Viral RNA in the influenza vaccine may have contributed to the development of ANCA-associated vasculitis in a patient following immunisation

ASIA Syndrome: State-of-the-Art and Future Perspectives

The expression "Autoimmune/inflammatory syndrome induced by adjuvants (ASIA)" was coined by Shoenfeld and colleagues in 2011. It defines a group of immune-mediated disorders that arise in people, with a genetic predisposition, following exposure to adjuvant agents. This syndrome has been reported after contact with silicone implants, medications, infections, metals, vaccines, and other substances. It typically occurs in individuals with a genetic predisposition, particularly involving genes, such as HLA-DRB1 (major histocompatibility complex, class II, DR beta 1) and PTPN22 (protein tyrosine phosphatase non-receptor type 22). Some stimuli lead to an overactivation of the immune system, prompt the production of autoantibodies, and finally cause autoimmune disorders. This narrative review aims to provide an overview of the ASIA syndrome with a special focus on the role of adjuvants in different vaccines, especially after the COVID-19 pandemic, and insights into development of new treatments.

A case of rapidly progressive glomerulonephritis with double-positive anti-GBM antibody and MPO-ANCA after SARS-CoV-2 vaccination and relapse during 1 year follow-up

Although mRNA vaccines for COVID-19 are highly beneficial and are recommended for patients with kidney disease, adverse reactions in some patients after vaccination have been problematic. Various vasculitis and renal disorders have been reported after vaccination; however, a causal relationship has not yet been identified. In this report, we describe a case of rapidly progressive glomerulonephritis that developed after SARS-CoV-2 vaccination, in which both anti-glomerular basement membrane (anti-GBM) and myeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA) were present. The patient's renal biopsy showed that of the 48 glomeruli in total, four showed global sclerosis and none showed segmental sclerosis. The biopsy showed 11 cellular glomerular crescents and 5 fibrocellular glomerular crescents. Renal function improved with steroids, rituximab, and plasma exchange. Approximately 9 months later, MPO-ANCA was again elevated, and the pulmonary lesions worsened, again requiring multidisciplinary treatment. This case suggests that caution should be exercised in the development of double-positive disease after vaccination, and that long-term observation may be necessary because of the possibility of relapse.

Understanding COVID-19 vaccine hesitancy in vasculitis patients

Objective

To identify the factors that impact COVID-19 vaccine decision-making in vaccine-hesitant vasculitis patients, and compare their perceptions with other rheumatology patients, given existence of data suggesting rheumatology patients may have disease-specific factors that influence their COVID-19 vaccine decision-making.

Methods

This cross-sectional study surveyed adult rheumatology patients from the Kaye Edmonton Clinic Rheumatology Clinic, in Canada, between June and August 2021, using an anonymous online questionnaire. Survey responses were analyzed for statistical differences using chi-square analysis.

Results

The COVID-19 Vaccine Perceptions Survey had a response rate of 70.9%. Of the total 231 respondents, 103 patients were diagnosed with vasculitis. At the time of the survey, 10.6% of vasculitis patients refused to receive a COVID-19 vaccine compared to 6.3% for other rheumatology patients. Compared to other rheumatology patients, vaccine-hesitant vasculitis patients were significantly more concerned about almost every aspect of available COVID-19 vaccines [e.g., safety (p < 0.001), components (p < 0.001)], and feared that they could contract SARS-CoV-2 from a vaccine (p < 0.001). These vaccine-hesitant patients were also significantly less pleased with the government's pandemic response, less confident in healthcare team-provided information (p < 0.001), and more likely to report that healthcare providers had no role in their COVID-19 vaccine decision-making (p < 0.001).

Conclusion

Vaccine-hesitant vasculitis patients may have multiple considerations influencing COVID-19 vaccine hesitancy, including vaccine and disease-specific concerns, along with unfavorable perceptions of the healthcare system (government and healthcare providers). Healthcare providers can address some of these concerns by initiating patient-centered discussions around immunizations to help support educated decision-making.

De Novo ANCA-Negative Pauci-Immune Crescentic Glomerulonephritis After COVID-19 mRNA Vaccination: A Case Report

To prevent the spread of the coronavirus disease 2019 (COVID-19) pandemic, vaccines have been authorized for emergency use and implemented worldwide. We present a case of de novo glomerulonephritis (GN) after use of the COVID-19 mRNA vaccine BNT162b2. A 48-year-old man with no relevant medical history was referred for sudden and persistent worsening of renal insufficiency 1.5 months after the second vaccine dose. He had arthralgia and skin rash a week after vaccination. Abdominal pain and diarrhea started 2 weeks later, and he was admitted to the hospital for enteritis treatment. Colonoscopy showed multiple ulcerations and petechiae suggestive of vasculitis in the terminal ileum. After prednisolone therapy, his gastrointestinal symptoms improved, but his renal function continued to deteriorate. Based on kidney biopsy findings and nephrotic-range proteinuria (5,306 mg/24 hours), he was diagnosed with anti-neutrophil cytoplasmic autoantibody (ANCA)-negative pauci-immune crescentic GN (CrGN). He received high-dose steroid pulse therapy and oral cyclophosphamide, and then, gradually underwent steroid tapering, with improvement in proteinuria and renal function over several weeks. Several cases of GN suspected to be related to COVID-19 vaccines have been reported. To our knowledge, this is the first case report of ANCA-negative pauci-immune crescentic CrGN with extrarenal involvement after COVID-19 mRNA vaccination. Our finding expands the spectrum of COVID-19 vaccine-associated GN.

New insights of antineutrophil cytoplasmic antibody-associated vasculitis from the perspective of COVID-19 vaccination

The occurrence of antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) has been reported since the coronavirus disease 2019 (COVID-19) vaccination, but whether there is a causal relationship or coincidence remains to be verified. We combined the term COVID-19 vaccination with each word of AAV to search for case reports and case series published in PubMed, EMBASE, and Web of Science databases before 13 March 2023. A total of 56 patients who developed AAV after COVID-19 vaccination were identified from 44 research centers. Of the 56 subjects, 43 (76.7%) were vaccinated with the mRNA vaccine, followed by the adenovirus vaccine (14.3%) and inactivated vaccine (9.0%) (P = 0.015). Compared with relapsed AAV, new-onset AAV patients had at least two other diseases previously (P < 0.001). Twenty-five (44.6%) patients presented symptoms after the first injection, and the medium onset time was 12 (1-77) days, while Twenty-eight (50.0%) patients developed symptoms after the second dose, and their medium period was 14 (1-60) days. Forty-four (78.5%) patients achieved remission after immunosuppressive agents, plasma exchange, and hemodialysis. One (1.8%) patient died from progressive respiratory failure and nine (16.1%) did not recover, leaving five patients permanently dependent on hemodialysis. Pathogenic ANCA may be activated by enhanced immune response and epitope spreading after COVID-19 vaccination and induced the occurrence of AAV, especially in genetically susceptible populations.

