Detection of anti-lactoferrin antibodies and anti-myeloperoxidase antibodies in autoimmune hepatitis: a retrospective study

Some Immune Parameters of Term Newborns at Birth Are Associated with the Concentration of Iron, Copper and Magnesium in Maternal Serum

The nutritional status of pregnant women is considered to affect fetal development and the health condition of newborns, including their immune system. We investigated the relationship between the concentrations of magnesium (Mg), calcium (Ca), zinc (Zn), iron (Fe) and copper (Cu) in maternal serum (MS) and the concentrations of IgG antibodies and antineutrophil cytoplasmatic auto-antibodies against lactoferrin (Lf-ANCA) in umbilical cord serum (UCS). IgG was considered as a promoter of immunity, and Lf-ANCA as an inhibitor. The examined group consisted of 98 pregnant women and their healthy term newborn children. The concentrations of mineral elements were measured by FAAS/FAES, while the concentrations of antibodies were determined by ELISA. Excessive MS Fe and insufficient MS Cu were related to insufficient UCS IgG and excessive UCS Lf-ANCA. The correlation analysis showed confirming results. Adequate UCS IgG and Lf-ANCA were related to MS Mg at the strictly lower limit of the reference values. The results obtained seem to suggest that an excess of Fe and a deficiency of Cu in pregnancy may adversely affect some immune parameters of newborns. Reference values for MS Mg are likely to require reconsideration. It would be advisable to monitor the nutritional status of pregnant women with minerals in order to support the immune capacity of newborns.

Molecular mimicry of the receptor-binding domain of the SARS-CoV-2 spike protein: from the interaction of spike-specific antibodies with transferrin and lactoferrin to the antiviral effects of human recombinant lactoferrin

The pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection involves dysregulations of iron metabolism, and although the mechanism of this pathology is not yet fully understood, correction of iron metabolism pathways seems a promising pharmacological target. The previously observed effect of inhibiting SARS-CoV-2 infection by ferristatin II, an inducer of transferrin receptor 1 (TfR1) degradation, prompted the study of competition between Spike protein and TfR1 ligands, especially lactoferrin (Lf) and transferrin (Tf). We hypothesized molecular mimicry of Spike protein as cross-reactivity of Spike-specific antibodies with Tf and Lf. Thus, strong positive correlations (R² > 0.95) were found between the level of Spike-specific IgG antibodies present in serum samples of COVID-19-recovered and Sputnik V-vaccinated individuals and their Tf-binding activity assayed with peroxidase-labeled anti-Tf. In addition, we observed cross-reactivity of Lf-specific murine monoclonal antibody (mAb) towards the SARS-CoV-2 Spike protein. On the other hand, the interaction of mAbs produced to the receptor-binding domain (RBD) of the Spike protein with recombinant RBD protein was disrupted by Tf, Lf, soluble TfR1, anti-TfR1 aptamer, as well as by peptides RGD and GHAIYPRH. Furthermore, direct interaction of RBD protein with Lf, but not Tf, was observed, with affinity of binding estimated by K_D to be 23 nM and 16 nM for apo-Lf and holo-Lf, respectively. Treatment of Vero E6 cells with apo-Lf and holo-Lf (1–4 mg/mL) significantly inhibited SARS-CoV-2 replication of both Wuhan and Delta lineages. Protective effects of Lf on different arms of SARS-CoV-2-induced pathogenesis and possible consequences of cross-reactivity of Spike-specific antibodies are discussed.

Seronegative autoimmune hepatitis in children : A real diagnostic challenge

BACKGROUND AND AIM

Classical autoimmune hepatitis (AIH) is characterized by the presence of conventional autoantibodies (anti-smooth muscle, antinuclear and anti-liver-kidney-microsomal antibodies). The absence of such autoantibodies in some patients does not preclude AIH diagnosis or the need for its treatment. This group of patients was termed seronegative AIH. Whether non-conventional autoantibodies can identify this group of patients is still elusive. We aimed to study the prevalence of seronegativity of conventional autoantibodies and the occurrence of non-conventional autoantibodies in children with AIH.

METHODS

In this study, 55 children with AIH were investigated for non-conventional autoantibodies (anti-neutrophil cytoplasmic antibodies, antibodies to soluble liver antigen, anti-tissue transglutaminase and antiplatelet antibodies). All the patients received immunosuppressive therapy and were assessed for treatment response.

RESULTS

Of the patients 44 had classical AIH (type 1, 70.09%, type 2, 9.09%) and 20% were seronegative. The four studied non-conventional autoantibodies occurred in four patients, one for each. All non-conventional autoantibodies were exclusively associated with type 1 AIH. The clinical profile, ultrasonographic findings, liver biochemistry and histopathological findings were comparable in the classical and seronegative AIH. The majority of patients with classical (72.7%) and seronegative (54.5%) AIH were treatment responders.

CONCLUSION

Seronegative AIH represents a substantial percentage of pediatric patients diagnosed with AIH. They were even negative for non-conventional autoantibodies. Furthermore, apart from autoantibodies, seronegative AIH is almost indistinguishable from the classical AIH and the majority of patients were treatment responders. This favorable response to immunosuppression deserves sustainable efforts for considering such a diagnosis and start therapy to halt disease progression is worthwhile.

Netting Neutrophils Activate Autoreactive B Cells in Lupus

Lupus erythematosus (LE) patients develop autoantibodies that form circulating immune complexes (ICs) with extracellular self-nucleic acids. These ICs are deposited into peripheral tissues, where they trigger detrimental organ inflammation. Recent evidence suggests that ICs contain LL37-DNA complexes derived from neutrophil extracellular traps (NETs) and that LE patients develop pathogenic autoantibodies against these structures, including Abs to LL37. However, the mechanism that leads to the generation of these Abs is unknown. In this study, we show that NETs directly trigger Ab production by human memory B cells. This occurs via LL37-DNA complexes present in NETs, which have the unique ability to gain access to endosomal compartments of B cells and to trigger TLR9 activation. In LE patients, NET-derived LL37-DNA complexes trigger polyclonal B cell activation via TLR9, but also specifically expand self-reactive memory B cells producing anti-LL37 Abs in an Ag-dependent manner. These findings suggest a unique link between neutrophils and B cells in which NETs trigger a concerted activation of TLR9 and BCR leading to anti-NET autoantibody production in lupus.

Latest advances in diagnosis of autoimmune liver disease

Autoimmune liver disease (AILD) includes autoimmune hepatitis, primary biliary cholangitis, primary sclerosing cholangitis, and overlap syndromes. AILD is the main inducing factor for late chronic liver failure, and in Western countries it is also one of the major liver diseases for which orthotopic liver transplantation is performed. In recent years, with the increasing incidence of AILD in both China and other countries, clinicians have paid more and more attention to AILD. Further standardization of diagnostic criteria for AILD has become a new hot research topic, and experts and scholars have put forward some corresponding opinions. This article describes the latest advances in the diagnosis of AILD.