Syndecan-1 Plays a Role in the Pathogenesis of Sjögren's Disease by Inducing B-Cell Chemotaxis through CXCL13-Heparan Sulfate Interaction.

In Sjögren's disease (SjD), the salivary glandular epithelial cells can induce the chemotaxis of B cells by secreting B-cell chemokines such as C-X-C motif chemokine ligand 13 (CXCL13). Syndecan-1 (SDC-1) is a major transmembrane heparan sulfate proteoglycan (HSPG) predominantly expressed on epithelial cells that binds to and regulates heparan sulfate (HS)-binding molecules, including chemokines. We aimed to determine whether SDC-1 plays a role in the pathogenesis of SjD by acting on the binding of HS to B-cell chemokines. To assess changes in glandular inflammation and SDC-1 concentrations in the submandibular gland (SMG) and blood, female NOD/ShiLtJ and sex- and age-matched C57BL/10 mice were used. In the SMG of NOD/ShiLtJ mice, inflammatory responses were identified at 8 weeks of age, but increased SDC-1 concentrations in the SMG and blood were observed at 6 weeks of age, when inflammation had not yet started. As the inflammation of the SMG worsened, the SDC-1 concentrations in the SMG and blood increased. The expression of the CXCL13 and its receptor C-X-C chemokine receptor type 5 (CXCR5) began to increase in the SMG at 6 weeks of age and continued until 12 weeks of age. Immunofluorescence staining in SMG tissue and normal murine mammary gland cells confirmed the co-localization of SDC-1 and CXCL13, and SDC-1 formed a complex with CXCL13 in an immunoprecipitation assay. Furthermore, NOD/ShiLtJ mice were treated with 5 mg/kg HS intraperitoneally thrice per week for 6-10 weeks of age, and the therapeutic effects in the SMG were assessed at the end of 10 weeks of age. NOD/ShiLtJ mice treated with HS showed attenuated salivary gland inflammation with reduced B-cell infiltration, germinal center formation and CXCR5 expression. These findings suggest that SDC-1 plays a pivotal role in the pathogenesis of SjD by binding to CXCL13 through the HS chain.

Unraveling the origins of pathogenic CXCL13+ helper T cells in systemic lupus erythematosus.

This Research Highlight discusses a recent publication, where the authors identified an increase in CXCL13+ peripheral helper T/follicular helper T cells, which was concomitant with a decrease in CD96+ T helper 22 (TH22) cells in patients with systemic lupus erythematosus. The genetic and epigenetic cues that reciprocally regulate this pathogenic imbalance of T-cell subsets were also identified, thus providing targets for therapeutic intervention.

Deciphering the interplay of HPV infection, MHC-II expression, and CXCL13+ CD4+ T cell activation in oropharyngeal cancer: implications for immunotherapy.

BACKGROUND: Human papillomavirus (HPV) infection has become an important etiological driver of oropharyngeal squamous cell carcinoma (OPSCC), leading to unique tumor characteristics. However, the interplay between HPV-associated tumor cells and tumor microenvironment (TME) remains an enigma. METHODS: We performed a single-cell RNA-sequencing (scRNA-seq) on HPV-positive (HPV+) and HPV-negative (HPV‒) OPSCC tumors, each for three samples, and one normal tonsil tissue. Ex vivo validation assays including immunofluorescence staining, cell line co-culture, and flow cytometry analysis were used to test specific subtypes of HPV+ tumor cells and their communications with T cells. RESULTS: Through a comprehensive single-cell transcriptome analysis, we uncover the distinct transcriptional signatures between HPV+ and HPV‒ OPSCC. Specifically, HPV+ OPSCC tumor cells manifest an enhanced interferon response and elevated expression of the major histocompatibility complex II (MHC-II), potentially bolstering tumor recognition and immune response. Furthermore, we identify a CXCL13+CD4+ T cell subset that exhibits dual features of both follicular and pro-inflammatory helper T cells. Noteworthily, HPV+ OPSCC tumor cells embrace extensive intercellular communications with CXCL13+CD4+ T cells. Interaction with HPV+ OPSCC tumor cells amplifies CXCL13 and IFNγ release in CD4+T cells, fostering a pro-inflammatory TME. Additionally, HPV+ tumor cells expressing high MHC-II and CXCL13+CD4+ T cell prevalence are indicative of favorable overall survival rates in OPSCC patients. CONCLUSIONS: Together, our study underscores a synergistic inflammatory immune response orchestrated by highly immunogenic tumor cells and CXCL13+CD4+ T cells in HPV+ OPSCC, offering useful insights into strategy development for patient stratification and effective immunotherapy in OPSCC.

