Secondary and ectopic lymphoid tissue responses in rheumatoid arthritis: from inflammation to autoimmunity and tissue damage/remodeling

Tertiary lymphoid organs in wild boar exposed to a low-virulent isolate of African swine fever virus

Despite the great interest in the development of a vaccine against African swine fever (ASF) in wild boar, the immunological mechanisms that induce animal protection are still unknown. For this purpose, tertiary lymphoid organs (TLOs) of wild boar were characterised and compared with mucosa-associated lymphoid tissues (MALTs) by histopathology, histomorphometry and immunohistochemistry (CD3, CD79, PAX5, LYVE1, fibronectin). In addition, real-time polymerase chain reaction (qPCR) and immunohistochemistry (p72) were used to evaluate the presence of ASF virus (ASFV) in blood and tissues samples, respectively. TLOs were observed in animals infected with a low-virulent ASFV isolate (LVI), animals co-infected with low and high-virulent ASFV isolates (LVI-HVI) and animals infected only with the high virulence isolate (HVI). TLOs in LVI and LVI-HVI groups were located adjacent to the mucosa and presented a similar structure to MALT. Immunoexpresion of p72 observed in the inflammatory cells adjacent to TLOs/MALTs confirmed its development and reactivity generated by ASF attenuated isolates. Immunohistochemical evaluation, based on cellular composition (T and B lymphocytes), and histomorphometrical study revealed a more pronounced maturation of TLOs/MALTs in the LVI-HVI group. It is currently unclear whether these formations play a protective role by contributing to local immunity in chronic inflammatory diseases. However, the structural similarities between TLOs and MALTs and the location of TLOs close to the mucosa suggest that they may perform a similar function, facilitating a local protective response. Nevertheless, further investigations are warranted to assess the cellular and humoral dynamics of these lymphoid organs induced by attenuated isolates.

Identification of a risk score model based on tertiary lymphoid structure-related genes for predicting immunotherapy efficacy in non-small cell lung cancer

BACKGROUND

Tertiary lymphoid structures (TLSs) affect the prognosis and efficacy of immunotherapy in patients with non-small cell lung cancer (NSCLC), but the underlying mechanisms are not well understood.

METHODS

TLSs were identified and categorized online from the Cancer Digital Slide Archive (CDSA). Overall survival (OS) and disease-free survival (DFS) were analyzed. GSE111414 and GSE136961 datasets were downloaded from the GEO database. GSVA, GO and KEGG were used to explore the signaling pathways. Immune cell infiltration was analyzed by xCell, ssGSEA and MCP-counter. The analysis of WGCNA, Lasso and multivariate cox regression were conducted to develop a gene risk score model based on the SU2C-MARK cohort.

RESULTS

TLS-positive was a protective factor for OS according to multivariate cox regression analysis (p = 0.029). Both the TLS-positive and TLS-mature groups exhibited genes enrichment in immune activation pathways. The TLS-mature group showed more activated dendritic cell infiltration than the TLS-immature group. We screened TLS-related genes using WGCNA. Lasso and multivariate cox regression analysis were used to construct a five-genes (RGS8, RUF4, HLA-DQB2, THEMIS, and TRBV12-5) risk score model, the progression free survival (PFS) and OS of patients in the low-risk group were markedly superior to those in the high-risk group (p < 0.0001; p = 0.0015, respectively). Calibration and ROC curves indicated that the combined model with gene risk score and clinical features could predict the PFS of patients who have received immunotherapy more accurately than a single clinical factor.

CONCLUSIONS

Our data suggested a pivotal role of TLSs formation in survival outcome and immunotherapy response of NSCLC patients. Tumors with mature TLS formation showed more activated immune microenvironment. In addition, the model constructed by TLS-related genes could predict the response to immunotherapy and is meaningful for clinical decision-making.

Tertiary lymphoid structural heterogeneity determines tumour immunity and prospects for clinical application

Tertiary lymphoid structures (TLS) are clusters of immune cells that resemble and function similarly to secondary lymphoid organs (SLOs). While TLS is generally associated with an anti-tumour immune response in most cancer types, it has also been observed to act as a pro-tumour immune response. The heterogeneity of TLS function is largely determined by the composition of tumour-infiltrating lymphocytes (TILs) and the balance of cell subsets within the tumour-associated TLS (TA-TLS). TA-TLS of varying maturity, density, and location may have opposing effects on tumour immunity. Higher maturity and/or higher density TLS are often associated with favorable clinical outcomes and immunotherapeutic response, mainly due to crosstalk between different proportions of immune cell subpopulations in TA-TLS. Therefore, TLS can be used as a marker to predict the efficacy of immunotherapy in immune checkpoint blockade (ICB). Developing efficient imaging and induction methods to study TA-TLS is crucial for enhancing anti-tumour immunity. The integration of imaging techniques with biological materials, including nanoprobes and hydrogels, alongside artificial intelligence (AI), enables non-invasive in vivo visualization of TLS. In this review, we explore the dynamic interactions among T and B cell subpopulations of varying phenotypes that contribute to the structural and functional diversity of TLS, examining both existing and emerging techniques for TLS imaging and induction, focusing on cancer immunotherapies and biomaterials. We also highlight novel therapeutic approaches of TLS that are being explored with the aim of increasing ICB treatment efficacy and predicting prognosis.

Pathophysiology and stratification of treatment-resistant rheumatoid arthritis

Early diagnosis and timely therapeutic intervention are clinical challenges of rheumatoid arthritis (RA), especially for treatment-resistant or difficult-to-treat patients. Little is known about the immunological mechanisms involved in refractory RA. In this review, we summarize previous research findings on the immunological mechanisms of treatment-resistant RA. Genetic prediction of treatment-resistant RA is challenging. Patients with and without anti-cyclic citrullinated peptide autoantibodies are considered part of distinct subgroups, especially regarding long-term clinical prognosis and treatment responses. B cells, T cells and other immune cells and fibroblasts are of pathophysiological importance and are associated with treatment responses. Finally, we propose a new hypothesis that stratifies patients with RA into two subgroups with distinct immunological pathologies based on our recent immunomics analysis of RA. One RA subgroup with a favorable prognosis is characterized by increased interferon signaling. Another subgroup with a worse prognosis is characterized by enhanced acquired immune responses. Increases in dendritic cell precursors and diversified autoreactive anti-modified protein antibodies may have pathophysiological roles, especially in the latter subgroup. These findings that improve treatment response predictions might contribute to future precision medicine for RA.

