm PE.

RESULTS

We identified 312 pregnancies that developed PE, of which 117 cases were diagnosed as preterm PE (< 37 weeks' gestation). There were 386 pregnancies complicated by severe composite placenta-associated adverse outcome, including preterm PE, 146 cases of severe SGA (birth weight < 3^rd percentile) neonate, 61 cases with placental abruption and 109 cases of early preterm birth < 34 gestational weeks. The triple-marker model containing biomarkers MAP, UtA-PI and PAPP-A achieved, at fixed false-positive rates of 10%, 15% and 20%, detection rates for preterm PE of 65.0%, 72.7% and 76.1%, respectively, and detection rates for severe composite placenta-associated adverse outcome of 34.7%, 41.7% and 46.4%, respectively. Replacing PAPP-A with PlGF or adding PlGF to the model did not improve the performance. Of women screening positive for preterm PE at a fixed 5% false-positive rate, an estimated 30% developed at least one placenta-associated adverse pregnancy outcome, including PE, placental abruption, SGA (birth weight < 10^th percentile) and preterm birth < 37 weeks.

CONCLUSIONS

The FMF competing-risks model for preterm PE was found to be effective in screening a mainland Chinese population. Women who screened positive for preterm PE had increased risk for other placenta-associated pregnancy complications. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

New-onset IgG autoantibodies in hospitalized patients with COVID-19

COVID-19 is associated with a wide range of clinical manifestations, including autoimmune features and autoantibody production. Here we develop three protein arrays to measure IgG autoantibodies associated with connective tissue diseases, anti-cytokine antibodies, and anti-viral antibody responses in serum from 147 hospitalized COVID-19 patients. Autoantibodies are identified in approximately 50% of patients but in less than 15% of healthy controls. When present, autoantibodies largely target autoantigens associated with rare disorders such as myositis, systemic sclerosis and overlap syndromes. A subset of autoantibodies targeting traditional autoantigens or cytokines develop de novo following SARS-CoV-2 infection. Autoantibodies track with longitudinal development of IgG antibodies recognizing SARS-CoV-2 structural proteins and a subset of non-structural proteins, but not proteins from influenza, seasonal coronaviruses or other pathogenic viruses. We conclude that SARS-CoV-2 causes development of new-onset IgG autoantibodies in a significant proportion of hospitalized COVID-19 patients and are positively correlated with immune responses to SARS-CoV-2 proteins.

mRNA Vaccination Induces Durable Immune Memory to SARS-CoV-2 with Continued Evolution to Variants of Concern

SARS-CoV-2 mRNA vaccines have shown remarkable efficacy, especially in preventing severe illness and hospitalization. However, the emergence of several variants of concern and reports of declining antibody levels have raised uncertainty about the durability of immune memory following vaccination. In this study, we longitudinally profiled both antibody and cellular immune responses in SARS-CoV-2 naïve and recovered individuals from pre-vaccine baseline to 6 months post-mRNA vaccination. Antibody and neutralizing titers decayed from peak levels but remained detectable in all subjects at 6 months post-vaccination. Functional memory B cell responses, including those specific for the receptor binding domain (RBD) of the Alpha (B.1.1.7), Beta (B.1.351), and Delta (B.1.617.2) variants, were also efficiently generated by mRNA vaccination and continued to increase in frequency between 3 and 6 months post-vaccination. Notably, most memory B cells induced by mRNA vaccines were capable of cross-binding variants of concern, and B cell receptor sequencing revealed significantly more hypermutation in these RBD variant-binding clones compared to clones that exclusively bound wild-type RBD. Moreover, the percent of variant cross-binding memory B cells was higher in vaccinees than individuals who recovered from mild COVID-19. mRNA vaccination also generated antigen-specific CD8+ T cells and durable memory CD4+ T cells in most individuals, with early CD4+ T cell responses correlating with humoral immunity at later timepoints. These findings demonstrate robust, multi-component humoral and cellular immune memory to SARS-CoV-2 and current variants of concern for at least 6 months after mRNA vaccination. Finally, we observed that boosting of pre-existing immunity with mRNA vaccination in SARS-CoV-2 recovered individuals primarily increased antibody responses in the short-term without significantly altering antibody decay rates or long-term B and T cell memory. Together, this study provides insights into the generation and evolution of vaccine-induced immunity to SARS-CoV-2, including variants of concern, and has implications for future booster strategies.

