The Formation and Function of Granulomas.

Granulomas are organized aggregates of macrophages, often with characteristic morphological changes, and other immune cells. These evolutionarily ancient structures form in response to persistent particulate stimuli-infectious or noninfectious-that individual macrophages cannot eradicate. Granulomas evolved as protective responses to destroy or sequester particles but are frequently pathological in the context of foreign bodies, infections, and inflammatory diseases. We summarize recent findings that suggest that the granulomatous response unfolds in a stepwise program characterized by a series of macrophage activations and transformations that in turn recruit additional cells and produce structural changes. We explore why different granulomas vary and the reasons that granulomas are protective and pathogenic. Understanding the mechanisms and role of granuloma formation may uncover new therapies for the multitude of granulomatous diseases that constitute serious medical problems while enhancing the protective function of granulomas in infections.

Immune aging - A mechanism in autoimmune disease.

Evidence is emerging that the process of immune aging is a mechanism leading to autoimmunity. Over lifetime, the immune system adapts to profound changes in hematopoiesis and lymphogenesis, and progressively restructures in face of an ever-expanding exposome. Older adults fail to generate adequate immune responses against microbial infections and tumors, but accumulate aged T cells, B cells and myeloid cells. Age-associated B cells are highly efficient in autoantibody production. T-cell aging promotes the accrual of end-differentiated effector T cells with potent cytotoxic and pro-inflammatory abilities and myeloid cell aging supports a low grade, sterile and chronic inflammatory state (inflammaging). In pre-disposed individuals, immune aging can lead to frank autoimmune disease, manifesting with chronic inflammation and irreversible tissue damage. Emerging data support the concept that autoimmunity results from aging-induced failure of fundamental cellular processes in immune effector cells: genomic instability, loss of mitochondrial fitness, failing proteostasis, dwindling lysosomal degradation and inefficient autophagy. Here, we have reviewed the evidence that malfunctional mitochondria, disabled lysosomes and stressed endoplasmic reticula induce pathogenic T cells and macrophages that drive two autoimmune diseases, rheumatoid arthritis (RA) and giant cell arteritis (GCA). Recognizing immune aging as a risk factor for autoimmunity will open new avenues of immunomodulatory therapy, including the repair of malfunctioning mitochondria and lysosomes.

New Therapeutic Approaches to Large-Vessel Vasculitis.

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are large-vessel vasculitides affecting the aorta and its branches. Arterial damage from these diseases may result in ischemic complications, aneurysms, and dissections. Despite their similarities, the management of GCA and TAK differs. Glucocorticoids are used frequently but relapses are common, and glucocorticoid toxicity contributes to significant morbidity. Conventional immunosuppressive therapies can be beneficial in TAK, though their role in the management of GCA remains unclear. Tumor necrosis factor inhibitors improve remission rates and appear to limit vascular damage in TAK; these agents are not beneficial in GCA. Tocilizumab is the first biologic glucocorticoid-sparing agent approved for use in GCA and also appears to be effective in TAK. A better understanding of the pathogenesis of both conditions and the availability of targeted therapies hold much promise for future management.

CTLA-4 Pathway Is Instrumental in Giant Cell Arteritis.

