Formation Of Tertiary Lymphoid Organs Research Articles

Mice with Lymphatic Dysfunction Develop Pathogenic Lung Tertiary Lymphoid Organs that Model an Autoimmune Emphysema Phenotype of COPD.

We have previously shown that mice with loss of C-type lectin-like type II (CLEC2), which have lymphatic dysfunction due to the role of CLEC2 in platelets for maintaining separation between the venous and lymphatic system, develop lung tertiary lymphoid organ (TLO) formation and lung injury that resembles an emphysema phenotype of chronic obstructive pulmonary disease (COPD). We now sought to investigate whether and how TLOs in these mice may play a pathogenic role in lung injury that is relevant to human disease. We found that inhibiting TLO formation using an anti-CD20 antibody in CLEC2-deficient mice partially blocked the development of emphysema. TLOs in CLEC2-deficient mice were rich in plasma cells and were a source of a broad array of autoantibodies. Chronic cigarette smoke exposure increased the size and number of lung TLOs in CLEC2-deficient mice, and was associated with increased markers of antigen presentation and maturation, leading to increased autoantibody deposition. Using lung tissue from COPD patients, we found an increase in lymphatic markers in patients with an emphysema phenotype and autoreactive TLOs compared to COPD patients without emphysema that lack prominent TLOs. Taken together, these results demonstrate that emphysema in mice with lymphatic dysfunction can be partially rescued by blocking TLO formation, and that these TLOs are source of autoantibodies that are exacerbated by cigarette smoke. Our work suggests that lymphatic dysfunction in mice may recapitulate some aspects an autoimmune emphysema phenotype that is seen in a subset of patients with COPD.

Lymphotoxins from distinct types of lymphoid cells differentially contribute to neuroinflammation.

Lymphotoxin α and lymphotoxin β (LTs), TNF superfamily members, are expressed in either soluble (LTα3) or membrane-bound (LTα1β2 or LTα2β1) forms. In the pathological context, LT-mediated signaling is known to exacerbate autoimmunity by perpetuating inflammation and promoting the formation of tertiary lymphoid organs. Despite this understanding, the exact roles of LTα and LTβ in the pathogenesis of the murine model of multiple sclerosis, and experimental autoimmune encephalomyelitis (EAE), remain controversial. Here, we employed a panel of gene-modified mice with cell-type restricted ablation of LTα (targeting both membrane-bound and soluble forms of LTs) to unravel the contributions of LTs from various lymphoid cells, namely T cells, type 3 innate lymphoid cells (ILC3) and B cells, in EAE. We found that the effects of LTα deletion were dependent on the cellular source. ILC3-derived lymphotoxins exerted a protective role in EAE by regulating the accumulation of IFN-ɣ- and GM-CSF-producing TH cells in the CNS. In contrast, T-cell-derived lymphotoxins promoted IL-17A- and GM-CSF-mediated TH responses in the periphery, whereas B-cell-derived lymphotoxins were pathogenic only in the autoantibody-mediated EAE model. Collectively, our findings unveil the multifaceted involvement of lymphotoxins in EAE pathogenesis and challenge the view that lymphotoxins play a solely pathogenic role in neuroinflammation.

Clinicopathological characteristics and predictors of outcome of rapidly progressive glomerulonephritis: a retrospective study.

