Deciphering Autoimmune Diseases: Unveiling the Diagnostic, Therapeutic, and Prognostic Potential of Immune Repertoire Sequencing.

Autoimmune diseases (AIDs) are immune system disorders where the body exhibits an immune response to its own antigens, causing damage to its own tissues and organs. The pathogenesis of AIDs is incompletely understood. However, recent advances in immune repertoire sequencing (IR-seq) technology have opened-up a new avenue to study the IR. These studies have revealed the prevalence in IR alterations, potentially inducing AIDs by disrupting immune tolerance and thereby contributing to our comprehension of AIDs. IR-seq harbors significant potential for the clinical diagnosis, personalized treatment, and prognosis of AIDs. This article reviews the application and progress of IR-seq in diseases, such as multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, and type 1 diabetes, to enhance our understanding of the pathogenesis of AIDs and offer valuable references for the diagnosis and treatment of AIDs.

Improved detection of tryptic immunoglobulin variable region peptides by chromatographic and gas-phase fractionation techniques.

The polyclonal repertoire of circulating antibodies potentially holds valuable information about an individual's humoral immune state. While bottom-up proteomics is well suited for serum proteomics, the vast number of antibodies and dynamic range of serum challenge this analysis. To acquire the serum proteome more comprehensively, we incorporated high-field asymmetric waveform ion-mobility spectrometry (FAIMS) or two-dimensional chromatography into standard trypsin-based bottom-up proteomics. Thereby, the number of variable region (VR)-related spectra increased 1.7-fold with FAIMS and 10-fold with chromatography fractionation. To match antibody VRs to spectra, we combined de novo searching and BLAST alignment. Validation of this approach showed that, as peptide length increased, the de novo accuracy decreased and BLAST performance increased. Through in silico calculations on antibody repository sequences, we determined the uniqueness of tryptic VR peptides and their suitability as antibody surrogate. Approximately one-third of these peptides were unique, and about one-third of all antibodies contained at least one unique peptide.

The TCR ß chain CDR3 insights of bovine liver immune repertoire under heat stress.

Objective: The liver plays a dual role in regulating temperature and immune responses. Examining the influence of Heat stress (HS) on liver T cells contributes significantly to understanding the intricate interplay between the immune system and hepatic tissues under thermal stress. This study focused on investigating the characteristics of the T-cell receptor (TCR) ß chain CDR3 repertoire in bovine liver samples under both HS and pair-fed (PF) environmental conditions. Methods: Sequencing data from six samples sourced from the GEO database underwent annotation. Utilizing immunarch and VDJtool software, the study conducted comprehensive analyses encompassing basic evaluation, clonality assessment, immune repertoire comparison, diversity estimation, gene usage profiling, VJ gene segment pairing scrutiny, clonal tracking, and Kmers analysis. Results: All four TCR chains, namely α, ß, γ, and δ, were detected, with the α chains exhibiting the highest detection frequency, followed closely by the ß chains. The prevalence of αß TCRs in bovine liver samples underscored their crucial role in governing hepatic tissue's physiological functions. The TCR ß CDR3 repertoire showcased substantial inter-individual variability, featuring diverse clonotypes exhibiting distinct amino acid lengths. Intriguingly, HS cattle displayed heightened diversity and clonality, suggesting potential peripheral T cell migration into the liver under environmental conditions. Notably, differential VJ gene pairings were observed in HS cattle compared to the PF, despite individual variations in V and J gene utilization. Additionally, while most high-frequency amino acid 5-mers remained consistent between the HS and PF, GELHF and YDYHF were notably prevalent in the HS group. Across all samples, a prevalent trend of high-frequency 5mers skewed towards polar and hydrophobic amino acids was evident. Conclusion: This study elucidates the characteristics of liver TCR ß chain CDR3 repertoire under HS conditions, enhancing our understanding of HS implications.

Reconstitution of peripheral blood T cell receptor ß immune repertoire in immune checkpoint inhibitors associated myocarditis.