TCR+/BCR+ dual-expressing cells and their associated public BCR clonotype are not enriched in type 1 diabetes

Ahmed and colleagues recently described a novel hybrid lymphocyte expressing both a B and T cell receptor, termed double expresser (DE) cells. DE cells in blood of type 1 diabetes (T1D) subjects were present at increased numbers and enriched for a public B cell clonotype. Here, we attempted to reproduce these findings. While we could identify DE cells by flow cytometry, we found no association between DE cell frequency and T1D status. We were unable to identify the reported public B cell clone, or any similar clone, in bulk B cells or sorted DE cells from T1D subjects or controls. We also did not observe increased usage of the public clone VH or DH genes in B cells or in sorted DE cells. Taken together, our findings suggest that DE cells and their alleged public clonotype are not enriched in T1D. This Matters Arising paper is in response to Ahmed et al. (2019), published in Cell. See also the response by Ahmed et al. (2021), published in this issue.

Altered function and differentiation of age-associated B cells contribute to the female bias in lupus mice

Differences in immune responses to viruses and autoimmune diseases such as systemic lupus erythematosus (SLE) can show sexual dimorphism. Age-associated B cells (ABC) are a population of CD11c+T-bet+ B cells critical for antiviral responses and autoimmune disorders. Absence of DEF6 and SWAP-70, two homologous guanine exchange factors, in double-knock-out (DKO) mice leads to a lupus-like syndrome in females marked by accumulation of ABCs. Here we demonstrate that DKO ABCs show sex-specific differences in cell number, upregulation of an ISG signature, and further differentiation. DKO ABCs undergo oligoclonal expansion and differentiate into both CD11c+ and CD11c- effector B cell populations with pathogenic and pro-inflammatory function as demonstrated by BCR sequencing and fate-mapping experiments. Tlr7 duplication in DKO males overrides the sex-bias and further augments the dissemination and pathogenicity of ABCs, resulting in severe pulmonary inflammation and early mortality. Thus, sexual dimorphism shapes the expansion, function and differentiation of ABCs that accompanies TLR7-driven immunopathogenesis.

Maintenance of the human memory T cell repertoire by subset and tissue site

BACKGROUND

Immune-mediated protection is mediated by T cells expressing pathogen-specific T cell antigen receptors (TCR) that are maintained at diverse sites of infection as tissue-resident memory T cells (TRM) or that disseminate as circulating effector-memory (TEM), central memory (TCM), or terminal effector (TEMRA) subsets in blood and tissues. The relationship between circulating and tissue resident T cell subsets in humans remains elusive, and is important for promoting site-specific protective immunity.

METHODS

We analyzed the TCR repertoire of the major memory CD4+ and CD8+T cell subsets (TEM, TCM, TEMRA, and TRM) isolated from blood and/or lymphoid organs (spleen, lymph nodes, bone marrow) and lungs of nine organ donors, and blood of three living individuals spanning five decades of life. High-throughput sequencing of the variable (V) portion of individual TCR genes for each subset, tissue, and individual were analyzed for clonal diversity, expansion and overlap between lineage, T cell subsets, and anatomic sites. TCR repertoires were further analyzed for TRBV gene usage and CDR3 edit distance.

RESULTS

Across blood, lymphoid organs, and lungs, human memory, and effector CD8+T cells exhibit greater clonal expansion and distinct TRBV usage compared to CD4+T cell subsets. Extensive sharing of clones between tissues was observed for CD8+T cells; large clones specific to TEMRA cells were present in all sites, while TEM cells contained clones shared between sites and with TRM. For CD4+T cells, TEM clones exhibited the most sharing between sites, followed by TRM, while TCM clones were diverse with minimal sharing between sites and subsets. Within sites, TRM clones exhibited tissue-specific expansions, and maintained clonal diversity with age, compared to age-associated clonal expansions in circulating memory subsets. Edit distance analysis revealed tissue-specific biases in clonal similarity.

CONCLUSIONS

Our results show that the human memory T cell repertoire comprises clones which persist across sites and subsets, along with clones that are more restricted to certain subsets and/or tissue sites. We also provide evidence that the tissue plays a key role in maintaining memory T cells over age, bolstering the rationale for site-specific targeting of memory reservoirs in vaccines and immunotherapies.