Mapping spatial heterogeneity in gastric cancer microenvironment

Gastric cancer (GC) is difficult to characterize due to its heterogeneity, and the complicated heterogeneity leads to the difficulty of precisely targeted therapy. The spatially heterogeneous composition plays a crucial role in GC onset, progression, treatment efficacy, and drug resistance. In recent years, the technological advancements in spatial omics has shifted our understanding of the tumor microenvironment (TME) from cancer-centered model to a dynamic and variant whole. In this review, we concentrated on the spatial heterogeneity within the primary lesions and between the primary and metastatic lesions of GC through the TME heterogeneity including the tertiary lymphoid structures (TLSs), the uniquely spatial organization. Meanwhile, the immune phenotype based on spatial distribution was also outlined. Furthermore, we recapitulated the clinical treatment in mediating spatial heterogeneity in GC, hoping to provide a systematic view of how spatial information could be integrated into anti-cancer immunity.

Tertiary lymphoid structures as local perpetuators of organ-specific immune injury: implication for lupus nephritis

In response to inflammatory stimuli in conditions such as autoimmune disorders, infections and cancers, immune cells organize in nonlymphoid tissues, which resemble secondary lymphoid organs. Such immune cell clusters are called tertiary lymphoid structures (TLS). Here, we describe the potential role of TLS in the pathogenesis of autoimmune disease, focusing on lupus nephritis, a condition that incurs major morbidity and mortality. In the kidneys of patients and animals with lupus nephritis, the presence of immune cell aggregates with similar cell composition, structure, and gene signature as lymph nodes and of lymphoid tissue-inducer and -organizer cells, along with evidence of communication between stromal and immune cells are indicative of the formation of TLS. TLS formation in kidneys affected by lupus may be instigated by local increases in lymphorganogenic chemokines such as CXCL13, and in molecules associated with leukocyte migration and vascularization. Importantly, the presence of TLS in kidneys is associated with severe tubulointerstitial inflammation, higher disease activity and chronicity indices, and poor response to treatment in patients with lupus nephritis. TLS may contribute to the pathogenesis of lupus nephritis by increasing local IFN-I production, facilitating the recruitment and supporting survival of autoreactive B cells, maintaining local production of systemic autoantibodies such as anti-dsDNA and anti-Sm/RNP autoantibodies, and initiating epitope spreading to local autoantigens. Resolution of TLS, along with improvement in lupus, by treating animals with soluble BAFF receptor, docosahexaenoic acid, complement inhibitor C4BP(β-), S1P1 receptor modulator Cenerimod, dexamethasone, and anti-CXCL13 further emphasizes a role of TLS in the pathogenesis of lupus. However, the mechanisms underlying TLS formation and their roles in the pathogenesis of lupus nephritis are not fully comprehended. Furthermore, the lack of non-invasive methods to visualize/quantify TLS in kidneys is also a major hurdle; however, recent success in visualizing TLS in lupus-prone mice by photon emission computed tomography provides hope for early detection and manipulation of TLS.

Tertiary lymphoid structures and B cells: An intratumoral immunity cycle

The generation of anti-tumor immunity in the draining lymph nodes is known as the cancer immunity cycle. Accumulating evidence supports the occurrence of such a cycle at tumor sites in the context of chronic inflammation. Here, we review the role of tertiary lymphoid structures (TLS) in the generation of T and B cell immunities, focusing on the impact of B cells that undergo full maturation, resulting in the generation of plasma cells (PCs) producing high-affinity IgG and IgA antibodies. In this context, we propose that antibodies binding to tumor cells induce macrophage or natural killer (NK)-cell-dependent apoptosis. Subsequently, released antigen-antibody complexes are internalized and processed by dendritic cells (DCs), amplifying antigen presentation to T cells. Immune complexes may also be fixed by follicular DCs (FDCs) in TLS, thereby increasing memory B cell responses. This amplification loop creates an intra-tumoral immunity cycle, capable of increasing sensitivity of tumors to immunotherapy even in cancers with low mutational burden.

The Role of CD4 T Cell Help in CD8 T Cell Differentiation and Function During Chronic Infection and Cancer

CD4 and CD8 T cells are key players in the immune response against both pathogenic infections and cancer. CD4 T cells provide help to CD8 T cells via multiple mechanisms, including licensing dendritic cells (DCs), co-stimulation, and cytokine production. During acute infection and vaccination, CD4 T cell help is important for the development of CD8 T cell memory. However, during chronic viral infection and cancer, CD4 helper T cells are critical for the sustained effector CD8 T cell response, through a variety of mechanisms. In this review, we focus on T cell responses in conditions of chronic Ag stimulation, such as chronic viral infection and cancer. In particular, we address the significant role of CD4 T cell help in promoting effector CD8 T cell responses, emerging techniques that can be utilized to further our understanding of how these interactions may take place in the context of tertiary lymphoid structures, and how this key information can be harnessed for therapeutic utility against cancer.

A novel monoclonal antibody against 6-sulfo sialyl Lewis x glycans attenuates murine allergic rhinitis by suppressing Th2 immune responses

Lymphocyte homing is mediated by the interaction between L-selectin on lymphocytes and its glycoprotein ligands modified with 6-sulfo sialyl Lewis x (6-sulfo sLex) glycans on high endothelial venules (HEVs) in peripheral lymph nodes (PLNs). However, the lack of specific antibodies reactive with both human and mouse 6-sulfo sLex has limited our understanding of its function in vivo. Here, we generated a novel monoclonal antibody, termed SF1, that specifically reacts with 6-sulfo sLex expressed on HEVs in both species in a manner dependent on sulfate, fucose, and sialic acid modifications. Glycan array and biolayer interferometry analyses indicated that SF1 specifically bound to 6-sulfo sLex with a dissociation constant of 6.09 × 10-9 M. SF1 specifically bound to four glycoproteins from PLNs corresponding to the molecular sizes of L-selectin ligand glycoproteins. Consistently, SF1 inhibited L-selectin-dependent lymphocyte rolling on 6-sulfo sLex-expressing cells ex vivo and lymphocyte homing to PLNs and nasal-associated lymphoid tissues in vivo. Furthermore, SF1 significantly attenuated ovalbumin-induced allergic rhinitis in mice in association with significant suppression of Th2 immune responses. Collectively, these results suggest that SF1 can be useful for the functional analysis of 6-sulfo sLex and may potentially serve as a novel therapeutic agent against immune-related diseases.

Epstein-Barr virus-acquired immunodeficiency in myalgic encephalomyelitis-Is it present in long COVID?

Both myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) and long COVID (LC) are characterized by similar immunological alterations, persistence of chronic viral infection, autoimmunity, chronic inflammatory state, viral reactivation, hypocortisolism, and microclot formation. They also present with similar symptoms such as asthenia, exercise intolerance, sleep disorders, cognitive dysfunction, and neurological and gastrointestinal complaints. In addition, both pathologies present Epstein-Barr virus (EBV) reactivation, indicating the possibility of this virus being the link between both pathologies. Therefore, we propose that latency and recurrent EBV reactivation could generate an acquired immunodeficiency syndrome in three steps: first, an acquired EBV immunodeficiency develops in individuals with "weak" EBV HLA-II haplotypes, which prevents the control of latency I cells. Second, ectopic lymphoid structures with EBV latency form in different tissues (including the CNS), promoting inflammatory responses and further impairment of cell-mediated immunity. Finally, immune exhaustion occurs due to chronic exposure to viral antigens, with consolidation of the disease. In the case of LC, prior to the first step, there is the possibility of previous SARS-CoV-2 infection in individuals with "weak" HLA-II haplotypes against this virus and/or EBV.