Globally, there are regional and time-based variations in the prevalence, etiology, and prognosis of rapidly progressive glomerulonephritis (RPGN). Prognosis of RPGN is poor, with a higher risk of death and end stage renal disease (ESRD) even with immunosuppressive medications. In the Middle East and North Africa, the studies on this disease are very limited. Therefore, we determined the predictors of outcome of RPGN. We retrospectively assessed 101 adult patients over age of 18, diagnosed with RPGN based on renal biopsy illustrating crescents in ≥ 50% of the glomeruli. Patients who had crescents in their renal biopsies that were < 50% and those who refused to consent to a renal biopsy were excluded. We categorized the patients into 3 groups based on immunohistochemistry; type I, type II and type III. Then, depending on renal loss, we divided them into ESRD and non-ESRD groups. The clinical history and physical examination were retrieved. Additionally, 24-hour urine protein, urine analysis, renal function tests, serum albumin, complete blood count, antinuclear antibodies, anti-double stranded DNA antibodies, ANCA antibodies and serum complement levels were checked. Each patient underwent a kidney biopsy for immunohistochemistry and light microscopy. The percentage of crescentic glomeruli, number of sclerosed glomeruli, tertiary lymphoid organ (TLO), neutrophil infiltration, endocapillary or mesangial hypercellularity, interstitial fibrosis with tubular atrophy (IFTA) were analyzed. Primary outcomes (remission, ESRD and mortality) and secondary outcomes were assessed. Type II was the most frequent cause of RPGN (47.5%), followed by type III (32.7%) and type I (19.8%). 32 patients (31.7%) died during follow up, whereas 60 patients (59.4%) developed ESRD. In 41 patients (40.6%), remission occurred. Oliguria, serum creatinine, and need for HD at presentation were significantly increased in ESRD group compared to non-ESRD group (P < 0.001 for each). Mesangial proliferation, IFTA, TLO formation, sclerotic glomeruli and fibrous crescents were also significantly increased in ESRD group in comparison to non-ESRD group (P < 0.001 for each). Glomerulosclerosis (P = 0.036), and IFTA (P = 0.008) were predictors of ESRD. Infections (P = 0.02), respiratory failure (P < 0.001), and heart failure (P = 0.004) were mortality risk factors. Type II RPGN was the most common. Infection was the most frequent secondary outcome. Oliguria, glomerulosclerosis, the requirement for hemodialysis at presentation, IFTA and TLO formation were predictors of ESRD. Respiratory failure, heart failure and infections were significant predictors of mortality.

Abstract B063: Tertiary lymphoid organogenesis and lymphocyte activation in human organ chips

Abstract The rates of tertiary lymphoid organ (TLO) formation in pancreatic cancer are very low but patients with TLO have dramatically better survival rates. Our goal is to understand how pancreatic cancer suppresses TLO so that we can improve patient survival and reduce recurrence. We integrated human cell lines from pancreatic and lung cancer with either high or low PDL1/L2 expression into our previously described lymphoid follicle (LF) chip (Goyal et al., Adv. Sci, 2022), where peripheral blood mononuclear cells are induced to form 3D TLO-like structures. The hot lung cancer cell line, which expressed high levels of PDL1/L2 and a “hot” phenotype in published murine studies, produced a high levels of cytokines and stimulated increased TLO formation in the LF chip. In contrast, the cold lung and pancreatic cell lines did not induce the cytokine signature or TLOs. Importantly, TLO formation correlated with increased B cell activation, anti-tumor CD8 activity and tumor cell death. We have coupled this in vitro study with analysis of the pancreatic cancer transcriptome from the Cancer Genome Atlas to identify therapeutic targets to promote TLO formation in pancreatic cancer. In ongoing studies, we are assessing the functionality of the lung cancer TLO in vitro and in vivo and identifying therapeutics that may improve TLO formation in pancreatic cancer. Citation Format: Yunhao Zhai, Pranav Prabhala, Lucas Barck, Min Wen Ku, Aditya Patil, Viktor Horvath, Russell A. Gould, Donald E. Ingber, Girija Goyal. Tertiary lymphoid organogenesis and lymphocyte activation in human organ chips [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B063.

Chronic stress induces colonic tertiary lymphoid organ formation and protection against secondary injury through IL-23/IL-22 signaling

