Hyperzincemia and hypercalprotectinemia: unsuccessful treatment with tacrolimus

Roles of S100A8, S100A9 and S100A12 in infection, inflammation and immunity

S100 proteins are small proteins that are only expressed in vertebrates. They are widely expressed in many different cell types and are involved in the regulation of calcium homeostasis, glucose metabolism, cell proliferation, apoptosis, inflammation and tumorigenesis. As members of the S100 protein subfamily of myeloid-related proteins, S100A8, S100A9 and S100A12 play a crucial role in resisting microbial infection and maintaining immune homeostasis. These proteins chelate the necessary metal nutrients of pathogens invading the host by means of 'nutritional immunity' and directly inhibit the growth of pathogens in the host. They interact with receptors on the cell surface to initiate inflammatory signal transduction, induce cytokine expression and participate in the inflammatory response and immune regulation. Furthermore, the increased content of these proteins during the pathological process makes them useful as disease markers for screening and detecting related diseases. This article summarizes the structure and function of the proteins S100A8, S100A9 and S100A12 and lays the foundation for further understanding their roles in infection, immunity and inflammation, as well as their potential applications in the prevention and treatment of infectious diseases.

PSTPIP1-Associated Myeloid-Related Proteinemia Inflammatory (PAMI) Syndrome: A Systematic Review

PSTPIP1 (proline-serine-threonine phosphatase-interactive protein 1)-associated myeloid-related proteinemia inflammatory (PAMI) syndrome, previously known as Hyperzincemia/Hypercalprotectinemia (Hz/Hc) syndrome, is a recently described, rare auto-inflammatory disorder caused by specific deleterious variants in the PSTPIP1 gene (p.E250K and p.E257K). The disease is characterized by chronic systemic inflammation, cutaneous and osteoarticular manifestations, hepatosplenomegaly, anemia, and neutropenia. Increased blood levels of MRP 8/14 and zinc distinguish this condition from other PSTPIP1-associated inflammatory diseases (PAID). The aim of this systematic review is to provide a comprehensive overview of the disease phenotype, course, treatment, and outcome based on reported cases. This systematic review adheres to the PRISMA guidelines (2020) for reporting. A literature search was performed in Embase, Medline, and Web of Science on 13 October 2022. The quality of the case reports and case series was assessed using the JBI checklists. Out of the 43 included patients with PAMI syndrome, there were 24 females and 19 males. The median age at onset was 3.9 years. The main clinical manifestations included anemia (100%), neutropenia (98%), cutaneous manifestations (74%), osteoarticular manifestations (72%), splenomegaly (70%), growth failure (57%), fever (51%), hepatomegaly (56%), and lymphadenopathy (39%). Systemic inflammation was described in all patients. Marked elevation of zinc and MRP 8/14 blood levels were observed in all tested patients. Response to treatment varied and no consistently effective therapy was identified. The most common therapeutic options were corticosteroids (N = 30), anakinra (N = 13), cyclosporine A (N = 11), canakinumab (N = 6), and anti-TNF (N = 14). Hematopoietic stem cell transplantation has been recently reported to be successful in five patients. Our review highlights the key characteristics of PAMI syndrome and the importance of considering this disease in the differential diagnosis of patients presenting with early-onset systemic inflammation and cytopenia.

PSTPIP1-associated myeloid-related proteinaemia inflammatory (PAMI) syndrome; a case presenting as a perinatal event with early central nervous system involvement?

BACKGROUND

We report a three-year-old girl with a potentially unique phenotype of perinatal onset and neurovascular features who was found to have PAMI syndrome. We also compare her case to those previously reported and review the differences between the PSTPIP1-associated inflammatory diseases (PAID) phenotypes and genotypes.

CASE PRESENTATION

The patient was found to have a heterozygous pathogenic variant in PSTPIP1 (c.748G > A p.E250K). This variant was shown to be absent in both parents and therefore de novo in the patient. A literature review was carried out through multiple databases using the terms PSTPIP1, PAID, PAPA syndrome and PAMI syndrome. This information was collected and used to form comparisons between the current literature and our reported case.

CONCLUSIONS

Our case contributes to the literature on PAMI syndrome whilst providing an example of a potentially unique clinical phenotype, giving insight into the pre-symptomatic phase of the condition. We highlight the importance of considering PAMI syndrome in the differential for early onset unexplained inflammation. In addition, we explore the possibility that perinatal neurovascular events could be an early feature of PAMI syndrome.

Rare cases of PAMI syndrome in both father and son with the same missense mutation in PSTPIP1 gene and literature review

PSTPIP1-associated myeloid-related proteinaemia inflammatory (PAMI) syndrome has been described as a rare and distinct clinical phenotype of PSTPIP1-associated inflammatory diseases. We report PSTPIP1 mutation in both father and son who have leukopenia and acne-like lesions. Through whole-exome sequencing on blood DNA, it is found a heterozygous mutation of PSTPIP1 gene c.748G>A on the father and son. The diagnosis of PAMI is made based on DNA sequencing results and clinical characteristics of typical lesions, leukopenia, and the markedly increased serum S100A8/A9 (calprotectin).

Extensive pyoderma gangrenosum-like lesions revealing a case of hyperzincemia and hypercalprotectinemia: when to suspect it?

Hyperzincemia and hypercalprotectinemia is a rare inflammatory disease caused by a mutation in the PSTPIP1 gene, with a dysregulation of calprotectin metabolism. Calprotectin is a zinc-binding protein with antimicrobial properties and pro-inflammatory action. The authors report the case of a 20 year-old girl with cutaneous ulcers comparable with pyoderma gangrenosum, growth failure and chronic anemia, who was given the diagnosis of hyperzincemia and hypercalprotectinemia. Measurement of serum zinc and calprotectin concentrations are indicated in these cases.