IgV somatic mutation of human anti-SARS-CoV-2 monoclonal antibodies governs neutralization and breadth of reactivity

Abs that neutralize SARS-CoV-2 are thought to provide the most immediate and effective treatment for those severely afflicted by this virus. Because coronavirus potentially diversifies by mutation, broadly neutralizing Abs are especially sought. Here, we report a possibly novel approach to rapid generation of potent broadly neutralizing human anti-SARS-CoV-2 Abs. We isolated SARS-CoV-2 spike protein-specific memory B cells by panning from the blood of convalescent subjects after infection with SARS-CoV-2 and sequenced and expressed Ig genes from individual B cells as human mAbs. All of 43 human mAbs generated in this way neutralized SARS-CoV-2. Eighteen of the forty-three human mAbs exhibited half-maximal inhibitory concentrations (IC50) of 6.7 × 10-12 M to 6.7 × 10-15 M for spike-pseudotyped virus. Seven of the human mAbs also neutralized (with IC50 < 6.7 × 10-12 M) viruses pseudotyped with mutant spike proteins (including receptor-binding domain mutants and the S1 C-terminal D614G mutant). Neutralization of the Wuhan Hu-1 founder strain and of some variants decreased when coding sequences were reverted to germline, suggesting that potency of neutralization was acquired by somatic hypermutation and selection of B cells. These results indicate that infection with SARS-CoV-2 evokes high-affinity B cell responses, some products of which are broadly neutralizing and others highly strain specific. We also identify variants that would potentially resist immunity evoked by infection with the Wuhan Hu-1 founder strain or by vaccines developed with products of that strain, suggesting evolutionary courses that SARS-CoV-2 could take.

Characterization of Plasmacytoid Dendritic Cells, Microbial Sequences, and Identification of a Candidate Public T-Cell Clone in Kikuchi-Fujimoto Disease

OBJECTIVES

Kikuchi-Fujimoto disease (KFD) is a self-limited lymphadenitis of unclear etiology. We aimed to further characterize this disease in pediatric patients, including evaluation of the CD123 immunohistochemical (IHC) staining and investigation of potential immunologic and infectious causes.

METHODS

Seventeen KFD cases and 12 controls were retrospectively identified, and the histologic and clinical features were evaluated. CD123 IHC staining was quantified by digital image analysis. Next generation sequencing was employed for comparative microbial analysis via RNAseq (5 KFD cases) and to evaluate the immune repertoire (9 KFD cases).

RESULTS

In cases of lymphadenitis with necrosis, >0.85% CD123+ cells by IHC was found to be six times more likely in cases with a final diagnosis of KFD (sensitivity 75%, specificity 87.5%). RNAseq based comparative microbial analysis did not detect novel or known pathogen sequences in KFD. A shared complementarity determining region 3 (CDR3) sequence and use of the same T-cell receptor beta variable region family was identified in KFD LNs but not controls, and was not identified in available databases.

CONCLUSIONS

Digital quantification of CD123 IHC can distinguish KFD from other necrotizing lymphadenitides. The presence of a unique shared CDR3 sequence suggests that a shared antigen underlies KFD pathogenesis.

Tissue localization and virus specificity shape the maintenance and function of human virus-specific memory T cells recognizing HCMV and influenza A

Generation and maintenance of memory T cells within tissue sites of infection is critical for long-term antiviral protection. Current knowledge of human antiviral responses is largely derived from studies sampling peripheral blood. Yet, little is known about human tissue-localized antiviral immunity. Utilizing our human donor tissue resource established in collaboration with LiveOnNY, we investigated how tissue, virus, and age shape T cell maintenance across diverse tissues and their function when presented with antigens derived from human cytomegalovirus (HCMV) or influenza A virus (flu). Using flow cytometry, we show that virus-specific CD8 T cells are maintained in diverse tissues with subset differentiation and distribution shaped by virus specificity and age. Compared to T cells recognizing HCMV, flu-specific T cells display higher levels of residency markers—CD69 and CD103—particularly in adult compared to pediatric donors. In contrast, HCMV-specific T cells are maintained in greater abundance as terminally-differentiated effector T cells. Sequencing of the T cell receptor CDR3b chain reveals that, while both HCMV- and flu-specific T cells demonstrate clonal overlap across multiple tissues, HCMV-specific T cells display greater clonality and less diversity. When presented with viral antigens, HCMV- and flu-specific T cells are polyfunctional. Additionally, single-cell transcriptome profiling reveals tissue localization is the primary determinant of antigen-driven responses. Together, these studies demonstrate the dynamics of T cell differentiation and maintenance throughout the human body, which is primarily driven by virus specificity, and the role of tissue localization in shaping antiviral response.