Hepatic and pulmonary involvement in a patient with PR3-ANCA vasculitis following SARS-CoV-2 vaccination: A case report

We here report the first case of anti-proteinase 3-positive anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis following the severe acute respiratory syndrome coronavirus 2 Pfizer-BioNTech vaccine presenting with prominent liver involvement and alveolar haemorrhage. Two weeks after vaccination, a 49-year-old man developed inflammatory arthralgias and hypertransaminasaemia. Two months later, fever and haemoptysis appeared; the patient tested positive for anti-proteinase 3 autoantibodies. High-dose steroids and rituximab were started, and complete remission was achieved. Systemic autoimmune diseases, including ANCA-associated vasculitis, should always be considered in the differential diagnosis of hypertransaminasaemia, especially when the clinical context is suspicious.

ANCA Associated Glomerulonephritis Following SARS-CoV-2 Vaccination: A Case Series and Systematic Review

Vaccines against SARS-CoV-2 (COVID-19) proved beneficial for COVID-19 disease attenuation and preventing virus spreading. Cumulative reports of the rarity of antineutrophil cytoplasmic autoantibodies (ANCA)-associated vasculitis (AAV) raise concerns about its relationship with COVID-19 vaccination. Several case reports described ANCA-associated pauci-immune glomerulonephritis (ANCA-GN) following COVID-19 vaccination with some uniqueness. We systematically reviewed COVID-19 vaccine-induced ANCA-GN from PubMed, SCOPUS, and Cochrane library databases until 1 January 2023 according to PRISMA guidelines and presented our three cases. Twenty-six cases from 25 articles, including our 3 cases, were analyzed. Most cases were diagnosed following the second dose of the COVID-19 vaccine (59%) with a median (IQR) interval onset of 14 (16) days. The highest prevalence was related to the mRNA-type vaccine. Anti-myeloperoxidase (MPO) ANCA was far more common than the other ANCAs, with various positive autoantibodies. Fourteen cases (out of 29 cases, 48%) had extra-kidney AAV manifestation. Although severe kidney injury was observed in 10/29 (34%), remission was achieved in 89% (25/28) with no death. The mechanisms of the vaccine-inducing ANCA-GN were postulated here. Since ANCA-GN after the COVID-19 vaccine was rare, the benefit of the COVID-19 vaccine could outweigh the risk of ANCA-GN side effects in the pandemic era.

Kidney Biopsy Findings in Patients with SARS-CoV-2 Infection or After COVID-19 Vaccination

BACKGROUND

Emerging case series described a temporal association between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination and de novo or relapsing kidney diseases. We aimed to further understand vaccination- and coronavirus disease 2019 (COVID-19)-associated kidney diseases.

METHODS

We present findings from native kidney biopsies of patients recently vaccinated against SARS-CoV-2 ( n =27) and those with COVID-19 ( n =15), reviewed at a single German center. Diagnoses were compared among all native kidney biopsies ( n =10,206) obtained between the prepandemic (2019), pandemic (2020), and vaccination periods (2021) to determine whether there was an increase in kidney diseases in the observed periods.

RESULTS

Biopsy indication was increased serum creatinine and/or new-onset proteinuria. Glomerulopathies (20/27, 74%) were more common than tubulointerstitial diseases in postvaccination patients, with necrotizing GN (8/27, 30%) and primary podocytopathies and other GN types (6/27, 22% each) the most common forms. Acute tubular injury was the most common kidney disease in patients with COVID-19, followed by thrombotic microangiopathy (TMA) and necrotizing GN. The postvaccination and COVID-19 infection groups had similar kidney function recovery rates (69% and 73%, respectively). Furthermore, the frequencies of necrotizing GN, pauci-immune GN, TMA, or primary podocytopathies at our center did not increase between 2019 and 2021.

CONCLUSIONS

We observed differences in entity frequencies between the SARS-CoV-2 vaccination or COVID-19 groups, with glomerulopathies being more common in patients after vaccination and tubulointerstitial diseases in patients with COVID-19. Cases of TMA were observed only in the COVID-19 group. We detected no increase in the frequency of necrotizing GN, TMA, or podocytopathies between 2019 and 2021.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Kidney Histopathology After COVID-19 and SARS-CoV-2 Vaccination, NCT05043168.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_05_08_CJN0000000000000106.mp3.

Cardiac Tamponade as a Complication of Microscopic Polyangiitis: A Case Associated With a COVID-19 mRNA Vaccine

Widespread uptake of the coronavirus disease 2019 (COVID-19) vaccinations has become the world's championed defense against the global pandemic. Four vaccines have been either approved or authorized for emergency use by the FDA, and at this time, over 13 billion doses of these vaccines have been administered around the world. Unfortunately, uncommon and sometimes unforeseen side effects such as small-vessel vasculitis have been reported. In this case report, we present a 74-year-old woman with a history of hypertension, type 2 diabetes mellitus, and hypothyroidism who developed microscopic polyangiitis (MPA) following the second dose of the Pfizer-BioNTech mRNA vaccine for COVID-19. The diagnosis of MPA was confirmed by a kidney biopsy. The autoimmune condition progressed to pericardial effusion and eventual cardiac tamponade, which is occasionally seen in the disease. In this patient's case, we suspect there to be a temporal association between mRNA COVID-19 vaccination and the development of MPA. Direct causation has not been determined.

