Anti-neutrophil cytoplasmic antibodies (ANCA): Antigen interactions and downstream effects

Effects and Action Mechanism of Huoxue Tongluo Formula on the Formation of Neutrophil Extracellular Traps

Excessive infiltration and uncontrolled activation of neutrophil extracellular traps (NETs) are likely to destroy normal tissue architecture and cause uncontrolled inflammation. The present research attempted to screen potential signaling pathways of Huoxue Tongluo Formula (HXTLF) affecting the formation of NETs using network pharmacology technique. Active chemical components of HXTLF and therapeutic targets related to vasculitis were screened, and a chemical components-targets network diagram of HXTLF was constructed by Cytoscape. Finally, the inhibitory effect and mechanism of HXTLF on the formation of NETs were explored in vitro using LPS-induced NETs. Immunofluorescence and Western blot were conducted to determine the protein fluorescence intensity and relative expression. The experimental results illustrated that HXTLF mediated the expression levels of H3Cit and myeloperoxidase (MPO) protein in neutrophils activated by LPS, inhibited NETs formation, and reduced the concentration of interleukin- (IL-) 1β, a proinflammatory factor in cells. Additionally, we activated and inhibited the AKT1 signaling pathway using the corresponding activator and inhibitor to explore the regulatory mechanism of HXTLF on AKT1 and other molecules in the treatment of vasculitis. The results demonstrated that HXTLF could inhibit the phosphorylation of AKT1, IKK, and NF-κB proteins, inhibit NETs formation, and reduce IL-1β concentration, indicating that AKT1 exerts a vital role in the treatment of vasculitis after HXTLF administration. The current study initially revealed the pharmacological mechanism of HXTLF for vasculitis management using network pharmacology techniques and tests in vitro, which is expected to provide important theoretical basis for elucidating the molecular mechanism of HXTLF and promoting its clinical application.

Antinuclear antibodies (ANAs) detected by indirect immunofluorescence (IIF) method in acute COVID-19 infection; future roadmap for laboratory diagnosis

INTRODUCTION

As in other viral infections, anti-nuclear antibodies (ANAs) are observed in SARS-CoV-2 infection. We investigated the presence of autoantibodies in acute COVID-19 and the association with early laboratory findings.

MATERIALS AND METHODS

We examined 50 sera (>18 years, 25 Female) from patients with acute COVID-19. ANAs (HEp-20-10 liver biochip), anti-neutrophil cytoplasmic antibody (ANCA, Europlus Granulocyte Mosaic 32) and anti-double stranded DNA were investigated with product of Euroimmune AG (Luebeck, Germany) by indirect immunofluorescence (IIF) method. Also, antibody against cyclic citrullinated peptide (anti-CCP) was examined by a chemiluminisens assay (Euroimmun AG, Luebeck, Germany). Samples from 50 blood bank donors collected before the COVID-19 pandemic were used as controls.

RESULTS

The IIF-ANA test was positive in 18% (N = 9/50) of the patients. The median time of sample collection was 7 days (range: 1-28 days) after diagnosis. ANA was positive in only one (2%) control sample. Five (55.5%) patients were ANA positive with a strong titer (3+). There was no relationship between antibody titration and time of sample collection (p = 0,55). Anti-CCP was detected in a nucleolar (3+) positive patient (2%). ANA was detected in 14.28% (N = 1/7, rods-rings (±), p = 0,78) of patients in the intensive care unit(ICU). Patients treated in the clinic have more and higher titers of ANA, mostly in nucleolar patterns, than ICU patients.

CONCLUSIONS

The variety of antibodies detected in acute COVID-19 and the uncertainty of how long they persist can lead to confusion, especially in the diagnosis of systemic autoimmune rheumatic diseases for IIF-ANA testing in immunology laboratories. Improvements in cell lines and methods will facilitate the diagnostic process.

COVID-19 and Immunological Dysregulation: Can Autoantibodies be Useful?

