Programme of self-reactive innate-like T cell-mediated cancer immunity.

Cellular transformation induces phenotypically diverse populations of tumour-infiltrating T cells1-5, and immune checkpoint blockade therapies preferentially target T cells that recognize cancer cell neoantigens6,7. Yet, how other classes of tumour-infiltrating T cells contribute to cancer immunosurveillance remains elusive. Here, in a survey of T cells in mouse and human malignancies, we identified a population of αß T cell receptor (TCR)-positive FCER1G-expressing innate-like T cells with high cytotoxic potential8 (ILTCKs). These cells were broadly reactive to unmutated self-antigens, arose from distinct thymic progenitors following early encounter with cognate antigens, and were continuously replenished by thymic progenitors during tumour progression. Notably, expansion and effector differentiation of intratumoural ILTCKs depended on interleukin-15 (IL-15) expression in cancer cells, and inducible activation of IL-15 signalling in adoptively transferred ILTCK progenitors suppressed tumour growth. Thus, the antigen receptor self-reactivity, unique ontogeny, and distinct cancer cell-sensing mechanism distinguish ILTCKs from conventional cytotoxic T cells, and define a new class of tumour-elicited immune response.

Multi-omics study reveals different pathogenesis of the generation of skin lesions in SLE and IDLE patients.

Lupus erythematosus (LE) is a heterogeneous, antibody-mediated autoimmune disease. Isolate discoid LE (IDLE) and systematic LE (SLE) are traditionally regarded as the two ends of the spectrum, ranging from skin-limited damage to life-threatening multi-organ involvement. Both belong to LE, but IDLE and SLE differ in appearance of skin lesions, autoantibody panels, pathological changes, treatments, and immunopathogenesis. Is discoid lupus truly a form of LE or is it a completely separate entity? This question has not been fully elucidated. We compared the clinical data of IDLE and SLE from our center, applied multi-omics technology, such as immune repertoire sequencing, high-resolution HLA alleles sequencing and multi-spectrum pathological system to explore cellular and molecular phenotypes in skin and peripheral blood from LE patients. Based on the data from 136 LE patients from 8 hospitals in China, we observed higher damage scores and fewer LE specific autoantibodies in IDLE than SLE patients, more uCDR3 sharing between PBMCs and skin lesion from SLE than IDLE patients, elevated diversity of V-J recombination in IDLE skin lesion and SLE PBMCs, increased SHM frequency and class switch ratio in IDLE skin lesion, decreased SHM frequency but increased class switch ratio in SLE PBMCs, HLA-DRB1*03:01:01:01, HLA-B*58:01:01:01, HLA-C*03:02:02:01, and HLA-DQB1*02:01:01:01 positively associated with SLE patients, and expanded Tfh-like cells with ectopic germinal center structures in IDLE skin lesions. These findings suggest a significant difference in the immunopathogenesis of skin lesions between SLE and IDLE patients. SLE is a B cell-predominate systemic immune disorder, while IDLE appears limited to the skin. Our findings provide novel insights into the pathogenesis of IDLE and other types of LE, which may direct more accurate diagnosis and novel therapeutic strategies.

Virus-induced genetics revealed by multidimensional precision medicine transcriptional workflow applicable to COVID-19.

Precision medicine requires the translation of basic biological understanding to medical insights, mainly applied to characterization of each unique patient. In many clinical settings, this requires tools that can be broadly used to identify pathology and risks. Patients often present to the intensive care unit with broad phenotypes, including multiple organ dysfunction syndrome (MODS) resulting from infection, trauma, or other disease processes. Etiology and outcomes are unique to individuals, making it difficult to cohort patients with MODS, but presenting a prime target for testing/developing tools for precision medicine. Using multitime point whole blood (cellular/acellular) total transcriptomics in 27 patients, we highlight the promise of simultaneously mapping viral/bacterial load, cell composition, tissue damage biomarkers, balance between syndromic biology versus environmental response, and unique biological insights in each patient using a single platform measurement. Integration of a transcriptome workflow yielded unexpected insights into the complex interplay between host genetics and viral/bacterial specific mechanisms, highlighted by a unique case of virally induced genetics (VIG) within one of these 27 patients. The power of RNA-Seq to study unique patient biology while investigating environmental contributions can be a critical tool moving forward for translational sciences applied to precision medicine.

High throughput sequencing of T-cell receptor repertoire using dry blood spots.