Anti-neutrophil Cytoplasmic Antibody-Associated Vasculitis With Periaortitis That Developed After mRNA COVID-19 Vaccination

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) has caused a global pandemic resulting in many deaths. As a result, vaccines to prevent the onset of coronavirus disease 2019 (COVID-19) have been developed and have demonstrated high efficacy in large-scale clinical trials. Adverse events that develop within a few days after vaccination are common, such as fever, malaise, body aches, and headaches, and have become widely known as transient reactions. However, as COVID-19 vaccines are administered worldwide, several studies have highlighted that long-term side effects associated with vaccines against SARS-CoV-2 may include serious adverse events. There has been an increase in reports of COVID-19 vaccinations being associated with the onset of autoimmune diseases, such as anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis. This is a report of ANCA-associated vasculitis with periaortitis following the second dose of COVID-19 mRNA vaccination, in which a 56-year-old man developed numbness and pain in his lower extremities three weeks after COVID-19 vaccination. Following the onset of sudden abdominal pain, a fluorodeoxyglucose-positron emission tomography scan revealed periaortic inflammation. Serum myeloperoxidase (MPO)-ANCA levels were significantly elevated, and renal biopsy revealed pauci-immune crescentic glomerulonephritis. Treatment with steroids and cyclophosphamide alleviated abdominal pain and numbness in the lower limbs, resulting in a decrease in MPO-ANCA titers. The side effects of COVID-19 vaccination are still unclear. This report has indicated that side effects associated with vaccines against COVID-19 may include ANCA-associated vasculitis. However, a causal relationship between COVID-19 vaccination and the development of ANCA-associated vasculitis has not yet been clearly demonstrated. COVID-19 vaccination will continue internationally, so it is necessary to accumulate similar case reports in the future.

Inflammatory Arthritis Associated with COVID-19 Vaccination

COVID-19 vaccines have been shown to be highly efficacious in preventing symptomatic COVID-19 infections throughout the pandemic. There have been emerging cases of inflammatory arthritis occurring in close relation to COVID-19 vaccination. We illustrate a case of new-onset inflammatory arthritis 10 days after receiving their second Vaxzevria COVID-19 vaccine. The patient responded dramatically to prednisolone treatment but subsequently required hydroxychloroquine due to persistent inflammatory joint symptoms. Inflammatory arthritis is an increasingly recognized rare adverse effect of COVID-19 vaccination and clinicians should actively consider this in patients with new or flares of inflammatory joint disease.

Autoimmune/inflammatory syndrome induced by adjuvants (ASIA) in 2023

In 2011, a syndrome entitled ASIA (Autoimmune/inflammatory Syndrome Induced by Adjuvants; Shoenfeld's syndrome) was first described. ASIA aimed to organize under a single umbrella, the existing evidence regarding certain environmental factors which possess immune stimulatory properties, in order to shed light on a common pathway of autoimmune pathogenesis. Such environmental immune stimulators, or adjuvants, include among others: aluminum salts as in vaccines, various medical implants, as well as various infectious agents. After the launch of the ASIA syndrome, the expansion and recognition of this syndrome by different researchers from different countries began. During the past decades, evidence had been accumulating that (auto)immune symptoms can be triggered by exposure to environmental immune stimulatory factors that act as an adjuvant in genetically susceptible individuals. A panoply of unexplained subjective and autonomic-related symptoms has been reported in patients with ASIA syndrome. The current review summarizes and updates accumulated knowledge from the past decades, describing new adjuvants- (e.g. polypropylene meshes) and vaccine- (e.g. HPV and COVID vaccines) induced ASIA. Furthermore, a direct association between inflammatory/autoimmune diseases with ASIA syndrome, will be discussed. Recent cases will strengthen some of the criteria depicted in ASIA syndrome such as clear improvement of symptoms by the removal of adjuvants (e.g. silicone breast implants) from the body of patients. Finally, we will introduce additional factors to be included in the criteria for ASIA syndrome such as: (1) dysregulated non-classical autoantibodies directed against G-protein coupled receptors (GPCRs) of the autonomic nervous system and (2)) small fiber neuropathy (SFN), both of which might explain, at least in part, the development of 'dysautonomia' reported in many ASIA patients.

Development of ANCA-associated vasculitis followed by SARS-CoV-2 vaccination in a patient with HLA-DRB1*09: 01 allele

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), presents with severe pneumonia and fatal systemic complications. Currently, SARS-CoV-2 vaccines are effective in reducing the risk of new onset and getting worse of the disease. However, autoimmune diseases such as antineutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV) have been reported to develop after COVID-19 vaccine administration. Case presentation: A 71-year-old woman presented with fever, malaise, urinary abnormalities and renal dysfunction after receiving the COVID-19 vaccine (Pfizer-BioNTech). We clinically diagnosed AAV with her manifestations and serological test (MPO-ANCA positive). Her clinical findings were improved after immunosuppressive therapy. We examined her genetic susceptibility to AAV and we found that her allele was HLA-DRB1*09:01, which is a risk allele of MPO-AAV. Mechanistically, SARS-CoV-2 vaccines would activate immunity, including neutrophils, and trigger AAV onset in this patient with a genetic risk to develop AAV. The pathophysiology of this case would share with that of autoimmune/inflammatory syndrome induced by adjuvants (ASIA) in the absence of external adjuvants.

Medium-vessel Vasculitis Presenting with Myalgia Following COVID-19 Moderna Vaccination

Coronavirus disease 2019 (COVID-19) vaccines have been delivered worldwide to prevent the spread of the disease, and almost all Japanese have received the mRNA vaccines "BNT162b2" (Pfizer-BioNTech) or "mRNA-1273" (Moderna). These vaccines have shown efficacy and safety with only minor adverse drug reactions. However, some patients develop severe adverse drug reactions, including autoimmune reactions. In addition, systemic vasculitis, mainly small-vessel vasculitis, following COVID-19 vaccination, has been reported. However, only a few investigators have reported medium-vessel vasculitis following vaccination. We herein report a case of medium-vessel vasculitis presenting with myalgia as the initial clinical manifestation following COVID-19 Moderna vaccination.

A case series of dermatomyositis following SARS-CoV-2 vaccination

BACKGROUND/OBJECTIVE

The most significant adverse events following SARS-CoV-2 vaccination are myocarditis and pericarditis. Myositis and dermatomyositis have been reported following SARS-CoV-2 infection, but vaccine-induced dermatomyositis (DM) has not been reported. Our case series aimed to characterize new onset dermatomyositis or disease-related flares following SARS-CoV-2 vaccination.

