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Background/Aims Real Time-Deformability Cytometry (RT-DC) is a novel technique able to identify morpho-rheological characteristics of individual cells such as size, deformability, and elasticity using only 50µl of whole blood. Cells in suspension flow through a microfluidic channel while hydrodynamic force is applied, leading to reversible deformation of individual cells from shear stress and pressure gradients. Cell brightness and area can be used to identify individual cell types. The morpho-rheological characteristics of immune cells in ANCA associated vasculitis (AAV) are unknown. Methods Whole blood from healthy controls (HC), patients with active AAV, or patients with AAV in remission was analysed using RT-DC. The diagnosis of AAV was based upon positive ANCA testing, with either (i) pauci-immune glomerulonephritis, or (ii) typical clinical features of extra-renal AAV. Patients with active disease may have received steroids prior to sampling but those who received other immunosuppression or cytotoxics were excluded. Remission was defined as BVAS of 0 with prednisolone dose ≤7.5mg/day. Blood was collected into K2 EDTA and diluted 1:20 in 1xPBS/0.6% methylcellulose. Cell suspensions were flowed across a Flic20 polydimethylsiloxane microfluidic chip, containing reservoirs connected by a measurement channel with a 20x20 μm2 cross-section. RT-DC measurements were collected at a flow rate of 0.12μL/s using a high-speed CMOS camera to capture images at a rate of 2000 frames/second. ShapeOut software was used to calculate cell size, deformation, and elasticity. Results There was no difference in neutrophil size between patients with active AAV (n = 15), patients with AAV in remission (n = 31), and HC (n = 15). Neutrophils from patients with active AAV were significantly stiffer than patients in remission or HC, displaying decreased deformation (median 0.084, 0.085, and 0.078 au respectively, p = 0.0068) and increased elasticity (median 0.973, 0.968 and 1.006 au respectively, p = 0.0196). In patients with active AAV, there was strong inverse correlation between neutrophil deformation and disease activity measured by BVAS score (r=-0.573, p = 0.032). Neutrophils isolated from healthy donors exhibited a trend towards decreased deformability when primed with TNF and stimulated with MPO-ANCA IgG compared to unstimulated or cells treated with healthy donor IgG (median 0.086, 0.085, and 0.083 for unstimulated, control IgG, and MPO-ANCA IgG respectively, ns). Conclusion Neutrophils from patients display distinct physical properties in active AAV which correlate with disease activity. Similar results are seen when neutrophils are stimulated in vitro with MPO-ANCA IgG. This phenotype of increased cell stiffness may lead to increased neutrophil retention in pulmonary and renal microvasculature, thus increasing the potential for neutrophil-endothelial cell interactions and microvascular damage. Morphorheological parameters can be rapidly measured using a small volume of whole blood; thus, RT-DC may be a useful technique to aid identification of disease activity in AAV and to guide treatment. Disclosure N. Pisacano: None. S.P. McAdoo: None. J. Guck: None. C.D. Pusey: None. E.R. Chilvers: None. A.C. Cowburn: None. K.M. Lodge: None. M.F. Prendecki: None.

ObjectivesTo investigate the prevalence of spike-protein antibodies following at least 3 COVID-19 vaccine doses in immunocompromised individuals.DesignCross-sectional study using UK national disease registries of individuals with solid organ transplants (SOT), rare autoimmune rheumatic diseases (RAIRD) and lymphoid malignancies (LM).SettingParticipants were identified, invited and recruited at home by accessing the NHS Blood and Transplant Registry for those UK individuals who had received a SOT; and the National Disease Registration Service at NHS Digital for identifying individuals within England with RAIRD or LM.Participants101972 people were invited, 28411 recruited, and 23036 provided serological data, comprising 9927 SOT recipients, 6516 with RAIRD, and 6593 with LM.InterventionsParticipants received a lateral flow immunoassay for spike-protein antibodies to perform at home together with an online questionnaire.Main outcome measuresOdds of detectable IgG spike-protein antibodies in immunosuppressed cohorts following at least three COVID-19 vaccine doses by participant demographic, disease type, and treatment related characteristicsResultsIgG spike-protein antibodies were undetectable in 23.3%, 14.1% and 20.7% of the SOT, RAIRD and LM cohorts, respectively. Participants had received three, four or ≥five vaccine doses at the time of testing in 28.5%, 61.8%, and 9.6%, respectively. In all groups, seropositivity was associated with younger age, higher number of vaccine doses and previous COVID-19 infection. Immunosuppressive medication reduced the likelihood of seropositivity: the lowest odds of seropositivity were found in SOT recipients receiving an anti-proliferative agent, calcineurin inhibitor and steroid concurrently, and those treated with anti-CD20 in the RAIRD and LM cohorts.ConclusionsApproximately one in five individuals with SOT, RAIRD and LM have no detectable IgG spike-protein antibodies despite three or more vaccines, but this proportion reduces with sequential booster doses. Choice of immunosuppressant and disease-type is strongly associated with serological response. Antibody testing could enable rapid identification of individuals who are most likely to benefit from additional COVID-19 interventions.Trial registrationClinicaltrials.gov,NCT05148806