PURPOSE: Immune checkpoint inhibitors (ICIs)-associated myocarditis was a rare yet severe complication observed in individuals undergoing immunotherapy. This study investigated the immune status and characteristics of patients diagnosed with ICIs- associated myocarditis. METHODS: A total of seven patients diagnosed with ICIs-associated myocarditis were included in the study, while five tumor patients without myocarditis were recruited as reference controls. Additionally, 30 healthy individuals were recruited as blank controls. Biochemical indices, electrocardiogram, and echocardiography measurements were obtained both prior to and following the occurrence of myocarditis. High-throughput sequencing of T cell receptor (TCR) was employed to assess the diversity and distribution characteristics of TCR CDR3 length, as well as the diversity of variable (V) and joining (J) genes of T lymphocytes in peripheral blood. RESULTS: In the seven patients with ICIs-associated myocarditis, Troponin T (TNT) levels exhibited a significant increase following myocarditis, while other parameters such as brain natriuretic peptide (BNP), QTc interval, and left ventricular ejection fraction (LVEF) did not show any significant differences. Through sequencing, it was observed that the diversity and uniformity of CDR3 in the ICIs-associated myocarditis patients were significantly diminished. Additionally, the distribution of CDR3 nucleotides deviated from normality, and variations in the utilization of V and J gene segments. CONCLUSION: The reconstitution of the TCR immune repertoire may play a pivotal role in the recognition of antigens in patients with ICIs-associated myocarditis.

RAIN: a Machine Learning-based identification for HIV-1 bNAbs.

Broadly neutralizing antibodies (bNAbs) are promising candidates for the treatment and prevention of HIV-1 infection. Despite their critical importance, automatic detection of HIV-1 bNAbs from immune repertoire is still lacking. Here, we developed a straightforward computational method for Rapid Automatic Identification of bNAbs (RAIN) based on Machine Learning methods. In contrast to other approaches using one-hot encoding amino acid sequences or structural alignment for prediction, RAIN uses a combination of selected sequence-based features for accurate prediction of HIV-1 bNAbs. We demonstrate the performance of our approach on non-biased, experimentally obtained sequenced BCR repertoires from HIV-1 immune donors. RAIN processing leads to the successful identification of novel HIV-1 bNAbs targeting the CD4-binding site of the envelope glycoprotein. In addition, we validate the identified bNAbs using in vitro neutralization assay and we solve the structure of one of them in complex with the soluble native-like heterotrimeric envelope glycoprotein by single-particle cryo-electron microscopy (cryo-EM). Overall, we propose a method to facilitate and accelerate HIV-1 bNAbs discovery from non-selected immune repertoires.

Comprehensive analysis of juvenile idiopathic arthritis patients' immune characteristics based on bulk and single-cell sequencing data.

Background: The pathogenesis of juvenile idiopathic arthritis (JIA) is strongly influenced by an impaired immune system. However, the molecular mechanisms underlying its development and progression have not been elucidated. In this study, the computational methods TRUST4 were used to construct a T-cell receptor (TCR) and B-cell receptor (BCR) repertoire from the peripheral blood of JIA patients via bulk RNA-seq data, after which the clonality and diversity of the immune repertoire were analyzed. Results: Our findings revealed significant differences in the frequency of clonotypes between the JIA and healthy control groups in terms of the TCR and BCR repertoires. This work identified specific V genes and J genes in TCRs and BCRs that could be used to expand our understanding of JIA. After single-cell RNA analysis, the relative percentages of CD14 monocytes were significantly greater in the JIA group. Cell-cell communication analysis revealed the significant role of the MIF signaling pathway in JIA. Conclusion: In conclusion, this work describes the immune features of both the TCR and BCR repertoires under JIA conditions and provides novel insight into immunotherapy for JIA.

Identification of the immune repertoire of γδ T-cell receptors in psoriasis.