MATERIALS AND METHODS

A total of 53 patients from our institution with a new or pre-existing diagnosis of DM were recruited and consented. Phone interviews were conducted to obtain vaccination status and symptoms following vaccination. Electronic medical records were reviewed to extract age, sex, autoantibody profiles, comorbidities, immunomodulatory therapies, creatine kinase (CK) values, and SARS-CoV-2 vaccination dates from the provincial vaccination registry. For patients who reported disease flares, records were reviewed for the onset and nature of symptoms, extent of organ involvement and changes in immunomodulation.

RESULTS

On average, patients received 2.62 vaccine doses (range 1-3 doses). A total of 3 of 51 patients (5.88%) experienced dermatomyositis symptoms following vaccination. Two patients were newly diagnosed with dermatomyositis, one requiring hospitalization. Reported symptom onset following vaccination ranged from 1 to 30 days. Of note, all of these patients had normal CK values, even though there was muscle biopsy-confirmed myositis in one patient. Eight patients in the cohort (15.1%) had asymptomatic CK elevation (<1.5 X ULN).

CONCLUSION

New onset dermatomyositis or flare up of pre-existing dermatomyositis may be a rare complication in SARS-CoV-2 vaccination although no studies can support a true correlation. Several pathophysiologic mechanisms are proposed.

Renal Side Effects of COVID-19 Vaccination

Background: The COVID-19 pandemic has imposed a challenge on global healthcare and has tremendously impacted everyone's lives. Vaccination is one of the most effective and vital strategies to halt the pandemic. However, new-onset and relapsed kidney diseases have been reported after COVID-19 vaccination. This narrative review was conducted to collect published data and generalize some hypotheses for the pathogenesis of renal side effects of COVID-19 vaccines. Methods: A systematic literature search of articles reporting renal adverse reactions, including in adults and children, in the PubMed and Web of Science databases until August 2022 was performed. Results: A total of 130 cases reporting a renal adverse reaction following COVID-19 vaccination from 90 articles were included in this review, of which 90 (69%) were new-onset kidney diseases, while 40 (31%) were relapsed kidney diseases. The most frequent renal side effects of COVID-19 vaccination were minimal change disease (52 cases), IgA nephropathy (48 cases), antineutrophil cytoplasmic autoantibody vasculitis (16 cases), and acute interstitial nephritis (12 cases). Other renal side effects occurred at a much lower frequency. Follow-up data were available for 105 patients, and 100 patients (95%) responded to the treatments. Conclusions: The number of reported cases is far less than the hundreds of millions of vaccinations, and the benefit of COVID-19 vaccination far outweighs its risks. This review will assist healthcare professionals, particularly nephrologists, who should be aware of these side effects and recognize them early and treat them efficiently.

Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Renal Vasculitis Following COVID-19 Vaccination: A Case Report and Literature Review

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is an immune-mediated disorder of small and medium-sized vessels, characterized by the production of autoantibodies that target the neutrophilic antigens leading to mononuclear cell infiltration and destruction of blood vessels in lungs, skin, and kidneys. Although rare, the coronavirus disease 2019 (COVID-19) vaccine may trigger autoimmune vasculitis. We report a rare case of ANCA-associated renal vasculitis following COVID-19 vaccination in a 59-year-old male who presented with flu-like symptoms and deranged renal function tests. He received his second dose of the Pfizer COVID-19 vaccine 17 days ago. His clinical picture, serological testing, and radiological imaging were concerned with glomerular disease. His serum was positive for ANCAs, and the renal biopsy specimen revealed pauci-immune glomerulonephritis. He was diagnosed with AAV-associated renal vasculitis following COVID-19 vaccination because no other etiology was identified. His clinical improvement after starting rituximab and steroids reinforced the diagnosis.

SARS-CoV-2 Vaccination as a Trigger for Perinuclear Antineutrophil Cytoplasmic Antibodies (p-ANCA) Associated With Rapidly Progressive Glomerulonephritis

The coronavirus disease 2019 (COVID-19) pandemic was devastating worldwide. The introduction of severe acute respiratory syndrome coronavirus 2 vaccination has reduced transmission, hospitalizations, and deaths, with infrequent major side effects. We present the case of a 51-year-old woman with rapidly progressive glomerulonephritis following COVID-19 vaccination with ChAdOx1 (AstraZeneca). Workup and histopathologic examination demonstrated active extracapillary proliferative lesions in cellular and fibrocellular crescents with extensive fibrinoid necrosis and karyorrhexis with diffuse glomerulonephritis, as well as positive perinuclear antineutrophil cytoplasmic antibodies. Treatment with cyclophosphamide and steroids was initiated with the improvement of renal function. Similar cases were seen with influenza vaccination, potentially describing vaccination as a possible trigger for anti-myeloperoxidase rapidly progressive glomerulonephritis.

Environmental factors influencing the risk of ANCA-associated vasculitis

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of diseases characterized by inflammation and destruction of small and medium-sized blood vessels. Clinical disease phenotypes include microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). The incidence of AAV has been on the rise in recent years with advances in ANCA testing. The etiology and pathogenesis of AAV are multifactorial and influenced by both genetic and environmental factors, as well as innate and adaptive immune system responses. Multiple case reports have shown that sustained exposure to silica in an occupational environment resulted in a significantly increased risk of ANCA positivity. A meta-analysis involving six case-control studies showed that silica exposure was positively associated with AAV incidence. Additionally, exposure to air pollutants, such as carbon monoxide (CO), is a risk factor for AAV. AAV has seasonal trends. Studies have shown that various environmental factors stimulate the body to activate neutrophils and expose their own antigens, resulting in the release of proteases and neutrophil extracellular traps, which damage vascular endothelial cells. Additionally, the activation of complement replacement pathways may exacerbate vascular inflammation. However, the role of environmental factors in the etiology of AAV remains unclear and has received little attention. In this review, we summarized the recent literature on the study of environmental factors, such as seasons, air pollution, latitude, silica, and microbial infection, in AAV with the aim of exploring the relationship between environmental factors and AAV and possible mechanisms of action to provide a scientific basis for the prevention and treatment of AAV.

ANCA-associated vasculitis following Johnson and Johnson COVID-19 vaccine

Introduction

Antineutrophil cytoplasmic autoantibodies associated vasculitis (AAV) is characterized by antibodies against antigens in cytoplasmic granules of neutrophils and predominantly affects small vessels. AAV after COVID-19 mRNA vaccination has been reported.

