The association between silica exposure and development of ANCA-associated vasculitis: systematic review and meta-analysis

Treatment strategies for ANCA-associated vasculitides: from standard protocols to future horizons

INTRODUCTION

ANCA-associated vasculitides (AAV), classified into granulomatosis with polyangiitis, microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis represent a group of disorders characterized by necrotizing vasculitis of small vessels, endothelial injury and tissue damage. The outcomes and prognosis of AAV have undergone significant changes with the introduction of glucocorticoids (GCs) and other immunosuppressants (cyclophosphamide, azathioprine, methotrexate, and mycophenolate mofetil). The enhanced understanding of pathogenesis has subsequently led to the incorporation into clinical practice of drugs targeting specific therapeutic targets.

AREAS COVERED

After an extensive literature search of Pubmed, Medline, Embase of the most recent evidence, we provide an overview of available treatments, highlighting how newer drugs have integrated into standard protocols. Our review also explores potential new therapeutic targets, including B cell depletion and inhibition, T cell inhibition, complement inhibition, and IL-5 and IgE inhibition.

EXPERT OPINION

There is hope that the new treatment targets currently under study in AAV may enable a faster and more lasting clinical response, ensuring the reduction of possible side effects from therapies. Moreover, numerous aspects necessitate further exploration in the future, such as tailoring of GCs, integration of GCs-sparing agents, efficacy of combination therapy, optimal maintenance therapy, to reduce organ-damage and improve quality of life.

Update on Silicosis

Although silicosis has been an established disease with a recognized cause for more than 100 years, many workers continue to be exposed to silica and new outbreaks of disease continue to occur. This article describes some of the well-established and new exposures, including denim sandblasting, artificial stone cutting, and some forms of "coal worker's pneumoconiosis." The authors review the imaging and pathology of acute silicosis (silicoproteinosis), simple silicosis, and progressive massive fibrosis and summarize known and putative associations of silica exposure, including tuberculosis, lung cancer, connective tissue disease (especially systemic sclerosis), and vasculitis.

Incidence, Prevalence, and Mortality of Eosinophilic Granulomatosis With Polyangiitis in Korea: A Nationwide Population-Based Study

PURPOSE

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare form of vasculitis with multiorgan involvement. The incidence and prevalence of EGPA vary geographically and ethnically. This study investigated the incidence, prevalence, and mortality of EGPA in a nationwide population-based cohort in Korea.

METHODS

This retrospective cohort study used data from the National Health Insurance database that covers almost all Korean residents. EGPA was identified using relevant diagnostic codes from 2007 to 2018. Newly diagnosed EGPA cases since 2007 and patients who visited outpatient clinics for EGPA at least three times were included. Age- and sex-adjusted standardized incidence and prevalence rates were analyzed.

RESULTS

A total of 843 patients with EGPA were identified. The mean annual standardized incidence between 2007 and 2018 was 1.2 (per 1,000,000 individuals). The incidence of EGPA has increased from 1.1 (per 1,000,000 individuals) in 2007 to 1.6 (per 1,000,000 individuals) in 2017. The standardized prevalence of EGPA has increased from 1.1(per 1,000,000 individuals) in 2007 to 11.2 (per 1,000,000 individuals) in 2018. The incidence and prevalence of EGPA were higher in women than in men. The standardized mortality rate was 1.61 (95% confidence interval [CI], 1.34-1.93) in total population, 1.59 (95% CI, 1.23-2.02) in males, and 1.63 (95% CI, 1.22-2.13) in females.

CONCLUSIONS

The incidence of EGPA has increased over the past decade. Incidence and prevalence rates were higher in females than in males. The overall mortality rate associated with EGPA was higher than that in the general population.

Association between sinusitis and incident rheumatic diseases: a population-based study

OBJECTIVES

To determine whether antecedent sinusitis is associated with incident rheumatic disease.

METHODS

This population-based case-control study included all individuals meeting classification criteria for rheumatic diseases between 1995 and 2014. We matched three controls to each case on age, sex and length of prior electronic health record history. The primary exposure was presence of sinusitis, ascertained by diagnosis codes (positive predictive value 96%). We fit logistic regression models to estimate ORs for incident rheumatic diseases and disease groups, adjusted for confounders.

RESULTS

We identified 1729 incident rheumatic disease cases and 5187 matched controls (mean age 63, 67% women, median 14 years electronic health record history). After adjustment, preceding sinusitis was associated with increased risk of several rheumatic diseases, including antiphospholipid syndrome (OR 7.0, 95% CI 1.8 to 27), Sjögren's disease (OR 2.4, 95% CI 1.1 to 5.3), vasculitis (OR 1.4, 95% CI 1.1 to 1.9) and polymyalgia rheumatica (OR 1.4, 95% CI 1.0 to 2.0). Acute sinusitis was also associated with increased risk of seronegative rheumatoid arthritis (OR 1.8, 95% CI 1.1 to 3.1). Sinusitis was most associated with any rheumatic disease in the 5-10 years before disease onset (OR 1.7, 95% CI 1.3 to 2.3). Individuals with seven or more codes for sinusitis had the highest risk for rheumatic disease (OR 1.7, 95% CI 1.3 to 2.4). In addition, the association between sinusitis and incident rheumatic diseases showed the highest point estimates for never smokers (OR 1.7, 95% CI 1.3 to 2.2).

CONCLUSIONS

Preceding sinusitis is associated with increased incidence of rheumatic diseases, suggesting a possible role for sinus inflammation in their pathogenesis.

ANCA-Associated Vasculitis: Practical Issues in Management

ANCA associated vasculitides are multi-system autoimmune diseases which are increasing in prevalence. In this review we will discuss the clinical manifestations and review the management options. We highlight the various trials of induction and maintenance therapy and discuss the areas of unmet need. These include understanding which patients are at highest risk of relapse, clinical adaptation of improved biomarkers of disease activity and tools to discuss long term prognosis.

Occupational Silica Exposure as a Potential Risk for Microscopic Polyangiitis

Microscopic polyangiitis is an important and common component of cytoplasmic antibody-associated vasculitides that can lead to serious morbidity and even death. A clear causative etiology has not been identified. Although silica is well known to produce lung damage, the negative renal effects of silica exposure should not be overlooked. We present a case of renal dysfunction associated with silica exposure, its diagnosis by renal biopsy, and the treatment method used. Environmental or occupational silica exposure can cause microscopic polyangiitis. Working in occupations with increased risk of silica exposure may result in serious medical problems.

Seasonal Influence on Development of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: A Retrospective Cohort Study Conducted at Multiple Institutions in Japan (J-CANVAS)

OBJECTIVE

To clarify seasonal and other environmental effects on the onset of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV).

METHODS

We enrolled patients with new-onset eosinophilic granulomatosis with polyangiitis (EGPA), microscopic polyangiitis (MPA), and granulomatosis with polyangiitis (GPA) registered in the database of a Japanese multicenter cohort study. We investigated the relationship between environmental factors and clinical characteristics. Seasons were divided into 4 (spring, summer, autumn, and winter), and the seasonal differences in AAV onset were analyzed using Pearson chi-square test, with an expected probability of 25% for each season.

RESULTS

A total of 454 patients were enrolled, with a mean age of 70.9 years and a female proportion of 55.5%. Overall, 74, 291, and 89 patients were classified as having EGPA, MPA, and GPA, respectively. Positivity for myeloperoxidase (MPO)-ANCA and proteinase 3 (PR3)-ANCA was observed in 355 and 46 patients, respectively. Overall, the seasonality of AAV onset significantly deviated from the expected 25% for each season (P = 0.001), and its onset was less frequently observed in autumn. In ANCA serotypes, seasonality was significant in patients with MPO-ANCA (P < 0.001), but not in those with PR3-ANCA (P = 0.97). Additionally, rural residency of patients with AAV was associated with PR3-ANCA positivity and biopsy-proven pulmonary vasculitis.