Psychological stress has been previously reported to worsen symptoms of inflammatory bowel disease (IBD). Similarly, intestinal tertiary lymphoid organs (TLOs) are associated with more severe inflammation. While there is active debate about the role of TLOs and stress in IBD pathogenesis, there are no studies investigating TLO formation in the context of psychological stress. Our mouse model of Crohn's disease-like ileitis, the SAMP1/YitFc (SAMP) mouse, was subjected to 56 consecutive days of restraint stress (RS). Stressed mice had significantly increased colonic TLO formation. However, stress did not significantly increase small or large intestinal inflammation in the SAMP mice. Additionally, 16S analysis of the stressed SAMP microbiome revealed no genus-level changes. Fecal microbiome transplantation into germ-free SAMP mice using stool from unstressed and stressed mice replicated the behavioral phenotype seen in donor mice. However, there was no difference in TLO formation between recipient mice. Stress increased the TLO formation cytokines interleukin-23 (IL-23) and IL-22 followed by up-regulation of antimicrobial peptides. SAMP × IL-23r-/- (knockout [KO]) mice subjected to chronic RS did not have increased TLO formation. Furthermore, IL-23, but not IL-22, production was increased in KO mice, and administration of recombinant IL-22 rescued TLO formation. Following secondary colonic insult with dextran sodium sulfate, stressed mice had reduced colitis on both histology and colonoscopy. Our findings demonstrate that psychological stress induces colonic TLOs through intrinsic alterations in IL-23 signaling, not through extrinsic influence from the microbiome. Furthermore, chronic stress is protective against secondary insult from colitis, suggesting that TLOs may function to improve the mucosal barrier.

B cells drive tertiary lymphoid organ formation in ileal inflammation

Abstract Crohn’s disease [CD] is one of the two most common forms of inflammatory bowel disease, affecting over half a million Americans. Like many other diseases with chronic inflammation, some patients with CD develop tertiary lymphoid organs [TLO] in areas of the gastrointestinal tract with active disease. TLOs are organized clusters of lymphocytes, similar in structure to secondary lymphoid organs, though they develop after birth and their contribution to pathogenesis in CD, or other diseases, is unclear. We, and others, have also found B cell rich lymphoid aggregates in the mesenteric fat of CD patients along dramatically remodeled lymphatic vessels. TNFΔARE/+ is a murine model of ileal inflammation that recapitulates several key features of ileal CD, including development of mesenteric tertiary lymphoid organs. Use of this model revealed that mesenteric TLOs block cellular and molecular export from the gut, leading us to wonder if mechanisms that interfere with their development might reduce ileitis. TNFΔARE/+ mice that lack B cells revealed that B cells are required for tertiary lymphoid organ formation in this model. Without these TLOs, lymphatic outflow from the intestine was restored. Nonetheless, histological and flow cytometric approaches reveal no difference in local inflammation in the ileum. However, systemic inflammation, as assessed by metabolic cages and changes in body weight over time, increased. This suggests that TLOs may act to trap inflammatory signals locally, preventing systemic dissemination of inflammatory cells or mediators. Work supported by NIH grants DP1-DK109668-04 and T32-DK077653-27 and the Kenneth Rainin Foundation

A18 DEVELOPMENT OF CHRONIC ILEITIS IN THE TNFΔARE MOUSE IS ASSOCIATED WITH A LOSS OF MESENTERIC LYVE1+ MACROPHAGES

Abstract Background Crohn’s disease (CD) is a form of inflammatory bowel disease that causes transmural inflammation of any part of the gastrointestinal (GI) tract but preferentially the terminal ileum and/or the colon. This chronic inflammation is not limited to the GI tract but also affects the mesentery of inflamed regions where it induces the formation of tertiary lymphoid organs (TLOs). The homeostatic LYVE1+ macrophages (LYmΦ) have been identified in many different organs including the mesentery. They have been shown to typically align along blood vessels where they participate in the control of collagen deposition and during inflammation, regulate vascular permeability and immune cell recruitment. Here we investigate the role of the mesenteric LYmΦ in a transgenic model of CD, the TNFΔARE mouse which develops terminal ileitis over time and expresses similar mesenteric alterations (TLOs) as seen in CD. Aims To determine whether the mesenteric LYmΦ population is altered during the development of chronic inflammation in the TNFΔARE mouse and whether they participate in the development of TLOs. Methods Confocal immunofluorescent imaging of the terminal ileal mesentery of TNFΔARE mice and littermate controls were preformed to identify changes to the populations of LYmΦ during the development of chronic inflammation. Myeloperoxidase activity was used to assess terminal ileitis. Results During the initial stage of ileitis (8 weeks) LYmΦs are present across the terminal ileal mesentery in both TNFΔARE and age-matched WT littermate controls with a subpopulation aligning along the collecting lymphatic vessels of the mesentery (n=6). At 20 weeks, while the ileitis progresses, aggregates of CD45+ cells have formed within the TNFΔARE mice where LYmΦs also accumulate (n=5). At 28 weeks when the ileitis worsens, the LYmΦs are greatly reduced from the terminal ileal mesentery as well as from the CD45+ cell aggregates (n=5). WT littermate controls never develop large CD45+ cell aggregates (n=5 for each time point). Antibodies to the LYVE1 cytosolic and extracellular domains confirmed the loss of the LYVE1 receptor over receptor cleavage, however, there was no correlation of altered collagen-1 deposition within the mesentery at 28 weeks. Conclusions Here we show a spatial relationship between LYmΦs and collecting lymphatic vessels as well as a decrease in LYmΦs during the development of chronic ileitis in the TNFΔARE mouse. Whether they contribute to TLO formation, or their loss exacerbates terminal ileitis is still unknown and under current investigation. Funding Agencies CCC