BACKGROUND: Giant cell arteritis (GCA) causes severe inflammation of the aorta and its branches and is characterized by intense effector T-cell infiltration. The roles that immune checkpoints play in the pathogenesis of GCA are still unclear. Our aim was to study the immune checkpoint interplay in GCA. METHODS: First, we used VigiBase, the World Health Organization international pharmacovigilance database, to evaluate the relationship between GCA occurrence and immune checkpoint inhibitors treatments. We then further dissected the role of immune checkpoint inhibitors in the pathogenesis of GCA, using immunohistochemistry, immunofluorescence, transcriptomics, and flow cytometry on peripheral blood mononuclear cells and aortic tissues of GCA patients and appropriated controls. RESULTS: Using VigiBase, we identified GCA as a significant immune-related adverse event associated with anti-CTLA-4 (cytotoxic T-lymphocyte-associated protein-4) but not anti-PD-1 (anti-programmed death-1) nor anti-PD-L1 (anti-programmed death-ligand 1) treatment. We further dissected a critical role for the CTLA-4 pathway in GCA by identification of the dysregulation of CTLA-4-derived gene pathways and proteins in CD4+ (cluster of differentiation 4) T cells (and specifically regulatory T cells) present in blood and aorta of GCA patients versus controls. While regulatory T cells were less abundant and activated/suppressive in blood and aorta of GCA versus controls, they still specifically upregulated CTLA-4. Activated and proliferating CTLA-4+ Ki-67+ regulatory T cells from GCA were more sensitive to anti-CTLA-4 (ipilimumab)-mediated in vitro depletion versus controls. CONCLUSIONS: We highlighted the instrumental role of CTLA-4 immune checkpoint in GCA, which provides a strong rationale for targeting this pathway.

Vitamin C inactivates c-Jun N-terminal kinase to stabilize heart and neural crest derivatives expressed 1 (Hand1) in regulating placentation and maintenance of pregnancy.

Vitamin C (VC) serves as a pivotal nutrient for anti-oxidation process, metabolic responses, and stem cell differentiation. However, its precise contribution to placenta development and gestation remains obscure. Here, we demonstrated that physiological levels of VC act to stabilize Hand1, a key bHLH transcription factor vital for the development trajectory of trophoblast giant cell (TGC) lineages, thereby promoting the differentiation of trophoblast stem cells into TGC. Specifically, VC administration inactivated c-Jun N-terminal kinase (JNK) signaling, which directly phosphorylates Hand1 at Ser48, triggering the proteasomal degradation of Hand1. Conversely, a loss-of-function mutation at Ser48 on Hand1 not only significantly diminished both intrinsic and VC-induced stabilization of Hand1 but also underscored the indispensability of this residue. Noteworthy, the insufficiency of VC led to severe defects in the differentiation of diverse TGC subtypes and the formation of labyrinth's vascular network in rodent placentas, resulting in failure of maintenance of pregnancy. Importantly, VC deficiency, lentiviral knockdown of JNK or overexpression of Hand1 mutants in trophectoderm substantially affected the differentiation of primary and secondary TGC in E8.5 mouse placentas. Thus, these findings uncover the significance of JNK inactivation and consequential stabilization of Hand1 as a hitherto uncharacterized mechanism controlling VC-mediated placentation and perhaps maintenance of pregnancy.

Clinicopathologic and prognostic characteristics of tumor budding-like in giant cell tumor of bone.

BACKGROUND: Currently, tumor budding (TB) is defined as an important factor for a poor prognosis in various types of cancers. The authors identified a significant presence of TB-like structures at the tumor invasive front in giant cell tumor of bone (GCTB), which may have the same biologic function as TB. The objective of this report was to describe the distribution of TB in GCTB and investigate its correlation with clinicopathologic characteristics, the immune microenvironment, survival prognosis, and response to denosumab treatment. METHODS: This multicenter cohort study included 426 patients with GCTB who received treatment between 2012 and 2021 at four centers. Two independent pathologists performed visual assessments of TBL structures in hematoxylin-and-eosin-stained tumor sections. Immunohistochemistry was used to evaluate tumor-infiltrating lymphocyte subtypes (CD3-positive, CD4-positive, CD8-positive, CD20-positive, programmed cell death protein-1-positive, programmed cell death-ligand 1positive, and FoxP3-positive) as well as Ki-67 expression levels in 426 tissue samples. These parameters were then analyzed for associations with patient outcomes (local recurrence-free survival [LRFS] and overall survival [OS]), clinicopathologic characteristics, and response to denosumab treatment. RESULTS: High-grade TB was associated with poorer LRFS and OS in both patient groups. In addition, TB was correlated with various clinicopathologic features, tumor-infiltrating lymphocyte expression, and response to denosumab treatment. TB outperformed the traditional Enneking and Campanacci staging systems in predicting patient LRFS and OS. CONCLUSIONS: The current data support the assessment of TBL structures as a reliable prognostic tool in GCTB, potentially aiding in the development of personalized treatment strategies for patients.