CONCLUSION

The onset of AAV was influenced by seasonal variations and was less frequently observed in autumn. In contrast, the occurrence of PR3-ANCA was triggered, not by season, but by rural residency.

Therapeutic Advances in Eosinophilic Granulomatosis with Polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA) is an eosinophilic vasculitis that affects a variety of organ systems. Historically, glucocorticoids and a variety of other immunosuppressants were used to abrogate the inflammation and tissue injury associated with EGPA. The management of EGPA has evolved greatly during the last decade with the development of novel targeted therapeutics that have resulted in significantly improved outcomes for these patients, with many more novel targeted therapies emerging.

Childhood-Onset ANCA- Associated Vasculitis: single center experience from Central California

BACKGROUND

Childhood-onset ANCA-associated vasculitides (AAV) are characterized by necrotizing inflammation and include granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Pediatric data is scare and there have been no prior studies examining the characteristics of pediatric AAV in Central California.

METHODS

This retrospective study comprised AAV patients ≤18 years of age, diagnosed between 2010 and 2021, in Central California. We analyzed initial presentation including demographics, clinical, laboratory characteristics, treatment, and initial outcomes.

RESULTS

Of 21 patients with AAV, 12 were categorized as MPA and 9 with GPA. Median age at diagnosis was 13.7 years in MPA cohort and 14 years in GPA. MPA cohort were majority females (92% versus 44%). 57% of the cohort were racial/ethnic minority including Hispanics (n = 9), Asians (n = 2), multiracial (n = 1) and 43% were white (n = 9). MPA patients were more frequently Hispanic (67%), meanwhile GPA patients were frequently white (78%). Median duration of symptoms prior to diagnosis was 14 days in MPA cohort and 21 days in GPA cohort. Renal involvement was frequent (100% in MPA and 78% in GPA). GPA cohort had frequent ear, nose and throat (ENT) involvement (89%). All patients were ANCA positive. All Hispanic patients were MPO positive, meanwhile 89% of white patients were PR3 positive. MPA cohort tended towards more severe disease with 67% requiring ICU admission and 50% requiring dialysis. Two deaths were reported in MPA cohort, related to Aspergillus pneumonia and pulmonary hemorrhage. In MPA cohort, 42% received cyclophosphamide in combination with steroids and 42% received rituximab in combination with steroids. GPA patients received cyclophosphamide, either with steroids alone (78%) or in combination with steroids and rituximab (22%).

CONCLUSIONS

Microscopic polyangiitis was the most frequent AAV subtype with female preponderance, shorter duration of symptoms at onset and higher proportion of racial/ ethnic minority patients. Hispanic children demonstrated frequent MPO positivity. Trends towards higher rates of ICU requirement and need for dialysis upon initial presentation was noted in MPA. Patients with MPA received rituximab more frequently. Future prospective studies are needed to understand differences in presentation and outcomes in childhood onset AAV between diverse racial-ethnic groups.

New Insights into Pathogenesis and Treatment of ANCA-Associated Vasculitis: Autoantibodies and Beyond

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a group of rare systemic diseases affecting small-caliber vessels. The damage caused by AAV mainly involves the lung and kidneys. AAV includes three different types: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Although the different phenotypic forms of AAV share common features, recent studies have shown that there are significant differences in terms of pathogenetic mechanisms involving both the adaptive and innate immune systems. Advances in our understanding of pathogenesis have enabled the development of immuno-targeted therapies. This review illustrates the characteristics of the various forms of AAV and the new therapies available for this disease that can have lethal consequences if left untreated.

Plasma exchange as an adjunctive therapy in anti-neutrophil cytoplasm antibody-associated vasculitis

INTRODUCTION

We summarize evidence for the role of therapeutic plasma exchange (TPE) in the treatment of anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV). TPE rapidly removes ANCA IgG, complement and coagulation factors important in the pathogenesis of AAV. TPE has been used in patients with rapidly deteriorating renal function to achieve early disease control, allowing time for immunosuppressive agents to prevent resynthesis of ANCA. The PEXIVAS trial challenged the utility of TPE in AAV, as it did not show benefit of adjunctive TPE on a combined end point of end stage kidney disease (ESKD) and death.

AREAS COVERED

We analyze data from PEXIVAS and other trials of TPE in AAV, an up-to-date meta-analysis, and recently published large cohort studies.

EXPERT OPINION

There remains a role for the use of TPE in AAV in certain groups of patients, in particular those with severe renal involvement (Cr >500 μmol/L or dialysis-dependent). It should be considered in patients with Cr >300 μmol/L and rapidly deteriorating function, or with life-threatening pulmonary hemorrhage. A separate indication is patients double positive for anti-GBM antibodies and ANCA. TPE may have the greatest benefit as part of steroid-sparing immunosuppressive treatment strategies.

Interstitial lung disease in ANCA-associated vasculitis: associated factors, radiographic features and mortality

OBJECTIVE

To evaluate the prevalence, clinical and radiographic features, and long-term outcomes of interstitial lung disease (ILD) in a United States-based ANCA-associated vasculitis (AAV) cohort.

METHODS

In this retrospective cohort study, we identified cases of ILD within the 2002-2019 Mass General Brigham AAV Cohort, a consecutive inception cohort of PR3- or MPO-ANCA+ AAV patients. ILD diagnosis and classification as fibrotic or non-fibrotic were confirmed by review of available chest imaging by two board-certified radiologists. Cox proportional hazard models, with age as the time scale, were used to estimate the association of AAV-ILD with all-cause mortality.

RESULTS

Of 684 patients in the MGB AAV Cohort, 91 (13%) had ILD which preceded the diagnosis of AAV by a mean of 2.2 years. AAV-ILD patients were older (67 vs 60 years, P < 0.001) than patients without ILD but the distribution of sex and race was similar. AAV-ILD patients were more often MPO-ANCA+ (93% vs 65%, P < 0.001); among MPO-ANCA+ patients (n = 470), 85 (18%) had ILD. The majority of ILD was fibrotic (76%) and UIP was the most common ILD pattern (42%). The baseline forced vital capacity (FVC) % predicted among ILD patients was 81 ± 20%. Fibrotic AAV-ILD was associated with a 58% higher risk of death (aHR 1.58, 95% CI 1.06, 2.37) compared with AAV patients without ILD.

CONCLUSION

ILD is a frequent complication of AAV, especially MPO-ANCA+ AAV, often preceding recognition of AAV. Fibrotic AAV-ILD is associated with a higher risk of death than AAV without ILD.

Occupational Silica Exposure and Pericarditis: An Uncommon Link

Granulomatosis with polyangiitis (GPA) is a multi-system necrotising vasculitis, particularly affecting small vessels. Upper respiratory tracts, lungs and kidneys are common target organs, while cardiac involvement would also be the first and rare manifestation of the disease. In GPA with cardiac involvement, structures such as the pericardium, myocardium, endocardium and conduction system could be involved. In the literature, there are reports of an association between autoimmune diseases and silica exposure. In our case, a 73-year-old sculptor with regular exposure to silica presented with pericarditis and was later diagnosed with granulomatosis with polyangiitis. This report provides additional evidence of an association between silica exposure and autoimmune vasculitis.