Tertiary lymphoid structures and B lymphocytes: a promising therapeutic strategy to fight cancer

Tertiary lymphoid structures (TLSs) are clusters of lymphoid cells with an organization that resembles that of secondary lymphoid organs. Both structures share common developmental characteristics, although TLSs usually appear in chronically inflamed non-lymphoid tissues, such as tumors. TLSs contain diverse types of immune cells, with varying degrees of spatial organization that represent different stages of maturation. These structures support both humoral and cellular immune responses, thus the correlation between the existence of TLS and clinical outcomes in cancer patients has been extensively studied. The finding that TLSs are associated with better prognosis in some types of cancer has led to the design of therapeutic strategies based on promoting the formation of these structures. Agents such as chemokines, cytokines, antibodies and cancer vaccines have been used in combination with traditional antitumor treatments to enhance TLS generation, with good results. The induction of TLS formation therefore represents a novel and promising avenue for the treatment of a number of tumor types.

Immune surveillance and humoral immune responses in kidney transplantation - A look back at T follicular helper cells

T follicular helper cells comprise a specialized, heterogeneous subset of immune-competent T helper cells capable of influencing B cell responses in lymphoid tissues. In physiology, for example in response to microbial challenges or vaccination, this interaction chiefly results in the production of protecting antibodies and humoral memory. In the context of kidney transplantation, however, immune surveillance provided by T follicular helper cells can take a life of its own despite matching of human leukocyte antigens and employing the latest immunosuppressive regiments. This puts kidney transplant recipients at risk of subclinical and clinical rejection episodes with a potential risk for allograft loss. In this review, the current understanding of immune surveillance provided by T follicular helper cells is briefly described in physiological responses to contrast those pathological responses observed after kidney transplantation. Sensitization of T follicular helper cells with the subsequent emergence of detectable donor-specific human leukocyte antigen antibodies, non-human leukocyte antigen antibodies their implication for kidney transplantation and lessons learnt from other transplantation "settings" with special attention to antibody-mediated rejection will be addressed.

Emerging synovial cell states in rheumatoid arthritis as potential therapeutic targets

PURPOSE OF REVIEW

To summarize recently discovered novel cell states in rheumatoid arthritis (RA) synovium that could have important implications for disease treatment.

RECENT FINDINGS

The use of multiomic technologies, including single-cell and spatial transcriptomics and mass cytometry, has led to the discovery of several novel cell states, which could have important implications for the treatment of RA. These cells can be found in patient blood, synovial fluid, or synovial tissue and span several immune cell subsets as well as stromal cell types. These diverse cell states may represent the targets of current or future therapeutics, while their fluctuations may inform the ideal timing for therapy. Future efforts are needed to implicate how each cell state functions in the pathophysiologic network within affected joints and how medications perturb each cell state and ultimately the tissue.

SUMMARY

Multiomic molecular technologies have afforded the discovery of numerous novel cellular states in RA synovium; the next challenge will be to link these states to pathophysiology and treatment response.

New insights into follicular regulatory T cells in the intestinal and tumor microenvironments

Follicular regulatory T (Tfr) cells are a novel and unique subset of effector regulatory T (Treg) cells that are located in germinal centers (GCs). Tfr cells express transcription profiles that are characteristic of both follicular helper T (Tfh) cells and Treg cells and negatively regulate GC reactions, including Tfh cell activation and cytokine production, class switch recombination and B cell activation. Evidence also shows that Tfr cells have specific characteristics in different local immune microenvironments. This review focuses on the regulation of Tfr cell differentiation and function in unique local immune microenvironments, including the intestine and tumor.

Tertiary lymphoid structures are critical for cancer prognosis and therapeutic response

Tertiary lymphoid structures (TLSs) are ectopic lymphocyte aggregates that form at sites of chronic inflammation, including cancers, in non-lymphoid tissues. Although the formation of TLSs is similar to that of secondary lymphoid organs, the pathogenic factors leading to TLS formation in cancerous tissues and the mechanisms underlying the role of these structures in the intra-tumoral adaptive antitumor immune response are not fully understood. The presence of TLSs may impact patient prognosis and treatment outcomes. This review examines the current understanding of TLSs in cancers, including their composition and formation as well as their potential to predict prognosis and therapeutic efficacy. We also summarize strategies to induce TLS formation for cancer treatment.

Podoplanin: Its roles and functions in neurological diseases and brain cancers

Podoplanin is a small mucin-like glycoprotein involved in several physiological and pathological processes in the brain including development, angiogenesis, tumors, ischemic stroke and other neurological disorders. Podoplanin expression is upregulated in different cell types including choroid plexus epithelial cells, glial cells, as well as periphery infiltrated immune cells during brain development and neurological disorders. As a transmembrane protein, podoplanin interacts with other molecules in the same or neighboring cells. In the past, a lot of studies reported a pleiotropic role of podoplanin in the modulation of thrombosis, inflammation, lymphangiogenesis, angiogenesis, immune surveillance, epithelial mesenchymal transition, as well as extracellular matrix remodeling in periphery, which have been well summarized and discussed. Recently, mounting evidence demonstrates the distribution and function of this molecule in brain development and neurological disorders. In this review, we summarize the research progresses in understanding the roles and mechanisms of podoplanin in the development and disorders of the nervous system. The challenges of podoplanin-targeted approaches for disease prognosis and preventions are also discussed.

The CXCL13/CXCR5 Immune Axis in Health and Disease—Implications for Intrathecal B Cell Activities in Neuroinflammation

The chemokine C-X-C- ligand 13 (CXCL13) is a major B cell chemoattractant to B cell follicles in secondary lymphoid organs (SLO) that proposedly recruits B cells to the cerebrospinal fluid (CSF) during neuroinflammation. CXCR5, the cognate receptor of CXCL13, is expressed on B cells and certain T cell subsets, in particular T follicular helper cells (Tfh cells), enabling them to follow CXCL13 gradients towards B cell follicles for spatial proximity, a prerequisite for productive T cell–B cell interaction. Tfh cells are essential contributors to B cell proliferation, differentiation, and high-affinity antibody synthesis and are required for germinal center formation and maintenance. Circulating Tfh cells (cTfh) have been observed in the peripheral blood and CSF. Furthermore, CXCL13/CXCR5-associated immune activities organize and shape adaptive B cell-related immune responses outside of SLO via the formation of ectopic lymphoid structures in inflamed tissues, including the central nervous system (CNS). This review summarizes the recent advances in our understanding of the CXCL13/CXCR5 immune axis and its role in vaccination, autoimmunity, and infection with a special focus on its relevance for intrathecal B cell activities in inflammatory CNS diseases.