As the severe acute respiratory syndrome coronavirus 2 pandemic evolved and became a global health threat, the safety of immunosuppression in antineutrophil cytoplasmic antibody-associated vasculitis (AAV) became of utmost important for clinicians and patients. Although timely initiation of immunosuppressive therapy is critical to quell the acute inflammation and prevent AAV-associated mortality and morbidity, concerns for increased susceptibility to Coronavirus Disease 2019 (COVID-19), delayed viral clearance, and decreased humoral response to infection led to speculation about modification in induction therapy practices may be deployed by physicians caring for patients with AAV. This international retrospective cohort study investigated the influence of the COVID-19 pandemic on AAV induction therapy and patient outcomes in different parts of the world by studying differences in treatment regimens in the United States, United Kingdom, and Europe.

ObjectiveThere is an urgent need to assess the impact of immunosuppressive therapies on the immunogenicity and efficacy of SARS-CoV-2 vaccination.MethodsSerological and T-cell ELISpot assays were used to assess the response to first-dose and second-dose SARS-CoV-2 vaccine (with either BNT162b2 mRNA or ChAdOx1 nCoV-19 vaccines) in 140 participants receiving immunosuppression for autoimmune rheumatic and glomerular diseases.ResultsFollowing first-dose vaccine, 28.6% (34/119) of infection-naïve participants seroconverted and 26.0% (13/50) had detectable T-cell responses to SARS-CoV-2. Immune responses were augmented by second-dose vaccine, increasing seroconversion and T-cell response rates to 59.3% (54/91) and 82.6% (38/46), respectively. B-cell depletion at the time of vaccination was associated with failure to seroconvert, and tacrolimus therapy was associated with diminished T-cell responses. Reassuringly, only 8.7% of infection-naïve patients had neither antibody nor T-cell responses detected following second-dose vaccine. In patients with evidence of prior SARS-CoV-2 infection (19/140), all mounted high-titre antibody responses after first-dose vaccine, regardless of immunosuppressive therapy.ConclusionSARS-CoV-2 vaccines are immunogenic in patients receiving immunosuppression, when assessed by a combination of serology and cell-based assays, although the response is impaired compared with healthy individuals. B-cell depletion following rituximab impairs serological responses, but T-cell responses are preserved in this group. We suggest that repeat vaccine doses for serological non-responders should be investigated as means to induce more robust immunological response.

Objective COVID-19 is a novel infectious disease with a broad spectrum of clinical severity. Patients with systemic vasculitis have an increased risk of serious infections and may be at risk of severe outcomes following COVID-19. We undertook this study to establish the risk factors for severe COVID-19 outcomes in these patients, including the impact of immunosuppressive therapies. Methods A multicenter cohort was developed through the participation of centers affiliated with national UK and Ireland vasculitis registries. Clinical characteristics and outcomes are described. Logistic regression was used to evaluate associations between potential risk factors and a severe COVID-19 outcome, defined as a requirement for advanced oxygen therapy, a requirement for invasive ventilation, or death. Results The cohort included 65 patients with systemic vasculitis who developed COVID-19 (median age 70 years, 49% women), of whom 25 patients (38%) experienced a severe outcome. Most patients (55 of 65 [85%]) had antineutrophil cytoplasmic antibody–associated vasculitis (AAV). Almost all patients required hospitalization (59 of 65 [91%]), 7 patients (11%) were admitted to intensive care, and 18 patients (28%) died. Background glucocorticoid therapy was associated with severe outcomes (adjusted odds ratio [OR] 3.7 [95% confidence interval 1.1–14.9]; P = 0.047), as was comorbid respiratory disease (adjusted OR 7.5 [95% confidence interval 1.9–38.2]; P = 0.006). Vasculitis disease activity and nonglucocorticoid immunosuppressive therapy were not associated with severe outcomes. Conclusion In patients with systemic vasculitis, glucocorticoid use at presentation and comorbid respiratory disease were associated with severe outcomes in COVID-19. These data can inform clinical decision-making relating to the risk of severe COVID-19 in this vulnerable patient group.