The γδ T cells are a subpopulation of T cells that are abundantly found in the skin and mucous membranes. Their reactivity to self-antigens and ability to secrete various cytokines make them a key component in psoriasis development. Although the correlation between the immune repertoire (IR) of γδ T-cell receptors and the occurrence and severity of psoriasis remains incompletely explored, high-throughput sequencing of γδ T cells has led to a deeper understanding of IR in psoriasis. This study investigated the differences between γδ T cells in patients with psoriasis and healthy controls. The γδ T cells were identified via immunofluorescence staining and a correlation analysis was performed according to the psoriasis area and severity index (PASI) scores. The IR sequencing method was used to detect IR in the γδ T-cell receptors. The findings demonstrated more skin γδ T cells in patients with psoriasis, which were positively correlated with the PASI score. There were subtle differences in most variable (V), diversity (D) and joining (J) gene segments and VJ/VDJ combination segments between patients with psoriasis and healthy controls. However, a higher diversity of complementarity-determining region 3 (CDR3) was observed in patients with psoriasis. In summary, the IR of skin γδ T cells was significantly altered in patients with psoriasis, and the diversity in the cell's CDR3 population is a promising biomarker for assessment of psoriasis severity.

Elucidating immunological characteristics of the adenoma-carcinoma sequence in colorectal cancer patients in South Korea using a bioinformatics approach.

Colorectal cancer (CRC) is one of the top five most common and life-threatening malignancies worldwide. Most CRC develops from advanced colorectal adenoma (ACA), a precancerous stage, through the adenoma-carcinoma sequence. However, its underlying mechanisms, including how the tumor microenvironment changes, remain elusive. Therefore, we conducted an integrative analysis comparing RNA-seq data collected from 40 ACA patients who visited Dongguk University Ilsan Hospital with normal adjacent colons and tumor samples from 18 CRC patients collected from a public database. Differential expression analysis identified 21 and 79 sequentially up- or down-regulated genes across the continuum, respectively. The functional centrality of the continuum genes was assessed through network analysis, identifying 11 up- and 13 down-regulated hub-genes. Subsequently, we validated the prognostic effects of hub-genes using the Kaplan-Meier survival analysis. To estimate the immunological transition of the adenoma-carcinoma sequence, single-cell deconvolution and immune repertoire analyses were conducted. Significant composition changes for innate immunity cells and decreased plasma B-cells with immunoglobulin diversity were observed, along with distinctive immunoglobulin recombination patterns. Taken together, we believe our findings suggest underlying transcriptional and immunological changes during the adenoma-carcinoma sequence, contributing to the further development of pre-diagnostic markers for CRC.

Immune checkpoint therapy responders display early clonal expansion of tumor infiltrating lymphocytes.

Immune checkpoint therapy (ICT) causes durable tumour responses in a subgroup of patients, but it is not well known how T cell receptor beta (TCRß) repertoire dynamics contribute to the therapeutic response. Using murine models that exclude variation in host genetics, environmental factors and tumour mutation burden, limiting variation between animals to naturally diverse TCRß repertoires, we applied TCRseq, single cell RNAseq and flow cytometry to study TCRß repertoire dynamics in ICT responders and non-responders. Increased oligoclonal expansion of TCRß clonotypes was observed in responding tumours. Machine learning identified TCRß CDR3 signatures unique to each tumour model, and signatures associated with ICT response at various timepoints before or during ICT. Clonally expanded CD8+ T cells in responding tumours post ICT displayed effector T cell gene signatures and phenotype. An early burst of clonal expansion during ICT is associated with response, and we report unique dynamics in TCRß signatures associated with ICT response.

A comparative analysis of TCR immune repertoire in COVID-19 patients.

The coronavirus disease 2019 (COVID-19) has merged as a global health threat since its outbreak in December 2019. Despite widespread recognition, there has been a paucity of studies focusing on the T cell receptor (TCR) bias in adaptive immunity induced by SARS-CoV-2. This research conducted a comparative analysis of the TCR immune repertoire to identify notable αß TCR bias sequences associated with the SARS-CoV-2 virus antigen. The present study encompassed 73 symptomatic COVID-19 patients, categorized as moderate/mild or severe/critical, along with 9 healthy controls. Our findings revealed specific TCR chains prominently utilized by moderate and severe patients, identified as TRAV30-J34-TRBV3-1-J2-7 and TRAV12-3-J6-TRBV28-J1-1, respectively. Additionally, our research explored critical TCR preferences in the bronchoalveolar lavage fluid (BALF) of COVID-19 patients at various disease stages. Indeed, monitoring the dynamics of immune repertoire changes in COVID-19 patients could serve as a crucial biomarker for predicting disease progression and recovery. Furthermore, the study explored TCR bias in both peripheral blood mononuclear cells (PBMCs) and BALF. The most common αß VJ pair observed in BALF was TRAV12-3-J18-TRBV7-6-J2-7. In addition, a comparative analysis with the VDJdb database indicated that the HLA-A*02:01 allele exhibited the widest distribution and highest frequency in COVID-19 patients across different periods. This comprehensive examination provided a global characterization of the TCR immune repertoire in COVID-19 patients, contributing significantly to our understanding of TCR bias induced by SARS-CoV-2.