Lung inflammation induced by silica particles triggers hippocampal inflammation, synapse damage and memory impairment in mice

BACKGROUND

Considerable evidence indicates that a signaling crosstalk between the brain and periphery plays important roles in neurological disorders, and that both acute and chronic peripheral inflammation can produce brain changes leading to cognitive impairments. Recent clinical and epidemiological studies have revealed an increased risk of cognitive impairment and dementia in individuals with impaired pulmonary function. However, the mechanistic underpinnings of this association remain unknown. Exposure to SiO₂ (silica) particles triggers lung inflammation, including infiltration by peripheral immune cells and upregulation of pro-inflammatory cytokines. We here utilized a mouse model of lung silicosis to investigate the crosstalk between lung inflammation and memory.

METHODS

Silicosis was induced by intratracheal administration of a single dose of 2.5 mg SiO₂/kg in mice_. Molecular and behavioral measurements were conducted 24 h and 15 days after silica administration. Lung and hippocampal inflammation were investigated by histological analysis and by determination of pro-inflammatory cytokines. Hippocampal synapse damage, amyloid-β (Aβ) peptide content and phosphorylation of Akt, a proxy of hippocampal insulin signaling, were investigated by Western blotting and ELISA. Memory was assessed using the open field and novel object recognition tests.

RESULTS

Administration of silica induced alveolar collapse, lung infiltration by polymorphonuclear (PMN) cells, and increased lung pro-inflammatory cytokines. Lung inflammation was followed by upregulation of hippocampal pro-inflammatory cytokines, synapse damage, accumulation of the Aβ peptide, and memory impairment in mice.

CONCLUSION

The current study identified a crosstalk between lung and brain inflammatory responses leading to hippocampal synapse damage and memory impairment after exposure to a single low dose of silica in mice.

The neutrophil: A key resourceful agent in immune‐mediated vasculitis

The term "vasculitis" refers to a group of rare immune-mediated diseases characterized by the dysregulated immune system attacking blood vessels located in any organ of the body, including the skin, lungs, and kidneys. Vasculitides are classified according to the size of the vessel that is affected. Although this observation is not specific to small-, medium-, or large-vessel vasculitides, patients show a high circulating neutrophil-to-lymphocyte ratio, suggesting the direct or indirect involvement of neutrophils in these diseases. As first responders to infection or inflammation, neutrophils release cytotoxic mediators, including reactive oxygen species, proteases, and neutrophil extracellular traps. If not controlled, this dangerous arsenal can injure the vascular system, which acts as the main transport route for neutrophils, thereby amplifying the initial inflammatory stimulus and the recruitment of immune cells. This review highlights the ability of neutrophils to "set the tone" for immune cells and other cells in the vessel wall. Considering both their long-established and newly described roles, we extend their functions far beyond their direct host-damaging potential. We also review the roles of neutrophils in various types of primary vasculitis, including immune complex vasculitis, anti-neutrophil cytoplasmic antibody-associated vasculitis, polyarteritis nodosa, Kawasaki disease, giant cell arteritis, Takayasu arteritis, and Behçet's disease.

Epidemiologic Opportunities and Challenges in Studying Environmental Risk Factors for Rheumatic Diseases

Most rheumatic diseases have a stronger environmental than hereditary etiology. This article summarizes the key environmental risk factors for rheumatic diseases, the data sources that generated these findings, and the key pitfalls with existing research that every rheumatology clinician should know. Emerging research opportunities hold promise to revolutionize this field, and soon.

Environmental Triggers for Vasculitis

Systemic vasculitides are autoimmune diseases characterized by vascular inflammation. Most types of vasculitis are thought to result from antigen exposure in genetically susceptible individuals, suggesting a likely role for environmental triggers in these conditions. Seasonal and geographic variations in incidence provide insight into the potential role of environmental exposures in these diseases. Many data support infectious triggers in some vasculitides, whereas other studies have identified noninfectious triggers, such as airborne pollutants, silica, smoking, and heavy metals. We review the known and suspected environmental triggers in giant cell arteritis, Takayasu arteritis, polyarteritis nodosa, Kawasaki disease, and antineutrophil cytoplasmic antibody-associated vasculitis.

Diagnosing and treating ANCA-associated vasculitis: an updated review for clinical practice

ANCA-associated vasculitides (AAV) are a group of rare, primary, systemic necrotizing small-vessel vasculitides. Granulomatosis with polyangiitis and microscopic polyangiitis account for ∼80–90% of all AAV. Exposure to silica dust, farming and chronic nasal Staphylococcus aureus carriage are associated with increased risk of developing AAV. When a diagnosis of AAV is suspected, as in patients with multisystem organ dysfunction or those with features such as chronic recurrent rhinosinusitis, cavitated lung nodules, palpable purpura or acute kidney injury, then appropriate further investigations are needed, including ANCA testing. In this scenario, a structured clinical assessment should be conducted, evaluating all the organs possibly involved, and tissue biopsy may be necessary for confirmation of the diagnosis. Therapeutic algorithms vary based on the severity of AAV, the clinical diagnosis/ANCA specificity, and the patient’s age, weight, comorbidities and prognosis. Recent data favour rituximab as a preferable option for both induction and maintenance of remission. In addition, regimens with less glucocorticoids are equally effective and safer in inducing remission compared with conventional regimens, and avacopan is an effective glucocorticoid-sparing option. In contrast, there is not compelling evidence to support the routine use of plasma exchange in addition to standard remission-induction therapy in AAV. ANCA and other biomarkers can be helpful in association with clinical assessment to guide diagnosis and treatment decisions. Patients should be frequently evaluated during follow-up for possible disease relapses or treatment-related morbidity, and for monitoring damage accrual, especially metabolic and cardiovascular damage.

Type of ANCA May Be Indispensable in Distinguishing Subphenotypes of Different Clinical Entities in ANCA-Associated Vasculitis

The traditional nomenclature system for classifying antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) based on clinical phenotype describes granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA) and microscopic polyangiitis (MPA) as distinct clinical entities. This classification has proved its expedience in clinical trials and everyday clinical practice; yet, a substantial overlap in clinical presentation still exists and often causes difficulties in prompt definition and clinical distinction. Additionally, new insights into the AAV pathogenesis point out that PR3 and MPO-AAV may not represent expressions of the same disease spectrum but rather two distinct disorders, as they display significant differences. Thus, it is supported that a classification based on ANCA serotype (PR3-ANCA, MPO-ANCA or ANCA-negative) could be more accurate and also closer to the nature of the disease compared to the phenotype-based one. This review aims to elucidate the major differences between PR3 and MPO-AAV in terms of epidemiology, pathogenesis, histological and clinical manifestations and response to therapeutic approaches.

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.

A toxicological profile of silica nanoparticles

Humans are regularly exposed to silica nanoparticles in environmental and occupational contexts, and these exposures have been implicated in the onset of adverse health effects. Existing reviews on silica nanoparticle toxicity are few and not comprehensive. There are natural and synthetic sources by which crystalline and amorphous silica nanoparticles are produced. These processes influence physiochemical properties, which are factors that can dictate toxicological effects. Toxicological assessment includes exposure scenario (e.g. environmental, occupational), route of exposure, toxicokinetics, and toxicodynamics. Broader considerations include pathology, risk assessment, regulation, and treatment after injury. This review aims to consolidate the most relevant and up-to-date research in these areas to provide an exhaustive toxicological profile of silica nanoparticles.

The relationship between animal flesh foods consumption and rheumatoid arthritis: a case-control study

Background

Rheumatoid arthritis (RA) is a chronic, systemic inflammatory, and debilitating autoimmune illness. The objective of the present study was to evaluate the relationship between animal flesh foods consumption and rheumatoid arthritis.