VND Genes Redundantly Regulate Cell Wall Thickening during Parasitic Nematode Infection.

Plant parasitic root-knot nematodes are major agricultural pests worldwide, as they infect plant roots and cause substantial damages to crop plants. Root-knot nematodes induce specialized feeding cells known as giant cells (GCs) in the root vasculature, which serve as nutrient reservoirs for the infecting nematodes. Here, we show that the cell walls of GCs thicken to form pitted patterns that superficially resemble metaxylem cells. Interestingly, VASCULAR-RELATED NAC-DOMAIN1 (VND1) was found to be upregulated, while the xylem-type programmed cell death marker XYLEM CYSTEINE PEPTIDASE 1 was downregulated upon nematode infection. The vnd2 and vnd3 mutants showed reduced secondary cell wall pore size, while the vnd1 vnd2 vnd3 triple mutant produced significantly fewer nematode egg masses when compared with the wild type. These results suggest that the GC development pathway likely shares common signaling modules with the metaxylem differentiation pathway and VND1, VND2, and VND3 redundantly regulate plant-nematode interaction through secondary cell wall formation.

Real-World Patient Experience of Pexidartinib for Tenosynovial Giant-Cell Tumor.

BACKGROUND: Pexidartinib (Turalio) is the only systemic therapy approved by the FDA for the treatment of adult patients with symptomatic tenosynovial giant-cell tumor (TGCT) associated with severe morbidity or functional limitations, and not amenable to improvement with surgery. This study assessed patient-reported treatment experiences and symptom improvement among patients receiving pexidartinib. METHODS: A cross-sectional, web-based survey collected data on demographics, disease history, pexidartinib dosing, and symptoms before and after pexidartinib use. RESULTS: Of 288 patients enrolled in the Turalio REMS program in May 2021, 83 completed the survey: mean age was 44.2 years, 62.7% were female, and most common tumor sites were in knee (61%) and ankle (12%). Mean initial dose was 622 mg/day: 29 patients reported reduction from initial dose and 8 had dose reduction after titrating up to a higher dose. At the time of survey completion, median time on pexidartinib was 6.0 months; 22 (26.5%) patients discontinued pexidartinib due to physician suggestion, abnormal laboratory results, side effect, or symptom improvement. Compared with before pexidartinib initiation, most patients reported improvement in overall TGCT symptom (78.3%) and physical function (77.2%) during pexidartinib treatment. Significant improvement was reported during pexidartinib treatment in worst stiffness numeric rating scale (NRS) (3.0 vs. 6.2, P < .05) and worst pain NRS (2.7 vs. 5.7, P < .05). CONCLUSION: Findings from this cross-sectional survey confirmed the benefit of pexidartinib in improving symptoms and functional outcomes among patients with symptomatic TGCTs from the patients' perspective. Future research is warranted to examine the long-term benefit and risk of pexidartinib.

Chondroid Synoviocytic Neoplasm: A Clinicopathologic, Immunohistochemical, and Molecular Genetic Study of a Distinctive Tumor of Synoviocytes.