The clinical applications of immunosequencing.

Technological advances in high-throughput sequencing have opened the door for the interrogation of adaptive immune responses at unprecedented scale. It is now possible to determine the sequences of antibodies or T-cell receptors produced by individual B and T cells in a sample. This capability, termed immunosequencing, has transformed the study of both infectious and non-infectious diseases by allowing the tracking of dynamic changes in B and T cell clonal populations over time. This has improved our understanding of the pathology of cancers, autoimmune diseases, and infectious diseases. However, to date there has been only limited clinical adoption of the technology. Advances over the last decade and on the horizon that reduce costs and improve interpretability could enable widespread clinical use. Many clinical applications have been proposed and, while most are still undergoing research and development, some methods relying on immunosequencing data have been implemented, the most widespread of which is the detection of measurable residual disease. Here, we review the diagnostic, prognostic, and therapeutic applications of immunosequencing for both infectious and non-infectious diseases.

Peripheral T cell immune repertoire is associated with the outcomes of acute spontaneous intracerebral hemorrhage.

Systematic immune responses have been identified in patients with acute spontaneous intracerebral hemorrhage (ICH). T cells have been established to participate in central nervous system damage and repair following brain injury. However, their contribution to the prognosis of patients with ICH remains to be elucidated. In this study, peripheral blood mononuclear cells (PBMCs) were collected from 45 patients with acute spontaneous ICH (<24 h from symptom onset). Our results exposed significant negative correlations between hematoma volume/white blood cell (WBC) density and Glasgow Coma Scale (GCS) score. Contrastingly, lymphocyte density was negatively correlated with hematoma volume and positively correlated with GCS score. Moreover, flow cytometry determined that ICH activated T cells despite their proportion being lower in blood. Afterward, immune repertoire sequencing (IR-seq) revealed a significant decrease in VJ, VDJ usage, and TCR clonotypes in ICH patients. Finally, variations in the complementarity-determining region 3 (CDR3) amino acid (aa) were also detected in ICH patients. This study reveals the occurrence of peripheral T-cell diminishment and activation in response to acute hematoma. ICH lesion also alters the T cell receptor (TCR) immune repertoire, which is associated with patient prognosis.

Identification of SARS-CoV-2-specific T cell and its receptor.

The T-cell receptor (TCR) repertoires exhibits distinct signatures associated with COVID-19 severity. However, the precise identification of vaccine-induced SARS-CoV-2-specific TCRs and T-cell immunity mechanisms are unknown. We developed a machine-learning model that can differentiate COVID-19 patients from healthy individuals based on TCR sequence features with an accuracy of 95.7%. Additionally, we identified SARS-CoV-2-specific T cells and TCR in HLA-A*02 vaccinated individuals by peptide stimulation. The SARS-CoV-2-specific T cells exhibited higher cytotoxicity and prolonged survival when targeting spike-pulsed cells in vitro or in vivo. The top-performing TCR was further tested for its affinity and cytotoxic effect against SARS-CoV-2-associated epitopes. Furthermore, single-cell RNA sequencing (scRNA-seq), immune repertoire sequencing (IR-seq) and flow cytometry were used to access vaccine-induced cellular immunity, which demonstrated that robust T cell responses (T cell activation, tissue-resident memory T cell (Trm) generation, and TCR clonal expansion) could be induced by intranasal vaccination. In summary, we identified the SARS-CoV-2-associated TCR repertoires profile, specific TCRs and T cell responses. This study provides a theoretical basis for developing effective immunization strategies.

Landscape of IGH germline genes of Chiroptera and the pattern of Rhinolophus affinis bat IGH CDR3 repertoire.