Breast cancer during pregnancy of Luminal A type overexpressed CXCL13.

Pregnancy-associated breast cancer has been increasing. In this study, we analyzed patients with breast cancer that occurred during pregnancy (PrBC) and compared their genetic profiles with those of patients with breast cancer that did not occur during pregnancy, within 1 year after childbirth nor during lactation (non-PrBC). We performed gene expression analyses of patients with PrBC and non-PrBC using microarrays and qRT-PCR. Microarray analysis showed that 355 genes were upregulated in the luminal-type PrBC group compared to those in the non-PrBC group. The C-X-C motif chemokine ligand 13 (CXCL13) gene was the most upregulated in the PrBC group compared to that in the non-PrBC group, especially in the luminal A-type (p = 0.016). This result was corroborated by the qRT-PCR analysis of microdissected cancer cells (p < 0.001). A negative correlation was observed between CXCL13 and estrogen receptor 1 (ESR1) mRNA expression levels in luminal A-type breast carcinoma (p < 0.001). Our results provide clues for a better understanding of breast cancer pathogenesis during pregnancy.

Antibody responses to immunoevasion proteins BBK32 and OspE constitute part of the serological footprint in neuroborreliosis but are insufficient to prevent the disease.

Lyme borreliosis, caused by Borrelia burgdorferi sensu lato, is the most common tickborne disease. Its neuronal form, neuroborreliosis, comprises 3 to 38% of borreliosis cases in Europe. Borrelia outer surface proteins and virulence factors, OspE and BBK32, have been previously reported to help cause infection by promoting attachment to human host epithelial cells and evading complement attack. We assessed the serological responses to BBK32 and OspE in 19 individuals diagnosed with neuroborreliosis to see whether antibodies that could both target the bacteria and neutralize the virulence mechanisms on the microbial surface emerge. Results evaluate levels of total protein, IgG and the chemokine CXCL13, a determinant for B-cell recruitment during neuroinflammation, in patients' cerebrospinal fluid samples. Antibody levels against BBK32 and OspE correlated with those against VlsE, a well-characterized diagnostic serological marker of the disease. A dual serological profile of the patients was observed. K-means clustering split the cohort into two discrete groups presenting distinct serological and CNS responses. One group contained young patients with low levels of anti-BBK32 and OspE antibodies. The other group showed stronger responses, possibly following prolonged infections or reinfections. Additionally, we assessed anti-ganglioside antibodies that could cause autoimmunity or complement dysregulation but observed that they did not correlate with neuroborreliosis in our patient cohort. The dual nature of antibody responses against the virulence factors BBK32 and OspE in neuroborreliosis patients may suggest the necessity of repeated exposures for efficient immune responses. Better protection could be achieved if the virulence factors were formulated into vaccines.

Identification of CXCL13 as a Promising Biomarker for Immune Checkpoint Blockade Therapy and PARP Inhibitor Therapy in Ovarian Cancer.

Ovarian cancer has poor response rates to immune checkpoint blockade (ICB) therapy, despite the use of genomic sequencing to identify molecular targets. Homologous recombination deficiency (HRD) is a conventional indicator of genomic instability (GI) and has been used as a marker for targeted therapies. Indicators reflecting HRD status have shown potential in predicting the efficacy of ICB treatment. Public databases, including TCGA, ICGC, and GEO, were used to obtain data. HRD scores, neoantigen load, and TMB were obtained from the TCGA cohort. Candidate biomarkers were validated in multiple databases, such as the Imvigor210 immunotherapy cohort and the open-source single-cell sequencing database. Immunohistochemistry was performed to further validate the results in independent cohorts. CXCL10, CXCL11, and CXCL13 were found to be significantly upregulated in HRD tumors and exhibited prognostic value. A comprehensive analysis of the tumor immune microenvironment (TIME) revealed that CXCL13 expression positively correlated with neoantigen load and immune cell infiltration. In addition, single-cell sequencing data and clinical trial results supported the utility of CXCL13 as a biomarker for ICB therapy. Not only does CXCL13 serve as a biomarker reflecting HRD status, but it also introduces a potentially novel perspective on prognostic biomarkers for ICB in ovarian cancer.