Tumors resembling tenosynovial giant cell tumor (TGCT) but additionally forming chondroid matrix are rare and most often involve the temporomandibular joint (TMJ). We studied 21 tumors consisting of synoviocytes (large, eosinophilic mononuclear cells containing hemosiderin) and chondroid matrix to better understand these unusual neoplasms. The tumors occurred in 10 males and 11 females, in the age group of 31 to 80 years (median, 50 years) and involved the TMJ region (16), extremities (4), and spine (1). As in conventional TGCT, all were composed of synoviocytes, small histiocytes, foamy macrophages, siderophages, and osteoclast-like giant cells in variably hyalinized background. Expansile nodules of large, moderately atypical synoviocytes were present, in addition to "chondroblastoma-like," "chondroma-like," or "phosphaturic mesenchymal tumor-like" calcified matrix. The synoviocytes expressed clusterin (17/19) and less often desmin (3/15). The tumors were frequently CSF1 positive by chromogenic in situ hybridization (8/13) but at best weakly positive for CSF1 by immunohistochemistry (0/3). Background small histiocytes were CD163 positive (12/12). All were FGF23 negative (0/10). Cells within lacunae showed a synoviocytic phenotype (clusterin positive; S100 protein and ERG negative). RNA-Seq was successful in 13 cases; fusions were present in 7 tumors, including FN1::TEK (5 cases); FN1::PRG4 (2 cases); and MALAT1::FN1, PDGFRA::USP35, and TIMP3::ZCCHC7 (1 case each). Three tumors contained more than 1 fusion (FN1::PRG4 with TIMP3::ZCCHC7, FN1::TEK with FN1::PRG4, and FN1::TEK with MALAT1::FN1). Clinical follow-up (17 patients; median follow-up duration 38 months; range 4-173 months) showed 13 (76%) to be alive without evidence of disease and 4 (24%) to be alive with persistent/recurrent local disease. No metastases or deaths from disease were observed. We conclude that these unusual tumors represent a distinct category of synoviocytic neoplasia, which we term "chondroid synoviocytic neoplasm," rather than simply ordinary TGCT with cartilage. Despite potentially worrisome morphologic features, they appear to behave in at most a locally aggressive fashion.

Clonal haematopoiesis across the age spectrum of vasculitis patients with Takayasu's arteritis, ANCA-associated vasculitis and giant cell arteritis.

OBJECTIVES: Ageing and inflammation are associated with clonal haematopoiesis (CH), the emergence of somatic mutations in haematopoietic cells. This study details CH in patients with systemic vasculitis in association with clinical, haematological and immunological parameters. METHODS: Patients with three forms of vasculitis were screened for CH in peripheral blood by error-corrected sequencing. Relative contributions of age and vasculitis on CH prevalence were calculated using multivariable logistic regression. Clonal hierarchies were assessed by proteogenomic single-cell DNA sequencing, and functional experiments were performed in association with CH status. RESULTS: Patients with Takayasu's arteritis (TAK; n=70; mean age=33.2 years), antineutrophil cytoplasmic antibody-associated vasculitis (AAV; n=47; mean age=55.3 years) and giant cell arteritis (GCA; n=59; mean age=71.2 years) were studied. CH, most commonly in DNMT3A and TET2, was detected in 34% (60/176) of patients versus 18% (28/151) of age-matched controls (p<0.01). Prevalence of CH was independently associated with age (standardised B=0.96, p<0.01) and vasculitis (standardised B=0.46, p<0.01), occurring in 61%, 32% and 13% of patients with GCA, AAV and TAK, respectively. Both branched and linear clonal trajectories showed myeloid-lineage bias, and CH was associated with markers of cellular activation. In GCA, mutations were detected in temporal artery biopsies, and clinical relapse correlated with CH in a dose-dependent relationship with clone size. CONCLUSIONS: Age was more strongly associated with CH prevalence than inflammation in systemic vasculitis. Clonal profile was dominated by DNMT3A mutations which were associated with relapse in GCA. CH is not likely a primary causal factor in systemic vasculitis but may contribute to inflammation.

Plasma proteome profiling in giant cell arteritis.