AIM2-inflammasome role in systemic lupus erythematous and rheumatoid arthritis

The inflammasome AIM2 regulates multiple aspects of innate immune functions and serves as a critical mediator of inflammatory responses. AIM2 inflammasome activation leads to the production of pro-inflammatory cytokines, IL-1β and IL-18 and participates triggering a pyroptosis response needed to counteract excessive cell proliferation. In addition, AIM2 expression and activation is wide regulated since alteration in its activity may derived in pathological consequences. Consequently, deregulated AIM2 activation contributes to the pathogenic processes of various inflammatory diseases. In this review, we will discuss the activation and function of AIM2 inflammasome, as well as its contribution in rheumatoid arthritis and systemic lupus erythematous pathology. Finally, we highlight the participation of the AIM2-inflammasome at the level of joint in rheumatoid arthritis and at kidney in systemic lupus erythematous. The development of therapeutic strategies based on modulation of AIM2-inflammasome activity should have a tissue-specific focus.

CD4+ Cytotoxic T Cells Involved in the Development of EBV-Associated Diseases

Activated cytotoxic CD4 T cells (HLA-DR+) play an important role in the control of EBV infection, especially in cells with latency I (EBNA-1). One of the evasion mechanisms of these latency cells is generated by gp42, which, via peripherally binding to the β1 domain of the β chain of MHC class II (HLA-DQ, -DR, and -DP) of the infected B lymphocyte, can block/alter the HLA class II/T-cell receptor (TCR) interaction, and confer an increased level of susceptibility towards the development of EBV-associated autoimmune diseases or cancer in genetically predisposed individuals (HLA-DRB1* and DQB1* alleles). The main developments predisposing the factors of these diseases are: EBV infection; HLA class II risk alleles; sex; and tissue that is infiltrated with EBV-latent cells, forming ectopic lymphoid structures. Therefore, there is a need to identify treatments for eliminating cells with EBV latency, because the current treatments (e.g., antivirals and rituximab) are ineffective.

Stromal and Immune Cell Dynamics in Tumor Associated Tertiary Lymphoid Structures and Anti-Tumor Immune Responses

Tertiary lymphoid structures (TLS) are ectopic lymphoid organs that have been observed in chronic inflammatory conditions including cancer, where they are thought to exert a positive effect on prognosis. Both immune and non-immune cells participate in the genesis of TLS by establishing complex cross-talks requiring both soluble factors and cell-to-cell contact. Several immune cell types, including T follicular helper cells (Tfh), regulatory T cells (Tregs), and myeloid cells, may accumulate in TLS, possibly promoting or inhibiting their development. In this manuscript, we propose to review the available evidence regarding specific aspects of the TLS formation in solid cancers, including 1) the role of stromal cell composition and architecture in the recruitment of specific immune subpopulations and the formation of immune cell aggregates; 2) the contribution of the myeloid compartment (macrophages and neutrophils) to the development of antibody responses and the TLS formation; 3) the immunological and metabolic mechanisms dictating recruitment, expansion and plasticity of Tregs into T follicular regulatory cells, which are potentially sensitive to immunotherapeutic strategies directed to costimulatory receptors or checkpoint molecules.

Immunofibroblasts regulate LTα3 expression in tertiary lymphoid structures in a pathway dependent on ICOS/ICOSL interaction

Immunofibroblasts have been described within tertiary lymphoid structures (TLS) that regulate lymphocyte aggregation at sites of chronic inflammation. Here we report, for the first time, an immunoregulatory property of this population, dependent on inducible T-cell co-stimulator ligand and its ligand (ICOS/ICOS-L). During inflammation, immunofibroblasts, alongside other antigen presenting cells, like dendritic cells (DCs), upregulate ICOSL, binding incoming ICOS + T cells and inducing LTα3 production that, in turn, drives the chemokine production required for TLS assembly via TNFRI/II engagement. Pharmacological or genetic blocking of ICOS/ICOS-L interaction results in defective LTα expression, abrogating both lymphoid chemokine production and TLS formation. These data provide evidence of a previously unknown function for ICOSL-ICOS interaction, unveil a novel immunomodulatory function for immunofibroblasts, and reveal a key regulatory function of LTα3, both as biomarker of TLS establishment and as first driver of TLS formation and maintenance in mice and humans.

Dynamic spectrum of ectopic lymphoid B cell activation and hypermutation in the RA synovium characterized by NR4A nuclear receptor expression

Ectopic lymphoid structures (ELS) can develop in rheumatoid arthritis (RA) synovial tissue, but the precise pathways of B cell activation and selection are not well understood. Here, we identify a synovial B cell population characterized by co-expression of a family of orphan nuclear receptors (NR4A1-3), which is highly enriched in RA synovial tissue. A transcriptomic profile of NR4A synovial B cells significantly overlaps with germinal center light zone B cells and an accrual of somatic hypermutation that correlates with loss of naive B cell state. NR4A B cells co-express lymphotoxins α and β and IL-6, supporting functions in ELS promotion. Expanded and shared clones between synovial NR4A B cells and plasma cells and the rapid upregulation with BCR stimulation point to in situ differentiation. Together, we identify a dynamic progression of B cell activation in RA synovial ELS, with NR4A transcription factors having an important role in local adaptive immune responses.

The role of B cells and their interactions with stromal cells in the context of inflammatory autoimmune diseases

Interactions between B cells and stromal cells have essential functions in immune cell development and responses. During chronic inflammation, the pro-inflammatory microenvironment leads to changes in stromal cells, which acquire a pathogenic phenotype specific to each organ and disease. B cells are recruited to the site of inflammation and interact with these pathogenic stromal cells contributing to the disease's severity. In addition to producing autoantibodies, B cells contribute to the pathogenesis of autoimmune inflammatory diseases by serving as professional antigen-presenting cells, producing cytokines, and through additional mechanisms. This review describes the role of B cells and their interactions with stromal cells in chronic inflammation, with a focus on human disease, using three selected autoimmune inflammatory diseases: rheumatoid arthritis, systemic lupus erythematosus and multiple sclerosis. Understanding B cells roles and their interaction with stromal cells will help develop new therapeutic options for the treatment of autoimmune diseases.

Activated Peripheral Blood B Cells in Rheumatoid Arthritis and Their Relationship to Anti-Tumor Necrosis Factor Treatment and Response: A Randomized Clinical Trial of the Effects of Anti-Tumor Necrosis Factor on B Cells

OBJECTIVE

B cells can become activated in germinal center (GC) reactions in secondary lymphoid tissue and in ectopic GCs in rheumatoid arthritis (RA) synovium that may be tumor necrosis factor (TNF) and lymphotoxin (LT) dependent. This study was undertaken to characterize the peripheral B cell compartment longitudinally during anti-TNF therapy in RA.