Constructing a prognostic model for colon cancer: insights from immunity-related genes.

BACKGROUND: Colon cancer (CC) is a malignancy associated with significant morbidity and mortality within the gastrointestinal tract. Recurrence and metastasis are the main factors affecting the prognosis of CC patients undergoing radical surgery; consequently, we attempted to determine the impact of immunity-related genes. RESULT: We constructed a CC risk model based on ZG16, MPC1, RBM47, SMOX, CPM and DNASE1L3. Consistently, we found that a significant association was found between the expression of most characteristic genes and tumor mutation burden (TMB), microsatellite instability (MSI) and neoantigen (NEO). Additionally, a notable decrease in RBM47 expression was observed in CC tissues compared with that in normal tissues. Moreover, RBM47 expression was correlated with clinicopathological characteristics and improved disease-free survival (DFS) and overall survival (OS) among patients with CC. Lastly, immunohistochemistry and co-immunofluorescence staining revealed a clear positive correlation between RBM47 and CXCL13 in mature tertiary lymphoid structures (TLS) region. CONCLUSION: We conclude that RBM47 was identified as a prognostic-related gene, which was of great significance to the prognosis evaluation of patients with CC and was correlated with CXCL13 in the TLS region.

Changes In Serum CXCL13 Levels Are Associated With Outcomes of Colorectal Cancer Patients Undergoing First-Line Oxaliplatin-Based Treatment.

Metastatic colorectal cancer (mCRC) currently lacks reliable biomarkers for precision medicine, particularly for chemotherapy-based treatments. This study examines the behavior of 11 CXC chemokines in the blood of 104 mCRC patients undergoing first-line oxaliplatin-based treatment to pinpoint predictive and prognostic markers. Serum samples were collected before treatment, at response evaluation (EVAR), and at disease progression or last follow-up. Chemokines were assessed in all samples using a Luminex® custom panel. CXCL13 levels increased at EVAR in responders, while in non-responders it decreased. Increasing levels of CXCL13 at EVAR, independently correlated with improved progression-free survival (PFS) and overall survival (OS). Nanostring® analysis in primary tumor samples showed CXCL13 gene expression's positive correlation not only with gene profiles related to an immunogenic tumor microenvironment, increased B cells and T cells (mainly CD8+) but also with extended OS. In silico analysis using RNAseq data from liver metastases treated or not with neoadjuvant oxaliplatin-based combinations, and deconvolution analysis using the MCP-counter algorithm, confirmed CXCL13 gene expression's association with increased immune infiltration, improved OS, and Tertiary Lymphoid Structures (TLSs) gene signatures, especially in neoadjuvant-treated patients. CXCL13 analysis in serum from 36 oxaliplatin-treated patients from the METIMMOX study control arm, reported similar findings. In conclusion, the increase of CXCL13 levels in peripheral blood and its association with the formation of TLSs within the metastatic lesions, emerges as a potential biomarker indicative of the therapeutic efficacy in mCRC patients undergoing oxaliplatin-based treatment.

Biomarkers and Signaling Pathways Implicated in the Pathogenesis of Idiopathic Multicentric Castleman Disease/Thrombocytopenia, Anasarca, Fever, Reticulin Fibrosis, Renal Insufficiency, and Organomegaly (TAFRO) Syndrome.

Idiopathic multicentric Castleman disease (iMCD) and TAFRO syndrome present a variety of symptoms thought to be caused by excessive inflammatory cytokines and chemokines, but the underlying mechanisms are unknown. iMCD is broadly classified into two types: iMCD-NOS and iMCD-TAFRO, which have distinct laboratory findings, pathological features, and responses to treatments. It is thought that iMCD-NOS, particularly the IPL type, responds favorably to IL-6 inhibitors due to its IL-6-centric profile. iMCD-TAFRO frequently progresses acutely and seriously, similar to TAFRO syndrome. Elevated levels of cytokines, including IL-1ß, TNF-α, IL-10, and IL-23, as well as chemokines like CXCL13 and CXCL-10 (especially in iMCD-TAFRO), SAA, and VEGF, have been linked to the disease's pathology. Recent research has identified key signaling pathways including PI3K/Akt/mTOR and JAK-STAT3, as well as those regulated by type I IFN, as crucial in iMCD-TAFRO. These results suggest that dominant pathways may vary between subtypes. Further research into the peripheral blood and lymph nodes is required to determine the disease spectrum of iMCD-NOS/iMCD-TAFRO/TAFRO syndrome.