Self-Tolerance of Vascular Tissues Is Broken Down by Vascular Dendritic Cells in Response to Systemic Inflammation to Initiate Regional Autoinflammation.

The correlation of infections with vascular autoinflammatory diseases such as vasculitis and atherosclerosis has been long recognized, and progressive inflammation with the formation of tertiary lymphoid organs in arterial adventitia intensively studied, the immunological basis of the nondiseased vasculatures that predispose to subsequent vascular autoimmunity during inflammation, however, is not well characterized. Here, we investigated the vascular immunity in situ of steady-state C57BL/6 mice and found that healthy vascular tissues contained a comprehensive set of immune cells with relatively higher proportion of innate components than lymphoid organs. Notably, a complete set of dendritic cell (DC) subsets was observed with monocyte-derived DCs (moDCs) constituting a major proportion; this is in contrast to moDCs being considered rare in the steady state. Interestingly, these vascular DCs constitutively expressed more suppressive factors with cDC1 for PD-L1 and moDCs for IL-10; this is concordant with the inhibitive phenotype of T cells in normal vascular tissues. The immunotolerant state of the vascular tissues, however, was readily eroded by systemic inflammation, demonstrated by the upregulation of proinflammatory cytokines and enhanced antigen presentation by vascular DCs to activate both cellular and humoral immunity in situ, which ultimately led to vascular destruction. Different vascular DC subsets elicited selective effects: moDCs were potent cytokine producers and B-cell activators, whereas cDCs, particularly, cDC1, were efficient at presenting antigens to stimulate T cells. Together, we unveil regional immunological features of vascular tissues to explain their dual facets under physiological versus pathological conditions for the better understanding and treatment of cardiovascular autoinflammation.

Ileitis-associated tertiary lymphoid organs arise at lymphatic valves and impede mesenteric lymph flow in response to tumor necrosis factor

Lymphangitis and the formation of tertiary lymphoid organs (TLOs) in the mesentery are features of Crohn's disease. Here, we examined the genesis of these TLOs and their impact on disease progression. Whole-mount and intravital imaging of the ileum and ileum-draining collecting lymphatic vessels (CLVs) draining to mesenteric lymph nodes from TNFΔARE mice, a model of ileitis, revealed TLO formation at valves of CLVs. TLOs obstructed cellular and molecular outflow from the gut and were sites of lymph leakage and backflow. Tumor necrosis factor (TNF) neutralization begun at early stages of TLO formation restored lymph transport. However, robustly developed, chronic TLOs resisted regression and restoration of flow after TNF neutralization. TNF stimulation of cultured lymphatic endothelial cells reprogrammed responses to oscillatory shear stress, preventing the induction of valve-associated genes. Disrupted transport of immune cells, driven by loss of valve integrity and TLO formation, may contribute to the pathology of Crohn's disease.