OBJECTIVE: Syk is a cytoplasmic protein tyrosine kinase that plays a role in signaling via B cell and Fc receptors (FcR). FcR engagement and signaling via Syk is thought to be important in antineutrophil cytoplasm antibody (ANCA) IgG-mediated neutrophil activation. This study was undertaken to investigate the role of Syk in ANCA-induced myeloid cell activation and vasculitis pathogenesis. METHODS: Phosphorylation of Syk in myeloid cells from healthy controls and ANCA-associated vasculitis (AAV) patients was analyzed using flow cytometry. The effect of Syk inhibition on myeloperoxidase (MPO)-ANCA IgG activation of cells was investigated using functional assays (interleukin-8 and reactive oxygen species production) and targeted gene analysis with NanoString. Total and phosphorylated Syk at sites of tissue inflammation in patients with AAV was assessed using immunohistochemistry and RNAscope in situ hybridization. RESULTS: We identified increased phosphorylated Syk at critical activatory tyrosine residues in blood neutrophils and monocytes from patients with active AAV compared to patients with disease in remission or healthy controls. Syk was phosphorylated in vitro following MPO-ANCA IgG stimulation, and Syk inhibition was able to prevent ANCA-mediated cellular responses. Using targeted gene expression analysis, we identified up-regulation of FcR- and Syk-dependent signaling pathways following MPO-ANCA IgG stimulation. Finally, we showed that Syk is expressed and phosphorylated in tissue leukocytes at sites of organ inflammation in AAV. CONCLUSION: These findings indicate that Syk plays a critical role in MPO-ANCA IgG-induced myeloid cell responses and that Syk is activated in circulating immune cells and tissue immune cells in AAV; therefore, Syk inhibition may be a potential therapeutic option.

Patients with end stage kidney disease receiving in-center hemodialysis (ICHD) have had high rates of SARS-CoV-2 infection. Following infection, patients receiving ICHD frequently develop circulating antibodies to SARS-CoV-2, even with asymptomatic infection. Here, we investigated the durability and functionality of the immune responses to SARS-CoV-2 infection in patients receiving ICHD. Three hundred and fifty-six such patients were longitudinally screened for SARS-CoV-2 antibodies and underwent routine PCR-testing for symptomatic and asymptomatic infection. Patients were regularly screened for nucleocapsid protein (anti-NP) and receptor binding domain (anti-RBD) antibodies, and those who became seronegative at six months were screened for SARS-CoV-2 specific T-cell responses. One hundred and twenty-nine (36.2%) patients had detectable antibody to anti-NP at time zero, of whom 127 also had detectable anti-RBD. Significantly, at six months, 71/111 (64.0%) and 99/116 (85.3%) remained anti-NP and anti-RBD seropositive, respectively. For patients who retained antibody, both anti-NP and anti-RBD levels were reduced significantly after six months. Eleven patients who were anti-NP seropositive at time zero, had no detectable antibody at six months; of whom eight were found to have SARS-CoV-2 antigen specific T cell responses. Independent of antibody status at six months, patients with baseline positive SARS-CoV-2 serology were significantly less likely to have PCR confirmed infection over the following six months. Thus, patients receiving ICHD mount durable immune responses six months post SARS-CoV-2 infection, with fewer than 3% of patients showing no evidence of humoral or cellular immunity., Graphical abstract

Objectives The pro-inflammatory activities of the calgranulins and HMGB1 can be counteracted by sRAGE, the soluble form of their shared receptor. To understand the role of these molecules in AAV and their potential as therapeutic targets we have studied (i) the relationship between these DAMPS and disease activity; (ii) the expression of RAGE and sRAGE in biopsy tissue and peripheral blood; and (iii) the effect of these molecules on ANCA-mediated cytokine production. Methods We examined circulating levels of calgranulins (S100A8/A9 and S100A12), HMGB1 and sRAGE by ELISA. RAGE was examined in AAV kidney and lung biopsies by immunohistochemistry and RAGE expression was monitored in peripheral blood by qPCR. In vitro, the effect of co-stimulating PBMC with ANCA and S100A8/A9 on cytokine production was studied by ELISA. Results We found significantly raised levels of calgranulins and HMGB1 in active AAV regardless of clinical phenotype (PR3+/MPO+ AAV). Levels of calgranulins showed significant correlations with each other. RAGE protein and message was raised in peripheral blood and in cells infiltrating kidney and lung biopsy tissue, while sRAGE was lowered. Furthermore, ANCA-mediated production of IL-8 from PBMC was significantly enhanced by the presence of S100A8/A9 in a RAGE/TLR4-dependent manner. Conclusions Raised circulating calgranulins provide a good marker of disease activity in AAV and are unlikely to be counteracted by sRAGE. Increased RAGE expression in AAV indicates receptor stimulation in active disease that may exacerbate ANCA-induced cytokine production. Targeting the RAGE pathway may provide a useful therapeutic approach in AAV.