Methods

Meat consumption was assessed by using a semi-quantitative Food Frequency Questionnaire (168 items) in a case-control study of 297 subjects (100 newly diagnosed cases and 197 healthy controls). An expert rheumatologist diagnosed patients based on the American College of Rheumatology definitions, 2010. Multivariate logistic regression, adjusted for lifestyle and nutritional confounders, was used to evaluate the relationship between dairy consumption and rheumatoid arthritis.

Results

Participants with greater consumption of fish and seafood were less likely to have RA (OR 0.52; 95% CI 0.27–0.98). Conversely, a higher processed meat intake was associated with increased odds of RA (OR 3.45; 95% CI 1.78–6.68). However, no significant association was found between red meats and poultry consumption and the risk of RA in the fully adjusted model.

Conclusions

The present study suggests an inverse association between fish and seafood consumption and the risk of RA. On the contrary, a higher amount of processed meat intake was associated with increased odds of RA. However, further studies are warranted to confirm the veracity of our findings.

Pulmonary Toxicity of Silica Linked to Its Micro- or Nanometric Particle Size and Crystal Structure: A Review

Silicon dioxide (SiO2) is a mineral compound present in the Earth’s crust in two mineral forms: crystalline and amorphous. Based on epidemiological and/or biological evidence, the pulmonary effects of crystalline silica are considered well understood, with the development of silicosis, emphysema, chronic bronchitis, or chronic obstructive pulmonary disease. The structure and capacity to trigger oxidative stress are recognized as relevant determinants in crystalline silica’s toxicity. In contrast, natural amorphous silica was long considered nontoxic, and was often used as a negative control in experimental studies. However, as manufactured amorphous silica nanoparticles (or nanosilica or SiNP) are becoming widely used in industrial applications, these paradigms must now be reconsidered at the nanoscale (<100 nm). Indeed, recent experimental studies appear to point towards significant toxicity of manufactured amorphous silica nanoparticles similar to that of micrometric crystalline silica. In this article, we present an extensive review of the nontumoral pulmonary effects of silica based on in vitro and in vivo experimental studies. The findings of this review are presented both for micro- and nanoscale particles, but also based on the crystalline structure of the silica particles.

The Relationship between Tumor Development and Sarcoidosis in Aspects of Carcinogenesis before and after the Onset of Sarcoidosis

Background and Objectives: It is still unclear whether sarcoidosis is likely to be associated with tumors. In addition, the use of an immune checkpoint inhibitor has been reported to initiate the onset of sarcoidosis. We retrospectively analyzed tumor development before and after the diagnosis of sarcoidosis and examined the impact of having a history of tumors on the activity or the severity of sarcoidosis. Materials and Methods: We recruited 312 consecutive cases of sarcoidosis and analyzed the tumor development before and after the onset of sarcoidosis. Results: Among them, 25 cases were diagnosed with malignant tumor after diagnosis of sarcoidosis. In the analysis of the tumor-development group after diagnosis of sarcoidosis, both serum angiotensin I-converting enzyme and mediastinal lymph node size were significantly reduced at the time of malignant tumor diagnosis compared to at the onset of sarcoidosis, indicating that the decreasing activity of sarcoidosis may be partly associated with tumor development. Furthermore, we examined 34 cases having tumor history before the onset of sarcoidosis and analyzed the effect of tumor history on the severity of sarcoidosis. Cases with a malignant tumor in the past were older and had less complicated organs of sarcoidosis than cases without malignant tumors in the past. Oral corticosteroid therapy was administrated more frequently in cases without malignant tumors in the past, indicating that the history of a malignant tumor may influence the severity of sarcoidosis. Conclusion: These results indicate that tumor development may be partly associated with the activity or severity of sarcoidosis.

Inhaled Silica Nanoparticles Causes Chronic Kidney Disease in Rats

INTRODUCTION

Silica nanoparticles (SiNPs) released during the burning of sugarcane have been postulated to have a role in chronic kidney disease of unknown etiology. We tested the hypothesis that pristine SiNPs of the size present in sugarcane might cause chronic kidney injury when administered through the lung in rats.

METHODS

We administered 200 nm or 300 nm amorphous SiNPs twice weekly (4 mg/dose) or vehicle by oropharyngeal aspiration for 13 weeks to rats followed by sacrifice after an additional 13 weeks (26 weeks total). Tissues were evaluated for presence of SiNPs and evidence of histologic injury.

RESULTS

Both sizes of SiNPs caused kidney damage, with early tubular injury and inflammation (at week 13) that continued to inflammation and chronic fibrosis at week 26 despite discontinuing the SiNP administration. Both sizes of SiNPs caused local inflammation in the lung and kidney and were detected in the serum and urine at week 13, and the 200 nm particles also localized to the kidney with no evidence of retention of the 300 nm particles. At week 26 there was some clearance of the 200 nm silica from the kidneys, and urinary levels of SiNPs were reduced but still significant in both the 200 and 300 nm exposed rats.

CONCLUSIONS

Inhaled SiNPs causes chronic kidney injury that progresses despite stopping the SiNP administration. These findings are consistent with the hypothesis that human exposure to amorphous silica nanoparticles found in burned sugarcane fields could have a participatory role in chronic kidney disease of unknown etiology.

Mechanisms of vascular damage in ANCA vasculitis

The discovery of anti-neutrophil cytoplasmic antibodies (ANCA) and their antigenic targets, myeloperoxidase (MPO) and proteinase 3 (PR3), has led to further understanding as to the pathophysiologic processes that underlie vascular and tissue damage in ANCA vasculitis. ANCA trigger neutrophil activation leading to vascular damage in ANCA vasculitis. However, decades of study have determined that neutrophil activation alone is not sufficient to cause disease. Inflammatory stimuli are drivers of ANCA autoantigen expression and ANCA production. Certain infections or bacterial peptides may be crucial players in the initial steps of ANCA immunopathogenesis. Genetic and epigenetic alterations of gene encoding for MPO and PR3 provide additional disturbances to the immune homeostasis which provide a substrate for pathogenic ANCA formation from an adaptive immune system predisposed to autoreactivity. Promoted by inflammatory cytokines, ANCA binding leads to neutrophil activation, a process characterized by conformational changes, production and release of cytotoxic substances, and alternative complement pathway activation, thus creating an intense inflammatory milieu. This cascade of events perpetuates a vicious cycle of further inflammatory cell recruitment and activation, culminating in tissue necrosis. Our understanding of the pathogenic process in ANCA vasculitis paves the way for the development of therapies targeting crucial steps in this process. The greater appreciation of the role for complement, monocytes, and the adaptive immune system has already led to novel complement blockers and is poised to lead to further innovations which will allow for tailored antigen- or cell-specific immunotherapy targeting the autoimmune process without exposure to undue risks or toxicities.