Disturbed glycolipid metabolism activates CXCL13-CXCR5 axis in senescent TSCs to promote heterotopic ossification.

Heterotopic ossification (HO) occurs as a common complication after injury, while its risk factor and mechanism remain unclear, which restricts the development of pharmacological treatment. Clinical research suggests that diabetes mellitus (DM) patients are prone to developing HO in the tendon, but solid evidence and mechanical research are still needed. Here, we combined the clinical samples and the DM mice model to identify that disordered glycolipid metabolism aggravates the senescence of tendon-derived stem cells (TSCs) and promotes osteogenic differentiation. Then, combining the RNA-seq results of the aging tendon, we detected the abnormally activated autocrine CXCL13-CXCR5 axis in TSCs cultured in a high fat, high glucose (HFHG) environment and also in the aged tendon. Genetic inhibition of CXCL13 successfully alleviated HO formation in DM mice, providing a potential therapeutic target for suppressing HO formation in DM patients after trauma or surgery.

Mesenteric Lymphatic B Cells Migrate to the Intestine and Aggravate DSS-Induced Colitis via the CXCR5-CXCL13 Axis.

The pathogenesis of inflammatory bowel disease (IBD) is still unknown. Mesenteric lymphatics (MLs), which are closely related to the intestine in both anatomy and physiology, have been suggested to be involved in IBD. In the present study, we aim to investigate the effects of ML immune cells on IBD and explore the potential associated mechanisms. Acute colitis was induced in rats using dextran sulfate sodium salt (DSS). Mesenteric lymphangiogenesis, ML stenosis, and dilation were observed, with an increased proportion of MLB cells in DSS-induced colitis rats. The adoptive transfer of B cells isolated from ML (MLB) was employed to investigate their effects on colitis. MLB cells derived from DSS-induced colitis rats exhibited a higher propensity to migrate to the intestine. The proportion of colonic T cells was altered, along with the aggravated colitis induced by the adoptive transfer of MLB cells derived from DSS-induced colitis rats. RNA sequencing revealed increased Cxcr5 expression in MLB cells from colitis rats, while real-time PCR indicated an upregulation of its ligand Cxcl13 in the colon of colitis rats. These findings suggest that MLB cells may migrate to the intestine and aggravate colitis. In summary, colonic T cells respond to MLB cells from colitis rats, and MLB cells aggravate DSS-induced colitis via the CXCR5-CXCL13 axis.

Effects of anti-CD20 therapy on circulating and intrathecal follicular helper T cell subsets in multiple sclerosis.

Follicular helper T (Tfh) cells and their interplay with B cells likely contribute to the pathogenesis of relapsing-remitting multiple sclerosis (RRMS). Tfh cells are enriched in cerebrospinal fluid (CSF) in RRMS, but effects of anti-CD20 therapy are unknown. We investigated Tfh cells in controls, untreated and anti-CD20-treated patients with RRMS using flow cytometry. CSF Tfh cells were increased in untreated patients. Compared to paired blood samples, CD25- Tfh cells were enriched in CSF in RRMS, but not in controls. Contrast-enhancing brain MRI lesions and IgG index correlated with CSF CD25- Tfh cell frequency in untreated patients with RRMS. Anti-CD20 therapy reduced the numbers of circulating PD1+ Tfh cells and CD25- Tfh cells, and the frequency of CSF CD25- Tfh cells. The study suggests that CD25- Tfh cells are recruited to the CSF in RRMS, associated with focal inflammation, and are reduced by anti-CD20 therapy.

Immunology and targeted therapy in Castleman disease.