Lymphohematopoietic graft-versus-host responses promote mixed chimerism in patients receiving intestinal transplantation

In humans receiving intestinal transplantation (ITx), long-term multilineage blood chimerism often develops. Donor T cell macrochimerism (≥4%) frequently occurs without graft-versus-host disease (GVHD) and is associated with reduced rejection. Here we demonstrate that patients with macrochimerism had high graft-versus-host (GvH) to host-versus-graft (HvG) T cell clonal ratios in their allografts. These GvH clones entered the circulation, where their peak levels were associated with declines in HvG clones early after transplant, suggesting that GvH reactions may contribute to chimerism and control HvG responses without causing GVHD. Consistently, donor-derived T cells, including GvH clones, and CD34+ hematopoietic stem and progenitor cells (HSPCs) were simultaneously detected in the recipients' BM more than 100 days after transplant. Individual GvH clones appeared in ileal mucosa or PBMCs before detection in recipient BM, consistent with an intestinal mucosal origin, where donor GvH-reactive T cells expanded early upon entry of recipient APCs into the graft. These results, combined with cytotoxic single-cell transcriptional profiles of donor T cells in recipient BM, suggest that tissue-resident GvH-reactive donor T cells migrated into the recipient circulation and BM, where they destroyed recipient hematopoietic cells through cytolytic effector functions and promoted engraftment of graft-derived HSPCs that maintain chimerism. These mechanisms suggest an approach to achieving intestinal allograft tolerance.

Distinct antibody and memory B cell responses in SARS-CoV-2 naïve and recovered individuals following mRNA vaccination

Novel mRNA vaccines for SARS-CoV-2 have been authorized for emergency use. Despite their efficacy in clinical trials, data on mRNA vaccine-induced immune responses are mostly limited to serological analyses. Here, we interrogated antibody and antigen-specific memory B cells over time in 33 SARS-CoV-2 naïve and 11 SARS-CoV-2 recovered subjects. SARS-CoV-2 naïve individuals required both vaccine doses for optimal increases in antibodies, particularly for neutralizing titers against the B.1.351 variant. Memory B cells specific for full-length spike protein and the spike receptor binding domain (RBD) were also efficiently primed by mRNA vaccination and detectable in all SARS-CoV-2 naive subjects after the second vaccine dose, though the memory B cell response declined slightly with age. In SARS-CoV-2 recovered individuals, antibody and memory B cell responses were significantly boosted after the first vaccine dose; however, there was no increase in circulating antibodies, neutralizing titers, or antigen-specific memory B cells after the second dose. This robust boosting after the first vaccine dose strongly correlated with levels of pre-existing memory B cells in recovered individuals, identifying a key role for memory B cells in mounting recall responses to SARS-CoV-2 antigens. Together, our data demonstrated robust serological and cellular priming by mRNA vaccines and revealed distinct responses based on prior SARS-CoV-2 exposure, whereby COVID-19 recovered subjects may only require a single vaccine dose to achieve peak antibody and memory B cell responses. These findings also highlight the utility of defining cellular responses in addition to serologies and may inform SARS-CoV-2 vaccine distribution in a resource-limited setting.

Enhanced removal of Congo red dye from aqueous solution by surface modified activated carbon with bacteria

AIMS

The adsorption behaviour and mechanisms of the surface modified activated carbon with bacteria was evaluated.

METHODS AND RESULTS

16S rRNA was employed to identify the hydrocarbon-degrading bacteria. The bacteria was characterized by TEM and electron microscope. The surface modified activated carbon with bacteria was characterized by SEM. The adsorption behaviour was tested by static adsorption and dynamic adsorption.