METHODS

Participants were randomized in a 2:1 ratio to receive standard dosing regimens of etanercept (n = 43) or adalimumab (n = 20) for 24 weeks. Eligible participants met the American College of Rheumatology 1987 criteria for RA, had clinically active disease (Disease Activity Score in 28 joints >4.4), and were receiving stable doses of methotrexate. The primary mechanistic end point was the change in switched memory B cell fraction from baseline to week 12 in each treatment group.

RESULTS

B cell subsets remained surprisingly stable over the course of the study regardless of treatment group, with no significant change in memory B cells. Blockade of TNF and LT with etanercept compared to blockade of TNF alone with adalimumab did not translate into significant differences in clinical response. The frequencies of multiple activated B cell populations, including CD21- double-negative memory and activated naive B cells, were higher in RA nonresponders at all time points, and CD95+ activated B cell frequencies were increased in patients receiving anti-TNF treatment in the nonresponder group. In contrast, frequencies of transitional B cells-a putative regulatory subset-were lower in the nonresponders.

CONCLUSION

Overall, our results support the notion that peripheral blood B cell subsets are remarkably stable in RA and not differentially impacted by dual blockade of TNF and LT with etanercept or single blockade of TNF with adalimumab. Activated B cells do associate with a less robust response.

Tertiary lymphoid structures in cancer

Ectopic lymphoid aggregates, termed tertiary lymphoid structures (TLSs), are formed in numerous cancer types, and, with few exceptions, their presence is associated with superior prognosis and response to immunotherapy. In spite of their presumed importance, the triggers that lead to TLS formation in cancer tissue and the contribution of these structures to intratumoral immune responses remain incompletely understood. Here, we discuss the present knowledge on TLSs in cancer, focusing on (i) the drivers of TLS formation, (ii) the function and contribution of TLSs to the antitumor immune response, and (iii) the potential of TLSs as therapeutic targets in human cancers.

Fibroblast pathology in inflammatory joint disease

Rheumatoid arthritis is an immune-mediated inflammatory disease in which fibroblasts contribute to both joint damage and inflammation. Fibroblasts are a major cell constituent of the lining of the joint cavity called the synovial membrane. Under resting conditions, fibroblasts have an important role in maintaining joint homeostasis, producing extracellular matrix and joint lubricants. In contrast, during joint inflammation, fibroblasts contribute to disease pathology by producing pathogenic levels of inflammatory mediators that drive the recruitment and retention of inflammatory cells within the joint. Recent advances in single-cell profiling techniques have transformed our ability to examine fibroblast biology, leading to the identification of specific fibroblast subsets, defining a previously underappreciated heterogeneity of disease-associated fibroblast populations. These studies are challenging the previously held dogma that fibroblasts are homogeneous and are providing unique insights into their role in inflammatory joint pathology. In this review, we discuss the recent advances in our understanding of how fibroblast heterogeneity contributes to joint pathology in rheumatoid arthritis. Finally, we address how these insights could lead to the development of novel therapies that directly target selective populations of fibroblasts in the future.

Recurrent Fulminant Myocarditis Accompanied by Lymphoid Follicle Formation in Myocardium

A 76-year-old man developed repeated fulminant myocarditis in a short period, and immunosuppressive therapy was remarkably effective. A pathologic evaluation showed that inflammatory cells had infiltrated the myocardium. Not only invasion of inflammatory cells but also the formation of lymphoid follicle was noted. Chronic myocardial inflammation was proven, but cardiac sarcoidosis was negative according to the results of various examinations. This is the first report of recurrent autoimmune myocarditis with a lymphoid follicle in the myocardium. These findings may suggest a novel pathogenesis of myocarditis.

Tertiary Lymphoid Organs: A Primer for Otolaryngologists

OBJECTIVES/HYPOTHESIS

Lymphoid neogenesis or the development of organised, de novo lymphoid structures has been described increasingly in chronically inflamed tissues. The presence of tertiary lymphoid organs (TLOs) has already been demonstrated to result in significant consequences for disease pathology, severity, prognosis and patient outcomes. Whilst the wider medical community has embraced TLOs as important markers of disease and potential therapeutic targets, the otolaryngology field has only begun turning to these entities in an academic capacity. This review aims to outline the role of tertiary lymphoid organs in disease and summarise key early findings in the ENT field. We also an overview of TLOs, their developmental process and clinicopathological implications.

STUDY DESIGN

Literature review.

METHODS

A literature search for all relevant peer-reviewed publications pertaining to TLOs and ENT diseases. Search was conducted using PubMed, Embase and CINAHL databases.

RESULTS

A total of 24 studies were identified relevant to the topic. The majority of TLO research in ENT fell into the areas of oral squamous cell carcinoma (SCC) and chronic rhinosinusitis (CRS).

CONCLUSIONS

Early research into both oral SCC and CRS suggests that TLOs have significant roles within ear, nose and throat (ENT) diseases. At this point in time, however, TLOs remain somewhat a mystery amongst otolaryngologists. As information in this field increases, we may develop a better understanding of how lymphoid neogenesis can influence disease outcomes amongst our patients and, ultimately, how they can be utilised in an immunotherapeutic manner. Laryngoscope, 131:1697-1703, 2021.

Expanded circulating follicular dendritic cells facilitate immune responses in chronic HBV infection

Background

The restoration of host hepatitis B virus (HBV)-specific antiviral immunity is an effective strategy for hepatitis B recovery. Follicular dendritic cells (FDCs) play a crucial role in immune regulation. The goal of the present study was to investigate the characteristics and functions of FDCs in chronic HBV infection.

Methods

The frequencies of FDCs in peripheral blood, liver, and spleen were measured in patients with chronic HBV infection. Isolated FDCs from splenic tissues of HBV-related liver cirrhosis-induced hypersplenism patients were cultured with autologous intrasplenic CD4⁺ T cells and CD19⁺ B cells.

Results

We observed that patients with chronic HBV infection had a significantly increased frequency of circulating FDCs compared to that of healthy controls. Additionally, the frequency of circulating FDCs was positively correlated with that of intrahepatic and intrasplenic counterparts. Moreover, positive correlations were observed between the frequencies of circulating FDCs and plasmablast and memory B cells, as well as C-X-C motif chemokine receptor type 5 (CXCR5)⁺CD4⁺ T cells and CXCR5⁺CD8⁺ T cells. Notably, in vitro experimental results demonstrated that FDCs derived from splenic tissues of chronic HBV patients facilitated interferon-γ and interleukin-21 production from autologous intrasplenic CD4⁺ T cells and promoted the proliferation of autologous intrasplenic CD19⁺ B cells.

Conclusions

Expanded FDCs in patients with chronic HBV infection may favor host immune responses against HBV. The identification of this unique population of cell may contribute to a better understanding of the immune regulatory mechanisms associated with chronic HBV infection and provide a potential immunotherapeutic target for this disease.