The emergence and re-emergence of abundant viruses from bats that impact human and animal health have resulted in a resurgence of interest in bat immunology. Characterizing the immune receptor repertoire is critical to understanding how bats coexist with viruses in the absence of disease and developing new therapeutics to target viruses in humans and susceptible livestock. In this study, IGH germline genes of Chiroptera including Rhinolophus ferrumequinum, Phyllostomus discolor, and Pipistrellus pipistrellus were annotated, and we profiled the characteristics of Rhinolophus affinis (RA) IGH CDR3 repertoire. The germline genes of Chiroptera are quite different from those of human, mouse, cow, and dog in evolution, but the three bat species have high homology. The CDR3 repertoire of RA is unique in many aspects including CDR3 subclass, V/J genes access and pairing, CDR3 clones, and somatic high-frequency mutation compared with that of human and mouse, which is an important point in understanding the asymptomatic nature of viral infection in bats. This study unveiled a detailed map of bat IGH germline genes on chromosome level and provided the first immune receptor repertoire of bat, which will stimulate new avenues of research that are directly relevant to human health and disease.IMPORTANCEThe intricate relationship between bats and viruses has been a subject of study since the mid-20th century, with more than 100 viruses identified, including those affecting humans. While preliminary investigations have outlined the innate immune responses of bats, the role of adaptive immunity remains unclear. This study presents a pioneering contribution to bat immunology by unveiling, for the first time, a detailed map of bat IGH germline genes at the chromosome level. This breakthrough not only provides a foundation for B cell receptor research in bats but also contributes to primer design and sequencing of the CDR3 repertoire. Additionally, we offer the first comprehensive immune receptor repertoire of bats, serving as a crucial library for future comparative analyses. In summary, this research significantly advances the understanding of bats' immune responses, providing essential resources for further investigations into viral tolerance and potential zoonotic threats.

Anchor Clustering for million-scale immune repertoire sequencing data.

BACKGROUND: The clustering of immune repertoire data is challenging due to the computational cost associated with a very large number of pairwise sequence comparisons. To overcome this limitation, we developed Anchor Clustering, an unsupervised clustering method designed to identify similar sequences from millions of antigen receptor gene sequences. First, a Point Packing algorithm is used to identify a set of maximally spaced anchor sequences. Then, the genetic distance of the remaining sequences to all anchor sequences is calculated and transformed into distance vectors. Finally, distance vectors are clustered using unsupervised clustering. This process is repeated iteratively until the resulting clusters are small enough so that pairwise distance comparisons can be performed. RESULTS: Our results demonstrate that Anchor Clustering is faster than existing pairwise comparison clustering methods while providing similar clustering quality. With its flexible, memory-saving strategy, Anchor Clustering is capable of clustering millions of antigen receptor gene sequences in just a few minutes. CONCLUSIONS: This method enables the meta-analysis of immune-repertoire data from different studies and could contribute to a more comprehensive understanding of the immune repertoire data space.

Application of immune repertoire sequencing in solid organ transplantation / 器官移植

Immune repertoire is defined as the sum of T cells and B cells, which possesses high diversity and enables immune system to respond to various antigen stimuli. With the development of sequencing technique, immune repertoire sequencing can be utilized to deeply understand the changes of lymphocyte clones when rejection occurs at the gene level, and also provide the possibility for the emergence of novel non-invasive diagnostic techniques based on immune repertoire sequencing. In recent years, more and more attempts have been made to apply immune repertoire sequencing in solid organ transplantation, especially in the fields of kidney transplantation, liver transplantation, heart transplantation and post-transplantation infection. In this article, research progresses on the application of immune repertoire sequencing in these fields were reviewed, and current status of immune repertoire sequencing in organ transplantation and its potential as a novel technique for early non-invasive diagnosis of rejection were summarized, aiming to provide reference for subsequent development and clinical application of this technique.

Comparison of the blood immune repertoire with clinical features in chronic lymphocytic leukemia patients treated with chemoimmunotherapy or ibrutinib.