OBJECTIVES: This study aimed to identify plasma proteomic signatures that differentiate active and inactive giant cell arteritis (GCA) from non-disease controls. By comprehensively profiling the plasma proteome of both patients with GCA and controls, we aimed to identify plasma proteins that (1) distinguish patients from controls and (2) associate with disease activity in GCA. METHODS: Plasma samples were obtained from 30 patients with GCA in a multi-institutional, prospective longitudinal study: one captured during active disease and another while in clinical remission. Samples from 30 age-matched/sex-matched/race-matched non-disease controls were also collected. A high-throughput, aptamer-based proteomics assay, which examines over 7000 protein features, was used to generate plasma proteome profiles from study participants. RESULTS: After adjusting for potential confounders, we identified 537 proteins differentially abundant between active GCA and controls, and 781 between inactive GCA and controls. These proteins suggest distinct immune responses, metabolic pathways and potentially novel physiological processes involved in each disease state. Additionally, we found 16 proteins associated with disease activity in patients with active GCA. Random forest models trained on the plasma proteome profiles accurately differentiated active and inactive GCA groups from controls (95.0% and 98.3% in 10-fold cross-validation, respectively). However, plasma proteins alone provided limited ability to distinguish between active and inactive disease states within the same patients. CONCLUSIONS: This comprehensive analysis of the plasma proteome in GCA suggests that blood protein signatures integrated with machine learning hold promise for discovering multiplex biomarkers for GCA.

Vascular disease persistence in giant cell arteritis: are stromal cells neglected?

Giant cell arteritis (GCA), the most common systemic vasculitis, is characterised by aberrant interactions between infiltrating and resident cells of the vessel wall. Ageing and breach of tolerance are prerequisites for GCA development, resulting in dendritic and T-cell dysfunction. Inflammatory cytokines polarise T-cells, activate resident macrophages and synergistically enhance vascular inflammation, providing a loop of autoreactivity. These events originate in the adventitia, commonly regarded as the biological epicentre of the vessel wall, with additional recruitment of cells that infiltrate and migrate towards the intima. Thus, GCA-vessels exhibit infiltrates across the vascular layers, with various cytokines and growth factors amplifying the pathogenic process. These events activate ineffective repair mechanisms, where dysfunctional vascular smooth muscle cells and fibroblasts phenotypically shift along their lineage and colonise the intima. While high-dose glucocorticoids broadly suppress these inflammatory events, they cause well known deleterious effects. Despite the emerging targeted therapeutics, disease relapse remains common, affecting >50% of patients. This may reflect a discrepancy between systemic and local mediators of inflammation. Indeed, temporal arteries and aortas of GCA-patients can show immune-mediated abnormalities, despite the treatment induced clinical remission. The mechanisms of persistence of vascular disease in GCA remain elusive. Studies in other chronic inflammatory diseases point to the fibroblasts (and their lineage cells including myofibroblasts) as possible orchestrators or even effectors of disease chronicity through interactions with immune cells. Here, we critically review the contribution of immune and stromal cells to GCA pathogenesis and analyse the molecular mechanisms by which these would underpin the persistence of vascular disease.

Senescent cells in giant cell arteritis display an inflammatory phenotype participating in tissue injury via IL-6-dependent pathways.

OBJECTIVES: Age is the strongest risk factor of giant cell arteritis (GCA), implying a possible pathogenetic role of cellular senescence. To address this question, we applied an established senescence specific multimarker algorithm in temporal artery biopsies (TABs) of GCA patients. METHODS: 75(+) TABs from GCA patients, 22(-) TABs from polymyalgia rheumatica (PMR) patients and 10(-) TABs from non-GCA/non-PMR patients were retrospectively retrieved and analysed. Synovial tissue specimens from patients with inflammatory arthritis and aorta tissue were used as disease control samples. Senescent cells and their histological origin were identified with specific cellular markers; IL-6 and MMP-9 were investigated as components of the senescent associated secretory phenotype by triple costaining. GCA or PMR artery culture supernatants were applied to fibroblasts, HUVECs and monocytes with or without IL-6R blocking agent to explore the induction of IL-6-associated cellular senescence. RESULTS: Senescent cells were present in GCA arteries at higher proportion compared with PMR (9.50% vs 2.66%, respectively, p<0.0001) and were mainly originated from fibroblasts, macrophages and endothelial cells. IL-6 was expressed by senescent fibroblasts, and macrophages while MMP-9 by senescent fibroblasts only. IL-6(+) senescent cells were associated with the extension of vascular inflammation (transmural inflammation vs adventitia limited disease: 10.02% vs 4.37%, respectively, p<0.0001). GCA but not PMR artery culture supernatant could induce IL-6-associated senescence that was partially inhibited by IL-6R blockade. CONCLUSIONS: Senescent cells with inflammatory phenotype are present in GCA arteries and are associated with the tissue inflammatory bulk, suggesting a potential implication in disease pathogenesis.