Recent Advances in Understanding the Role of TIGIT+ Follicular Helper T Cells in IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a fibro-inflammatory disease characterized by elevated serum IgG4 levels and massive infiltration of IgG4+plasma cells. Although storiform fibrosis, obliterative phlebitis and IgG4+plasma cell infiltration are well described pathological features in this disease, the excessive formation of tertiary lymphoid organs (TLOs), particularly in the early phase of the disease lesions, has gained much attention. TLOs of IgG4-RD are orchestrated by specific immune cell subsets including follicular helper T cells (Tfh), CD20+ B cells, and CD21+ follicular dendritic cells (FDCs). Tfh is the key player of this disease because recent studies have suggested the pathological role of this immune cell subset in formation of TLOs, helping IgG4+plasma cell differentiation, inducing storiform fibrosis by secreting interleukin-4, and activating cytotoxic T cells by secreting interleukin-21. We have recently identified a new Tfh subset which expresses T cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT). TIGIT+Tfh efficiently produces interleukin-21 through OX40 signal, and the increase in peripheral TIGIT+Tfh cells reflects disease activity in IgG4-RD. TIGIT is important to mediate the retention and positioning of TIGIT+Tfh within TLOs through interaction with CD155 expressed on CD21+ FDCs. In this review, we summarize and discuss recent progress in understanding the pathogenesis of IgG4-RD, focusing on TIGIT+Tfh.

Long-term B cell depletion associates with regeneration of kidney function.

BackgroundChronic kidney disease (CKD) is a common condition that increases mortality and the risk of cardiovascular and other morbidities regardless of underlying renal condition. Chronic inflammation promotes renal fibrosis. Recently, renal B cell infiltrates were described in chronic kidney disease of various etiologies beyond autoimmunity.MethodsWe here investigated B cells and indicators of tertiary lymphoid structure formation in human renal biopsies. Renal function was studied during long‐term B cell depletion in human patients with membranous nephropathy and with CKD of unknown origin.ResultsCytokine profiles of tertiary lymphoid structure formation were detected in human renal interstitium in a range of kidney diseases. Complex B cell structures consistent with tertiary lymphoid organ formation were evident in human membranous nephropathy. Here, B cell density did not significantly associate with proteinuria severity, but with worse excretory renal function. Proteinuria responses mostly occurred within the first 6 months of B cell depletion. In contrast, recovery of excretory kidney function was observed only after 18 months of continuous therapy, consistent with a structural process. Renal tertiary lymphatic structures were also detected in the absence of autoimmune kidney disease. To start to address whether B cell depletion may affect CKD in a broader population, we assessed kidney function in neurologic patients with CKD of unknown origin. In this cohort, eGFR significantly increased within 24 months of B cell depletion.ConclusionLong‐term B cell depletion associated with significant improvement of excretory kidney function in human CKD. Kinetics and mechanisms of renal B cell aggregation should be investigated further to stratify the impact of B cells and their aggregates as therapeutic targets.

Tertiary lymphoid organs drive disrupted gut to lymph node communication through association with collecting lymphatic vessels

Abstract The concept that impaired lymphatic flow during the progression of Crohn’s disease, a major form of inflammatory bowel disease, emerged decades ago, but remains unresolved. In Crohn’s disease, tertiary lymphoid organs (TLOs) are associated with collecting lymphatic vessels (CLVs) of the mesentery that govern lymph outflow from the intestine. Whether TLOs affect lymph transport is unknown. In the TNFDARE mouse model of Crohn’s-like ileitis, TLOs formed at valve regions which supported lymphangiogenic outgrowths to the TLOs. Photoconversion approaches to study cell trafficking indicated that TLOs received immune cells traveling from the intestine but scarcely allowed their egress, effectively trapping DCs, B, and T cells. Using adoptive transfer of microbiota-dependent TCR we found reduced overall Tregs differentiation and their presence shifted from the lymph nodes to TLOs, altering intestinal-induced responses. Strikingly, although anti-TNF therapy dampens gut inflammation, TLO are refractory the therapy. Moreover, passage of soluble fluorescent tracer through TLO-rich CLVs was also impeded, indicating transport defects were intrinsic to the CLVs. Indeed, lymph flow diverted at TLO to neighboring CLV branches, where dysfunctional valves allowed lymph return to the gut wall, accompanied by lymph leakage at the TLOs. Culturing lymphatic endothelial cells with TNF demonstrate that the cytokine alone can reduce key genes found in lymphatic valves. These data indicate that TNF disrupts lymphatic valve maintenance pathways, promoting formation of mesenteric TLOs that broadly impair lymph transit of molecules and cells from the intestine, impairing immune surveillance of the mucosal barrier, altering homeostasis.

