Amino acid sequences of 60B8 antigens induced in HL-60 cells by 1,25-dihydroxyvitamin D3. The antigens are identical with macrophage-related protein-14 and -8

Post-translational modifications on the metal-sequestering protein calprotectin

Human calprotectin (CP, S100A8/S100A9 oligomer) is an abundant neutrophil protein that contributes to innate immunity by sequestering nutrient metal ions in the extracellular space. This process starves invading microbial pathogens of essential metal nutrients, which can inhibit growth and colonization. Over the past decade, fundamental and clinical studies have revealed that the S100A8 and S100A9 subunits of CP exhibit a variety of post-translational modifications (PTMs). This review summarizes PTMs on the CP subunits that have been detected and highlights two recent studies that evaluated the structural and functional consequences of methionine and cysteine oxidation on CP. Collectively, these investigations indicate that the molecular speciation of extracellular CP is complex and composed of multiple proteoforms. Moreover, PTMs may impact biological function and the lifetime of the protein. It is therefore important that post-translationally modified CP species receive consideration and integration into the current working model for how CP functions in nutritional immunity.

Multifarious diagnostic possibilities of the S100 protein family: predominantly in pediatrics and neonatology

BACKGROUND

Numerous articles related to S100 proteins have been recently published. This review aims to introduce this large protein family and its importance in the diagnostics of many pathological conditions in children and adults.

DATA SOURCES

Based on original publications found in database systems, we summarize the current knowledge about the S100 protein group and highlight the most important proteins with focus on pediatric use.

RESULTS

The S100 family is composed of Ca²⁺ and Zn²⁺ binding proteins, which are present only in vertebrates. Some of these proteins can be used as diagnostic markers in cardiology (S100A1, S100A12), oncology (S100A2, S100A5, S100A6, S100A14, S100A16, S100P, S100B), neurology (S100B), rheumatology (S100A8/A9, S100A4, S100A6, and S100A12), nephrology and infections (S100A8, S100A9, S100A8/A9, S100A12). The most useful S100 proteins in pediatrics are S100A8, S100A9, heterodimers S100A8/A9, S100B and S100A12.

CONCLUSIONS

The S100 family members are promising biomarkers and provide numerous possibilities for implementation into clinical practice to optimize the differential diagnostic process.

Seroprevalence of Helicobacter pylori infection in patients with connective tissue diseases

To assess the possibility that Helicobacter pylori might be an etiologic agent, titers of anti-H. pylori IgG in sera of patients with connective tissue diseases [rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), polymyositis or dermatomyositis (PM/DM), progressive systemic sclerosis (PSS), mixed connective tissue disease (MCTD) and Sjögren's syndrome (SjS)] were compared with those of non-patient (healthy) volunteers and of patients with chronic pulmonary diseases (CPD) by ELISA using an extract of sonicated H. pylori as the antigen. Among patients with connective tissue diseases, those with SLE and RA had anti-H. pylori titers as low as healthy volunteers. Patients with SjS had much higher average titers than patients with CPD (P < 0.05). We previously reported that levels of myeloid calcium-binding protein (MRP8 and MRP14) were elevated in the serum of patients with connective tissue diseases. No correlation was found between serum levels of anti-H. pylori IgG and of MRP, a novel marker of inflammation. Furthermore, sera with high IgG titers were selected, and their reactivity with the H. pylori antigen were analyzed by Western blotting. H. pylori antigens with a variety of molecular masses were immunostained with sera from patients and from healthy volunteers, but a 16-kDa antigen was only immunostained by reaction with the sera of patients with MCTD and SjS, although the number of test samples was small.

Calprotectin-mediated zinc chelation as a biostatic mechanism in host defence

The S-100 Ca2+ binding protein, calprotectin, isolated from neutrophil lysates, has been reported to exhibit zinc reversible biostatic activity in vitro. We verified these findings with C. albicans and investigated whether the growth inhibition resulted from zinc deprivation due to chelation by calprotectin. Calprotectin concentrations of 250 micrograms/ml significantly inhibited the growth of C. albicans. This was reversed by supplementing culture medium with 10 microM ZnSO4. Incubation of calprotectin in culture medium for 24 h prior to inoculation significantly reduced the minimum inhibitory concentration. When this latter medium was ultrafiltered to remove the calprotectin and then inoculated with C. albicans, significant growth inhibition was still present: again it was reversed by zinc. These findings implicate zinc chelation as a novel, potentially important host defence function of an abundant neutrophil protein.

Calprotectin (the L1 protein) during surgery in patients with rheumatoid arthritis

Calprotectin (L1) is a major leukocyte protein which is released during activation or death of neutrophil granulocytes and monocytes. Previous studies have shown that L1 may be a useful marker of disease activity in patients with adult or juvenile rheumatoid arthritis (RA). In the present study, the plasma concentrations of L1 were analysed during shoulder-joint surgery in 16 patients with adult or juvenile RA. Decreased L1 concentrations were found 48 h postoperatively. Thereafter, the L1 concentrations were increased at 72 h, with a following decrease until day 14 postoperatively. In contrast, increased serum concentrations of both C-reactive protein (CRP) and orosomucoid (i.e. alpha 1-acid glycoprotein) were found at 48 h after surgery. Plasma samples obtained before and after surgery were analysed by gel filtration. Approximately 3/4 of the plasma L1 was found in fractions corresponding to the native molecule, while the rest was detected in higher molecular mass fractions. The distribution of L1 antigen in low and high molecular mass regions did not differ between the pre- and postoperative plasma samples. The L1 protein consists of light and heavy chains. Increased serum levels of the cystic fibrosis antigen, which is identical to L1 light chain, have been described in patients with cystic fibrosis. The existence of circulating free L1 chains was presently investigated in plasma obtained before and after surgery. After gel filtration of plasma samples, no free L1 chains were detected by use of enzyme immunoassay and dot blot.