ANCA Associated Vasculitis Subtypes: Recent Insights and Future Perspectives

The ANCA associated vasculitides (AAVs) affect a range of internal organs including ear nose and throat, respiratory tract, kidneys, skin and nervous system. They include granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA) and microscopic polyangiitis (MPA). The AAVs are treated with high dose glucocorticoids, immunosuppressants, and targeted biological medications. Since the 1990s classification criteria for the AAVs have been based on clinical features, laboratory tests and basic imaging; an initiative to update the classification criteria incorporating newer tests, for example, anti-neutrophil cytoplasmic antibodies (ANCA) and novel imaging techniques will be published this year. There is also evidence for classification of patients based on ANCA subtype; those with anti-proteinase 3 antibodies (PR3) or anti-myeloperoxidase antibodies (MPO) have differences in response to treatment and clinical outcomes. An update is described within this review. The pathogenesis of AAV involves necrotizing inflammation of small to medium blood vessels involving multiple immunological pathways. We present an update on emerging evidence related to auto-antibodies, complement and lymphocyte pathways. This review describes emerging treatment regimens, including evidence for plasma exchange in severe disease and the inhibitor of the complement C5a receptor (C5aR) inhibitor, Avacopan. Lastly, patient reported outcomes are key secondary outcomes in randomised controlled trials and increasingly clinical practice, we report development in disease specific and glucocorticoid-specific PROs.

Prevalence of ANCA-associated vasculitis amid natural gas drilling sites in West Virginia

BACKGROUND

The epidemiology of ANCA-associated vasculitis (AAV) varies by ethnicity and region. Environmental exposure has been implicated in the pathophysiology of MPO-AAV. The aim of this study was to evaluate the epidemiology of AAV and explore a potential relationship with environmental factors in north central West Virginia.

METHODS

This is a retrospective cohort study of 212 patients diagnosed with AAV at West Virginia University and its affiliated hospitals from January 1, 1990 to December 31, 2019. We assessed prevalence of AAV over time according to patient's zip codes and counties. Silica exposure through natural gas extraction was considered as a possible environmental factor.

RESULTS

The proportion of patients with MPO-ANCA increased after 2010 (37.5% before 2010 vs 61% after 2010, p = 0.008). At the same time, the prevalence of AAV in Monongalia and surrounding counties has increased significantly after 2010 from 64.8 to 141.9 cases per million (p = 0.001). The increase in prevalence of AAV was primarily due to an increase in MPO-AAV (43 vs 101.7 cases per million before and after 2010, respectively, p = 0.028). During this time, the production of natural gas through fracking increased, rising more than tenfold after 2010 (p-value < 0.001). Heat mapping reveals that the increase in cases of AAV occurred in areas of increased fracking activity.

CONCLUSIONS

There was an increase in the prevalence of patients who were newly diagnosed with AAV over time in north central West Virginia. Further studies are required to ascertain the potential role of environmental exposure in the pathophysiology of AAV.

Global epidemiology of vasculitis

The many forms of vasculitis are characterized by inflammation of blood vessels, leading to potentially long-term sequelae including vision loss, aneurysm formation and kidney failure. Accurate estimation of the incidence and prevalence has been hampered by the absence of reliable diagnostic criteria and the rarity of these conditions; however, much progress has been made over the past two decades, although data are still lacking from many parts of the world including the Indian subcontinent, China, Africa and South America. Giant cell arteritis occurs in those aged 50 years and over and seems to mainly affect persons of northern European ancestry, whereas Takayasu arteritis occurs mainly in those aged under 40 years. By contrast, Kawasaki disease mainly occurs in children aged under 5 years and is most common in children of Asian ancestry, and IgA vasculitis occurs in children and adolescents. Although much less common than giant cell arteritis, the different forms of antineutrophil cytoplasmic antibody-associated vasculitis are being increasingly recognized in most populations and occur more frequently with increasing age. Behçet syndrome occurs most commonly along the ancient silk road between Europe and China. Much work needs to be done to better understand the influence of ethnicity, geographical location, environment and social factors on the development of vasculitis.

Antineutrophil cytoplasmic antibody-associated interstitial lung disease: a review

Over the past three decades, an increasing number of publications have reported the association between interstitial lung disease (ILD) and anti-neutrophil cytoplasmic antibody (ANCA) or ANCA-associated vasculitis (AAV). With this increased awareness, we have reviewed the literature to date and provide an update in this narrative review. The vast majority of cases of ILD have been shown to be in the setting of positive anti-myeloperoxidase antibody and can be present in up to 45% of patients of microscopic polyangiitis, though cases of ILD associated with proteinase 3 ANCA have rarely been reported. Pulmonary fibrosis and ANCA positivity can occur with or without systemic involvement. The pathogenetic mechanisms establishing the relationship between ANCA and the development of pulmonary fibrosis remain unclear. Histologic and radiographic features of ANCA-ILD most commonly reveal usual interstitial pneumonia or non-specific interstitial pneumonia patterns, though other atypical features such as bronchiolitis have been described. ILD in the setting of AAV has been associated with worse outcomes, and thus early identification and treatment in these patients is appropriate. We advocate that ANCA antibody testing be performed as a baseline evaluation in patients presenting with idiopathic interstitial pneumonia. Suggested treatment of ANCA-ILD includes immunosuppression and/or antifibrotic agents, though supporting data and clinical trials to substantiate use of these therapies are needed.

Pathogenesis-based new perspectives of management of ANCA-associated vasculitis

While the pathogenesis of anti-neutrophil cytoplasmic autoantibody associated vasculitis (AAV) is still not fully elucidated, there is a mounting evidence that it is initiated by inflammation and activation of innate immunity in the presence of predisposing factors, innate immunity, aberrant responses of the adaptive immune system, and complement system activation. Biologics targeting inflammation-related molecules in the immune system have been explored to treat AVV, and these treatments have provided revolutionary advances. When focusing on the pathogenic mechanisms of AVV, this review presents the new findings regarding novel therapeutic approaches for the management of these conditions.

ANCA in systemic sclerosis, when vasculitis overlaps with vasculopathy: a devastating combination of pathologies

In patients with SSc, the coexistence of ANCA-associated vasculitis (SSc-AAV) has been reported to be associated with a severe disease course, including significant pulmonary and renal involvement. The presence of ANCA is not uncommon in patients with SSc, and therefore clinicians must maintain a high index of clinical suspicion about SSc-AAV. p-ANCA and anti-myeloperoxidase antibodies are the most common antibodies observed. Patients typically present with clinical features of microscopic polyangiitis or renal-limited vasculitis. There are multiple areas of potential interaction in the pathogenesis of SSc and AAV, which can exacerbate/compound vascular disease. In addition, similar patterns of major internal organ involvement (e.g. lung and kidneys) are seen in both conditions. We highlight a diagnostic approach to SSc-AAV and the paucity of data to inform management. As such, SSc-AAV is typically treated as per isolated AAV, which can potentially be hazardous in patients with SSc (e.g. due to the association between high-dose steroid and scleroderma renal crisis). We propose that this rare clinical entity warrants rigorous investigation, including definition of a therapeutic strategy to ameliorate the potentially devastating combination of pathologies in SSc-AAV.

Prevalence and clinical impact of systemic autoimmune rheumatic disease in patients with silicosis

BACKGROUND

Silicosis is associated with an increased risk of developing systemic autoimmune rheumatic disease (SARD). The prognostic implications of this association are poorly characterized. The aim of this study was to determine the prevalence of SARD and autoimmune markers in a cohort of patients with exposure to silica and assess their impact on prognosis.

METHOD

We performed a prospective observational study of all patients attending the dedicated silicosis clinic of our pulmonology unit between 2009 and December 2017. Diagnosis was confirmed by a rheumatologist according to Spanish Rheumatology Society criteria. Autoimmune markers, pulmonary function tests, radiological progression, visits to the emergency department and primary care center, and hospital admissions for respiratory causes, and mortality were analyzed.