Background To investigate whether serum chitinase-3-like 1 protein (YKL-40) is associated with disease activity in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Methods ELISA was performed in serum samples from AAV patients who were enrolled in our prospective observational cohort to estimate levels of YKL-40. Birmingham vasculitis activity score (BVAS) (version 3), five factor score (FFS), and short form-36 (SF-36), as well as clinical and laboratory data were collected. Kidney expression of YKL-40 was assessed by immunohistochemical staining using renal biopsy tissues from ANCA-associated glomerulonephritis patients (AAGN). Severe AAV and FFS were defined as BVAS ≥ 12 and FFS ≥ 2, and the correlations between laboratory variables, BVAS, FFS, and SF-36 score were assessed using linear regression analysis. The optimal cut-off of serum YKL-40 for severe AAV and high FFS was calculated using the receiver operator characteristic curve analysis. Results Of the included 60 patients, 32 (53.3%), 17 (28.3%), and 11 (18.3%) were classified as microscopic polyangiitis, granulomatosis with polyangiitis, and eosinophilic granulomatosis with polyangiitis. The median BVAS and FFS were 7.0 and 1.0, whereas the mean SF-36 physical and mental component scores were 50.5 and 58.3. Serum YKL-40 level was higher in patients with severe AAV and high FFS compared to those without (p = 0.007 and p 221.3 ng/mL and > 227.1 ng/mL than those without (relative risk 2.852 and 7.000). In 12 patients with serial YKL-40 testing, 11 patients (91.7%) exhibited a reduction in serum YKL-40 levels following a decrease in disease activity (p Conclusion Our findings suggest that serum YKL-40 may be a clinically useful biomarker to assess AAV disease activity. Trial registration Retrospectively registered.

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) is a rare systemic autoimmune disease that is characterized by necrotizing inflammation of predominantly the small blood vessels and the presence of circulating ANCAs directed against myeloperoxidase or proteinase 3. Current treatment strategies for severe disease, supported by the findings of several well-coordinated randomized controlled trials, aim to induce remission with high-dose glucocorticoids and either rituximab or cyclophosphamide, followed by relapse prevention with a period of sustained low-dose treatment. This approach has dramatically improved outcomes in AAV; however, a significant proportion of patients develop serious treatment-related side effects or experience relapse. Recent advances in our understanding of the pathogenesis of AAV have led to the identification of novel therapeutic targets that may address these problems, including strategies directed at the aberrant adaptive autoimmune response (B and T cell-directed treatments) and those targeting innate immune elements (complement, monocytes, and neutrophils). It is anticipated that these novel treatments, used alone or in combination, will lead to more effective and less toxic treatment regimens for patients with AAV.

We aimed to describe the outcomes of Omicron infection in kidney transplant recipients (KTR), compare the efficacy of the community therapeutic interventions and report the safety profile of molnupiravir.From 142 KTRs diagnosed with COVID-19 infection after Omicron had become the dominant variant in the UK, 116 (78.9%) cases were diagnosed in the community; 47 receiving sotrovimab, 21 molnupiravir and 48 no treatment. 10 (20.8%) non-treated patients were hospitalised following infection, which was significantly higher than the sotrovimab group (2.1%), p=0.0048, but not the molnupiravir treated group (14.3%), p=0.47. The only admission following sotrovimab occurred in a patient infected with BA.2. One patient from the molnupiravir and no-treatment groups required ICU support, and both subsequently died, with one other death in the no-treatment group. No patient receiving sotrovimab died. 6/116 (5.2%) patients required dialysis following their diagnosis; 2 (9.5%) patients receiving molnupiravir and 4 (8.3%) no-treatment. This requirement was significantly higher in the molnupiravir group compared with the sotrovimab treated patients, in whom no patient required dialysis, p=0.035. Both molnupiravir treated patients requiring dialysis had features of systemic thrombotic microangiopathy.Post-vaccination serostatus was available in 110 patients. Seropositive patients were less likely to require hospital admission compared with seronegative patients, 6 (7.0%) and 6 (25.0%) respectively, p=0.023. Seropositive patients were also less likely to require dialysis therapy, p=0.016.In conclusion, sotrovimab treatment in the community was associated with superior patient and transplant outcomes; it’s clinical efficacy against the BA.2 variant requires a rapid review. The treatment benefit of molnupiravir was not evident, and wider safety reporting in transplant patients is needed.

Patients with end-stage kidney disease (ESKD) are at high risk of severe COVID-19. Here, we performed longitudinal blood sampling of ESKD haemodialysis patients with COVID-19, collecting samples pre-infection, serially during infection, and after clinical recovery. Using plasma proteomics, and RNA-sequencing and flow cytometry of immune cells, we identified transcriptomic and proteomic signatures of COVID-19 severity, and found distinct temporal molecular profiles in patients with severe disease. Supervised learning revealed that the plasma proteome was a superior indicator of clinical severity than the PBMC transcriptome. We showed that both the levels and trajectory of plasma LRRC15, a proposed co-receptor for SARS-CoV-2, are the strongest predictors of clinical outcome. Strikingly, we observed that two months after the acute infection, patients still display dysregulated gene expression related to vascular, platelet and coagulation pathways, including PF4 (platelet factor 4), which may explain the prolonged thrombotic risk following COVID-19.

