Hyperzincemia with systemic inflammation: a heritable disorder of calprotectin metabolism with rheumatic manifestations?

Intestinal inflammation marker calprotectin regulates epithelial intestinal zinc metabolism and proliferation in mouse jejunal organoids

Calprotectin (CP), a heterodimer of S100A8 and S100A9, is expressed by neutrophils and a number of innate immune cells and is used widely as a marker of inflammation, particularly intestinal inflammation. CP is a ligand for toll-like receptor 4 (TLR4) and the receptor for advanced glycation end products (RAGE). In addition, CP can act as a microbial modulatory agent via a mechanism termed nutritional immunity, depending on metal binding, most notably Zn2+. The effects on the intestinal epithelium are largely unknown. In this study we aimed to characterize the effect of calprotectin on mouse jejunal organoids as a model epithelium, focusing on Zn2+ metabolism and cell proliferation. CP addition upregulated the expression of the Zn2+ absorptive transporter Slc39a4 and of methallothionein Mt1 in a Zn2+-sensitive manner, while downregulating the expression of the Zn2+ exporter Slc30a2 and of methallothionein 2 (Mt2). These effects were greatly attenuated with a CP variant lacking the metal binding capacity. Globally, these observations indicate adaptation to low Zn2+ levels. CP had antiproliferative effects and reduced the expression of proliferative and stemness genes in jejunal organoids, effects that were largely independent of Zn2+ chelation. In addition, CP induced apoptosis modestly and modulated antimicrobial gene expression. CP had no effect on epithelial differentiation. Overall, CP exerts modulatory effects in murine jejunal organoids that are in part related to Zn2+ sequestration and partially reproduced in vivo, supporting the validity of mouse jejunal organoids as a model for mouse epithelium.

Infection-associated decrease of serum creatine kinase levels in Fukuyama congenital muscular dystrophy

BACKGROUND

Marked decreases in serum creatine kinase levels have been noted in Duchenne and Becker muscular dystrophies as rare complications of autoimmune or autoinflammatory diseases.

SUBJECTS AND METHODS

The influence of systemic inflammation on serum creatine kinase levels was reviewed from the charts of three subjects with Fukuyama congenital muscular dystrophy.

RESULTS

A total of 30 infectious events were identified. Elevated serum C-reactive protein levels coincided with decreased creatine kinase levels on 19 occasions. In one subject, administration of 2 mg/kg/d prednisolone for bronchial asthma resulted in a decrease in creatine kinase level on six other occasions.

CONCLUSION

Apart from an increase in endogenous cortisol secretion, certain inflammation-related molecules could play a role in mitigating muscle cell damage in Fukuyama congenital muscular dystrophy during febrile infectious episodes. Corticosteroids may be a promising agent for the treatment of muscular symptoms in this disorder.

HSCT is effective in patients with PSTPIP1-associated myeloid-related proteinemia inflammatory (PAMI) syndrome

BACKGROUND

Proline-serine-threonine phosphatase-interacting protein 1-associated myeloid-related proteinemia inflammatory (PAMI) syndrome is a novel genetic disorder, causing hypercalprotectinemia and hyperzincemia with inflammatory complications accompanied by cytopenia. Immunosuppressive and/or anticytokine therapy is of limited effect.

OBJECTIVES

Because of cytokine production in nonhematopoietic tissues, the potential therapeutic effect of allogeneic hematopoietic stem cell transplantation (HSCT) in autoinflammatory disorders, including PAMI syndrome, has remained uncertain.

METHODS

Five patients with PAMI syndrome underwent allogeneic HSCT with myeloablative (4) or reduced-intensity (1) conditioning regimens. Lack of PAMI disease control served as indication for the HSCT in 4 patients and myelodysplastic syndrome development in 1.

RESULTS

All 5 patients engrafted; however, 1 patient at day +13 developed hemophagocytic syndrome, followed by graft rejection at day +17. After 5.5 months, a second HSCT was performed from an alternative donor. A further patient at day +116 developed an intense inflammatory syndrome with significant serositis and severe mitral and aortic valve regurgitation, controlled with adalimumab, tacrolimus, and prednisone. No other noninfectious inflammatory episodes, or acute or chronic graft-versus-host disease, occurred in any patient. At the last follow-up (median, 2.2 years), all 5 patients have predominantly or complete donor chimerism and adequate immune recovery and are free of any PAMI symptoms.