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.

S100 Proteins As an Important Regulator of Macrophage Inflammation

The S100 proteins, a family of calcium-binding cytosolic proteins, have a broad range of intracellular and extracellular functions through regulating calcium balance, cell apoptosis, migration, proliferation, differentiation, energy metabolism, and inflammation. The intracellular functions of S100 proteins involve interaction with intracellular receptors, membrane protein recruitment/transportation, transcriptional regulation and integrating with enzymes or nucleic acids, and DNA repair. The S100 proteins could also be released from the cytoplasm, induced by tissue/cell damage and cellular stress. The extracellular S100 proteins, serving as a danger signal, are crucial in regulating immune homeostasis, post-traumatic injury, and inflammation. Extracellular S100 proteins are also considered biomarkers for some specific diseases. In this review, we will discuss the multi-functional roles of S100 proteins, especially their potential roles associated with cell migration, differentiation, tissue repair, and inflammation.

S100 Proteins As an Important Regulator of Macrophage Inflammation

The S100 proteins, a family of calcium-binding cytosolic proteins, have a broad range of intracellular and extracellular functions through regulating calcium balance, cell apoptosis, migration, proliferation, differentiation, energy metabolism, and inflammation. The intracellular functions of S100 proteins involve interaction with intracellular receptors, membrane protein recruitment/transportation, transcriptional regulation and integrating with enzymes or nucleic acids, and DNA repair. The S100 proteins could also be released from the cytoplasm, induced by tissue/cell damage and cellular stress. The extracellular S100 proteins, serving as a danger signal, are crucial in regulating immune homeostasis, post-traumatic injury, and inflammation. Extracellular S100 proteins are also considered biomarkers for some specific diseases. In this review, we will discuss the multi-functional roles of S100 proteins, especially their potential roles associated with cell migration, differentiation, tissue repair, and inflammation.

Single amino acid charge switch defines clinically distinct proline-serine-threonine phosphatase-interacting protein 1 (PSTPIP1)-associated inflammatory diseases

BACKGROUND

Hyperzincemia and hypercalprotectinemia (Hz/Hc) is a distinct autoinflammatory entity involving extremely high serum concentrations of the proinflammatory alarmin myeloid-related protein (MRP) 8/14 (S100A8/S100A9 and calprotectin).

OBJECTIVE

We sought to characterize the genetic cause and clinical spectrum of Hz/Hc.

METHODS

Proline-serine-threonine phosphatase-interacting protein 1 (PSTPIP1) gene sequencing was performed in 14 patients with Hz/Hc, and their clinical phenotype was compared with that of 11 patients with pyogenic arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome. PSTPIP1-pyrin interactions were analyzed by means of immunoprecipitation and Western blotting. A structural model of the PSTPIP1 dimer was generated. Cytokine profiles were analyzed by using the multiplex immunoassay, and MRP8/14 serum concentrations were analyzed by using an ELISA.

RESULTS

Thirteen patients were heterozygous for a missense mutation in the PSTPIP1 gene, resulting in a p.E250K mutation, and 1 carried a mutation resulting in p.E257K. Both mutations substantially alter the electrostatic potential of the PSTPIP1 dimer model in a region critical for protein-protein interaction. Patients with Hz/Hc have extremely high MRP8/14 concentrations (2045 ± 1300 μg/mL) compared with those with PAPA syndrome (116 ± 74 μg/mL) and have a distinct clinical phenotype. A specific cytokine profile is associated with Hz/Hc. Hz/Hc mutations altered protein binding of PSTPIP1, increasing interaction with pyrin through phosphorylation of PSTPIP1.

CONCLUSION

Mutations resulting in charge reversal in the y-domain of PSTPIP1 (E→K) and increased interaction with pyrin cause a distinct autoinflammatory disorder defined by clinical and biochemical features not found in patients with PAPA syndrome, indicating a unique genotype-phenotype correlation for mutations in the PSTPIP1 gene. This is the first inborn autoinflammatory syndrome in which inflammation is driven by uncontrolled release of members of the alarmin family.

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.

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.

The endogenous Toll-like receptor 4 agonist S100A8/S100A9 (calprotectin) as innate amplifier of infection, autoimmunity, and cancer

The innate immune system is crucial for initiation and amplification of inflammatory responses. During this process, phagocytes are activated by PAMPs that are recognized by PRRs. Phagocytes are also activated by endogenous danger signals called alarmins or DAMPs via partly specific, partly common PRRs. Two members of the S100 protein family, S100A8 and S100A9, have been identified recently as important endogenous DAMPs. The complex of S100A8 and S100A9 (also called calprotectin) is actively secreted during the stress response of phagocytes. The association of inflammation and S100A8/S100A9 was discovered more than 20 years ago, but only now are the molecular mechanisms involved in danger signaling by extracellular S100A8/S100A9 beginning to emerge. Taking advantage of mice lacking the functional S100A8/S100A9 complex, these molecules have been identified as endogenous activators of TLR4 and have been shown to promote lethal, endotoxin-induced shock. Importantly, S100A8/S100A9 is not only involved in promoting the inflammatory response in infections but was also identified as a potent amplifier of inflammation in autoimmunity as well as in cancer development and tumor spread. This proinflammatory action of S100A8/S100A9 involves autocrine and paracrine mechanisms in phagocytes, endothelium, and other cells. As a net result, extravasation of leukocytes into inflamed tissues and their subsequent activation are increased. Thus, S100A8/S100A9 plays a pivotal role during amplification of inflammation and represents a promising new therapeutic target.