INTRODUCTION: Castleman disease (CD) is a benign lymphoproliferative disease causing severe systemic inflammation. Interleukin-6 (IL-6) is a major pathogenesis of multicentric CD (MCD), but only 30-60% of patients respond to IL-6 inhibitors. Novel agents for IL-6 inhibitor-refractory cases are needed. Clinical data and samples are being collected on a large scale and the clinical, pathological, and pathogenetic aspects are being elucidated. AREAS COVERED: The pathological and clinical classification of CD is outlined. Focusing on idiopathic MCD (iMCD), this review identifies therapeutic targets and summarizes currently recommended drugs and promising therapeutic candidates. EXPERT OPINION: The pathogenesis of MCD has been implicated in the activation of the Janus kinase (JAK)-transcriptional signaling activator (STAT) 3 pathway and the phosphatidylinositol 3-kinase (PI3K)/Akt/mechanical target of rapamycin (mTOR) signaling pathway. iMCD-TAFRO (thrombocytopenia, anasarca, fever/elevated CRP, reticulin myelofibrosis/renal dysfunction, organ enlargement) is resistant to IL-6 inhibitors, and cyclosporine and mTOR inhibitors are sometimes effective. JAK inhibitors and mTOR inhibitors may be therapeutic agents for iMCD. Recently, we have shown that peripheral helper T (Tph) cell abnormalities are at the core of iMCD pathogenesis. Therapies targeting chemokine (C-X-C motif) ligand 13 (CXCL13) produced by Tph cells and blocking the Tph-CXCL13-B cell pathway may satisfy unmet need in refractory cases.

CXCL13 as a biomarker in the diagnostics of European lyme Neuroborreliosis - A prospective multicentre study in Austria.

Background: 'Definite Neuroborreliosis (NB)' is diagnosed with the presence of NB-specific symptoms, cerebrospinal fluid (CSF) pleocytosis and an elevated Borrelia Burgdorferi antibody index. However, some diagnostic uncertainties exist. The B-cell chemokine CXCL13 represents an emerging biomarker for the diagnosis and treatment of NB because its intrathecal concentration rises prior to the Borrelia antibody index and drops rapidly after antibiotic therapy. Nevertheless, due to lacking prospective data, a definite CXCL13 cut-off for the diagnosis of NB is still pending. Objective: Definition of a CSF CXCL13 cut-off for the diagnosis of acute and untreated NB in a prospective study setting. Design and methods: This multicentre prospective study involved 6 neurological departments treating patients in the Lower Austria district (1.7 million inhabitants). The controls were patients scheduled for a spinal tap but not clinically diagnosed with NB. Demographic data, clinical characteristics and blood counts, as well as inflammatory CSF values and CSF CXCL13-concentration were analysed. Results: We recruited 440 adult patients, of whom 42 have been diagnosed as having an acute and untreated 'definite NB'. Three hundred ninety-eight patients were assigned to the control group. The median intrathecal CXCL13 concentration was 2384 pg/ml for patients with NB and 0 pg/ml for controls. The difference was highly statistically significant (P ≤ .001). A CSF CXCL13 cut-off of 271 pg/ml resulted in a sensitivity of 95.2% and a specificity of 97.2% for the confirmation or exclusion of NB. Conclusion: Based on our results, we propose a CSF CXCL13 cut-off of 271 pg/ml with Euroimmun-Elisa for the diagnosis of acute and untreated NB. Due to its high sensitivity and specificity, CXCL13 is a strong candidate biomarker for routine NB assessment, especially in clinically unclear cases.

Immune interplay from circulation to local lesion in pemphigus pathogenesis.

Pemphigus, a potentially lethal autoimmune skin disease, is mediated by desmoglein-specific antibodies, manifesting cutaneous and mucosal blisters and erosions. The interaction between multiple immune counterparts contributes to the progress of pemphigus. Currently, the emergence of bioinformatic analysis enables investigators to gain a global picture of the pemphigus immune network, based on the exhaustive pedigree annotation of multiple subsets. T helper subsets dominate the landscape as mentioned previously, and innate immune cells have been involved as well. Of particular interests is which phenotype of T cells orchestrates the autoimmune process and chronic inflammation in a certain condition. In this review, the circulatory and peripheral immune cells and cytokine components constituting the immune microenvironment are separately discussed to provide a perspective on pemphigus pathogenesis, with particular reference to insights provided by the bioinformation technique.

Unraveling the Heterogeneity of CD8+ T-Cell Subsets in Liver Cirrhosis: Implications for Disease Progression.