BACKGROUND From population studies, solid organ transplant recipients are at increased risk of mortality from RT-PCR confirmed COVID-19 infection. The risk factors associated with infection acquisition and mortality in transplant recipients using serological data have not been reported. METHODS From 1725 maintenance transplant recipients, 855 consecutive patients were screened for SARS-CoV-2 antibodies. Serological screening utilized assays to detect both the N protein and receptor binding domain antibodies. Thirty-three of 855 (3.9%) of the screened patients had prior infection confirmed with RT-PCR. Twenty-one additional patients from our 1725 maintenance cohort with RT-PCR confirmed infection were included in our analysis. RESULTS Eighty-nine of 855 (10.4%) patients tested positive for SARS-CoV-2 antibodies. Fifty-nine of 89 (66.3%) cases were patients newly identified as exposed, while 30/89 (33.7%) seropositive patients had previous infection confirmed by RT-PCR. A diagnosis of SARS-CoV-2 (RT-PCR or Ab+) was associated with being from a noncaucasoid background, P = 0.015; having a diagnosis of diabetes, P = 0.028 and a history of allograft rejection, P

Purpose of review This review summarises the evidence for the use of therapeutic plasma exchange (TPE) in anti-neutrophil cytoplasm antibody (ANCA)–associated vasculitis. TPE is an extra-corporeal treatment which efficiently removes IgG and other pathogenic small molecules from the blood. There are several mechanistic reasons why this should be of benefit in AAV including the well-described pathogenicity of ANCA. Recent findings The recently published PEXIVAS trial is the largest study of TPE in AAV to date. It did not show a benefit for adjunctive TPE on a primary end point of ESRD or death. There was no difference in serious adverse events between those treated with TPE and those treated with immunosuppressive drugs alone. Conclusions Based on the results of PEXIVAS, most patients with AAV should not be treated with adjunctive TPE. However, there are subgroups of patients with AAV for whom TPE may still be of benefit, including those with double positivity for anti-GBM antibodies and ANCA.

Background Immune complexes within glomerular capillary walls cause crescentic GN (CrGN). Monocytes and macrophages are important in mediating CrGN, but little work has been done to phenotype the subpopulations involved and determine their respective contributions to glomerular inflammation. Methods Live glomerular imaging using confocal microscopy monitored intravascular monocyte subset behavior during nephrotoxic nephritis (NTN) in a novel WKY-hCD68-GFP monocyte/macrophage reporter rat strain. Flow cytometry and qPCR further analyzed ex vivo the glomerular leukocyte infiltrate during NTN. Results Non-classical monocytes surveyed the glomerular endothelium via lymphocyte function-associated antigen 1 (LFA-1) in the steady state. During NTN, non-classical monocytes were recruited first, but subsequent recruitment and retention of classical monocytes was associated with glomerular damage. Monocytes recruited to the glomerular vasculature did not undergo transendothelial migration. This finding suggests that inflammation in immune complex-mediated CrGN is predominantly intravascular, driven by dynamic interactions between intravascular blood monocytes and the endothelium. Glomerular endothelium and non-classical monocytes overexpressed a distinct chemokine axis, which may orchestrate inflammatory myeloid cell recruitment and expression of damage mediators. Reduced classical monocyte recruitment in Lewis rats during NTN confirmed a role for CD16 in mediating glomerular damage. Conclusions Monocyte subsets with distinct phenotypes and effector functions may be important in driving inflammation in experimental CrGN resulting from immune complexes formed within the glomerular capillary wall. LFA-1-dependent endothelial surveillance by non-classical monocytes may detect immune complexes through CD16, orchestrating the inflammatory response through intravascular retention of classical monocytes, which results in glomerular damage and proteinuria.

P2RX7, an ionotropic receptor for extracellular ATP, is expressed on immune cells, including macrophages, monocytes and dendritic cells and is up-regulated on non-immune cells following injury. P2RX7 plays a role in many biological processes, including production of pro-inflammatory cytokines such as IL-1β via the canonical inflammasome pathway. P2RX7 has been shown to be important in inflammation and fibrosis and may also play a role in autoimmunity. We have developed and phenotyped a novel P2RX7 knock-out (KO) inbred rat strain and taking advantage of the human-resembling unique histopathological features of rat models of glomerulonephritis, we induced three models of disease: nephrotoxic nephritis, experimental autoimmune glomerulonephritis, and experimental autoimmune vasculitis. We found that deletion of P2RX7 does not protect rats from models of experimental glomerulonephritis or the development of autoimmunity. Notably, treatment with A-438079, a P2RX7 antagonist, was equally protective in WKY WT and P2RX7 KO rats, revealing its 'off-target' properties. We identify a novel ATP/P2RX7/K+ efflux-independent and caspase-1/8-dependent pathway for production of IL-1β in rat dendritic cells, which was absent in macrophages. Taken together, these results comprehensively establish that inflammation and autoimmunity in glomerulonephritis is independent of P2RX7 and reveals the off-target properties of drugs previously known as selective P2RX7 antagonists. Rat mononuclear phagocytes may be able to utilise an 'alternative inflammasome' pathway to produce IL-1β independently of P2RX7, which may account for the susceptibility of P2RX7 KO rats to inflammation and autoimmunity in glomerulonephritis. This article is protected by copyright. All rights reserved.