Case presentation

We report a rare case of AAV in a patient who presented with rapidly progressive glomerulonephritis (RPGN) after Johnson & Johnson COVID-19 vaccine administration.

Discussion

The temporal causal association between autoimmune manifestations like AAV and COVID-19 vaccines can be explained by hypothesized mechanisms like molecular mimicry, defective neutrophilic apoptosis, polyclonal activation, and systemic proinflammatory cytokine response. These mechanisms are likely to trigger autoimmune responses in genetically susceptible individuals. Still there are many research going on to fill the research gap on the development of ANCA associated with COVID-19 vaccines.

Conclusion

Increasing reports of rare adverse effects like AAV following COVID-19 vaccination warrants the further study and evaluation of immune responses induced by those vaccines. Considering the potential severity of COVID-19 and the rarity of the above-mentioned adverse effects, COVID-19 vaccination should not be withheld.

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AAV following adenovirus vector vaccine has not been reported previously.

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Increasing reports of rare adverse effects like AAV following COVID-19 vaccination warrants the further study

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And evaluation of immune responses induced by those vaccines.

Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Glomerulonephritis in a 15-year-old Patient After Receiving the Second Dose of the BBIBP-CorV (Sinopharm) COVID-19 Vaccine: A Case Report

Introduction: Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is a group of multisystemic autoimmune diseases that can involve organs such as kidneys and respiratory tracts. Since the initiation of COVID-19 vaccines, there have been few cases of antineutrophil cytoplasmic antibody (ANCA) glomerulonephritis development after receiving vaccine doses. Case Presentation: This report describes a 15-year-old man who has developed ANCA-associated glomerulonephritis (AAGN) after receiving the second dose of BBIBP-CorV (Sinopharm) COVID-19 vaccine. Conclusions: Development of AAGN after both natural SARS-CoV-2 infection and following other vaccinations raises the question of the possible causality between the two. Considering the widespread use of COVID-19 vaccines, it is highly important to investigate their possible side effects.

New-Onset Acute Kidney Disease Post COVID-19 Vaccination

The coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused an exceptional setback to the global economy and health. Vaccination is one of the most effective interventions to markedly decrease severe illness and death from COVID-19. In recent years, there have been increasingly more reports of new acute kidney injury (AKI) after COVID-19 vaccination. Podocyte injury, IgA nephropathy, vasculitis, tubulointerstitial injury, and thrombotic microangiopathy appear to be the main pathological phenotypes. Nonetheless, whether the link between the COVID-19 vaccine and acute kidney disease (AKD) is causal or coincidental remains to be verified. Here, we generalize some hypotheses for the emergence of AKD and its pathogenesis in response to certain COVID-19 vaccines. In fact, the enormous benefits of mass vaccination against COVID-19 in preventing COVID-19 morbidity and mortality cannot be denied. The purpose of this review is to assist in the clinical assessment and management of AKD following COVID-19 vaccination.

New Onset of Eosinophilic Granulomatosis with Polyangiitis Following mRNA-Based COVID-19 Vaccine

Anti-SARS-CoV-2 vaccines are safe and effective, also in individuals with allergic and immune-mediated diseases (IMDs). There are reports suggesting that vaccines may be able to trigger de-novo or exacerbate pre-existing IMDs in predisposed individuals. Eosinophilic granulomatosis with polyangiitis (EGPA) is a small-vessel vasculitis characterized by asthma, eosinophilia, and eosinophil-rich granulomatous inflammation in various tissues. We describe the case of a 63-year-old man who experienced cardiac, pulmonary, and neurological involvement one day after the administration of the booster dose of anti-SARS-CoV-2 vaccine (mRNA-1273). A diagnosis of EGPA was made and the patient was treated with high-dose steroids and cyclophosphamide, with a good clinical response. Interestingly, our patient had experienced a significant worsening of his pre-existing asthma six months earlier, just after the first two vaccine shots with the ChAdOx1 anti-SARS-CoV-2 vaccine. It is impossible to know whether our patient would have had developed EGPA following natural SARS-CoV-2 infection or at some point in his life regardless of infectious stimuli. Nevertheless, our report may suggest that caution should be paid during the administration of additional vaccine doses in individuals who experienced an increase in IMD severity that persisted over time following previous vaccine shots.

Development of Alveolar Hemorrhage After Pfizer-BioNTech COVID-19 mRNA Vaccination in a Patient With Renal-Limited Anti-neutrophil Cytoplasmic Antibody-Associated Vasculitis: A Case Report

Since the coronavirus disease 2019 (COVID-19) pandemic continues and a new variant of the virus has emerged, the COVID-19 vaccination campaign has progressed. Rare but severe adverse outcomes of COVID-19 vaccination such as anaphylaxis and myocarditis have begun to be noticed. Of note, several cases of new-onset antineutrophil cytoplasmic antibody-associated vasculitis (AAV) after COVID-19 mRNA vaccination have been reported. However, relapse of AAV in remission has not been recognized enough as an adverse outcome of COVID-19 vaccination. We report, to our knowledge, a first case of renal-limited AAV in remission using every 6-month rituximab administration that relapsed with pulmonary hemorrhage, but not glomerulonephritis, following the first dose of the Pfizer-BioNTech COVID-19 vaccine. The patient received the COVID-19 vaccine more than 6 months after the last dose of rituximab according to the recommendations. However, his CD19+ B cell counts were found to be increased after admission, indicating that our case might have been prone to relapse after COVID-19 vaccination. Although our case cannot establish causality between AAV relapse and COVID-19 mRNA vaccination, a high level of clinical vigilance for relapse of AAV especially in patients undergoing rituximab maintenance therapy following COVID-19 vaccination should be maintained. Furthermore, elapsed time between rituximab administration and COVID-19 mRNA vaccination should be carefully adjusted based on AAV disease-activity.

A Case of Antineutrophil Cytoplasmic Antibodies (ANCA)-Associated Vasculitis Post COVID-19 Vaccination

In this report, we examine the case of a patient who developed antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis after receiving the Pfizer-BioNTech coronavirus disease 2019 (COVID-19) vaccine. This is a case of a 62-year-old female who received the first dose of COVID-19 vaccine in July 2021 before presenting a few weeks later with migrating polyarthralgia and hemoptysis. Autoimmune workup was positive for ANCA against proteinase 3 (PR3).