Should all patients with polymyalgia rheumatica have a vascular ultrasound assessment?

There is a growing appreciation that both giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are closely interrelated conditions that have significant overlap in aetiology, clinical characteristics and treatment regimens. Subclinical GCA in PMR is becoming increasingly recognised, and there is evolving evidence that this may be a more aggressive disease phenotype than PMR. Ultrasound (US) lends itself well as a screening tool for GCA in PMR; it is inexpensive, non-invasive, widely available, lacks ionising radiation, may be performed at the bedside and is recommended by EULAR as a first-line investigation for suspected GCA. There is insufficient evidence to currently recommend that all patients with PMR should have a US assessment for vascular involvement. However, as clinical and laboratory parameters alone do not accurately diagnose patients with subclinical GCA, we suggest that vascular US will be increasingly performed by rheumatologists in practice to identify these patients with PMR, preferably as part of larger prospective outcome studies.

Treat-to-target recommendations in giant cell arteritis and polymyalgia rheumatica.

OBJECTIVES: To develop treat-to-target (T2T) recommendations in giant cell arteritis (GCA) and polymyalgia rheumatica (PMR). METHODS: A systematic literature review was conducted to retrieve data on treatment targets and outcomes in GCA/PMR as well as to identify the evidence for the effectiveness of a T2T-based management approach in these diseases. Based on evidence and expert opinion, the task force (29 participants from 10 countries consisting of physicians, a healthcare professional and a patient) developed recommendations, with consensus obtained through voting. The final level of agreement was provided anonymously. RESULTS: Five overarching principles and six-specific recommendations were formulated. Management of GCA and PMR should be based on shared decisions between patient and physician recognising the need for urgent treatment of GCA to avoid ischaemic complications, and it should aim at maximising health-related quality of life in both diseases. The treatment targets are achievement and maintenance of remission, as well as prevention of tissue ischaemia and vascular damage. Comorbidities need to be considered when assessing disease activity and selecting treatment. CONCLUSION: These are the first T2T recommendations for GCA and PMR. Treatment targets, as well as strategies to assess, achieve and maintain these targets have been defined. The research agenda highlights the gaps in evidence and the need for future research.

Subclinical giant cell arteritis increases the risk of relapse in polymyalgia rheumatica.

OBJECTIVE: The aim of the present study was to determine the clinical significance of subclinical giant cell arteritis (GCA) in polymyalgia rheumatica (PMR) and ascertain its optimal treatment approach. METHODS: Patients with PMR who fulfilled the 2012 European Alliance of Associations for Rheumatology/American College of Rheumatology Provisional Classification Criteria for PMR, did not have GCA symptoms and were routinely followed up for 2 years and were stratified into two groups, according to their ultrasound results: isolated PMR and PMR with subclinical GCA. The outcomes (relapses, glucocorticoid use and disease-modifying antirheumatic drug treatments) between groups were compared. RESULTS: We included 150 patients with PMR (50 with subclinical GCA) with a median (IQR) follow-up of 22 (20-24) months. Overall, 47 patients (31.3 %) had a relapse, 31 (62%) in the subclinical GCA group and 16 (16%) in the isolated PMR group (p<0.001). Among patients with subclinical GCA, no differences were found in the mean (SD) prednisone starting dosage between relapsed and non-relapsed patients (32.4±15.6 vs 35.5±12.1 mg, respectively, p=0.722). Patients with subclinical GCA who relapsed had a faster prednisone dose tapering in the first 3 months compared with the non-relapsed patients, with a mean dose at the third month of 10.0±5.2 versus 15.2±7.9 mg daily (p<0.001). No differences were found between relapsing and non-relapsed patients with subclinical GCA regarding age, sex, C reactive protein and erythrocyte sedimentation rate. CONCLUSIONS: Patients with PMR and subclinical GCA had a significantly higher number of relapses during a 2-year follow-up than patients with isolated PMR. Lower starting doses and rapid glucocorticoid tapering in the first 3 months emerged as risk factors for relapse.