Background/Aims: : Liver cirrhosis involves chronic inflammation and progressive fibrosis. Among various immune cells, CD8+ T cells are considered a major contributor to hepatic inflammation and fibrosis. However, the exact molecular pathways governing CD8+ T-cell-mediated effects in cirrhosis remain unclear. Methods: : This study analyzed transcriptomic and single-cell sequencing data to elucidate CD8+ T-cell heterogeneity and implications in cirrhosis. Results: : Weighted gene co-expression analysis of bulk RNA-seq data revealed an association between cirrhosis severity and activated T-cell markers like HLA and chemokine genes. Furthermore, single-cell profiling uncovered eight CD8+ T-cell subtypes, notably, effector memory (Tem) and exhausted (Tex) T cells. Tex cells, defined by PDCD1, LAG3, and CXCL13 expression, were increased in cirrhosis, while Tem cells were decreased. Lineage tracing and differential analysis highlighted CXCL13+ Tex cells as a terminal, exhausted subtype of cells with roles in PD-1 signaling, glycolysis, and T-cell regulation. CXCL13+ Tex cells displayed T-cell exhaustion markers like PDCD1, HAVCR2, TIGIT, and TNFRSF9. Functional analysis implicated potential roles of these cells in immunosuppression. Finally, a CXCL13+ Tex-cell gene signature was found that correlated with cirrhosis severity and poorer prognosis of liver cancer. Conclusions: : In summary, this comprehensive study defines specialized CD8+ T-cell subpopulations in cirrhosis, with CXCL13+ Tex cells displaying an exhausted phenotype associated with immune dysregulation and advanced disease. Key genes and pathways regulating these cells present potential therapeutic targets.

Moesin deficiency leads to lupus-like nephritis with accumulation of CXCL13-producing patrolling monocytes.

Moesin is a member of the ezrin-radixin-moesin (ERM) family of proteins that link plasma membrane proteins to the cortical cytoskeleton and thus regulate diverse cellular processes. Mutations in the human moesin gene cause a primary immunodeficiency called X-linked moesin-associated immunodeficiency (X-MAID), which may be complicated by an autoimmune phenotype with kidney involvement. We previously reported that moesin-deficient mice exhibit lymphopenia similar to that of X-MAID and develop a lupus-like autoimmune phenotype with age. However, the mechanism through which moesin defects cause kidney pathology remains obscure. Here, we characterized immune cell infiltration and chemokine expression in the kidney of moesin-deficient mice. We found accumulation of CD4+ T and CD11b+ myeloid cells and high expression of CXCL13, whose upregulation was detected before the onset of overt nephritis. CD4+ T cell population contained IFN-γ-producing effectors and expressed the CXCL13 receptor CXCR5. Among myeloid cells, Ly6Clo patrolling monocytes and MHCIIlo macrophages markedly accumulated in moesin-deficient kidneys and expressed high CXCL13 levels, implicating the CXCL13-CXCR5 axis in nephritis development. Functionally, Ly6Clo monocytes from moesin-deficient mice showed reduced migration toward sphingosine 1-phosphate. These findings suggest that moesin plays a role in regulating patrolling monocyte homeostasis, and that its defects lead to nephritis associated with accumulation of CXCL13-producing monocytes and macrophages.

Beyond T cell toxicity - Intrathecal chemokine CXCL13 indicating B cell involvement in immune-related adverse events following checkpoint inhibition: A two-case series and literature review.

BACKGROUND AND PURPOSE: This study was undertaken to raise awareness of a role of B cells in immune checkpoint inhibitor (ICI)-associated neurological immune-related adverse events (nirAE). METHODS: A systematic literature review was made, with case observations of a melanoma and a non-small cell lung cancer (NSCLC) patient who developed ICI-associated nirAE with cerebrospinal fluid (CSF) findings indicating B cell involvement. RESULTS: Two patients receiving ipilimumab/nivolumab for melanoma and chemotherapy/pembrolizumab for NSCLC developed nirAE in the form of myocarditis/myositis/myasthenia gravis overlap syndrome (triple M) and cerebellitis plus longitudinal transverse myelitis (c-LETM), respectively. Intrathecal inflammation with chemokine C-X-C motif ligand (CXCL13) elevation was present in both patients; the triple M case had acetylcholine receptor antibodies, antititin reactivity, altered CD4/CD8 T cell ratio in blood, and depressed programmed death-1 (PD-1) expression on CSF T cells; the c-LETM case showed intrathecal antibody production and plasma cells. Both patients insufficiently responded to first-line treatment. The NSCLC case improved upon administration of B cell-depleting therapy with rituximab, whereas the melanoma patient died before escalation therapy was initiated. Literature research revealed one additional ICI-associated LETM case with intrathecal CXCL13 elevation, three cases with ICI-associated aquaporin-4 antibody neuromyelitis spectrum disorder, and evidence of B cell-mediated toxicity based on antibody-mediated immune pathologies in ICI-associated immune-related adverse events. CONCLUSIONS: The case observations highlight the plethora of uncertainties in diagnosis and treatment of ICI-associated nirAE, exemplify the heterogeneity of immune mechanisms involved, and suggest a role of B cells, which may be underdiagnosed. Intrathecal CXCL13 may serve as a biomarker of B cell involvement in nirAE, supported by intrathecal immunoglobulin synthesis, presence of plasma cells, and/or recruitment of cognate immune cells.