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of CD19+ CD5+ clonal B lymphocytes in the blood, bone marrow, and peripheral lymphoid organs. Treatment options for patients range from historical chemoimmunotherapy (CIT) to small molecule inhibitors targeting pro-survival pathways in leukemic B cells, such as the Bruton's tyrosine kinase inhibitor ibrutinib (IBR). Using biobanked blood samples obtained pre-therapy and at standard response evaluation timepoints, we performed an in-depth evaluation of the blood innate and adaptive immune compartments between pentostatin-based CIT and IBR and looked for correlations with clinical sequelae. CD4+ conventional T cells and CD8+ cytotoxic T cells responded similarly to CIT and IBR, although exhaustion status differed. Both treatments dramatically increased the prevalence and functional status of monocyte, dendritic cell, and natural killer cell subsets. As expected, both regimens reduced clonal B cell levels however, we observed no substantial recovery of normal B cells. Although improvements in most immune subsets were observed with CIT and IBR at response evaluation, both patient groups remained susceptible to infections and secondary malignancies during the study.

RNA-Seq and Immune Repertoire Analysis of Normal and Hepatocellular Carcinoma Relapse After Liver Transplantation.

Background: Hepatocellular carcinoma (HCC) relapse is the main reason for the poor prognosis of HCC after Liver transplantation (LT). This study aimed to explore the molecular mechanisms and immune repertoire profiles of HCC relapse. Material and Methods: RNA-seq of blood samples from patients with normal (n=12) and HCC relapse (n=6) after LT was performed to identify differentially expressed genes (DEGs) and key signalling pathways. The DEGs and immune genes were further analyzed by bioinformatics. TRUST4 was used to analyze the differences in the immune repertoire between the two groups. Another 11 blood samples from patients with HCC who had received LT were collected for RT-qPCR verification of key genes. Results: A total of 131 upregulated and 157 downregulated genes were identified using RNA-seq, and GO enrichment analysis revealed that the top 15 pathways were immune-related. The PPI network identified 10 key genes. Immune infiltration analysis revealed a significant difference in the five immune cell types between the two groups. A total of 83 intersecting genes were obtained by intersecting DEGs and immune genes. 6 key genes, including MX1, ISG15, OAS1, PRF1, SPP1, and THBS1 were obtained according to the intersection of DEGs, PPI network top 10 genes and immune intersecting genes. Immune repertoire analysis showed that the usage frequency of variable (V) and joining (J) genes in the normal group was higher than that in the relapse group. RT-qPCR validation showed that the expression levels of key genes were consistent with the RNA-seq results. Conclusion: Our study identified key pathways and genes that could help determine whether transplant recipients are more prone to HCC relapse. Immune repertoire analysis revealed a difference in the usage frequency of VJ genes between the normal and relapse groups, providing a research direction for immunotherapy in patients with HCC relapse after liver transplantation.

The dynamic TRß/IGH CDR3 repertoire features in patients with liver transplantation.

OBJECTIVE: At present, little is known about the immune mechanism of liver transplantation caused by decompensated cirrhosis. Lymphocytes play an essential important role in the immune rejection of liver transplantation. In this study, we aimed to comprehensively analyze changes in complementary determinant 3 (CDR3) repertoire of T cell receptor ß chain (TRß) and immunoglobulin heavy chain (IGH) in liver transplantation patients and healthy controls (HC). METHODS: High-throughput sequencing technology was used to study the characteristics of TRß/IGH CDR3 repertoire, and identify the amino acid sequences of TRß and IGH associated with liver transplantation patients and HC. RESULTS: We found that some TRß and IGH CDR3 repertoire characteristics differed between liver transplant patients and HC. The diversity of TRß CDR3 increased in the liver transplantation group. First and seven days after live transplantation patients showed a lower degree of T cell clone amplification compared to the HC group. The CDR3 repertoire of the TRß/IGH chain was certainly biased in the use of some V, D, and J gene segments, TRß/IGH V-J combined frequency was also skewed and TRß CDR3 clonotypes were shared at a higher degree in the liver transplantation patients. Importantly, one amino acid sequence in the decompensated cirrhosis group was significantly higher than that in the healthy group. It should be noted that the frequency of some CDR3 sequences is closely correlated with the different stages of liver transplantation, and these sequences may play a key role in liver transplantation. CONCLUSION: Based on the above results, we can better understand the dynamic changes of TCß/IGH CDR3 repertoire in patients during liver transplantation.