RESULTS

Overall, 489 cases of silicosis and 95 cases of exposure were studied. In total, 54 (11.0%) patients with silicosis had SARD: 12 (2.4%) rheumatoid arthritis, 10 (2.0%) systemic lupus erythematosus, 10 (2.0%) systemic sclerosis, 3 (0.6%) Sjögren syndrome, 2 (0.4%) vasculitis associated with anti-neutrophil cytoplasmic antibodies (ANCA +), 6 (1.2%) psoriatic arthritis, 3 (0.6%) ankylosing spondylitis, and 8 (1.6%) other autoimmune diseases with no special features. The patients with SARD visited the emergency room more often (63.0% vs. 42.5%; p = 0.004), and progressed more rapidly (22.2 vs. 11.7%; p = 0.030).

CONCLUSIONS

The presence of systemic rheumatic autoimmune diseases involves radiological progression and a higher clinical impact.

ANCA-associated renal vasculitis is associated with rurality but not seasonality or deprivation in a complete national cohort study

Background

Small studies suggest an association between ANCA-associated vasculitis (AAV) incidence and rurality, seasonality and socioeconomic deprivation. We examined the incidence of kidney biopsy-proven AAV and its relationship with these factors in the adult Scottish population.

Methods

Using the Scottish Renal Biopsy Registry, all adult native kidney biopsies performed between 2014 and 2018 with a diagnosis of granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) were identified. The Scottish Government Urban Rural Classification was used for rurality analysis. Seasons were defined as autumn (September–November), winter (December–February), spring (March–May) and summer (June–August). Patients were separated into quintiles of socioeconomic deprivation using the validated Scottish Index of Multiple Deprivation and incidence standardised to age. Estimated glomerular filtration rate and urine protein:creatinine ratio at time of biopsy were used to assess disease severity.

Results

339 cases of renal AAV were identified, of which 62% had MPA and 38% had GPA diagnosis. AAV incidence was 15.1 per million population per year (pmp/year). Mean age was 66 years and 54% were female. Incidence of GPA (but not MPA) was positively associated with rurality (5.2, 8.4 and 9.1 pmp/year in ‘urban’, ‘accessible remote’ and ‘rural remote’ areas, respectively; p=0.04). The age-standardised incidence ratio was similar across all quintiles of deprivation (p=ns).

Conclusions

Seasonality and disease severity did not vary across AAV study groups. In this complete national cohort study, we observed a positive association between kidney biopsy-proven GPA and rurality.

Classification of ANCA-associated vasculitis: differences based on ANCA specificity and clinicopathologic phenotype

The classification of vasculitis according to a schema with universal acceptance is challenging, given the heterogeneous and protean nature of these diseases. Formal nomenclature and classification criteria for anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) have suffered several changes since their first description; none provides comprehensive diagnostic and classification criteria. Different factors account for the difficulties in the classification of vasculitis, including the incomplete understanding of the pathogenesis, the multisystemic nature of the disease, the non-specific patterns of vascular involvement, the overlap between entities, and the presence of various classification systems. The present article reviews the classification of AAV considering different points of view, including clinical, serologic, pathogenetic, organ predilection, therapeutic, and prognostic factors, and provides perspectives on future challenges in the understanding of AAV. There is an unmet need for a unifying view of the disease spectrum that considers the constantly evolving paradigms.

ANCA-associated vasculitis after COVID-19

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) are systemic autoimmune diseases that may lead to renal failure due to the infiltration of mononuclear cells and the destruction of small- and medium-sized blood vessels. It has been shown that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may trigger the presentation or exacerbation of autoimmune diseases. Crescentic glomerulonephritis (GN) has rarely been reported in patients with Coronavirus disease-2019 (COVID-19). We present rare two cases with AAV after a recent diagnosis of COVID-19. The first case was 26-year-old male patient, who was presented with acute kidney injury after COVID-19. Serum creatinine increased and active urine sediment was seen. Serological evaluation showed anti-myeloperoxidase antibody was at a level of 80.6 U/mL. Kidney biopsy showed necrotizing GN with cellular crescents. Methylprednisolone, cyclophosphamide and plasma exchange were administered. He was discharged with hemodialysis. Second case was a 36-year-old female who was hospitalized because of fever, cough and dyspnea. After she was diagnosed with COVID-19, she had total hearing loss, with cavitary lesions on bilateral lung parenchyma and an acute kidney injury. Serological evaluation showed an elevated anti-proteinase-3 with a level of 1:32. Kidney biopsy showed necrotizing GN with cellular crescents. Renal function improved after methylprednisolone and cyclophosphamide treatment. With a systematic review of the literature, we found four cases of new-onset AAV due to COVID-19. Herein, we discuss two cases and provide a literature review on cases of new-onset pauci-immune GN after COVID-19 infection.

Advances in the genomics of ANCA-associated vasculitis-a view from East Asia

Recent genome-wide association studies (GWAS) in populations of European ancestry have identified several susceptibility genes to anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The most significant association was observed in HLA-DP variants in granulomatosis with polyangiitis and proteinase 3 (PR3)-ANCA positive vasculitis, while HLA-DQ variants were strongly associated with microscopic polyangiitis (MPA) and myeloperoxidase (MPO)-ANCA positive vasculitis (MPO-AAV). In non-HLA genes, SERPINA1, PRTN3 and PTPN22 were identified as susceptibility genes to AAV. The observations in GWAS suggested the presence of shared and non-shared susceptibility genes among AAV subsets. Epidemiological features of AAV are strikingly different in the East Asian populations; the proportions of MPO-AAV among total AAV, MPO-ANCA positive patients among GPA, and patients with interstitial lung disease among total AAV are considerably higher in Japan as compared with Europe. Such population differences suggest the critical role for genetic background behind these conditions. Although no GWAS has been reported in the Asian populations so far, the association of HLA-class II alleles with MPA and MPO-AAV was identified. Future genomics studies on AAV, especially from Asian populations, will provide valuable information to elucidate the molecular mechanisms and to identify molecular targets for AAV.

Prevalence of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis and spatial association with quarries in a French Northeast region

OBJECTIVE

Silica is one of the strongest environmental substances linked with autoimmunity. The aim of this study was to assess the prevalence of granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and renal limited vasculitis (RLV) in a French northeast region, and their geospatial association with quarries.

METHODS

Potential ANCA-Associated Vasculitis (AAV) cases were identified using three sources: hospital records, immunology laboratories and the National Health Insurance System. Patients who resided in Alsace on January 1, 2016 and fulfilled ACR AAV criteria or Chapel Hill Consensus Conference 2012 definition were included. Incomplete case ascertainment was corrected using capture-recapture analysis. The spatial association between the number of cases and quarries in each administrative entity was assessed using geographical weighted regression (GWR).

RESULTS

From 910 potential AAV cases, we identified 185 patients meeting inclusion criteria: 120 GPA, 35 MPA, 30 RLV. The number of cases missed by any source was 6.4 (95%CI 3.6-11.5). Accordingly, the 2016 estimated prevalence in Alsace was 65.5 cases per million inhabitants (95%CI 47.3-93.0) for GPA, 19.1 (95%CI 11.3-34.3) for MPA, and 16.8 (95%CI 8.7-35.2) for RLV. The risk of AAV was significantly increased in communes with quarries (OR: 2.51 [95%CI: 1.66-3.80]) and GWR revealed a significant spatial association between quarries and GPA cases (p = 0.039), and, regarding ANCA serotype, between quarries and both PR3-AAV (p = 0.04) and MPO-AAV (p = 0.03)."

CONCLUSION

In a region with a high density of quarries, the spatial association of AAV with quarries supports the role of silica as a specific environmental factor.