Recent Advances in Smart Biomaterials for the Detection and Treatment of Autoimmune Diseases

Autoimmune diseases are a group of debilitating illnesses that are often idiopathic in nature. The steady rise in the prevalence of these conditions warrants new approaches for diagnosis and treatment. Stimuli-responsive biomaterials also known as "smart", "intelligent" or "recognitive" biomaterials are widely studied for their applications in drug delivery, biosensing and tissue engineering due to their ability to produce thermal, optical, chemical, or structural changes upon interacting with the biological environment. This critical analysis highlights studies within the last decade that harness the recognitive capabilities of these biomaterials towards the development of novel detection and treatment options for autoimmune diseases.

Tolerogenic vaccines: Targeting the antigenic and cytokine niches of FOXP3+ regulatory T cells

FOXP3+ regulatory T cells (Tregs) constitute a critical barrier that enforces tolerance to both the self-peptidome and the extended-self peptidome to ensure tissue-specific resistance to autoimmune, allergic, and other inflammatory disorders. Here, we review intuitive models regarding how T cell antigen receptor (TCR) specificity and antigen recognition efficiency shape the Treg and conventional T cell (Tcon) repertoires to adaptively regulate T cell maintenance, tissue-residency, phenotypic stability, and immune function in peripheral tissues. Three zones of TCR recognition efficiency are considered, including Tcon recognition of specific low-efficiency self MHC-ligands, Treg recognition of intermediate-efficiency agonistic self MHC-ligands, and Tcon recognition of cross-reactive high-efficiency agonistic foreign MHC-ligands. These respective zones of TCR recognition efficiency are key to understanding how tissue-resident immune networks integrate the antigenic complexity of local environments to provide adaptive decisions setting the balance of suppressive and immunogenic responses. Importantly, deficiencies in the Treg repertoire appear to be an important cause of chronic inflammatory disease. Deficiencies may include global deficiencies in Treg numbers or function, subtle 'holes in the Treg repertoire' in tissue-resident Treg populations, or simply Treg insufficiencies that are unable to counter an overwhelming molecular mimicry stimulus. Tolerogenic vaccination and Treg-based immunotherapy are two therapeutic modalities meant to restore dominance of Treg networks to reverse chronic inflammatory disease. Studies of these therapeutic modalities in a preclinical setting have provided insight into the Treg niche, including the concept that intermediate-efficiency TCR signaling, high IFN-β concentrations, and low IL-2 concentrations favor Treg responses and active dominant mechanisms of immune tolerance. Overall, the purpose here is to assimilate new and established concepts regarding how cognate TCR specificity of the Treg repertoire and the contingent cytokine networks provide a foundation for understanding Treg suppressive strategy.

Biological mechanisms of ectopic lymphoid structure formation and their pathophysiological significance

Ectopic lymphoid structures (ELS) or tertiary lymphoid organs are structures with the organization similar to the one of secondary lymphoid organs, formed in non-lymphoid tissues. They are considered to be an important site for the lymphocytic physiological and pathological role in conditions such are chronic infections, autoimmune diseases, cancer, and allograft rejection. Although similar to the secondary lymphoid tissues, the initiation of ELS formation is not preprogramed and requires chronic inflammation, expression of homeostatic chemokines, and lymphotoxin beta receptor activation. Importantly, while ELS formation may be considered beneficiary in antimicrobial and antitumor immunity, the persistence of these active lymphoid structures within the tissue increase the chance for development of autoimmunity and lymphoma. This paper is providing an overview of biological mechanisms involved in ELS formation, as well as the overview of the pathophysiological role of these structures. In addition, the paper discusses the possibility to therapeutically target ELS formation, bearing in mind their bivalent nature and role in different pathophysiological conditions.

Established rheumatoid arthritis. The pathogenic aspects

The development of rheumatoid arthritis (RA), at least in its autoantibody-positive subset, evolves through a series of events starting well before the appearance of synovitis. The distinction between 'early' and 'established' RA is, therefore, an evolving concept. In routine practice, however, the management of RA still starts with the occurrence of clinically detectable synovitis. As such, the synovial membrane remains a major target for the exploitation of possible stage-specific drivers of the disease. The recognition of a 'window of opportunity', in which treatment is more likely to succeed, raises the hypothesis that there might be a period in which the biological processes of RA are less mature and potentially reversible. The present review aims to provide a general picture of the modifications occurring in RA synovium, analysing the contribution of both infiltrating immune cells and stromal cells. When available, differences between early and established RA will be discussed.

Extracellular traps and PAD4 released by macrophages induce citrullination and auto-antibody production in autoimmune arthritis

The mechanisms underlying the transition of rheumatoid arthritis (RA) systemic autoimmunity to the joints remain largely unknown. Here, we demonstrate that macrophages in the secondary lymphoid organs (SLOs) and synovial ectopic lymphoid-like structures (ELSs) express peptidylarginine deiminase 4 (PAD4) in murine collagen induced arthritis (CIA) and synovial biopsies from RA patients. Moreover, peptidyl citrulline colocalized with macrophages in SLOs and ELSs, and depletion of macrophages in CIA decreased lymphoid tissue citrullination and serum anti-citrullinated protein/peptide antibody (ACPA) levels. Furthermore, PAD was released from activated murine and RA synovial tissue and fluid (SF) macrophages which functionally deiminated extracellular proteins/peptides in vitro. Additionally, activated murine and SF macrophages displayed macrophage extracellular trap formation (METosis) and release of intracellular citrullinated histones. Moreover, presentation of citrullinated proteins induced ACPA production in vitro. Thus, lymphoid tissue macrophages contribute to self-antigen citrullination and ACPA production, indicating that their selective targeting would potentially ameliorate citrullination-dependent autoimmune disorders.

The Role of Endothelial Cells and TNF-Receptor Superfamily Members in Lymphoid Organogenesis and Function During Health and Inflammation

Lymph nodes (LNs) are crucial for the orchestration of immune responses. LN reactions depend on interactions between incoming and local immune cells, and stromal cells. To mediate these cellular interactions an organized vascular network within the LN exists. In general, the LN vasculature can be divided into two components: blood vessels, which include the specialized high endothelial venules that recruit lymphocytes from the bloodstream, and lymphatic vessels. Signaling via TNF receptor (R) superfamily (SF) members has been implicated as crucial for the development and function of LNs and the LN vasculature. In recent years the role of cell-specific signaling of TNFRSF members in different endothelial cell (EC) subsets and their roles in development and maintenance of lymphoid organs has been elucidated. Here, we discuss recent insights into EC-specific TNFRSF member signaling and highlight its importance in different EC subsets in LN organogenesis and function during health, and in lymphocyte activation and tertiary lymphoid structure formation during inflammation.