CONCLUSIONS

Allogeneic HSCT seems to be an effective option to cure cytopenia and severe autoinflammation in PAMI syndrome and may be a curative option for other proline-serine-threonine phosphatase-interacting protein 1-associated inflammatory disorders with poor therapeutic control.

PSTPIP1-associated myeloid-related proteinemia inflammatory syndrome: A rare cause of childhood neutropenia associated with systemic inflammation and hyperzincemia

Neutropenia in pediatric patients can be due to a variety of disorders. We describe two patients who underwent extensive evaluation over many years for arthralgias and moderate neutropenia of unclear etiology. Genetic testing identified a pathogenic variant in PSTPIP1 (proline-serine-threonine phosphatase-interacting protein 1) in both patients. Markedly elevated inflammatory markers and zinc levels confirmed the rare diagnosis of PSTPIP1-associated myeloid-related proteinemia inflammatory (PAMI) syndrome, tailoring treatment. Neutropenia is common in patients with PAMI syndrome. Unique mutations seen in PAMI syndrome may account for the specific phenotypic features of this disorder.

Whole genome microarray expression analysis in blood identifies pathways linked to signs and symptoms of a patient with hypercalprotectinaemia and hyperzincaemia

A child, 2 years with the 'hypercalprotectinaemia with hyperzincaemia' clinical syndrome, presented with atypical symptoms and signs, notably persistent fever of approximately 38°C, thrombocythaemia of > 700 × 10⁹ /l and a predominance of persistent intestinal symptoms. In an effort to find a cure by identifying the dysregulated pathways we analysed whole-genome mRNA expression by the Affymetrix HG U133 Plus 2·0 array in blood on three occasions 3-5 months apart. Major up-regulation was demonstrated for the Janus kinase/signal transducer and activators of transcription (JAK/STAT) pathway including, in particular, CD177, S100A8, S100A9 and S100A12, accounting for the thrombocytosis; a large number of interleukins, their receptors and activators, accounting for the febrile apathic state; and the high mobility group box 1 (HMBG1) gene, possibly accounting for part of the intestinal symptoms. These results show that gene expression array technology may assist the clinician in the diagnostic work-up of individual patients with suspected syndromal states of unknown origin, and the expression data can guide the selection of optimal treatment directed at the identified target pathways.

The predictive value of low plasma copper and high plasma zinc in detecting zinc-induced copper deficiency

BACKGROUND

Zinc-induced copper deficiency is a condition whose diagnosis is often delayed allowing severe and usually irreversible neurology symptoms to develop. Plasma copper concentrations are usually low and plasma zinc concentrations high. The aim of this study was to measure the predictive value of this combination of results as a means of facilitating its early diagnosis.

METHODS

Low plasma copper (≤6 µmol/L) and high plasma zinc results (>18 µmol/L) were retrieved from the laboratory database from 2000 to 2014. Medical records and laboratory notes of the corresponding 20 patients found were accessed to determine which were likely to have zinc-induced copper deficiency.

RESULTS

Fifteen (75%) patients were diagnosed with zinc-induced copper deficiency which was symptomatic in 13. Of the five remaining patients, two were treated with zinc because of Wilson's disease which was the cause of hypocupraemia, two were treated parenterally with zinc, and insufficient information was available in the final patient.

CONCLUSIONS

The combination of a low plasma copper and high plasma zinc is strongly predictive for the diagnosis of zinc-induced copper deficiency. There is the therefore an opportunity for the reporting biochemist to facilitate in its earlier diagnosis so enabling treatment to be implemented before the condition deteriorates.

Nutritional Immunity: S100 Proteins at the Host-Pathogen Interface

The S100 family of EF-hand calcium (Ca(2+))-binding proteins is essential for a wide range of cellular functions. During infection, certain S100 proteins act as damage-associated molecular patterns (DAMPs) and interact with pattern recognition receptors to modulate inflammatory responses. In addition, these inflammatory S100 proteins have potent antimicrobial properties and are essential components of the immune response to invading pathogens. In this review, we focus on S100 proteins that exhibit antimicrobial properties through the process of metal limitation, termed nutritional immunity, and discuss several recent advances in our understanding of S100 protein-mediated metal sequestration at the site of infection.