BACKGROUND: Immunology research, particularly next generation sequencing (NGS) of the immune T-cell receptor ß (TCRß) repertoire, has advanced progression in several fields, including treatment of various cancers and autoimmune diseases. This study aimed to identify the TCR repertoires from dry blood spots (DBS), a method that will help collecting real-world data for biomarker applications. METHODS: Finger-prick blood was collected onto a Whatman filter card. RNA was extracted from DBS of the filter card, and fully automated multiplex PCR was performed to generate a TCRß chain library for next generation sequencing (NGS) analysis of unique CDR3s (uCDR3). RESULTS: We demonstrated that the dominant clonotypes from the DBS results recapitulated those found in whole blood. According to the statistical analysis and laboratory confirmation, 40 of 2-mm punch disks from the filter cards were enough to detect the shared top clones and have strong correlation in the uCDR3 discovery with whole blood. uCDR3 discovery was neither affected by storage temperatures (room temperature versus - 20 °C) nor storage durations (1, 14, and 28 days) when compared to whole blood. About 74-90% of top 50 uCDR3 clones of whole blood could also be detected from DBS. A low rate of clonotype sharing, 0.03-1.5%, was found among different individuals. CONCLUSIONS: The DBS-based TCR repertoire profiling method is minimally invasive, provides convenient sampling, and incorporates fully automated library preparation. The system is sensitive to low RNA input, and the results are highly correlated with whole blood uCDR3 discovery allowing study scale-up to better understand the relationship and mutual influences between the immune and diseases.

DNA polymerase preference determines PCR priming efficiency.

BACKGROUND: Polymerase chain reaction (PCR) is one of the most important developments in modern biotechnology. However, PCR is known to introduce biases, especially during multiplex reactions. Recent studies have implicated the DNA polymerase as the primary source of bias, particularly initiation of polymerization on the template strand. In our study, amplification from a synthetic library containing a 12 nucleotide random portion was used to provide an in-depth characterization of DNA polymerase priming bias. The synthetic library was amplified with three commercially available DNA polymerases using an anchored primer with a random 3' hexamer end. After normalization, the next generation sequencing (NGS) results of the amplified libraries were directly compared to the unamplified synthetic library. RESULTS: Here, high throughput sequencing was used to systematically demonstrate and characterize DNA polymerase priming bias. We demonstrate that certain sequence motifs are preferred over others as primers where the six nucleotide sequences at the 3' end of the primer, as well as the sequences four base pairs downstream of the priming site, may influence priming efficiencies. DNA polymerases in the same family from two different commercial vendors prefer similar motifs, while another commercially available enzyme from a different DNA polymerase family prefers different motifs. Furthermore, the preferred priming motifs are GC-rich. The DNA polymerase preference for certain sequence motifs was verified by amplification from single-primer templates. We incorporated the observed DNA polymerase preference into a primer-design program that guides the placement of the primer to an optimal location on the template. CONCLUSIONS: DNA polymerase priming bias was characterized using a synthetic library amplification system and NGS. The characterization of DNA polymerase priming bias was then utilized to guide the primer-design process and demonstrate varying amplification efficiencies among three commercially available DNA polymerases. The results suggest that the interaction of the DNA polymerase with the primer:template junction during the initiation of DNA polymerization is very important in terms of overall amplification bias and has broader implications for both the primer design process and multiplex PCR.

Seven-chain adaptive immune receptor repertoire analysis in rheumatoid arthritis reveals novel features associated with disease and clinically relevant phenotypes.

BACKGROUND: In rheumatoid arthritis (RA), the activation of T and B cell clones specific for self-antigens leads to the chronic inflammation of the synovium. Here, we perform an in-depth quantitative analysis of the seven chains that comprise the adaptive immune receptor repertoire (AIRR) in RA. RESULTS: In comparison to controls, we show that RA patients have multiple and strong differences in the B cell receptor repertoire including reduced diversity as well as altered isotype, chain, and segment frequencies. We demonstrate that therapeutic tumor necrosis factor inhibition partially restores this alteration but find a profound difference in the underlying biochemical reactivities between responders and non-responders. Combining the AIRR with HLA typing, we identify the specific T cell receptor repertoire associated with disease risk variants. Integrating these features, we further develop a molecular classifier that shows the utility of the AIRR as a diagnostic tool. CONCLUSIONS: Simultaneous sequencing of the seven chains of the human AIRR reveals novel features associated with the disease and clinically relevant phenotypes, including response to therapy. These findings show the unique potential of AIRR to address precision medicine in immune-related diseases.

Immune repertoire analysis of normal Chinese donors at different ages.