CONCLUSION

The adsorption efficiency of the modified activated carbon was high when pH was weak acidic, and the adsorption capacity increased with the increase of temperature ranging from 20 to 35°C. The adsorption capacity peaked at 234·6 mg g^-1 at 25°C, which was sixfold higher than that of activated carbon. The pseudo-first-order kinetic can more accurately assess Congo red adsorption on the two adsorbents. The adsorption of Congo red by bacteria surface modified activated carbon fitted well with the Langmuir's model. The adsorption process was endothermic, and the biological floccules were formed during the adsorption. The physical adsorption is the main driving force.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results indicate that the bacteria surface-modified activated carbon can be used effectively as an adsorbent to eliminate Congo red from aqueous solutions.

Longitudinal Analysis Reveals Distinct Antibody and Memory B Cell Responses in SARS-CoV2 Naïve and Recovered Individuals Following mRNA Vaccination

Novel mRNA vaccines for SARS-CoV2 have been authorized for emergency use and are currently being administered to millions of individuals worldwide. Despite their efficacy in clinical trials, there is limited data on vaccine-induced immune responses in individuals with a prior SARS-CoV2 infection compared to SARS-CoV2 naïve subjects. Moreover, how mRNA vaccines impact the development of antibodies as well as memory B cells in COVID-19 experienced versus COVID-19 naïve subjects remains poorly understood. In this study, we evaluated antibody responses and antigen-specific memory B cell responses over time in 33 SARS-CoV2 naïve and 11 SARS-CoV2 recovered subjects. mRNA vaccination induced significant antibody and memory B cell responses against full-length SARS-CoV2 spike protein and the spike receptor binding domain (RBD). SARS-CoV2 naïve individuals benefitted from both doses of mRNA vaccine with additional increases in antibodies and memory B cells following booster immunization. In contrast, SARS-CoV2 recovered individuals had a significant immune response after the first dose with no increase in circulating antibodies or antigen-specific memory B cells after the second dose. Moreover, the magnitude of the memory B cell response induced by vaccination was lower in older individuals, revealing an age-dependence to mRNA vaccine-induced B cell memory. Side effects also tended to associate with post-boost antibody levels, but not with post-boost memory B cells, suggesting that side effect severity may be a surrogate of short-term antibody responses. The frequency of pre-vaccine antigen-specific memory B cells in SARS-CoV2 recovered individuals strongly correlated with post-vaccine antibody levels, supporting a key role for memory B cells in humoral recall responses to SARS-CoV2. This observation may have relevance for future booster vaccines and for responses to viral variants that partially escape pre-existing antibodies and require new humoral responses to be generated from memory B cells. Finally, post-boost antibody levels were not correlated with post-boost memory responses in SARS-CoV2 naïve individuals, indicating that short-term antibody levels and memory B cells are complementary immunological endpoints that should be examined in tandem when evaluating vaccine response. Together, our data provide evidence of both serological response and immunological memory following mRNA vaccination that is distinct based on prior SARS-CoV2 exposure. These findings may inform vaccine distribution in a resource-limited setting.

New-Onset IgG Autoantibodies in Hospitalized Patients with COVID-19

Coronavirus Disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), is associated with a wide range of clinical manifestations, including autoimmune features and autoantibody production. We developed three different protein arrays to measure hallmark IgG autoantibodies associated with Connective Tissue Diseases (CTDs), Anti-Cytokine Antibodies (ACA), and anti-viral antibody responses in 147 hospitalized COVID-19 patients in three different centers. Autoantibodies were identified in approximately 50% of patients, but in <15% of healthy controls. When present, autoantibodies largely targeted autoantigens associated with rare disorders such as myositis, systemic sclerosis and CTD overlap syndromes. Anti-nuclear antibodies (ANA) were observed in ∼25% of patients. Patients with autoantibodies tended to demonstrate one or a few specificities whereas ACA were even more prevalent, and patients often had antibodies to multiple cytokines. Rare patients were identified with IgG antibodies against angiotensin converting enzyme-2 (ACE-2). A subset of autoantibodies and ACA developed de novo following SARS-CoV-2 infection while others were transient. Autoantibodies tracked with longitudinal development of IgG antibodies that recognized SARS-CoV-2 structural proteins such as S1, S2, M, N and a subset of non-structural proteins, but not proteins from influenza, seasonal coronaviruses or other pathogenic viruses. COVID-19 patients with one or more autoantibodies tended to have higher levels of antibodies against SARS-CoV-2 Nonstructural Protein 1 (NSP1) and Methyltransferase (ME). We conclude that SARS-CoV-2 causes development of new-onset IgG autoantibodies in a significant proportion of hospitalized COVID-19 patients and are positively correlated with immune responses to SARS-CoV-2 proteins.