Tolerance, immunosuppression, and immune modulation: impacts on lung allograft survival.

Immune responses following lung transplantation continue to result in high rates of allograft failure and rejection, and current immunosuppression does not address the unique immunologic properties of the lung. Here, we review recent studies on lung allograft tolerance and alloimmunity and discuss implications for immunosuppression. Processes governing tolerance and alloimmunity in lung allografts differ from other solid organs. Recent studies have suggested that allorecognition is regulated at the level of the lung graft. Furthermore, certain cell populations essential for lung allograft tolerance may facilitate rejection in other organs. Induction of lung allograft tolerance is associated with the formation of tertiary lymphoid organs, which are enriched in regulatory T cells and play an important role in preventing rejection. Recent discoveries regarding alloactivation and the regulation of tolerance following lung transplantation have introduced exciting potential avenues for the development of lung-specific immunosuppression.

IL-21 treatment recovers follicular helper T cells and neutralizing antibody production in respiratory syncytial virus infection.

Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infections in children under 1 year. RSV vaccines are currently unavailable, and children suffering from multiple reinfections by the same viral strain fail to develop protective responses. Although RSV-specific antibodies can be detected upon infection, these have limited neutralizing capacity. Follicular helper T (Tfh) cells are specialized in providing signals to B cells and help the production and affinity maturation of antibodies, mainly via interleukin (IL) 21 secretion. In this study, we evaluated whether RSV could inhibit Tfh responses. We observed that Tfh cells fail to upregulate IL-21 production upon RSV infection. In the lungs, RSV infection downregulated the expression of IL-21/interleukin-21 receptor (IL-21R) in Tfh cells and upregulated programmed death-ligand 1 (PD-L1) expression in dendritic cells (DCs) and B cells. PD-L1 blockade during infection recovered IL-21R expression in Tfh cells and increased the secretion of IL-21 in a DC-dependent manner. IL-21 treatment decreased RSV viral load and lung inflammation, inducing the formation of tertiary lymphoid organs in the lung. It also decreased regulatory follicular T cells, and increased Tfh cells, B cells, antibody avidity and neutralization capacity, leading to an overall improved anti-RSV humoral response in infected mice. Passive immunization with purified immunoglobulin G from IL-21-treated RSV-infected mice protected against RSV infection. Our results unveil a pathway by which RSV affects Tfh cells by increasing PD-L1 expression on antigen-presenting cells, highlighting the importance of an IL-21-PD-L1 axis for the generation of protective responses to RSV infection.

Lymphatic Proliferation Ameliorates Pulmonary Fibrosis after Lung Injury

Despite many reports about pulmonary blood vessels in lung fibrosis, the contribution of lymphatics to fibrosis is unknown. We examined the mechanism and consequences of lymphatic remodeling in mice with lung fibrosis after bleomycin injury or telomere dysfunction. Widespread lymphangiogenesis was observed after bleomycin treatment and in fibrotic lungs of prospero homeobox 1-enhanced green fluorescent protein (Prox1-EGFP) transgenic mice with telomere dysfunction. In loss-of-function studies, blocking antibodies revealed that lymphangiogenesis 14 days after bleomycin treatment was dependent on vascular endothelial growth factor (Vegf) receptor 3 signaling, but not on Vegf receptor 2. Vegfc gene and protein expression increased specifically. Extensive extravasated plasma, platelets, and macrophages at sites of lymphatic growth were potential sources of Vegfc. Lymphangiogenesis peaked at 14 to 28 days after bleomycin challenge, was accompanied by doubling of chemokine (C-C motif) ligand 21 in lung lymphatics and tertiary lymphoid organ formation, and then decreased as lung injury resolved by 56 days. In gain-of-function studies, expansion of the lung lymphatic network by transgenic overexpression of Vegfc in club cell secretory protein (CCSP)/VEGF-C mice reduced macrophage accumulation and fibrosis and accelerated recovery after bleomycin treatment. These findings suggest that lymphatics have an overall protective effect in lung injury and fibrosis and fit with a mechanism whereby lung lymphatic network expansion reduces lymph stasis and increases clearance of fluid and cells, including profibrotic macrophages.