Measles vaccination - An underestimated prevention measure: Analyzing a fatal case in Hildesheim, Germany.

Measles and rubella are targeted for elimination in the WHO region Europe. To reach the elimination goal, vaccination coverage of 95% must be achieved and sustained, the genotype information has to be provided for 80% of all outbreaks and transmission chains of a certain variant must not be detected for >12 months. The latter information is collected at Germany's National Reference Center Measles, Mumps, Rubella (NRC MMR). We describe here an outbreak of measles occurring in Hildesheim. The outbreak comprised 43 cases and lasted 14 weeks. Surprisingly, a high number of vaccination failures was observed since 11 cases had received two doses of the MMR vaccine and 4 additional cases were vaccinated once. A 33-year-old woman passed away during the outbreak. She was the mother of 5 children between 4 and 16 years of age. Two schoolchildren contracted measles and passed it on to the rest of the family. Due to delivery bottlenecks, the vaccination of the mother was delayed. She developed measles-like symptoms 3 days after vaccination and was found dead on the morning of day 8 after vaccination. A post-mortem examination was done to identify the cause of death. Moreover, molecular characterization of the virus was performed to analyze whether she was infected by the wildtype virus circulating at that time in Hildesheim or whether the vaccine may have been a concomitant and aggravating feature of her death. The result showed that the samples taken from her at the time of death and during necropsy contained the wildtype measles virus variant corresponding to MVs/Gir Somnath.IND/42.16 (WHO Seq-ID D8-4683) that fueled the Hildesheim outbreak and circulated in Germany from March 2018 to March 2020. The vaccine virus was not detected. Moreover, two aspects uncovered by the post-mortem examination were remarkable; the woman died from giant cell pneumonia, which is a complication seen in immune-suppressed individuals and she was actively using cannabis. THC is known to influence the immune system, but literature reports describing the effects are limited.

Impaired IL-6-induced JAK-STAT signaling in CD4+ T cells associates with longer treatment duration in giant cell arteritis.

INTRODUCTION: The IL-12-IFNγ-Th1 and the IL-6-IL-23-Th17 axes are considered the dominant pathogenic pathways in Giant Cell Arteritis (GCA). Both pathways signal via activation of the downstream JAK/STAT proteins. We hypothesized that phosphorylated STAT (pSTAT) signatures in circulating immune cells may aid to stratify GCA-patients for personalized treatment. METHODS: To investigate pSTAT expression, PBMCs from treatment-naive GCA-patients (n = 18), infection controls (INF, n = 11) and age-matched healthy controls (HC, n = 15) were stimulated in vitro with IL-6, IL-2, IL-10, IFN-γ, M-CSF or GM-CSF, and stained with CD3, CD4, CD19, CD45RO, pSTAT1, pSTAT3, pSTAT5 antibodies, and analyzed by flow cytometry. Serum IL-6, sIL-6-receptor and gp130 were measured by Luminex. The change in percentages of pSTAT3+CD4+T-cells was evaluated at diagnosis and at 3 months and 1-year of follow-up. Kaplan-Meier analyses was used to asses prognostic accuracy. RESULTS: Analysis of IL-6 stimulated immune cell subsets revealed a significant decrease in percentages of pSTAT3+CD4+T-cells of GCA-patients and INF-controls compared to HCs. Following patient stratification according to high (median>1.5 pg/mL) and low (median<1.5 pg/mL) IL-6 levels, we observed a reduction in the pSTAT3 response in GCA-patients with high serum IL-6. Percentages of pSTAT3+CD4+T-cells in patients with high serum IL-6 levels at diagnosis normalized after glucocorticoid (GC) treatment. Importantly, we found that patients with low percentages of pSTAT3+CD4+T-cells at baseline require longer GC-treatment. CONCLUSION: Overall, in GCA, the percentages of in vitro IL-6-induced pSTAT3+CD4+T-cells likely reflect prior in vivo exposure to high IL-6 and may serve as a prognostic marker for GC-treatment duration and may assist improving personalized treatment options in the future.