BackgroundSolid organ transplant recipients have attenuated immune responses to SARS-CoV-2 vaccines. Emerging evidence suggests at least equivalent immunogenicity of heterologous compared with homologous vaccine regimens in the general population. In this study, we report on immune responses to 3rd dose BNT162b2 vaccines in transplant recipients either primed with ChAdOx1 or BNT162b2.Methods700 kidney transplant recipients were prospectively screened for serological responses (median time of 33 (21-52) days) following 3 primary doses of a SARS-CoV2 vaccine. All vaccine doses were received post-transplant, and all 3rd doses were BNT162b2. All participants had serological testing performed post-2nd vaccination at a median time of 34 (IQR 26-46) days following the 2nd inoculation, and at least once prior to their 1st dose of vaccine.Results366/700 (52.3%) participants were primed with BNT162b2, whilst 334/700 (47.7) had received ChAdOx1. Overall, 139/700 (19.9%) participants had evidence of prior infection. Of 561 infection naïve participants, 263 (46.9%) had no detectable anti-S following 2-doses of vaccine (V2). 134 (23.9%) participants remained seronegative post 3rd vaccine (V3); 54/291 (18.6%) and 79/270 (29.3%) of participants receiving BNT162b2 and ChAdOx1 respectively, p=0.0029. Median anti-S concentrations were significantly higher post-V3 in patients who had received BNT162b2 compared with ChAdOx1, at 612 (27-234) versus 122 (7.1-1111) BAU/ml respectively, pCellular responses were investigated in 30 infection naïve participants at a median time of 35 (24-46) days post-V3. Eighteen of 30 (60.0%) participants had undetectable T-cell responses. There were neither qualitative or quantitative differences in T-cell responses between those patients who received BNT162b2 or ChAdOx1 as their first 2-doses, with 10/16 (62.5%) and 8/14 (57.1%) respectively having undetectable T-cell responses, p=0.77.ConclusionA significant proportion of transplant recipients remain seronegative following 3 doses of SARS-CoV-2 vaccines, with anti-S concentrations lower in patients receiving heterologous versus homologous vaccinations.

BackgroundEmerging data suggest a reduction in SARS-CoV-2 vaccine effectiveness against Omicron SARS-CoV-2 infection. There is also evidence to show that Omicron is less pathogenic than previous variants. For clinically vulnerable populations, a less pathogenic variant may still have significant impact on morbidity and mortality. Herein we assess the clinical impact of Omicron infection, and vaccine effectiveness, in an in-centre haemodialysis (IC-HD) population.MethodsOne thousand, one hundred and twenty-one IC-HD patients were included in the analysis, all patients underwent weekly screening for SARS-CoV-2 infection via RT-PCR testing between 1st December 2021 and 16th January 2022. Screening for infection via weekly RT-PCR testing and 3-monthly serological assessment started prior to the vaccine roll out in 2020.ResultsOmicron infection was diagnosed in 145/1121 (12.9%) patients over the study period, equating to an infection rate of 3.1 per 1000 patient days. Vaccine effectiveness (VE) against Omicron infection in patients who had received a booster vaccine was 58 (23-75)%, p=0.002; VE was seen in patients who received either ChAdOx1, VE of 47(2-70)%, p=0.034, or BNT162b2, VE of 66 (36-81)%, p=0.0005, as their first two doses. No protection against infection was seen in patients who were partially vaccinated (2-doses), p=0.83. Prior infection was associated with reduced likelihood of Omicron infection, HR 0.69 (0.50-0.96), p=0.0289. Four (2.8%) patients died within 28 days of infection diagnosis, with no excess mortality was seen in patients with infection.Conclusion3-doses of SARS-CoV-2 vaccines are required in ICHD to provide protection against Omicron infection.

Large-vessel vasculitis (LVV) manifests as inflammation of the aorta and its major branches and is the most common primary vasculitis in adults. LVV comprises two distinct conditions, giant cell arteritis and Takayasu arteritis, although the phenotypic spectrum of primary LVV is complex. Non-specific symptoms often predominate and so patients with LVV present to a range of health-care providers and settings. Rapid diagnosis, specialist referral and early treatment are key to good patient outcomes. Unfortunately, disease relapse remains common and chronic vascular complications are a source of considerable morbidity. Although accurate monitoring of disease activity is challenging, progress in vascular imaging techniques and the measurement of laboratory biomarkers may facilitate better matching of treatment intensity with disease activity. Further, advances in our understanding of disease pathophysiology have paved the way for novel biologic treatments that target important mediators of disease in both giant cell arteritis and Takayasu arteritis. This work has highlighted the substantial heterogeneity present within LVV and the importance of an individualized therapeutic approach. Future work will focus on understanding the mechanisms of persisting vascular inflammation, which will inform the development of increasingly sophisticated imaging technologies. Together, these will enable better disease prognostication, limit treatment-associated adverse effects, and facilitate targeted development and use of novel therapies.