Antineutrophil Cytoplasmic Antibody-associated Vasculitis after COVID-19 Vaccination with Pfizer-BioNTech

The extent of rare side effects of mRNA vaccines for coronavirus disease 2019 (COVID-19) remains unclear. Several cases of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) following COVID-19 vaccination have been reported. We herein report a 72-year-old man who presented with a fever after receiving the second dose of the Pfizer-BioNTech COVID-19 vaccine. He was diagnosed with acute kidney injury due to myeloperoxidase-ANCA-associated vasculitis and was treated with intermittent hemodialysis, high-dose prednisolone, and intravenous rituximab. His general symptoms and renal impairment subsequently improved. When systemic symptoms are prolonged or renal abnormalities appear after COVID-19 vaccination, the possibility of AAV should be considered.

Case Report: Anti-neutrophil Cytoplasmic Antibody-Associated Vasculitis With Acute Renal Failure and Pulmonary Hemorrhage May Occur After COVID-19 Vaccination

The rare and severe adverse effects associated with coronavirus disease of 2019 (COVID-19) vaccination have been under-appreciated, resulting in many instances of inappropriate management. We describe the case of an elderly woman who developed anti-neutrophil cytoplasmic antibody-associated vasculitis with pulmonary renal syndrome approximately 3 weeks after the first dose of COVID-19 mRNA vaccination (Moderna). Her nasopharyngeal polymerase chain reaction test for the COVID-19 RNA virus was negative. Gross hematuria, heavy proteinuria, acute renal failure (serum creatinine up to 6.5 mg/dL), and hemoptysis coupled with a marked increase in serum anti-myeloperoxidase-O antibody were observed. Renal biopsy showed severe vasculitis with pauci-immune crescent glomerulonephritis. The pulmonary hemorrhage was resolved and renal function improved following combined plasma exchange and the administration of systemic steroids and anti-CD20 therapy. The early examination of urinalysis and renal function may be crucial for identifying glomerulonephritis and acute renal failure in susceptible patients after COVID-19 vaccination.

De-Novo Antineutrophil Cytoplasmic Antibody-Associated Vasculitis Following the mRNA-1273 (Moderna) Vaccine for COVID-19

Antineutrophil cytoplasmic antibody (ANCA) is a systemic autoimmune disorder characterized by antibodies directed against small- and moderate-sized vessels. While there are few reported cases of autoimmune illnesses associated with influenza vaccination, two cases of de-novo anti-proteinase (PR3) ANCA-associated pauci immune glomerulonephritis are reported after the mRNA-1273 coronavirus disease 2019 (COVID-19) vaccine. Here, we report the third case of ANCA-associated glomerulonephritis after the mRNA-1273 COVID-19 vaccine. Our patient presented with acute kidney injury and sub-nephrotic proteinuria four days after receiving the second dose of the COVID vaccine. He was found to have elevated c-ANCA and anti-PR3 antibodies. Renal biopsy confirmed focal necrotizing and diffuse crescentic glomerulonephritis. He was diagnosed with pauci immune glomerulonephritis. The patient achieved remission 10 weeks after the diagnosis with successful treatment.

Post-COVID-19 vaccination IgA vasculitis in an adult

Leukocytoclastic vasculitis has been reported in the setting of COVID‐19 infection and post‐COVID‐19 vaccination. We report a case of IgA vasculitis (IgAV) post‐COVID‐19 vaccination, with immunoglobulin A (IgA) immune deposits in the skin and renal involvement. SARS‐CoV spike protein immunohistochemical staining was negative. IgAV with skin and renal involvement is a potential reaction to COVID‐19 vaccination.

New-Onset and Relapsed Kidney Histopathology Following COVID-19 Vaccination: A Systematic Review

INTRODUCTION

The introduction of COVID-19 vaccination programs has become an integral part of the major strategy to reduce COVID-19 numbers worldwide. New-onset and relapsed kidney histopathology have been reported following COVID-19 vaccination, sparking debate on whether there are causal associations. How these vaccines achieve an immune response to COVID-19 and the mechanism that this triggers kidney pathology remains unestablished. We describe the results of a systematic review for new-onset and relapsed kidney histopathology following COVID-19 vaccination.

METHODS

A systematic literature search of published data up until 31 August 2021 was completed through the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guideline. Research articles reporting new onset or relapsed kidney histopathology in adult patients (>18 years) following COVID-19 vaccination were included for qualitative review. Only full-text articles published in the English language were selected for review.

RESULTS

Forty-eight cases from thirty-six articles were included in the qualitative synthesis of this systematic review. Minimal change disease (19 cases) was the most frequent pathology observed, followed by IgA nephropathy (14 cases) and vasculitis (10 cases). Other cases include relapse of membranous nephropathy, acute rejection of kidney transplant, relapse of IgG4 nephritis, new-onset renal thrombotic microangiopathy, and scleroderma renal crisis following COVID-19 vaccination. There was no mortality reported in any of the included cases. Patients in all but one case largely recovered and did not require long-term renal replacement therapy.

CONCLUSION

This systematic review provides insight into the relationship between various kidney pathologies that may have followed COVID-19 vaccination. Despite these reported cases, the protective benefits offered by COVID-19 vaccination far outweigh its risks. It would be recommended to consider early biopsy to identify histopathology amongst patients presenting with symptoms relating to new-onset kidney disease following vaccination and to monitor symptoms for those with potential relapsed disease.

De Novo and Relapsing Glomerulonephritis following SARS-CoV-2 mRNA Vaccination in Microscopic Polyangiitis

Vaccination against SARS-CoV-2 is the most important advance in the fight against the ongoing coronavirus pandemic. Recent case reports show that the SARS-CoV-2 vaccines can very rarely cause de novo or relapsing glomerular disease. Here, we report two female patients with microscopic polyangiitis, who developed severe glomerulonephritis after immunisation with the BNT162b2 mRNA vaccine. One patient with a possible ongoing but undiagnosed disease developed severe necrotising glomerulonephritis after the second vaccination. In the other patient with a long-lasting disease, rituximab maintenance therapy had been postponed because of the coronavirus pandemic. She noted macrohematuria immediately after the second vaccine dose and developed a severe renal relapse leading to end-stage kidney disease. We suggest that patients with ANCA-associated vasculitis be carefully monitored for disease activity immediately before and after receiving the SARS-CoV-2 vaccination, especially if maintenance therapy has been interrupted. Ultimately, mRNA vaccines should probably be avoided in these patients.