Metal limitation and toxicity at the interface between host and pathogen

Metals are required cofactors for numerous fundamental processes that are essential to both pathogen and host. They are coordinated in enzymes responsible for DNA replication and transcription, relief from oxidative stress, and cellular respiration. However, excess transition metals can be toxic due to their ability to cause spontaneous, redox cycling and disrupt normal metabolic processes. Vertebrates have evolved intricate mechanisms to limit the availability of some crucial metals while concurrently flooding sites of infection with antimicrobial concentrations of other metals. To compete for limited metal within the host while simultaneously preventing metal toxicity, pathogens have developed a series of metal regulatory, acquisition, and efflux systems. This review will cover the mechanisms by which pathogenic bacteria recognize and respond to host-induced metal scarcity and toxicity.

The role of calprotectin in pediatric disease

Calprotectin (CP) is a calcium- and zinc-binding protein of the S100 family expressed mainly by neutrophils with important extracellular activity. The aim of the current review is to summarize the latest findings concerning the role of CP in a diverse range of inflammatory and noninflammatory conditions among children. Increasing evidence suggests the implication of CP in the diagnosis, followup, assessment of relapses, and response to treatment in pediatric pathological conditions, such as inflammatory bowel disease, necrotizing enterocolitis, celiac disease, intestinal cystic fibrosis, acute appendicitis, juvenile idiopathic arthritis, Kawasaki disease, polymyositis-dermatomyositis, glomerulonephritis, IgA nephropathy, malaria, HIV infection, hyperzincemia and hypercalprotectinemia, and cancer. Further studies are required to provide insights into the actual role of CP in these pathological processes in pediatrics.

Nutritional immunity: transition metals at the pathogen-host interface

Transition metals occupy an essential niche in biological systems. Their electrostatic properties stabilize substrates or reaction intermediates in the active sites of enzymes, and their heightened reactivity is harnessed for catalysis. However, this heightened activity also renders transition metals toxic at high concentrations. Bacteria, like all living organisms, must regulate their intracellular levels of these elements to satisfy their physiological needs while avoiding harm. It is therefore not surprising that the host capitalizes on both the essentiality and toxicity of transition metals to defend against bacterial invaders. This Review discusses established and emerging paradigms in nutrient metal homeostasis at the pathogen-host interface.

Tissue zinc levels in a child with hypercalprotectinaemia and hyperzincaemia: A case report and a review of the literature

BACKGROUND

A girl suffering from a rare syndrome of unknown aetiology, termed hypercalprotectinaemia, was evaluated for tissue zinc status, because calprotectin is a protein which chelates Zn at multiple binding-sites, which might have affected the distribution of Zn in her body.

METHODS

Measurement of serum, urine, hair and nail zinc (Zn) concentration, complemented with measurement of total Zn in ultrafiltrates of plasma.

RESULTS

Her serum Zn concentration was 105-133 μmol/L. Zn levels in her hair (102 μg/g), nail (90 μg/g) and urine (3-12 μmol/L; 20-80 μg/dL) were all at the lower end of the reference intervals described in the sparse literature. Zn concentrations in ultrafiltrates of plasma were below the detection limit (<100 nmol/L). Thus, the elevated serum Zn did not translate into a similarly increased level of Zn in any of the tissues tested, nor in free Zn concentrations. Instead it appeared to be a result of Zn being chelated to binder proteins, most probably calprotectin.

CONCLUSION

Her grossly elevated serum calprotectin concentration is probably able to raise circulating total Zn concentrations without raising ionized concentrations, but this Zn remains confined to the circulating blood as well as to excreted body fluids, particularly faeces.