ObjectiveTo investigate the occurrence of cardiovascular events (CVEs) in a large cohort of patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) across the European Union, China, Turkey, Russia, the United Kingdom, and the USA.MethodsPatients with a definite diagnosis of AAV who were followed for ≥ 3 months and had sufficient documentation were included. Data on myocardial infarction (MI) and stroke were collected retrospectively from tertiary vasculitis centers. Univariate and multivariate Cox regression models were used to estimate hazard ratios (HRs) and 95% CIs.ResultsOver a median follow-up of 62.0 months (IQR 22.6-100.0), CVEs (mostly MIs) occurred in 245 (10.7%) of 2286 patients with AAV, with a higher frequency in China and the UK. On multivariate regression analysis, older age (55-64.9 yrs, HR 2.93, 95% CI 1.99-4.31), smoking (HR 1.98, 95% CI 1.48-2.64), Chinese origin (HR 4.24, 95% CI 3.07-5.85), and pulmonary (HR 1.50, 95% CI 1.09-2.06) and kidney (HR 3.02, 95% CI 2.08-4.37) involvement were independent variables associated with a higher occurrence of CVEs.ConclusionWe showed that geographic region and both traditional and disease-specific (kidney involvement in particular) factors were independently associated with CVEs. Proper assessment and management of modifiable cardiovascular (CV) risk factors are essential for prevention of CV morbidity in patients with AAV.

Antibody mediated rejection is a major cause of renal allograft loss. Circulating preformed donor specific antibodies (DSA) can result as a consequence of blood transfusion, pregnancy or prior transplantation. Current treatment strategies are limited due to partial or transient efficacy, adverse side-effects or patient unsuitability. Previous in vivo studies exploring autoimmune diseases have shown that spleen tyrosine kinase (SYK) signalling is involved in the development of pathogenic autoantibody. The role of SYK in allogenic antibody production is unknown, and we investigated this in a rodent model of sensitization, established by the transfusion of F344 whole blood into LEW rats. Two-week treatment of sensitized rats with selective SYK inhibitor fostamatinib strongly blocked circulating DSA production without affecting overall total immunoglobulin levels, and inhibition was sustained up to 5 weeks post-completion of the treatment regimen. Fostamatinib treatment did not affect mature B cell subset or plasma cell levels, which remained similar between non-treated controls, vehicle treated and fostamatinib treated animals. Our data indicate fostamatinib may provide an alternative therapeutic option for patients who are at risk of sensitization following blood transfusion while awaiting renal transplant.

Vaccination against SARS-CoV-2 seems to be safe in patients with immunity-mediated kidney disease, although their immunological responses to vaccination are impaired. Further strategies, including the administration of additional vaccine doses and passive immunization with long-acting monoclonal antibodies, might increase protection in this vulnerable patient group.

Background A major clinical feature of severe coronavirus diease 2019 (COVID‐19) is microvascular thrombosis linked to endothelial cell activation. Consistent with this, a number of studies have shown that patients with severe COVID‐19 have highly elevated plasma levels of von Willebrand Factor (VWF) that may contribute to the prothrombotic phenotype. In the current study, we investigated the extent of endothelial activation in patients receiving hemodialysis who had either mild or severe COVID‐19. Methods Plasma VWF, ADAMTS‐13, angiopoietin‐2 (Ang2), and syndecan‐1 levels were determined by ELISA. The sialic acid content of VWF was investigated using a modified ELISA to measure elderberry bark lectin, specific for sialic acid residues, binding to VWF. Results Patients receiving hemodialysis with severe COVID‐19 had significantly higher plasma levels of VWF and lower ADAMTS‐13. VWF levels peaked and were sustained during the first 10 days after positive confirmation of infection. While Ang2 trended toward being higher in severely ill patients, this did not reach significance; however, severely ill patients had significantly higher soluble syndecan‐1 levels, with high levels related to risk of death. Finally, higher VWF levels in severely ill patients were correlated with lower VWF sialic acid content. Conclusions Severe COVID‐19 in patients undergoing hemodialysis is associated with both acute and sustained activation of the endothelium, leading to alteration of the VWF/ADAMTS‐13 axis. Lower VWF sialic acid content represents altered VWF processing and further confirms the disturbance caused to the endothelium in COVID‐19.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis can present with life-threatening lung-kidney syndromes. However, many controlled treatment trials excluded patients with diffuse alveolar hemorrhage or severely impaired glomerular filtration rates, and so the optimum treatment in these cases is unclear. In this retrospective cohort study, we report the outcomes of 64 patients with life-threatening disease treated with a combination regimen of rituximab, low-dose intravenous cyclophosphamide, oral glucocorticoids, and plasma exchange. At entry, the median estimated glomerular filtration rate was 9 mL/min, 47% of patients required dialysis, and 52% had diffuse alveolar hemorrhage. All patients received a minimum of seven plasma exchanges, and the median cumulative doses of rituximab, cyclophosphamide, and glucocorticoid were 2, 3, and 2.6 g, respectively, at six months. A total of 94% of patients had achieved disease remission (version 3 Birmingham Vasculitis Activity Score of 0) at this time point, and 67% of patients who required dialysis recovered independent kidney function. During long-term follow-up (median duration 46 months), overall patient survival was 85%, and 69% of patients remained free from end-stage kidney disease, which compares favorably to a historic cohort with severe disease treated with a conventional induction regimen. Combination treatment was associated with prolonged B cell depletion and low rates of relapse; 87% of patients were in continuous remission at month 36. The serious infection rate during total follow-up was 0.28 infections/patient/year, suggesting that combination treatment is not associated with an enduring risk of infection. Thus, we suggest that combination immunosuppressive therapy may permit glucocorticoid avoidance and provide rapid and prolonged disease control in patients with severe ANCA-associated vasculitis.