Case Report: ANCA-Associated Vasculitis Presenting With Rhabdomyolysis and Pauci-Immune Crescentic Glomerulonephritis After Pfizer-BioNTech COVID-19 mRNA Vaccination

As the coronavirus disease 2019 (COVID-19) pandemic is ongoing and new variants of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) are emerging, there is an urgent need for COVID-19 vaccines to control disease outbreaks by herd immunity. Surveillance of rare safety issues related to these vaccines is progressing, since more granular data emerge with regard to adverse events of COVID-19 vaccines during post-marketing surveillance. Interestingly, four cases of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) presenting with pauci-immune crescentic glomerulonephritis (GN) after COVID-19 mRNA vaccination have already been reported. We here expand our current knowledge of this rare but important association and report a case of AAV presenting with massive rhabdomyolysis and pauci-immune crescentic GN after Pfizer-BioNTech COVID-19 mRNA vaccination. As huge vaccination programs are ongoing worldwide, post-marketing surveillance systems must continue to assess vaccine safety important for the detection of any events associated with COVID-19 vaccination. This is especially relevant in complex diseases where diagnosis is often challenging, as in our patient with AAV presenting with massive rhabdomyolysis and pauci-immune crescentic GN.

ANCA-Associated Vasculitis Following Pfizer-BioNTech COVID-19 Vaccine

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread around the world. As of the end of June 2021, there were approximately 181 million confirmed cases and more than 3.9 million deaths across the globe. The colossal impact of coronavirus disease 2019 (COVID-19) is driving the biggest vaccination campaign in human history. All 3 vaccines authorized for emergency use by the US Food and Drug Administration (Pfizer-BioNTech, Moderna, and Janssen/Johnson & Johnson) have been thoroughly studied and found to be safe and effective in preventing severe COVID-19 cases. While short-term side effects of COVID-19 vaccine resemble those of other vaccines, long-term side effects remain unknown. Rare side effects continue to surface as millions of people receive COVID-19 vaccines around the world, as compared with the thousands enrolled in the clinical trials. We report a case of new-onset renal-limited ANCA-associated vasculitis (AAV) in a 78-year-old woman with previously normal kidney function after receiving the Pfizer-BioNTech COVID-19 vaccine. The patient developed acute kidney injury with proteinuria and microscopic hematuria with many dysmorphic red blood cells in the urine. Anti-myeloperoxidase antibody titer was elevated. Kidney biopsy showed pauci-immune crescentic necrotizing glomerulonephritis. Kidney function improved after treatment with steroids and rituximab. Our patient had normal routine laboratory testing before the vaccination. Although this case cannot demonstrate a causal relationship between COVID-19 vaccination and AAV, ongoing surveillance for similar complications would be prudent as worldwide vaccination efforts continue.

A worldwide pharmacoepidemiological update of drug-associated ANCA-associated vasculitis at the time of targeted therapies

OBJECTIVE

The literature data supporting the role of a drug in the onset of drug-associated anti-neutrophil cytoplasmic antibody-associated vasculitis (DA-AAV) mainly rely on case reports or short series and implicate old treatments. The advent of new treatments may have modified the epidemiology of these adverse drug reactions (ADRs). We therefore aimed to update this list by using a pharmacovigilance-based data mining approach.

METHODS

We collected data on ADRs reported with the MedDRA preferred term "Anti-neutrophil cytoplasmic antibody positive vasculitis" up to November 2020 from the World Health Organization pharmacovigilance database (VigiBase^® ). For each retrieved drug, a case/noncase analysis was performed, and disproportionate reporting was calculated by using the information component (IC). A positive IC₀₂₅ value, which is the lower end of the 95% credibility interval, was considered significant.

RESULTS

A total of 483 deduplicated individual case safety reports of DA-AAV involving 15 drugs with an IC₀₂₅ >0 were retrieved. DA-AAV occurred in 264 (71.2%, n=371) women, the median age at onset was 62 years [45-72], and the median time to onset between the introduction of the suspected drug and DA-AAV was 9 months [1-36]. DA-AAV occurrence was considered serious in 472 (97.7%, n=481) cases and fatal in 43 (8.9%) cases. The drugs associated with the highest disproportionate reporting were hydralazine, propylthiouracil, thiamazole, sofosbuvir, minocycline, carbimazole, mirabegron, and nintedanib.

CONCLUSION

This study strengthens the previously suspected association but also identifies 3 new drugs that may cause DA-AAV. Particular attention should be given to these drugs by prescribers and in experimental studies.

Pathogenicity of Proteinase 3-Anti-Neutrophil Cytoplasmic Antibody in Granulomatosis With Polyangiitis: Implications as Biomarker and Future Therapies

Granulomatosis with polyangiitis (GPA) is a rare but serious necrotizing auto-immune vasculitis. GPA is mostly associated with the presence of Anti-Neutrophil Cytoplasmic Antibody (ANCA) targeting proteinase 3 (PR3-ANCA), a serine protease contained in neutrophil granules but also exposed at the membrane. PR3-ANCAs have a proven fundamental role in GPA: they bind neutrophils allowing their auto-immune activation responsible for vasculitis lesions. PR3-ANCAs bind neutrophil surface on the one hand by their Fab binding PR3 and on the other by their Fc binding Fc gamma receptors. Despite current therapies, GPA is still a serious disease with an important mortality and a high risk of relapse. Furthermore, although PR3-ANCAs are a consistent biomarker for GPA diagnosis, relapse management currently based on their level is inconsistent. Indeed, PR3-ANCA level is not correlated with disease activity in 25% of patients suggesting that not all PR3-ANCAs are pathogenic. Therefore, the development of new biomarkers to evaluate disease activity and predict relapse and new therapies is necessary. Understanding factors influencing PR3-ANCA pathogenicity, i.e. their potential to induce auto-immune activation of neutrophils, offers interesting perspectives in order to improve GPA management. Most relevant factors influencing PR3-ANCA pathogenicity are involved in their interaction with neutrophils: level of PR3 autoantigen at neutrophil surface, epitope of PR3 recognized by PR3-ANCA, isotype and glycosylation of PR3-ANCA. We detailed in this review the advances in understanding these factors influencing PR3-ANCA pathogenicity in order to use them as biomarkers and develop new therapies in GPA as part of a personalized approach.