Cytokines in heart failure

The natural history of heart failure (HF) is not linear, because changes in the heart structure and function start long before the disease becomes clinically evident. Many different cytokines originating from intracardiac tissues (cardiomyocytes, cardiac endothelial cells, cardiac fibroblasts, and cardiac infiltrated immune cells) or extracardiac tissues (adipose tissue, gut, and lymphoid organs) have been identified in HF. Because the levels of circulating cytokines correlate with the development and severity of HF, these mediators may have both pathophysiological importance, through their ability to modulate inflammation, myocyte stress/stretch, myocyte injury and apoptosis, fibroblast activation and extracellular matrix remodeling, and utility as clinical predictive biomarkers. A greater understanding of the mechanisms mediated by the multifaceted network of cytokines, leading to distinct HF phenotypes (HF with reduced or preserved ejection fraction), is urgently needed for the development of new treatment strategies. In this chapter, all these issues were thoroughly discussed, pointing on the practical considerations concerning the clinical use of the cytokines as prognostic biomarkers and potential therapeutic targets in HF.

Clinical Applications of Synovial Biopsy

The synovial tissue is a primary target of multiple diseases characterized by different pathogenic mechanisms, including infective, deposition, neoplastic, and chronic immune-inflammatory pathologies. Synovial biopsy can have a relevant role in differential diagnosis of specific conditions in clinical practice, although its exploitation remains relatively limited. In particular, no validated synovial-tissue-derived biomarkers are currently available in the clinic to aid in the diagnosis and management in most frequent forms of chronic inflammatory arthropathies, namely rheumatoid arthritis (RA) and the spondyloarthritides (SpA). In this brief review, we will discuss the current spectrum of clinical applications of synovial biopsy in routine rheumatologic care and will provide an analysis of the perspectives for its potential exploitation in patients with chronic inflammatory arthritides.

Exploiting CD22 To Selectively Tolerize Autoantibody Producing B-Cells in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that primarily affects the synovial joints and can lead to bone erosion and cartilage damage. One hallmark of RA is anticitrullinated protein autoantibodies (ACPA) and memory citrulline-specific B-cells, which have been implicated in RA pathogenesis. While depletion of B-cells with Rituximab improves clinical responses in RA patients, this treatment strategy leaves patients susceptible to infections. Here we use of Siglec-engaging Tolerance-inducing Antigenic Liposomes (STALs) to selectively target the citrulline-specific B-cells. ACPA production from purified human RA patients' B-cells in vitro was achieved through a set of stimulation conditions, which includes the following: BAFF, anti-CD40, IL-21, and LPS. In vivo generation of citrulline specific B-cells and ACPA production was accomplished by antigenic liposomes consisting of monophosphoryl lipid A (MPLA) and a cyclic citrullinated peptide (CCP) administered to SJL/J mice. We show that STALs that codisplay a high affinity CD22 glycan ligand and synthetic citrullinated antigen (CCP STALs) can prevent ACPA production from RA patients' memory B-cells in vitro. These CCP STALs were also effective in inducing tolerance to citrullinated antigens in SJL/J mice. The results demonstrate that tolerization of the B-cells responsible for ACPA can be achieved by exploiting the inhibitory receptor CD22 with high-affinity glycan ligands. Such a treatment strategy could be beneficial in the treatment of RA.

Mechanisms of Neurodegeneration and Axonal Dysfunction in Progressive Multiple Sclerosis

Multiple Sclerosis (MS) is a major cause of neurological disability, which increases predominantly during disease progression as a result of cortical and grey matter structures involvement. The gradual accumulation of disability characteristic of the disease seems to also result from a different set of mechanisms, including in particular immune reactions confined to the Central Nervous System such as: (a) B-cell dysregulation, (b) CD8⁺ T cells causing demyelination or axonal/neuronal damage, and (c) microglial cell activation associated with neuritic transection found in cortical demyelinating lesions. Other potential drivers of neurodegeneration are generation of oxygen and nitrogen reactive species, and mitochondrial damage, inducing impaired energy production, and intra-axonal accumulation of Ca²⁺, which in turn activates a variety of catabolic enzymes ultimately leading to progressive proteolytic degradation of cytoskeleton proteins. Loss of axon energy provided by oligodendrocytes determines further axonal degeneration and neuronal loss. Clearly, these different mechanisms are not mutually exclusive and could act in combination. Given the multifactorial pathophysiology of progressive MS, many potential therapeutic targets could be investigated in the future. This remains however, an objective that has yet to be undertaken.

Tertiary Lymphoid Structures: Autoimmunity Goes Local

Tertiary lymphoid structures (TLS) are frequently observed in target organs of autoimmune diseases. TLS present features of secondary lymphoid organs such as segregated T and B cell zones, presence of follicular dendritic cell networks, high endothelial venules and specialized lymphoid fibroblasts and display the mechanisms to support local adaptive immune responses toward locally displayed antigens. TLS detection in the tissue is often associated with poor prognosis of disease, auto-antibody production and malignancy development. This review focuses on the contribution of TLS toward the persistence of the inflammatory drive, the survival of autoreactive lymphocyte clones and post-translational modifications, responsible for the pathogenicity of locally formed autoantibodies, during autoimmune disease development.

T Cells That Help B Cells in Chronically Inflamed Tissues

Chronically inflamed tissues commonly accrue lymphocyte aggregates that facilitate local T cell-B cell interactions. These aggregates can range from small, loosely arranged lymphocyte clusters to large, organized ectopic lymphoid structures. In some cases, ectopic lymphoid structures develop germinal centers that house prototypical T follicular helper (Tfh) cells with high expression of Bcl6, CXCR5, PD-1, and ICOS. However, in many chronically inflamed tissues, the T cells that interact with B cells show substantial differences from Tfh cells in their surface phenotypes, migratory capacity, and transcriptional regulation. This review discusses observations from multiple diseases and models in which tissue-infiltrating T cells produce factors associated with B cell help, including IL-21 and the B cell chemoattractant CXCL13, yet vary dramatically in their resemblance to Tfh cells. Particular attention is given to the PD-1^hi CXCR5⁻ Bcl6^low T peripheral helper (Tph) cell population in rheumatoid arthritis, which infiltrates inflamed synovium through expression of chemokine receptors such as CCR2 and augments synovial B cell responses via CXCL13 and IL-21. The factors that regulate CD4⁺ T cell production of CXCL13 and IL-21 in these settings are also discussed. Understanding the range of T cell populations that can provide help to B cells within chronically inflamed tissues is essential to recognize these cells in diverse inflammatory conditions and to optimize either broad or selective therapeutic targeting of B cell-helper T cells.

Co-expression of CD21L and IL17A defines a subset of rheumatoid synovia, characterised by large lymphoid aggregates and high inflammation

OBJECTIVE

To determine whether the expression of IL17A and CD21L genes in inflamed rheumatoid synovia is associated with the neogenesis of ectopic lymphoid follicle-like structures (ELS), and if this aids the stratification of rheumatoid inflammation and thereby distinguishes patients with rheumatoid arthritis that might be responsive to specific targeted biologic therapies.