Characteristics and prognosis of ANCA-positive retroperitoneal fibrosis: A systematic literature review.

Anti-neutrophil cytoplasmic autoantibody (ANCA)-positive retroperitoneal fibrosis (RPF) is extremely rare. This study aimed to clarify the clinical characteristics and prognosis of patients with ANCA-positive RPF. We conducted a systematic literature review of articles reporting on ANCA-positive RPF from the database inception dates until March 8, 2020. We identified 19 patients with ANCA-positive RPF with a mean age of 62 years; a male dominance (68.4%) was noted. Most patients presented with systemic symptoms and/or lower back or abdominal pain. Proteinase 3 (PR3) -ANCA positivity was predominant compared with myeloperoxidase (MPO)-ANCA (63.2% vs. 36.8%, respectively), and all patients showed elevated serum C-reactive protein levels. Of note, 26.7% of patients had isolated RPF without any other ANCA-associated systemic organ involvement. Regarding typical manifestations of ANCA- associated vasculitis, ear, nose, and throat involvement occurred in 26.3%, lung involvement in 36.8%, and kidney involvement (rapidly progressive glomerulonephritis) in 31.6% of patients. Necrosis and granulomatous inflammation, vasculitis, and multinucleated giant cells were pathologically observed in tissue sections of RPF, whereas tertiary lymphoid organ formation was not identified. Glucocorticoids with or without other immunosuppressive treatments were effective in most patients, but 4 patients experienced disease relapse during the clinical course. All relapsed patients were positive for PR3-ANCA. Clinical features of ANCA-positive RPF are associated with systemic inflammatory components such as fever and elevated serum C-reactive protein levels. ANCA-. positive RPF presents as an "isolated" involved organ in one-third of patients. Immunosuppressive treatments are effective, but the disease can recur, particularly in PR3-ANCA-positive patients.

Novel histopathologic predictors for renal outcomes in crescentic glomerulonephritis.

IntroductionCrescentic glomerulonephritis (CrGN) is a histologic feature of severe glomerular injury, clinically characterized by a rapid decline of renal function when not treated in a timely fashion. Factors associated with CrGN prognosis have not been thoroughly investigated. This study investigated the prognostic predictors of renal outcomes associated with CrGN, such as the histopathologic classification of anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis, arteriosclerosis, and tertiary lymphoid organ (TLO) formation.MethodsA total of 114 patients diagnosed with CrGN between 2010 and 2018 at two university-based hospitals has been retrospectively analyzed. Relationships between potential predictors and renal outcomes were analyzed using Cox proportional hazards model and linear regression analysis.ResultsThe mean age was 61.0 ± 15.3 years, and 49.1% were male. Among them, 92 (80.7%) and 11 (9.6%) patients were positive for ANCA and for anti-glomerular basement membrane antibody, respectively. During the median follow-up of 458.0 days, 55 patients (48.2%) had advanced to end-stage renal disease (ESRD). Cox proportional hazards analysis revealed that patients under the mixed and sclerotic classes had worse renal survival compared to those in the focal class (mixed: hazard ratio [HR], 3.74; 95% confidence interval [CI], 1.18 to 11.82; P = 0.025; sclerotic: HR, 4.84; 95% CI, 1.44 to 16.32; P = 0.011). Severe arteriosclerosis was also associated with poor renal survival (HR, 2.44; 95% CI, 1.04 to 5.77; P = 0.042). TLOs were observed in 41 patients (36.0%). Moreover, TLO formation was also a prognostic factor for ESRD (HR, 1.82; 95% CI, 1.03 to 3.21; P = 0.040). In the multivariate linear regression analysis, age and sclerotic class were independent predictors for the change in estimated glomerular filtration rate during 1 year after biopsy.ConclusionsSpecific histopathologic findings, histopathologic classification, severity of arteriosclerosis, and TLO formation provide helpful information in predicting renal outcomes associated with CrGN.

Chronic Inflammation: A Common Promoter in Tertiary Lymphoid Organ Neogenesis.