Impact of macrophage infiltration in patients with st-segment elevation myocardial infarction caused by plaque erosion: an in vivo optical coherence tomography study

Background

Chronic inflammatory infiltration is a common process for atherosclerosis development. However, autopsy studies reveal that incidence rate of inflammatory infiltrates are less abundant in plaque erosion compared with plaque rupture.

Purpose

Studies performed by optical coherence tomography (OCT) have allowed to establish the severity of plaque inflammation by assessing macrophage infiltration (MØI). In this study, we aimed at assessing the impaction of MØI in plaque erosion among patients with STEMI by using OCT.

Methods

A total of 1561 patients with ST-segment elevation myocardial infarctions (STEMI) who underwent OCT imaging were enrolled in this study. According to the exclusion criteria, 312 patients with STEMI exhibiting plaque erosion were classified as MØI or no MØI.

Results

163 (52.2%) patients had MØI at the site of plaque erosion, whereas 149 (47.8%) patients had no evidence of MØI and patients of MØI group were significantly older (P=0.015). The result of angiography showed the prevalence of multi-vessel disease appeared more frequency (P=0.021) and diameter stenosis% were higher (P=0.031) in MØI group. OCT results showed the minimum fibrous-cap thickness was thinner (P&lt;0.001) and the maximum lipid arc was larger (P=0.005) in MØI group. Some patients underwent imaging follow-up at 1 year. There was no significant difference in the culprit plaque morphology progress among two groups (Figure 1A-1D).

Conclusions

This study demonstrated that plaque inflammation can increase culprit lesion severity and plaque vulnerability in patients with STEMI caused by plaque erosion.

Figure 1

Funding Acknowledgement

Type of funding source: None

Mining the Antibody Repertoire for Solutions to SARS-CoV-2

In this issue of Cell Host & Microbe, Nielsen and colleagues sequence antibody repertoires of patients with severe COVID-19 to reveal potentially convergent features on the background of a larger, polyclonal response. Their findings suggest that, as databases improve, it may be possible to monitor virus-specific B cells after infection or vaccination using antibody sequencing.

Comprehensive mapping of immune perturbations associated with severe COVID-19

Although critical illness has been associated with SARS-CoV-2-induced hyperinflammation, the immune correlates of severe COVID-19 remain unclear. Here, we comprehensively analyzed peripheral blood immune perturbations in 42 SARS-CoV-2 infected and recovered individuals. We identified extensive induction and activation of multiple immune lineages, including T cell activation, oligoclonal plasmablast expansion, and Fc and trafficking receptor modulation on innate lymphocytes and granulocytes, that distinguished severe COVID-19 cases from healthy donors or SARS-CoV-2-recovered or moderate severity patients. We found the neutrophil to lymphocyte ratio to be a prognostic biomarker of disease severity and organ failure. Our findings demonstrate broad innate and adaptive leukocyte perturbations that distinguish dysregulated host responses in severe SARS-CoV-2 infection and warrant therapeutic investigation.

Immunologic perturbations in severe COVID-19/SARS-CoV-2 infection

Although critical illness has been associated with SARS-CoV-2-induced hyperinflammation, the immune correlates of severe COVID-19 remain unclear. Here, we comprehensively analyzed peripheral blood immune perturbations in 42 SARS-CoV-2 infected and recovered individuals. We identified broad changes in neutrophils, NK cells, and monocytes during severe COVID-19, suggesting excessive mobilization of innate lineages. We found marked activation within T and B cells, highly oligoclonal B cell populations, profound plasmablast expansion, and SARS-CoV-2-specific antibodies in many, but not all, severe COVID-19 cases. Despite this heterogeneity, we found selective clustering of severe COVID-19 cases through unbiased analysis of the aggregated immunological phenotypes. Our findings demonstrate broad immune perturbations spanning both innate and adaptive leukocytes that distinguish dysregulated host responses in severe SARS-CoV-2 infection and warrant therapeutic investigation.