METHODS

Expression of IL17A and CD21L genes was assessed by RT-PCR, qRT-PCR and dPCR in synovia from 54 patients with rheumatoid arthritis. A subset of synovia (n = 30) was assessed by immunohistology for the presence of CD20+ B-lymphocytes and size of CD20+ B-lymphocyte aggregates as indicated by maximum radial cell count. The molecular profiles of six IL17A+/CD21L+ and six IL17A-/CD21L- synovia were determined by complementary DNA microarray analysis.

RESULTS

By RT-PCR, 26% of synovia expressed IL17A and 52% expressed CD21L. This provided the basis for distinguishing four subgroups of rheumatoid synovia: IL17A+/CD21L+ (18.5% of synovia), IL17A+/CD21L- (7.5%), IL17A-/CD21L+ (33.3%) and IL17A-/CD21L- (40.7%). While the subgroups did not predict clinical outcome measures, comparisons between the synovial subgroups revealed the IL17A+/CD21L+ subgroup had significantly larger CD20+ B-lymphocyte aggregates (P = 0.007) and a gene expression profile skewed toward B-cell- and antibody-mediated immunity. In contrast, genes associated with bone and cartilage remodelling were prominent in IL17A-/CD21L- synovia.

CONCLUSIONS

Rheumatoid synovia can be subdivided on the basis of IL17A and CD21L gene expression. Ensuing molecular subgroups do not predict clinical outcome for patients but highlight high inflammation and the predominance of B-lymphocyte mediated mechanisms operating in IL17A+/CD21L+ synovia. This may provide a rationale for more refined therapeutic selection due to the distinct molecular profiles associated with IL17A+/CD21L+ and IL17A-/CD21L- rheumatoid synovia.

Role of chemokines in ectopic lymphoid structures formation in autoimmunity and cancer

Ectopic (or tertiary) lymphoid structures (ELS) are organized aggregates of lymphocytes resembling secondary lymphoid organs and developing in chronically inflamed nonlymphoid tissues during persistent infections, graft rejection, autoimmune conditions, and cancer. In this review, we will first depict the mechanisms regulating ELS generation, focusing on the role played by lymphoid chemokines. We will then characterize ELS forming in target organs during autoimmune conditions, here exemplified by rheumatoid arthritis, and cancer, highlighting the relevance of the tissue-specific factors. Finally, we will discuss the clinical significance of ELS and the therapeutic potential of their inhibition and/or enhancement depending on the disease considered.

Sulforaphane Modulates Joint Inflammation in a Murine Model of Complete Freund's Adjuvant-Induced Mono-Arthritis

Rheumatoid arthritis (RA) is characterized by inflammation of one or more joints, and affects ~1% of the adult population worldwide. Sulforaphane (SFN) is a natural compound that has been suggested as an antioxidant. Here, SFN’s effects were evaluated in a murine mono-arthritis model. Mono-arthritis was induced in mice by a single intra-articular injection of Complete Freund’s Adjuvant (CFA-10 µg/joint, in 10 µL) into the ipsilateral joint. The contralateral joint received an equal volume of PBS. On the 4th day post-joint inflammation induction, animals received either SFN (10 mg/kg) or vehicle (3% DMSO in saline), intraperitoneally (i.p.), twice a day for 3 days. Joint swelling and secondary mechanical allodynia and hyperalgesia were evaluated over 7 days post-CFA. After this period, animals were culled and their blood and synovial fluid samples were collected for analysis of cell populations, cytokine release and thioredoxin reductase (TrxR) activity. Knee joint samples were also collected for histology. SFN reduced joint swelling and damage whilst increasing the recruitment of Ly6C⁺ and Ly6G⁺ cells to CFA-injected joints. SFN-treated animals presented down-regulation of CD11b and CD62L on synovial fluid Ly6G⁺ cells. Synovial fluid samples obtained from CFA-injected joints and plasma samples of SFN-treated mice presented higher levels of IL-6 and increased activity of TrxR, in comparison with controls. These results indicate that SFN reduces knee joint damage by modulating cell activation/migration to the joints, cytokine production and increasing the activity of TrxR, and therefore, may represent an alternative treatment to joint inflammation.

Characterization of mesenchymal stem/stromal cells with lymphoid tissue organizer cell potential in tonsils from children

Lymphoid tissue organizer (LTo) cells, identified in mouse and human embryos, are thought to be precursors of stromal cells in secondary lymphoid organs. Whether LTo cells are present in human adults, however remains unknown. We obtained 15 stromal cell lines from tonsils from children who underwent tonsillectomy, and studied the antigen phenotype of these tonsil stromal cell (TSC) lines by flow cytometry and RT-PCR. Cell lines met the minimal criteria proposed by the International Society for Cellular Therapy to define human mesenchymal stem/stromal cells (MSCs): plastic-adherent capacity; expression of CD73, CD90 and CD105, lack of CD45, CD19 and HLA-DR; and capacity to differentiate into adipocytes, osteoblasts and chondrocytes. Furthermore, our TSC lines exhibited an antigen phenotype and functional characteristics very similar to those seen in murine embryo LTo cells: they expressed chemokines CCL19, CCL21 and CXCL13, cytokines TRANCE and IL-7, and adhesion molecules ICAM-1, mucosal addressin cell adhesion molecule (MadCAM)-1 and VCAM-1. The expression of LTo cell-associated markers and functions were upregulated by lymphotoxin (LT)α1β2 and TNF, two cytokines involved in the development and maturation of secondary lymphoid tissues. Our results show that TSCs are tonsil MSCs that differentiate into LTo-like cells in response to the effects of these cytokines.

Generation of Recombinant Monoclonal Antibodies from Single B Cells Isolated from Synovial Tissue of Rheumatoid Arthritis Patients

Ectopic lymphoid structure (ELS) can form in the target tissues of patients with chronic inflammatory autoimmune diseases such as rheumatoid arthritis (RA) and Sjögren's syndrome (SS). Although it is still not clear why ELS form only in a subset of patients, it is well known that these structures can acquire features of ectopic germinal centers and contribute actively to the production of autoantibodies. Here, we describe a method to generate recombinant monoclonal antibodies from single ELS⁺ synovial tissue B cells obtained from RA patients. This chapter gives a detailed description of the method beginning from the mononuclear cell preparation from RA synovial tissue, single-cell sort of B cells by flow cytometry, amplification of the immunoglobulin (Ig) genes (both heavy- and light-chain genes) by PCR, and subsequent Ig gene expression vector cloning for full recombinant IgG1 monoclonal antibody (rmAb) production in vitro. The recombinant mAbs generated can be then characterized for (1) analysis of the Ig gene repertoires for clonal studies, (2) immunoreactivity profile, and (3) functional studies both in vitro and in vivo.