ANCA-Associated Vasculitis: An Update

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) represents a group of small vessel vasculitides characterized by granulomatous and neutrophilic tissue inflammation, often associated with the production of antibodies that target neutrophil antigens. The two major antigens targeted by ANCAs are leukocyte proteinase 3 (PR3) and myeloperoxidase (MPO). AAV can be classified into 3 categories based on patterns of clinical involvement: namely, granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic GPA (EGPA). Clinically, AAV involves many organ systems including the lungs, kidneys, skin, and nervous system. The prognosis of AAV has improved dramatically due to advances in the understanding of its pathogenesis and treatment modalities. This review will highlight some of the recent updates in our understanding of the pathogenesis, clinical manifestations, and treatment options in patients with AAV focusing on kidney involvement.

Treatment Updates in Antineutrophil Cytoplasmic Autoantibodies (ANCA) Vasculitis

ANCA vasculitis is a small-vessel vasculitis (SVV) resulting in inflammation of small- and medium-sized blood vessels. Since the initial description of SVV, there have been tremendous advances in our understanding of its pathogenesis. Over the last decade, we have made significant progress in understanding the pathogenesis and improving the treatment and prognosis of patients with ANCA vasculitis. Patient and renal survival has improved, and treatment is moving toward individualizing care, minimizing severe adverse events, and preventing relapse. This review focuses on treatment updates in ANCA vasculitis, duration of therapy, and management of relapses. We also describe the existing treatment protocols used at our institution.

Occupational Exposures and Smoking in Eosinophilic Granulomatosis With Polyangiitis: A Case-Control Study

OBJECTIVE

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Environmental agents and occupational exposures may confer susceptibility to EGPA, but data are scarce. This study was undertaken to investigate the association between occupational exposures (e.g., silica, farming, asbestos, and organic solvents) and other environmental agents (e.g., smoking) and the risk of EGPA.

METHODS

Patients with newly diagnosed EGPA (n = 111) and general population controls (n = 333) who were matched for age, sex, and geographic area of origin were recruited at a national referral center for EGPA. Exposures were assessed using a dedicated questionnaire administered by a specialist in occupational medicine, under blinded conditions. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

Exposures to silica (OR 2.79 [95% CI 1.55-5.01], P = 0.001), organic solvents (OR 3.19 [95% CI 1.91-5.34], P < 0.001), and farming (OR 2.71 [95% CI 1.71-4.29], P < 0.001) were associated with an increased risk of EGPA. Co-exposure to silica and farming yielded an OR of 9.12 (95% CI 3.06-27.19, P < 0.001), suggesting a multiplicative effect between these 2 exposures. Smoking (current and former smokers combined) was significantly less frequent among patients with EGPA compared to controls (OR 0.49 [95% CI 0.29-0.70], P < 0.001). The pack-year index was also lower among patients with EGPA (OR 0.96 [95% CI 0.94-0.98], P < 0.001). The association of silica and farming was primarily aligned with ANCA-positive EGPA, while the association of smoking status and organic solvents was primarily aligned with ANCA-negative EGPA.

CONCLUSION

The environment can influence susceptibility to EGPA. Exposure to silica, farming, or organic solvents is associated with an increased risk of EGPA, while smoking is associated with a lower risk. These exposures seem to have distinct effects on different EGPA subsets.

Pathogenesis and pathology of anti-neutrophil cytoplasmic antibody（ANCA）-associated vasculitis

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AAV is characterized by necrotizing small vessel vasculitis with positive serum ANCA.

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MPO/PR3-ANCA and neutrophils play central roles in AAV pathogenicity.

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Dysregulated complement system primes neutrophils.

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MPO-ANCA directly activates neutrophils to induce NETosis followed by releasing NETs.

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B cells, T cells, and dendritic cells also contribute to the pathogenicity of AAV.

Silicosis: An Update and Guide for Clinicians

This overview provides an update on silicosis epidemiology with review of exposures and emerging trends in acute and accelerated silicosis in the twenty-first century. The silicosis epidemics in mining, denim sandblasting, and engineering stone industries are highlighted. Clinical presentations of silicosis and silica-related conditions such as autoimmune, kidney, and mycobacterial disease, as well as lung cancer, are discussed. Important aspects of the new OSHA 2017 Silica Standard are presented. This review also includes practical guidance for clinicians to address questions that may arise when evaluating silica-exposed patients and to the public health responses needed following a diagnosis of silica-related disease.

Omega-3 fatty acid intake suppresses induction of diverse autoantibody repertoire by crystalline silica in lupus-prone mice

Inhalation of crystalline silica (cSiO2) in the workplace is etiologically linked to lupus and other autoimmune diseases. Exposing lupus-prone NZBWF1 mice to respirable cSiO2 unleashes a vicious cycle of inflammation and cell death in the lung that triggers interferon-regulated gene expression, ectopic lymphoid structure (ELS) development, elevation of local and systemic autoantibodies (AAbs), and glomerulonephritis. However, cSiO2-induced inflammation and onset of autoimmunity can be prevented by inclusion of the ω-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) into the diet of these mice. Since cSiO2 both causes cell death and interferes with efferocytosis, secondary necrosis of residual cell corpses might provide a rich and varied autoantigen (AAg) source in the lung. While it is known that the particle induces anti-nuclear and anti-dsDNA AAbs in NZBWF1 mice, the full extent of the cSiO2-induced AAb response relative to specificity and isotype is not yet understood. The purpose of this study was to test the hypotheses that cSiO2 exposure induces a wide spectrum of AAbs in the pulmonary and systemic compartments, and that dietary DHA intervention prevents these changes. Archived tissue fluid samples were obtained from a prior study in which NZBWF1 mice were fed purified isocaloric diets containing no DHA (control) or DHA corresponding calorically to human doses of 2 and 5 g/day. Mice were intranasally instilled with 1 mg cSiO2 or saline vehicle weekly for 4 weeks, then groups euthanized 1, 5, 9, or 13 weeks post-instillation (PI) of the last cSiO2 dose. Bronchoalveolar lavage fluid (BALF) and plasma from each time point were subjected to AAb profiling using a microarray containing 122 AAgs. cSiO2 triggered robust IgG and IgM AAb responses against lupus-associated AAgs, including DNA, histones, ribonucleoprotein, Smith antigen, Ro/SSA, La/SSB, and complement as early as 1 week PI in BALF and 5 weeks PI in plasma, peaking at 9 and 13 weeks PI, respectively. Importantly, cSiO2 also induced AAbs to AAgs associated with rheumatoid arthritis (collagen II, fibrinogen IV, fibrinogen S, fibronectin, and vimentin), Sjögren's syndrome (α-fodrin), systemic sclerosis (topoisomerase I), vasculitis (MPO and PR3), myositis (Mi-2, TIF1-γ, MDA5), autoimmune hepatitis (LC-1), and celiac disease (TTG). cSiO2 elicited comparable but more modest IgA AAb responses in BALF and plasma. cSiO2-induced AAb production was strongly associated with time dependent inflammatory/autoimmune gene expression, ELS development, and glomerulonephritis. AAb responses were dose-dependently suppressed by DHA supplementation and negatively correlated with the ω-3 index, an erythrocyte biomarker of ω-3 content in tissue phospholipids. Taken together, these findings suggest that cSiO2 exposure elicits a diverse multi-isotype repertoire of AAbs, many of which have been reported in individuals with lupus and other autoimmune diseases. Furthermore, induction of this broad AAb spectrum could be impeded by increasing ω-3 tissue content via dietary DHA supplementation.