OBJECTIVES: This study investigated the characteristics of the immune repertoire in normal Chinese individuals of different ages. MATERIALS AND METHODS: In this study, all seven receptor chains from both B and T cells in peripheral blood of 16 normal Chinese individuals from two age groups were analyzed using high-throughput sequencing and dimer-avoided multiplex PCR amplification. Normal in this study is defined as no chronic, infectious or autoimmune disease within 6 months prior to blood draw. RESULTS: We found that compared with the younger group, the clonal expression of T-cell receptor repertoire increased in the older group, while diversity decreased. In addition, we found that the T-cell receptor repertoire was more significantly affected by age than the B-cell receptor repertoire, including significant differences in the use of the unique TCR-alpha and TCR-beta V-J gene combinations, in the two groups of normal participants. We further analyzed the degree of complementarity determining region 3 sequence sharing between the two groups, and found shared TCR-alpha, TCR-gamma, immunoglobulin-kappa and immunoglobulin-lambda chain complementarity determining region 3 sequences in all subjects. CONCLUSION: Taken together, our study gives us a better understanding of the immune repertoire of different normal Chinese people, and these results can be applied to the treatment of age-related diseases. Immune repertoire analysis also allows us to observe participant's wellness, aiding in early-stage diagnosis.

CTLA-4 expression by B-1a B cells is essential for immune tolerance.

CTLA-4 is an important regulator of T-cell function. Here, we report that expression of this immune-regulator in mouse B-1a cells has a critical function in maintaining self-tolerance by regulating these early-developing B cells that express a repertoire enriched for auto-reactivity. Selective deletion of CTLA-4 from B cells results in mice that spontaneously develop autoantibodies, T follicular helper (Tfh) cells and germinal centers (GCs) in the spleen, and autoimmune pathology later in life. This impaired immune homeostasis results from B-1a cell dysfunction upon loss of CTLA-4. Therefore, CTLA-4-deficient B-1a cells up-regulate epigenetic and transcriptional activation programs and show increased self-replenishment. These activated cells further internalize surface IgM, differentiate into antigen-presenting cells and, when reconstituted in normal IgH-allotype congenic recipient mice, induce GCs and Tfh cells expressing a highly selected repertoire. These findings show that CTLA-4 regulation of B-1a cells is a crucial immune-regulatory mechanism.

A human monoclonal antibody blocks malaria transmission and defines a highly conserved neutralizing epitope on gametes.

Malaria elimination requires tools that interrupt parasite transmission. Here, we characterize B cell receptor responses among Malian adults vaccinated against the first domain of the cysteine-rich 230 kDa gamete surface protein Pfs230, a key protein in sexual stage development of P. falciparum parasites. Among nine Pfs230 human monoclonal antibodies (mAbs) that we generated, one potently blocks transmission to mosquitoes in a complement-dependent manner and reacts to the gamete surface; the other eight show only low or no blocking activity. The structure of the transmission-blocking mAb in complex with vaccine antigen reveals a large discontinuous conformational epitope, specific to domain 1 of Pfs230 and comprising six structural elements in the protein. The epitope is conserved, suggesting the transmission-blocking mAb is broadly functional. This study provides a rational basis to improve malaria vaccines and develop therapeutic antibodies for malaria elimination.

Persistence of SARS-CoV-2-specific B and T cell responses in convalescent COVID-19 patients 6-8 months after the infection.

BACKGROUND: Monitoring the adaptive immune responses during the natural course of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection provides useful information for the development of vaccination strategies against this virus and its emerging variants. We thus profiled the serum anti-SARS-CoV-2 antibody (Ab) levels and specific memory B and T cell responses in convalescent coronavirus disease 2019 (COVID-19) patients. METHODS: A total of 119 samples from 88 convalescent donors who experienced mild to critical disease were tested for the presence of elevated anti-spike and anti-receptor binding domain Ab levels over a period of 8 months. In addition, the levels of SARS-CoV-2 neutralizing Abs and specific memory B and T cell responses were tested in a subset of samples. FINDINGS: Anti-SARS-CoV-2 Abs were present in 85% of the samples collected within 4 weeks after the onset of symptoms in COVID-19 patients. Levels of specific immunoglobulin M (IgM)/IgA Abs declined after 1 month, while levels of specific IgG Abs and plasma neutralizing activities remained relatively stable up to 6 months after diagnosis. Anti-SARS-CoV-2 IgG Abs were still present, although at a significantly lower level, in 80% of the samples collected at 6-8 months after symptom onset. SARS-CoV-2-specific memory B and T cell responses developed with time and were persistent in all of the patients followed up for 6-8 months. CONCLUSIONS: Our data suggest that protective adaptive immunity following natural infection of SARS-CoV-2 may persist for at least 6-8 months, regardless of disease severity. Development of medium- or long-term protective immunity through vaccination may thus be possible. FUNDING: This project was supported by the European Union's Horizon 2020 research and innovation programme (ATAC, no. 101003650), the Italian Ministry of Health (Ricerca Finalizzata grant no. GR-2013-02358399), the Center for Innovative Medicine, and the Swedish Research Council. J.A. was supported by the SciLifeLab/KAW national COVID-19 research program project grant 2020.