Chronic exposure to arsenite induces S100A8 and S100A9 expression in rat RBL-2H3 mast cells

To investigate the effects of chronic exposure to arsenite on the gene expression profiles of mast cells, microarray analysis was performed on rat basophilic leukemia RBL-2H3 cells exposed to arsenite for 28 days. Upregulated genes include calcium-binding S100 proteins such as S100A9, S100A10, S100A6, and S100A13, and granzymes B and C. Among S100 proteins, S100A9 showed the highest expression (8.62-fold of untreated cells) after 4-weeks of exposure to arsenite. As S100A8 and S100A9 comprise a heterodimer called calprotectin, and are implicated in the development of atherosclerosis and cancer, mRNA levels of both S100A8 and S100A9 were analyzed. The results demonstrated that exposure of RBL-2H3 cells to arsenite for a few weeks induces marked increases in mRNA levels of S100A8 and S100A9.

S100A8 and S100A9 inhibit neutrophil oxidative metabolism in-vitro: involvement of adenosine metabolites

Neutrophils are short-lived granulocytic cells of the innate immune system specialized in the production of reactive oxygen species. S100A8 and S100A9 and their heterocomplex calprotectin play a role in neutrophil recruitment and represent 40% of neutrophil cytosolic protein weight. The present study was designed to test the effect of S100A8 and S100A9 on the rate of neutrophil oxidative metabolism. It is hypothesized that the two S100 proteins inhibit neutrophil associated oxidation. Granulocytes freshly isolated from healthy volunteers were tested for their ability to oxidize dichlorofluorescindiacetate (DCFH-DA) in-vitro. The data showed that S100A8 and S100A9 inhibited spontaneous and stimulated oxidation of the DCFH-DA probe by neutrophils. The inhibition of neutrophil oxidative metabolism by S100A8 and S100A9 was markedly reduced by the enzymatic activity of adenosine deaminase. Inhibitors of the P1 adenosine receptors also reduced the anti-oxidative effect of S100A8/A9 providing further support for the involvement of adenosine metabolites in S100A8/ A9 anti-oxidative effect.

Effect of human immunodeficiency virus infection on S100A8/A9 inhibition of peripheral neutrophils oxidative metabolism

Neutrophils are endowed with a highly active oxidative metabolism that is crucial for their antimicrobial functions but can produce oxidative conditions disruptive to the host. Opportunistic infections associated with HIV disease and ex vivo studies of neutrophils from HIV patients suggest that neutrophil dysfunctions significantly contribute to HIV disease. The calcium-binding proteins S100A8 and S100A9 are abundant cytosolic constituents of human neutrophils. Our previous work has shown that S100A8 and S100A9 inhibit neutrophil oxidative metabolism. In this study, we tested the hypothesis that neutrophils from HIV infected subjects respond differently to S100A8 and S100A9 when compared to neutrophils isolated from control HIV naive subjects. Neutrophils, freshly isolated from whole blood, were tested in a 96-well plate assay for their ability to oxidize the DCFH-DA probe. The neutrophils from HIV+ and HIV- subjects were stimulated with LPS and inhibited with recombinant S100A8 and S100A9. Our data indicate that when compared to neutrophils isolated from HIV- subjects, neutrophils from HIV+ subjects display an exaggerated response to LPS and a diminished response to S100A8 and S100A9 inhibition. Our data support our hypothesis and signify that, in HIV disease, dysregulated neutrophil responses to endotoxins stimulation and S100A8/A9 inhibition may contribute to a higher risk for oxidative stress associated ailments. The mechanism for the observed differences in neutrophil response and their biological significance in the course of HIV disease should be addressed in further studies.

The essential toxin: impact of zinc on human health

Compared to several other metal ions with similar chemical properties, zinc is relatively harmless. Only exposure to high doses has toxic effects, making acute zinc intoxication a rare event. In addition to acute intoxication, long-term, high-dose zinc supplementation interferes with the uptake of copper. Hence, many of its toxic effects are in fact due to copper deficiency. While systemic homeostasis and efficient regulatory mechanisms on the cellular level generally prevent the uptake of cytotoxic doses of exogenous zinc, endogenous zinc plays a significant role in cytotoxic events in single cells. Here, zinc influences apoptosis by acting on several molecular regulators of programmed cell death, including caspases and proteins from the Bcl and Bax families. One organ where zinc is prominently involved in cell death is the brain, and cytotoxicity in consequence of ischemia or trauma involves the accumulation of free zinc. Rather than being a toxic metal ion, zinc is an essential trace element. Whereas intoxication by excessive exposure is rare, zinc deficiency is widespread and has a detrimental impact on growth, neuronal development, and immunity, and in severe cases its consequences are lethal. Zinc deficiency caused by malnutrition and foods with low bioavailability, aging, certain diseases, or deregulated homeostasis is a far more common risk to human health than intoxication.