Silica-related diseases in the modern world

Silicosis is an ancient and potentially fatal pneumoconiosis caused by exposure to respirable crystalline silica. Silicosis is historically a disease of miners; however, failure to recognize and control the risk associated with silica exposure in contemporary work practices such as sandblasting denim jeans and manufacturing of artificial stone benchtops has led to re-emergence of silicosis around the world. This review outlines the mineralogy, epidemiology, clinical and radiological features of the various forms of silicosis and other silica-associated diseases. Perspective is provided on the most recent studies shedding light on pathogenesis, including the central role of innate immune effector cells and subsequent inflammatory cascades in propagating pulmonary fibrosis and the extrapulmonary manifestations, which uniquely characterize this pneumoconiosis. Clinical conundrums in differential diagnosis, particularly between silicosis and sarcoidosis, are highlighted, as is the importance of obtaining a careful occupational history in the patient presenting with pulmonary infiltrates and/or fibrosis. While silicosis is a completely preventable disease, unfortunately workers around the world continue to be affected and experience progressive or even fatal disease. Although no treatments have been proven, opportunities to intervene to prevent progressive disease, founded in a thorough cellular and molecular understanding of the immunopathology of silicosis, are highlighted.

Environmental risk factors associated with ANCA associated vasculitis: A systematic mapping review

BACKGROUND

Anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) is a rare multi-system autoimmune disease, characterised by a pauci-immune necrotising small-vessel vasculitis, with a relapsing and remitting course. Like many autoimmune diseases, the exact aetiology of AAV, and the factors that influence relapse are unknown. Evidence suggests a complex interaction of polygenic genetic susceptibility, epigenetic influences and environmental triggers. This systematic mapping review focuses on the environmental risk factors associated with AAV. The aim was to identify gaps in the literature, thus informing further research.

METHODS

Articles that examined any environmental risk factor in AAV disease activity (new onset disease or relapse) were included. Studies had to make explicit reference to AAV, which includes the 3 clinico-pathological phenotypes (GPA, MPA and EGPA), rather than isolated ANCA-positivity. All articles identified were English-language, full manuscripts involving adult humans (>16 years). There was no restriction on publication date and all study designs, except single case reports, were included. The systematic search was performed on 9th December 2019, using the following databases: EMBASE, Medline (Ovid), Cochrane Library, CINAHL and Web of Science.

RESULTS

The search yielded a total of 2375 articles. 307 duplicates were removed, resulting in the title and abstract of 2068 articles for screening. Of these, 1809 were excluded. Thus, 259 remained for full-text review, of which 181 were excluded. 78 articles were included in this review. The most notable findings support the role of various pollutants - primarily silica and other environmental antigens released during natural disasters and through farming. Assorted geoepidemiological triggers were also identified including seasonality and latitude-dependent factors such as UV radiation. Finally, infection was tightly associated, but the exact microorganism(s) is not clear - Staphylococcus aureus is the most presently convincing.

CONCLUSION

The precise aetiology of AAV has yet to be elucidated. It is likely that different triggers, and the degree to which they influence disease activity, vary by subgroup (e.g. ANCA subtype, geographic region). There is a need for more interoperable disease registries to facilitate international collaboration and hence large-scale epidemiological studies, with novel analytical techniques.

Requisite Omega-3 HUFA Biomarker Thresholds for Preventing Murine Lupus Flaring

Lupus is a systemic autoimmune disease typified by uncontrolled inflammation, disruption of immune tolerance, and intermittent flaring - events triggerable by environmental factors. Preclinical and clinical studies reveal that consumption of the marine ω-3 highly unsaturated fatty acids (HUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) might be used as a precision nutrition intervention to lessen lupus symptoms. The anti-inflammatory and pro-resolving effects of ω-3 HUFAs are inextricably linked to their presence in membrane phospholipids. The ω-3 HUFA score, calculated as [100 × (ω-3 HUFAs/(ω-3 HUFAs + ω-6 HUFAs))] in red blood cells (RBCs), and the Omega-3 Index (O3I), calculated as [100 × ((DHA+EPA)/total fatty acids)] in RBCs, are two biomarkers potentially amenable to relating tissue HUFA balance to clinical outcomes in individuals with lupus. Using data from three prior preclinical DHA supplementation studies, we tested the hypothesis that the ω-3 HUFA score and the O3I inversely correlate with indicators of autoimmune pathogenesis in the cSiO2-triggered lupus flaring model. The three studies employed both low and high fat rodent diets, as well as more complex diets emulating the U.S. dietary pattern. The ω-3 HUFA scores in RBCs were comparatively more robust than the O3I at predicting HUFA balances in the kidney, liver, spleen, and lung. Importantly, increases in both the ω-3 HUFA score (>40%) and the O3I (>10%) were strongly associated with suppression of cSiO2-triggered (1) expression of interferon-regulated genes, proinflammatory cytokine production, leukocyte infiltration, and ectopic lymphoid structure development in the lung, (2) pulmonary and systemic autoantibody production, and (3) glomerulonephritis. Collectively, these findings identify achievable ω-3 HUFA scores and O3I thresholds that could be targeted in future human intervention studies querying how ω-3 HUFA consumption influences lupus and other autoimmune diseases.

Protocol and establishment of a Queensland renal biopsy registry in Australia

Background

Renal biopsy is often required to obtain information for diagnosis, management and prognosis of kidney disease that can be broadly classified into acute kidney injury (AKI) and chronic kidney disease (CKD). The most common conditions identified on renal biopsy are glomerulonephritis and tubulo-interstitial disorders. There is a paucity of information on management strategies and therapeutic outcomes in AKI and CKD patients. A renal biopsy registry will provide information on biopsy-proven kidney disorders to improve disease understanding and tracking, healthcare planning, patient care and outcomes.

Methods

A registry of patients, that includes biopsy-proven kidney disease, was established through the collaboration of nephrologists from Queensland Hospital and Health Services and pathologists from Pathology Queensland services. The registry is in keeping with directions of the Advancing Kidney Care 2026 Collaborative, established in September 2018 as a Queensland Health initiative. Phase 1 of the registry entailed retrospective acquisition of data from all adult native kidney biopsies performed in Queensland, Australia, from 2002 to 2018. Data were also linked with the existing CKD.QLD patient registry. From 2019 onwards, phase 2 of the registry involves prospective collection of all incident consenting patients referred to Queensland public hospitals and having a renal biopsy. Annual reports on patient outcomes will be generated and disseminated.

Discussion

Establishment of the Queensland Renal Biopsy Registry (QRBR) aims to provide a profile of patients with biopsy-proven kidney disease that will lead to better understanding of clinico-pathological association and facilitate future research. It is expected to improve patient care and outcomes.

ANCA vasculitis and IgA nephropathy linked to silica exposure

There is a recognized association between silica exposure and Antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV); however, no clear association between silica exposure and Immunoglobulin A (IgA) nephropathy. We describe the case of a 26-year-old male stonemason who presents with hilar lymphadenopathy, haematuria and acute kidney injury related to silica exposure, AAV and IgA nephropathy. He was asymptomatic on presentation; urinalysis revealed glomerular haematuria (&gt;1000 red blood cells/L) and proteinuria (protein-to-creatinine ratio 84 mg/mmol). ANCA anti-myeloperoxidase serology was strongly positive. Mediastinal lymph node biopsy revealed multiple necrotizing granulomas with silica inclusions, and renal biopsy demonstrated crescentic glomerulonephritis and mesangial IgA staining. The patient was treated with cyclophosphamide and high-dose prednisolone with subsequent improvement in renal function. To our knowledge, this is the first report of both ANCA vasculitis and IgA nephropathy in the setting of silica exposure. This case highlights the relevance of occupational exposures in renal disease, and the immune-stimulatory effect of silica.