HMGB1 Promotes Myeloid Egress and Limits Lymphatic Clearance of Malignant Pleural Effusions.

Pleural effusions, when benign, are attributed to cardiac events and suffusion of fluid within the pleural space. When malignant, lymphatic obstruction by tumor and failure to absorb constitutively produced fluid is the predominant formulation. The prevailing view has been challenged recently, namely that the lymphatics are only passive vessels, carrying antigenic fluid to secondary lymphoid sites. Rather, lymphatic vessels can be a selective barrier, efficiently coordinating egress of immune cells and factors within tissues, limiting tumor spread and immune pathology. An alternative explanation, offered here, is that damage associated molecular pattern molecules, released in excess, maintain a local milieu associated with recruitment and retention of immune cells associated with failed lymphatic clearance and functional lymphatic obstruction. We found that levels of high mobility group box 1 (HMGB1) were equally elevated in both benign and malignant pleural effusions (MPEs) and that limited diversity of T cell receptor expressing gamma and delta chain were inversely associated with these levels in MPEs. Acellular fluid from MPEs enhanced γδ T cell proliferation in vitro, while inhibiting cytokine production from γδ T cells and monocytes as well as restricting monocyte chemotaxis. Novel therapeutic strategies, targeting HMGB1 and its neutralization in such effusions as well as direct delivery of immune cells into the pleural space to reconstitute normal physiology should be considered.

Corrigendum: Longitudinal Analysis of T and B Cell Receptor Repertoire Transcripts Reveal Dynamic Immune Response in COVID-19 Patients.

[This corrects the article .].

Longitudinal Analysis of T and B Cell Receptor Repertoire Transcripts Reveal Dynamic Immune Response in COVID-19 Patients.

Severe COVID-19 is associated with profound lymphopenia and an elevated neutrophil to lymphocyte ratio. We applied a novel dimer avoidance multiplexed polymerase chain reaction next-generation sequencing assay to analyze T (TCR) and B cell receptor (BCR) repertoires. Surprisingly, TCR repertoires were markedly diminished during the early onset of severe disease but recovered during the convalescent stage. Monitoring TCR repertoires could serve as an indicative biomarker to predict disease progression and recovery. Panoramic concurrent assessment of BCR repertoires demonstrated isotype switching and a transient but dramatic early IgA expansion. Dominant B cell clonal expansion with decreased diversity occurred following recovery from infection. Profound changes in T cell homeostasis raise critical questions about the early events in COVID-19 infection and demonstrate that immune repertoire analysis is a promising method for evaluating emergent host immunity to SARS-CoV-2 viral infection, with great implications for assessing vaccination and other immunological therapies.

Expression, purification and preliminary X-ray analysis of proliferating cell nuclear antigen from the archaeon Thermococcus thioreducens.

Proliferating cell nuclear antigen (PCNA) is a DNA sliding clamp which confers processivity on replicative DNA polymerases. PCNA also acts as a sliding platform that enables the association of many DNA-processing proteins with DNA in a non-sequence-specific manner. In this investigation, the PCNA from the hyperthermophilic archaeon Thermococcus thioreducens (TtPCNA) was cloned, overexpressed in Escherichia coli and purified to greater than 90% homogeneity. TtPCNA crystals were obtained by sitting-drop vapor-diffusion methods and the best ordered crystal diffracted to 1.86 A resolution using synchrotron radiation. The crystals belonged to the hexagonal space group P6(3), with unit-cell parameters a = b = 89.0, c = 62.8 A. Crystals of TtPCNA proved to be amenable to complete X-ray analysis and future structure determination.

Recombinant production, crystallization and preliminary X-ray analysis of PCNA from the psychrophilic archaeon Methanococcoides burtonii DSM 6242.