Polymyalgia rheumatica shows metabolomic alterations that are further altered by glucocorticoid treatment: Identification of metabolic correlates of fatigue.

OBJECTIVE: In polymyalgia rheumatica (PMR), glucocorticoids (GCs) relieve pain and stiffness, but fatigue may persist. We aimed to explore the effect of disease, GCs and PMR symptoms in the metabolite signatures of peripheral blood from patients with PMR or the related disease, giant cell arteritis (GCA). METHODS: Nuclear magnetic resonance spectroscopy was performed on serum from 40 patients with untreated PMR, 84 with new-onset confirmed GCA, and 53 with suspected GCA who later were clinically confirmed non-GCA, and 39 age-matched controls. Further samples from PMR patients were taken one and six months into glucocorticoid therapy to explore relationship of metabolites to persistent fatigue. 100 metabolites were identified using Chenomx and statistical analysis performed in SIMCA-P to examine the relationship between metabolic profiles and, disease, GC treatment or symptoms. RESULTS: The metabolite signature of patients with PMR and GCA differed from that of age-matched non-inflammatory controls (R2 > 0.7). There was a smaller separation between patients with clinically confirmed GCA and those with suspected GCA who later were clinically confirmed non-GCA (R2 = 0.135). In PMR, metabolite signatures were further altered with glucocorticoid treatment (R2 = 0.42) but did not return to that seen in controls. Metabolites correlated with CRP, pain, stiffness, and fatigue (R2 ≥ 0.39). CRP, pain, and stiffness declined with treatment and were associated with 3-hydroxybutyrate and acetoacetate, but fatigue did not. Metabolites differentiated patients with high and low fatigue both before and after treatment (R2 > 0.9). Low serum glutamine was predictive of high fatigue at both time points (0.79-fold change). CONCLUSION: PMR and GCA alter the metabolite signature. In PMR, this is further altered by glucocorticoid therapy. Treatment-induced metabolite changes were linked to measures of inflammation (CRP, pain and stiffness), but not to fatigue. Furthermore, metabolite signatures distinguished patients with high or low fatigue.

Neointimal myofibroblasts contribute to maintaining Th1/Tc1 and Th17/Tc17 inflammation in giant cell arteritis.

Vascular smooth muscle cells (VSMCs) have been shown to play a role in the pathogenesis of giant cell arteritis (GCA) through their capacity to produce chemokines recruiting T cells and monocytes in the arterial wall and their ability to migrate and proliferate in the neointima where they acquire a myofibroblast (MF) phenotype, leading to vascular stenosis. This study aimed to investigate if MFs could also impact T-cell polarization. Confocal microscopy was used to analyze fresh fragments of temporal artery biopsies (TABs). Healthy TAB sections were cultured to obtain MFs, which were then treated or not with interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) and analyzed by immunofluorescence and RT-PCR. After peripheral blood mononuclear cells and MFs were co-cultured for seven days, T-cell polarization was analyzed by flow cytometry. In the neointima of GCA arteries, we observed a phenotypic heterogeneity among VSMCs that was consistent with a MF phenotype (α-SMA+CD90+desmin+MYH11+) with a high level of STAT1 phosphorylation. Co-culture experiments showed that MFs sustain Th1/Tc1 and Th17/Tc17 polarizations. The increased Th1 and Tc1 polarization was further enhanced following the stimulation of MFs with IFN-γ and TNF-α, which induced STAT1 phosphorylation in MFs. These findings correlated with increases in the production of IL-1ß, IL-6, IL-12 and IL-23 by MFs. Our study showed that MFs play an additional role in the pathogenesis of GCA through their ability to maintain Th17/Tc17 and Th1/Tc1 polarizations, the latter being further enhanced in case of stimulation of MF with IFN-γ and TNF-α.