Increase in plasma calprotectin during long‐distance running

Running leads to biochemical and hematological changes consistent with an inflammatory reaction to tissue injury. We report changes in the plasma concentration of the leukocyte-derived protein calprotectin after long-distance running. Blood samples were collected from runners before and after a marathon, half-marathon, a 30-km cross-country run, a military ranger-training course and short-term maximal physical exercise until exhaustion, VO2max. Leukocyte counts, plasma calprotectin concentration and calprotectin per neutrophilic granulocyte were assayed using a new method. During the marathon, half-marathon, the 30-km run, the ranger-training course and the VO2max exercise, calprotectin levels increased 96.3-fold, 13.3-fold, 20.1-fold, 7.5-fold and 3.4-fold, respectively. These changes may reflect damage to the tissues or vascular endothelium, causing microthrombi with subsequent activation of neutrophils. These cells are known to phagocytose platelets in microthrombi and may contribute to the prevention of clinical thrombosis. The half-life of calprotectin in plasma was about 5 h. The content of calprotectin per neutrophil remained unchanged during exercise at a level similar to that in healthy blood donors: mean: 25 pg/cell, range 18.8-33.6. A reference interval (mean +/- 2 SD) of 18.6-31.4 pg/cell is suggested.

Hazards associated with pregnancies and deliveries in lysinuric protein intolerance

Lysinuric protein intolerance (LPI) is an autosomal recessive transport disorder of the dibasic amino acids. The defect leads to deficiency of lysine, arginine, and ornithine and, secondarily, to a functional disorder of the urea cycle. Transient postprandial hyperammonemia and subsequent persistent protein aversion, linked with several other biochemical and clinical characteristics of the disease, suggest an increased risk for maternal and fetal complications during pregnancy and delivery. Our unique material on the outcomes of 18 pregnancies of 9 Finnish mothers with LPI and the follow-up of their 19 children shows that maternal LPI is truly associated with increased risk of anemia, toxemia, and intrauterine growth retardation during pregnancy and bleeding complications during delivery. Successful pregnancies and deliveries can still be achieved with careful follow-up of blood pressure and laboratory values. The children of the mothers with LPI generally develop normally. Special care of maternal protein nutrition and control of ammonemia, anemia, and toxemia during pregnancy are essential. We propose centralization of deliveries to obstetric units with capability to deal with bleeding complications and rare inborn errors of metabolism.

Hyperzincaemia and hypercalprotectinaemia: a new disorder of zinc metabolism

BACKGROUND

Calprotectin (complex of S100A8 and S100A9) is the major calcium and zinc-binding protein of phagocytes. We report a new syndrome with recurrent infections, inflammation, and hyperzincaemia associated with excessively high plasma concentrations of calprotectin.

METHODS

We measured calprotectin in plasma and protein fractions by ELISA assay and zinc by atomic absorption spectrometry. Plasma proteins were fractionated by size exclusion chromatography and electrophoresis. Mass spectra of purified proteins were determined by MALDI-TOFMS.

FINDINGS

We assessed five patients, two of whom are related. All patients had much the same biochemical findings of hyperzincaemia (77-200 micromol/L, reference range 11-18 micromol/L) and raised plasma calprotectin concentrations (1.4-6.5 g/L, reference range <1 mg/L). All patients presented with recurrent infections, hepatosplenomegaly, anaemia, and evidence of systemic inflammation. Three patients had cutaneous inflammation and three presented in infancy with severe growth failure. Size exclusion chromatography showed that zinc and calprotectin were associated in a broad fraction with molecular weight range 100-300 kDa. Analysis by electrophoresis and mass spectrometry showed that the patients' protein contained normal S100A8 and S100A9 subunits.

INTERPRETATION

Dysregulation of zinc metabolism associated with accumulation in plasma of S100A8 and S100A9 defines a new disease, which encompasses a pathological role for dysregulation of two members of the large S100 protein family.