Coronavirus disease 2019 (COVID-19) is often associated with interstitial pneumonia. However, there is insufficient knowledge on the presence of autoimmune serological markers in patients with COVID-19. We analyzed the presence and role of autoantibodies in patients with COVID-19-associated pneumonia. We prospectively studied 33 consecutive patients with COVID-19, 31 (94%) of whom had interstitial pneumonia, and 25 age-matched and sex-matched patients with fever and/or pneumonia with etiologies other than COVID-19 as the pathological control group. All patients were tested for the presence of antinuclear antibodies (ANAs), anti-antiphospholipid antibodies, and anti-cytoplasmic neutrophil antibodies (ANCAs). Clinical, biochemical, and radiological parameters were also collected. Fifteen of 33 patients (45%) tested positive for at least one autoantibody, including 11 who tested positive for ANAs (33%), 8 who tested positive for anti-cardiolipin antibodies (immunoglobulin (Ig)G and/or IgM; 24%), and 3 who tested positive for anti-β2-glycoprotein antibodies (IgG and/or IgM; 9%). ANCA reactivity was not detected in any patient. Patients that tested positive for auto-antibodies had a significantly more severe prognosis than other patients did: 6 of 15 patients (40%) with auto-antibodies died due to COVID-19 complications during hospitalization, whereas only 1 of 18 patients (5.5%) who did not have auto-antibodies died (P = 0.03). Patients with poor prognosis (death due to COVID-19 complications) had a significantly higher respiratory rate at admission (23 breaths per minute vs. 17 breaths per minute; P = 0.03) and a higher frequency of auto-antibodies (86% vs. 27%; P = 0.008). In conclusion, auto-antibodies are frequently detected in patients with COVID-19 possibly reflecting a pathogenetic role of immune dysregulation. However, given the small number of patients, the association of auto-antibodies with an unfavorable prognosis requires further multicenter studies.

Autoantibodies Against Lysosome Associated Membrane Protein-2 (LAMP-2) in Pediatric Chronic Primary Systemic Vasculitis

Background

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a small vessel vasculitis in adults and children that commonly affects the kidneys. Although the frequent antigenic, and presumed pathogenic, targets of ANCA in AAV are proteinase-3 (PR3) and myeloperoxidase (MPO), ANCA against lysosome associated membrane protein-2 (LAMP-2), a lesser known ANCA antigen that is expressed on the glomerular endothelium, are present in some adults with AAV-associated renal disease. LAMP-2-ANCA has not been assessed in children with chronic systemic vasculitis, and, if present, would be a potentially valuable biomarker given that treatment decisions for these pediatric patients at diagnosis are largely informed by kidney function.

Methods

A custom ELISA, using commercially available reagents, was designed to detect autoantibodies to human LAMP-2 in serum. Sera obtained from 51 pediatric patients at the time of diagnosis of chronic primary systemic vasculitis (predominantly AAV) were screened. LAMP-2-ANCA titers were evaluated for correlation with clinical metrics of disease activity (pediatric vasculitis activity score [pVAS], C-reactive protein [CRP] concentration, and erythrocyte sedimentation rate [ESR]), MPO- and PR3-ANCA titers, and renal function (glomerular filtration rate [GFR], renal-specific pVAS, and serum creatinine concentration).

Results

LAMP-2-ANCA (>1,000 ng/ml) were detected in 35% (n = 18) of pediatric systemic vasculitis patients, of which, 10 (20% of all patients) were found to have high positive titers (>1,500 ng/ml). Undetectable or negative titres (<500 ng/ml) were identified in 12% (n = 6) of patients, those with titers between 500 and 1,000 ng/ml were considered low with unknown clinical relevance (53%, n = 27). Although LAMP-2-ANCA titers did not significantly differ between patients with AAV versus ANCA-negative vasculitis, only AAV patients had high concentrations (>1,500 ng/ml) of LAMP-2-ANCA. LAMP-2-ANCA titers did not correlate with measures of disease activity (pVAS, CRP, or ESR) at the time of diagnosis. In contrast, for patients with 12-month post diagnosis follow-up, a negative correlation was observed between the change in GFR (from diagnosis to 12-month follow-up) and LAMP-2-ANCA titer at diagnosis.

Conclusions

Moderate to high LAMP-2-ANCA titers were detected in 35% (18/51) of children with chronic systemic vasculitis affecting small-to-medium vessels. Although the highest concentrations of LAMP-2-ANCA in this population were observed in individuals positive for classic ANCA (MPO- or PR3-ANCA), similar to previous reports on adult patients, LAMP-2-ANCA titers do not correlate with classic ANCA titers or with overall disease activity at diagnosis. Renal disease is a common manifestation in systemic small-medium vessel vasculitis (both in adults and children, though more severe in children) and our preliminary data suggest LAMP-2-ANCA at diagnosis may be a risk factor for more severe renal disease.