2020 international consensus on ANCA testing beyond systemic vasculitis

This document follows up on a 2017 revised international consensus on anti-neutrophil cytoplasm antibodies (ANCA) testing in granulomatosis with polyangiitis and microscopic polyangiitis and focuses on the clinical and diagnostic value of ANCA detection in patients with connective tissue diseases, idiopathic interstitial pneumonia, autoimmune liver diseases, inflammatory bowel diseases, anti-glomerular basement membrane (GBM) disease, infections, malignancy, and during drug treatment. Current evidence suggests that in certain settings beyond systemic vasculitis, ANCA may have clinical, pathogenic and/or diagnostic relevance. Antigen-specific ANCA targeting proteinase-3 and myeloperoxidase should be tested by solid phase immunoassays in any patient with clinical features suggesting ANCA-associated vasculitis and in all patients with anti-GBM disease, idiopathic interstitial pneumonia, and infective endocarditis associated with nephritis, whereas in patients with other aforementioned disorders routine ANCA testing is not recommended. Among patients with autoimmune liver diseases or inflammatory bowel diseases, ANCA testing may be justified in patients with suspected autoimmune hepatitis type 1 who do not have conventional autoantibodies or in case of diagnostic uncertainty to discriminate ulcerative colitis from Crohn's disease. In these cases, ANCA should be tested by indirect immunofluorescence as the target antigens are not yet well characterized. Many questions concerning the optimal use of ANCA testing in patients without ANCA-associated vasculitis remain to be answered.

Autoinflammatory/autoimmunity syndrome induced by adjuvants (ASIA; Shoenfeld's syndrome): A new flame

In the present review, recent findings regarding autoimmune/inflammatory syndrome by adjuvants (ASIA) are described. Patients with ASIA present with complaints such as fatigue, cognitive impairment, arthralgias, myalgias, pyrexia, dry eyes and dry mouth. During the last few years, it has been postulated that these symptoms in patients with foreign body implants are due to a chronic inflammatory process and an adjuvant effect of the implanted biomaterial. Ultimately, these inflammatory reactions result in (an increase of) allergies, autoimmune diseases, immune deficiency and/or lymphomas. Pre-existent allergic disease has been found to be an important risk factor for the development of ASIA after foreign body implantation. Explantation of the foreign body results in the majority of patients in an amelioration of the symptoms. There is an urgent need to start adequately adjusted epidemiological studies to obtain better evidence which percentage of patients does develop symptoms and/or diseases such as ASIA, immune deficiency, and/or autoimmune diseases after implant surgery.

Discrepancies in the evaluation of the safety of the human papillomavirus vaccine

Despite being more than ten years since its introduction, global acceptance to the human papillomavirus (HPV) vaccine is still low. The immunogenetic background of the host, and HPV antigen recognition, are important in natural HPV infection, and should be taken into account in the understanding of adverse autoimmune reactions by the HPV vaccine in certain groups. There is no doubt of the benefit of vaccines in the reduction of the incidence of infectious diseases, and in the case of HPV, the prevention of persistent infection that would lead to cervical cancer. Side-effects, however, should be closely monitored and reported without any bias, to ensure that the benefits of vaccines outweigh the risks of adverse reactions. In this article we bring the attention on certain adverse effects of the vaccine against HPV that have not been well studied as they are not well defined. We also compare the different approaches on HPV vaccine policies regarding its adverse reactions in countries like Japan and Colombia, vs. the recommendations issued by the WHO.

MPO-ANCA associated vasculitis with mononeuritis multiplex following influenza vaccination

Background

Although influenza vaccines are generally safe and effective, a variety of autoimmune phenomena have been reported after vaccination over the past years, such as Guillain–Barre syndrome, rheumatoid arthritis, pemphigus vulgaris, psoriasis, giant cell arteritis and anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV).

Case report

We describe the case of a 67-year old man who presented with a myeloperoxidase-ANCA associated vasculitis with renal involvement and mononeuritis multiplex after seasonal influenza vaccination. He was initially treated with intravenous cyclophosphamide and high-dose prednisolone followed by maintenance treatment consisting of azathioprine and prednisolone.

Conclusion

We hypothesize that seasonal influenza vaccination triggered a systemic immune response in a susceptible patient to develop AAV with renal involvement and vasculitic neuropathy. In general, seasonal influenza vaccinations are considered to be safe, however, clinicians should be aware of this rare phenomenon.

Toll-like receptor 7 deficiency protects apolipoprotein E-deficient mice from diet-induced atherosclerosis

Toll-like receptor 7 (TLR7) mediates autoantigen and viral RNA-induced cytokine production. Increased TLR7 expression in human atherosclerotic lesions suggests its involvement in atherogenesis. Here we demonstrated TLR7 expression in macrophages, smooth muscle cells (SMCs), and endothelial cells from mouse atherosclerotic lesions. To test a direct participation of TLR7 in atherosclerosis, we crossbred TLR7-deficient (Tlr7 ^-/-) mice with apolipoprotein E-deficient (Apoe ^-/-) mice and produced Apoe ^-/- Tlr7 ^-/- and Apoe ^-/- Tlr7 ^+/+ littermates, followed by feeding them an atherogenic diet to produce atherosclerosis. Compared to Apoe ^-/- Tlr7 ^+/+ mice, Apoe ^-/- Tlr7 ^-/- mice showed reduced aortic arch and sinus lesion areas. Reduced atherosclerosis in Apoe ^-/- Tlr7 ^-/- mice did not affect lesion macrophage-positive area and CD4⁺ T-cell number per lesion area, but reduced lesion expression of inflammatory markers major histocompatibility complex-class II and IL6, lesion matrix-degrading proteases cathepsin S and matrix metalloproteinase-9, and systemic serum amyloid A levels. TLR7 deficiency also reduced aortic arch SMC loss and lesion intima and media cell apoptosis. However, TLR7 deficiency did not affect aortic wall elastin fragmentation and collagen contents, or plasma lipoproteins. Therefore, TLR7 contributes to atherogenesis in Apoe ^-/- mice by regulating lesion and systemic inflammation. A TLR7 antagonist may mitigate atherosclerosis.