Tertiary lymphoid organs (TLOs) frequently develop locally in adults in response to non-resolving inflammation. Chronic inflammation leads to the differentiation of stromal fibroblast cells toward lymphoid tissue organizer-like cells, which interact with lymphotoxin immune cells. The interaction initiates lymphoid neogenesis by recruiting immune cells to the site of inflammation and ultimately leads to the formation of TLOs. Mature TLOs harbor a segregated T-cell zone, B-cell follicles with an activated germinal center, follicular dendritic cells, and high endothelial venules, which architecturally resemble those in secondary lymphoid organs. Since CXCL13 and LTα1β2 play key roles in TLO neogenesis, they might constitute potential biomarkers of TLO activity. The well-developed TLOs actively regulate local immune responses and influence disease progression, and they are thereby regarded as the powerhouses of local immunity. In this review, we recapitulated the determinants for TLOs development, with great emphasis on the fundamental role of chronic inflammation and tissue-resident stromal cells for TLO neogenesis, hence offering guidance for therapeutic interventions in TLO-associated diseases.

Pathogenesis of atherosclerosis in the tunica intima, media, and adventitia of coronary arteries: An updated review.

Atherosclerosis is a chronic inflammatory disease of arteries and it affects the structure and function of all three layers of the coronary artery wall. Current theories suggest that the dysfunction of endothelial cells is one of the initial steps in the development of atherosclerosis. The view that the tunica intima normally consists of a single layer of endothelial cells attached to the subendothelial layer and internal elastic membrane has been questioned in recent years. The structure of intima changes with age and it becomes multilayered due to migration of smooth muscle cells from the media to intima. At this stage, the migration and proliferation of smooth muscle cells do not cause pathological changes in the intima. The multilayering of intima is classically considered to be an important stage in the development of atherosclerosis, but in fact atherosclerotic plaques develop only focally due to the interplay of various processes that involve the resident and invading inflammatory cells. The tunica media consists of multiple layers of smooth muscle cells that produce the extracellular matrix, and this layer normally does not contain microvessels. During the development of atherosclerosis, the microvessels from the tunica adventitia or from the lumen may penetrate thickened media to provide nutrition and oxygenation. According to some theories, the endothelial dysfunction of these nutritive vessels may significantly contribute to the atherosclerosis of coronary arteries. The adventitia contains fibroblasts, progenitor cells, immune cells, microvessels, and adrenergic nerves. The degree of inflammatory cell infiltration into the adventitia, which can lead to the formation of tertiary lymphoid organs, correlates with the severity of atherosclerotic plaques. Coronary arteries are surrounded by perivascular adipose tissue that also participates in the atherosclerotic process.

CCL21 Expression in β-Cells Induces Antigen-Expressing Stromal Cell Networks in the Pancreas and Prevents Autoimmune Diabetes in Mice.

Tumors induce tolerance toward their antigens by producing the chemokine CCL21, leading to the formation of tertiary lymphoid organs (TLOs). Ins2-CCL21 transgenic, nonobese diabetic (NOD) mice express CCL21 in pancreatic β-cells and do not develop autoimmune diabetes. We investigated by which mechanisms CCL21 expression prevented diabetes. Ins2-CCL21 mice develop TLOs by 4 weeks of age, consisting of naive CD4+ T cells compartmentalized within networks of CD45-gp38+CD31- fibroblastic reticular cell (FRC)-like cells. Importantly, 12-week-old Ins2-CCL21 TLOs contained FRC-like cells with higher contractility, regulatory, and anti-inflammatory properties and enhanced expression of β-cell autoantigens compared with nontransgenic NOD TLOs found in inflamed islets. Consistently, transgenic mice harbored fewer autoreactive T cells and a higher proportion of regulatory T cells in the islets. Using adoptive transfer and islet transplantation models, we demonstrate that TLO formation in Ins2-CCL21 transgenic islets is critical for the regulation of autoimmunity, and although the effect is systemic, the induction is mediated locally likely by lymphocyte trafficking through TLOs. Overall, our findings suggest that CCL21 promotes TLOs that differ from inflammatory TLOs found in type 1 diabetic islets in that they resemble lymph nodes, contain FRC-like cells expressing β-cell autoantigens, and are able to induce systemic and antigen-specific tolerance leading to diabetes prevention.