Tertiary Lymphoid Structure-Associated B Cells Enhance CXCL13+CD103+CD8+ Tissue-Resident Memory T-Cell Response to Programmed Cell Death Protein 1 Blockade in Cancer Immunotherapy.

BACKGROUND & AIMS: Although the presence of tertiary lymphoid structures (TLS) correlates with positive responses to immunotherapy in many solid malignancies, the mechanism by which TLS enhances antitumor immunity is not well understood. The present study aimed to investigate the underlying cross talk circuits between B cells and tissue-resident memory T (Trm) cells within the TLS and to understand their role in the context of immunotherapy. METHODS: Immunostaining and H&E staining of TLS and chemokine (C-X-C motif) ligand 13 (CXCL13)+ cluster of differentiation (CD)103+CD8+ Trm cells were performed on tumor sections from patients with gastric cancer (GC). The mechanism of communication between B cells and CXCL13+CD103+CD8+ Trm cells was determined in vitro and in vivo. The effect of CXCL13+CD103+CD8+ Trm cells in suppressing tumor growth was evaluated through anti-programmed cell death protein (PD)-1 therapy. RESULTS: The presence of TLS and CXCL13+CD103+CD8+ Trm cells in tumor tissues favored a superior response to anti-PD-1 therapy in patients with GC. Additionally, our research identified that activated B cells enhanced CXCL13 and granzyme B secretion by CD103+CD8+ Trm cells. Mechanistically, B cells facilitated the glycolysis of CD103+CD8+ Trm cells through the lymphotoxin-α/tumor necrosis factor receptor 2 (TNFR2) axis, and the mechanistic target of rapamycin signaling pathway played a critical role in CD103+CD8+ Trm cells glycolysis during this process. Moreover, the presence of TLS and CXCL13+CD103+CD8+ Trm cells correlated with potent responsiveness to anti-PD-1 therapy in a TNFR2-dependent manner. CONCLUSIONS: This study further reveals a crucial role for cellular communication between TLS-associated B cell and CXCL13+CD103+CD8+ Trm cells in antitumor immunity, providing valuable insights into the potential use of the lymphotoxin-α/TNFR2 axis within CXCL13+CD103+CD8+ Trm cells for advancing immunotherapy strategies in GC.

Prognostic relevance of the C-X-C motif chemokine ligand 13 and interleukin-8 in predicting the transition from clinically isolated syndrome to multiple sclerosis.

The initial phase of multiple sclerosis (MS), often known as clinically isolated syndrome (CIS), is a critical period for identifying individuals at high risk of progressing to full-blown MS and initiating timely treatment. In this study, we aimed to evaluate the prognostic value of C-X-C motif chemokine ligand 13 (CXCL13) and interleukin-8 (IL-8) as potential markers for CIS patients' conversion to MS. Our study encompassed patients with CIS, those with relapsing-remitting MS (RRMS), and control subjects, with sample analysis conducted on both cerebrospinal fluid (CSF) and serum. Patients were categorized into four groups: CIS-CIS (no MS development within 2 years), CIS-RRMS (conversion to RRMS within 2 years), RRMS (already diagnosed), and a control group (CG) with noninflammatory central nervous system disorders. Results showed significantly elevated levels of CXCL13 in CSF across all patient groups compared with the CG (p < 0.0001, Kruskal-Wallis test). Although CXCL13 concentrations were slightly higher in the CIS-RRMS group, statistical significance was not reached. Similarly, significantly higher levels of IL-8 were detected in CSF samples from all patient groups compared with the CG (p < 0.0001, Kruskal-Wallis test). Receiver operating characteristic analysis in the CIS-RRMS group identified both CXCL13 (area under receiver operating characteristic curve = .959) and IL-8 (area under receiver operating characteristic curve = .939) in CSF as significant predictors of CIS to RRMS conversion. In conclusion, our study suggests a trend towards elevated CSF IL-8 and CSF CXCL13 levels in CIS patients progressing to RRMS. These findings emphasize the importance of identifying prognostic markers to guide appropriate treatment strategies for individuals in the early stages of MS.