BackgroundAttenuated immune responses to mRNA SARS-CoV-2 vaccines have been reported in solid organ transplant recipients. Most studies have assessed serological responses alone, and there is limited immunological data on vector-based vaccines in this population. This study compares the immunogenicity of BNT162b2 with ChAdOx1 in a cohort of kidney transplant patients, assessing both serological and cellular responses.Methods920 patients were screened for spike protein antibodies (anti-S) following 2 doses of either BNT162b2 (n=490) or ChAdOx1 (n=430). 106 patients underwent assessment with T-cell ELISpot assays. 65 health care workers were used as a control group.ResultsAnti-S was detected in 569 (61.8%) patients. Seroconversion rates in infection-naïve patients who received BNT162b2 were higher compared with ChAdOx1, at 269/410 (65.6%) and 156/358 (43.6%) respectively, p1st year post-transplant and receiving BNT162b2 was associated with seroconversion.Only 28/106 (26.4%) of patients had detectable T-cell responses. There was no difference in detection between infection-naïve patients who received BNT162b2, 7/40 (17.5%), versus ChAdOx1, 2/39 (5.1%), p=0.15. There was also no difference in patients with prior infection who received BNT162b2, 8/11 (72.7%), compared with ChAdOx1, 11/16 (68.8%), p=0.83.ConclusionsEnhanced humoral responses were seen with BNT162b2 compared with ChAdOx1 in kidney transplant patients. T-cell responses to both vaccines were markedly attenuated. Clinical efficacy data is still required but immunogenicity data suggests weakened responses to both vaccines in transplant patients, with ChAdOx1 less immunogenic compared with BNT162b2.

BackgroundLimited data exists on the immunogenicity of vector-based SARS-CoV-2 vaccines in patients with kidney disease. Given their use in over 180 countries, such data is of upmost importance to inform policy on optimal vaccination strategies. This study compares the immunogenicity of BNT162b2 with ChAdOx1 in patients receiving haemodialysis.Methods1021 patients were screened for spike protein antibodies (anti-S) following 2 doses of either BNT162b2 (n=523) or ChAdOx1 (n=498). 191 patients underwent assessment with T-cell ELISpot assays. 65 health care workers were used as a control group.ResultsAnti-S was detected in 936 (91.2%) of patients post-vaccination. There was no difference in seroconversion rates between infection-naïve patients who received BNT162b2, 248/281 (88.3%), compared with ChAdOx1, 227/272 (83.5%), p=0.11. Anti-S concentrations were higher following BNT162b, 462(152-1171) BAU/ml, compared with ChAdOx-1 79(20-213) BAU/ml, pOnly 73 (38.2%) of patients had detectable T-cell responses post-vaccination, with no proportional difference between infection-naïve patients who received BNT162b2, 2/19 (10.5%), versus ChAdOx1, 15/75 (20.0%), p=0.34. There were no quantitative differences in T-cell responses in infection-naïve patients, with a median 2(0-16) SFU/106PBMCs and 10(4-28) SFU/106PBMCs in those receiving BNT162b2 and ChAdOx1 respectively, p=0.35. These responses were significantly weaker compared with healthy controls.ConclusionsEnhanced immunogenicity was seen with BNT162b2 compared with ChAdOx1, driven by superior humoral responses, with attenuated T-cell responses to both vaccines. Comparative data on clinical efficacy is now required.Significance StatementLimited data exist on the immunogenicity of vector-based SARS-CoV-2 vaccines in patients with kidney disease. Given their use in over 180 countries worldwide, such data are of upmost importance to inform policy on optimal vaccination strategies. This study compares the immunogenicity of BNT162b2 (n=523) against the adenovirus vector vaccine, ChAdOx1 (n=498), in 1021 haemodialysis patients. In infection-naïve patients, overall seroconversion rates were comparable, however, spike protein antibody concentrations were significantly higher following BNT162b2. No difference in T-cell responses was seen, however, all naïve patients had weaker responses compared with healthy controls. Equivalent attenuated cellular responses to both vaccines, with greater humoral responses to BNT162b2, suggests BNT162b2 has superior immunogenicity in this patient population, with data on clinical efficacy required.