Proliferating cell nuclear antigen (PCNA) is a DNA-clamping protein that is responsible for increasing the processivity of the replicative polymerases during DNA replication and repair. The PCNA from the eurypsychrophilic archaeon Methanococcoides burtonii DSM 6242 (MbPCNA) has been targeted for protein structural studies. A recombinant expression system has been created that overproduces MbPCNA with an N-terminal hexahistidine affinity tag in Escherichia coli. As a result, recombinant MbPCNA with a molecular mass of 28.3 kDa has been purified to at least 95% homogeneity and crystallized by vapor-diffusion equilibration. Preliminary X-ray analysis revealed a trigonal hexagonal R3 space group, with unit-cell parameters a = b = 102.5, c = 97.5 angstrom. A singleMbPCNA crystal was subjected to complete diffraction data-set collection using synchrotron radiation and reflections were measured to 2.40 angstrom resolution. The diffraction data were of suitable quality for indexing and scaling and an unrefined molecular-replacement solution has been obtained.

PCR-based gene synthesis to produce recombinant proteins for crystallization.

BACKGROUND: Gene synthesis technologies are an important tool for structural biology projects, allowing increased protein expression through codon optimization and facilitating sequence alterations. Existing methods, however, can be complex and not always reproducible, prompting researchers to use commercial suppliers rather than synthesize genes themselves. RESULTS: A PCR-based gene synthesis method, referred to as SeqTBIO, is described to efficiently assemble the coding regions of two novel hyperthermophilic proteins, PAZ (Piwi/Argonaute/Zwille) domain, a siRNA-binding domain of an Argonaute protein homologue and a deletion mutant of a family A DNA polymerase (PolA). The gene synthesis procedure is based on sequential assembly such that homogeneous DNA products can be obtained after each synthesis step without extensive manipulation or purification requirements. Coupling the gene synthesis procedure to in vivo homologous recombination techniques allows efficient subcloning and site-directed mutagenesis for error correction. The recombinant proteins of PAZ and PolA were subsequently overexpressed in E. coli and used for protein crystallization. Crystals of both proteins were obtained and they were suitable for X-ray analysis. CONCLUSION: We demonstrate, by using PAZ and PolA as examples, the feasibility of integrating the gene synthesis, error correction and subcloning techniques into a non-automated gene to crystal pipeline such that genes can be designed, synthesized and implemented for recombinant expression and protein crystallization.

Belimumab promotes negative selection of activated autoreactive B cells in systemic lupus erythematosus patients.

Belimumab has therapeutic benefit in active systemic lupus erythematosus (SLE), especially in patients with high-titer anti-dsDNA antibodies. We asked whether the profound B cell loss in belimumab-treated SLE patients is accompanied by shifts in the immunoglobulin repertoire. We enrolled 15 patients who had been continuously treated with belimumab for more than 7 years, 17 matched controls, and 5 patients who were studied before and after drug initiation. VH genes of sort-purified mature B cells and plasmablasts were subjected to next-generation sequencing. We found that B cell-activating factor (BAFF) regulates the transitional B cell checkpoint, with conservation of transitional 1 (T1) cells and approximately 90% loss of T3 and naive B cells after chronic belimumab treatment. Class-switched memory B cells, B1 B cells, and plasmablasts were also substantially depleted. Next-generation sequencing revealed no redistribution of VH, DH, or JH family usage and no effect of belimumab on representation of the autoreactive VH4-34 gene or CDR3 composition in unmutated IgM sequences, suggesting a minimal effect on selection of the naive B cell repertoire. Interestingly, a significantly greater loss of VH4-34 was observed among mutated IgM and plasmablast sequences in chronic belimumab-treated subjects than in controls, suggesting that belimumab promotes negative selection of activated autoreactive B cells.

Immune Repertoire Diversity Correlated with Mortality in Avian Influenza A (H7N9) Virus Infected Patients.

Specific changes in immune repertoires at genetic level responding to the lethal H7N9 virus are still poorly understood. We performed deep sequencing on the T and B cells from patients recently infected with H7N9 to explore the correlation between clinical outcomes and immune repertoire alterations. T and B cell repertoires display highly dynamic yet distinct clonotype alterations. During infection, T cell beta chain repertoire continues to contract while the diversity of immunoglobulin heavy chain repertoire recovers. Patient recovery is correlated to the diversity of T cell and B cell repertoires in different ways - higher B cell diversity and lower T cell diversity are found in survivors. The sequences clonally related to known antibodies with binding affinity to H7 hemagglutinin could be identified from survivors. These findings suggest that utilizing deep sequencing may improve prognostication during influenza infection and could help in development of antibody discovery methodologies for the treatment of virus infection.