One Sentence Summary

Broad immune perturbations in severe COVID-19.

Human influenza A-specific memory T cells reside within multiple tissues and elicit a tissue-specific antiviral response when presented with viral antigens

Generation of memory T cells specific for conserved viral epitopes provides heterosubtypic protection to influenza infection. Previous mouse studies have shown that tissue-resident memory T cells (TRM) are critical for optimal protection. However, knowledge of human antiviral response is largely derived from blood. With our unique human donor tissue resource established in collaboration with LiveOnNY, we investigate the maintenance of influenza-specific T cells across diverse tissue sites and their response when presented with viral antigens. Using multimer staining and flow cytometry, we show that influenza-specific CD8 T cells are maintained in the lung tissue site of infection, as well as in blood, bone marrow, multiple lymph nodes, and small intestines. Compared to T cells recognizing persistent cytomegalovirus infection, influenza-specific T cells display higher levels of canonical residency markers—CD69 and CD103. Additionally, deep sequencing of the T cell receptor CDR3b repertoire reveals that influenza-specific T cells isolated from human tissue donors without active infection are clonally expanded and display a high degree of clonal overlap across tissue sites. When presented with viral antigens, influenza-specific T cells in all sites are polyfunctional and rapidly respond through cytokine production. Together, these studies reveal the dynamics of immune memory maintenance and antiviral response across tissues in the human body in response to influenza A virus.

Human T cell immunity in barrier sites is phenotypically distinct but clonally connected to other sites

The gut, lung, and skin are physical and immunological barriers that serve as the first line of defense against pathogens and foreign substances. Due to sampling limitations, previous studies have been limited to studying human barrier sites in isolation and often in the context of specific diseases. Our donor tissue resource established in collaboration with LiveOnNY offers a unique opportunity to examine human barrier T cell immunity as a network and elucidate how barrier sites are connected to each other and to lymphoid sites (lymph nodes, bone marrow, spleen). Here, using cytometry by time-of-flight (CyTOF) and T cell receptor (TCR) CDR3b sequencing, we investigate the unique defining characteristics and connectivity of T cells in barrier tissue – gut, lung, and skin – to lymphoid sites and blood. Through high-dimensional marker analysis by CyTOF, our results show that T cell subset composition and phenotype across 8 different sites comprise 33 clusters that are highly conserved between donors of different ages (22–70 yrs). Skin and gut T cells are distinct from each other and from lung, lymphoid sites, and blood, while lung T cells share features with lymphoid sites and blood. TCR repertoire analysis shows that, though majority of gut and skin T cell clones are unique to the tissue, expanded clones within these barrier sites share clonal overlap with other barrier and lymphoid sites. Moreover, T cells in the lung exhibit increased sharing with lymphoid sites and blood. Together, these results reveal how human T cells are compartmentalized in the skin and gut through site-specific adaptations while demonstrating that gut, lung, and skin barrier T cells are connected through shared specificities in a network of immune protection across the body.

The Transcription Factor T-bet Resolves Memory B Cell Subsets with Distinct Tissue Distributions and Antibody Specificities in Mice and Humans

B cell subsets expressing the transcription factor T-bet are associated with humoral immune responses and autoimmunity. Here, we examined the anatomic distribution, clonal relationships, and functional properties of T-bet⁺ and T-bet^- memory B cells (MBCs) in the context of the influenza-specific immune response. In mice, both T-bet^- and T-bet⁺ hemagglutinin (HA)-specific B cells arose in germinal centers, acquired memory B cell markers, and persisted indefinitely. Lineage tracing and IgH repertoire analyses revealed minimal interconversion between T-bet^- and T-bet⁺ MBCs, and parabionts showed differential tissue residency and recirculation properties. T-bet⁺ MBCs could be subdivided into recirculating T-bet^lo MBCs and spleen-resident T-bet^hi MBCs. Human MBCs displayed similar features. Conditional gene deletion studies revealed that T-bet expression in B cells was required for nearly all HA stalk-specific IgG2c antibodies and for durable neutralizing titers to influenza. Thus, T-bet expression distinguishes MBC subsets that have profoundly different homing, residency, and functional properties, and mediate distinct aspects of humoral immune memory.