Prolidase deficiency and systemic lupus erythematosus

Multiorgan Failure and Sepsis in an ICU Patient with Prolidase Enzyme Deficiency-The Specificity of Treatment and Care: A Case Report

Background and Objectives: Prolidase deficiency (PD) is a rare, life-threatening, genetically determined disease with an incidence of 1-2 cases per 1 million births. The disease inhibits collagen synthesis, which leads to organ and systems failure, including hepato- and splenomegaly, immune disorders, chronic ulcerative wounds, respiratory infections, and pulmonary fibrosis. The complexity of the problems associated with this disease necessitates a comprehensive approach and the involvement of an interdisciplinary team. The objective was to present the treatment and care plan, as well as complications of PD, in a young woman following admission to an intensive care unit (ICU). Materials and Methods: A retrospective observational single-case study. Results: A 26-year-old woman with PD was hospitalized in the ICU for acute respiratory failure. The presence of difficult-to-heal extensive leg ulcers and the patient's immunocompromised condition resulted in the development of sepsis with multiple organ failure (respiratory and circulatory, liver and kidney failure). Complex specialized treatment consisting of wound preparation, limb amputation, the minimization of neuropathic pain, mechanical ventilation, renal replacement therapy, circulatory stabilization, and the prevention of complications of the disease and of therapy were applied. On the 83rd day of hospitalization, the patient expired. Conclusions: Despite the use of complex treatment and care, due to the advanced nature of the disease and the lack of therapies with proven efficacy, treatment was unsuccessful. There is a need for evidence-based research to develop effective treatment guidelines for PD.

Polygenic autoimmune disease risk alleles impacting B cell tolerance act in concert across shared molecular networks in mouse and in humans

Most B cells produced in the bone marrow have some level of autoreactivity. Despite efforts of central tolerance to eliminate these cells, many escape to periphery, where in healthy individuals, they are rendered functionally non-responsive to restimulation through their antigen receptor via a process termed anergy. Broad repertoire autoreactivity may reflect the chances of generating autoreactivity by stochastic use of germline immunoglobulin gene segments or active mechanisms may select autoreactive cells during egress to the naïve peripheral B cell pool. Likewise, it is unclear why in some individuals autoreactive B cell clones become activated and drive pathophysiologic changes in autoimmune diseases. Both of these remain central questions in the study of the immune system(s). In most individuals, autoimmune diseases arise from complex interplay of genetic risk factors and environmental influences. Advances in genome sequencing and increased statistical power from large autoimmune disease cohorts has led to identification of more than 200 autoimmune disease risk loci. It has been observed that autoantibodies are detectable in the serum years to decades prior to the diagnosis of autoimmune disease. Thus, current models hold that genetic defects in the pathways that control autoreactive B cell tolerance set genetic liability thresholds across multiple autoimmune diseases. Despite the fact these seminal concepts were developed in animal (especially murine) models of autoimmune disease, some perceive a disconnect between human risk alleles and those identified in murine models of autoimmune disease. Here, we synthesize the current state of the art in our understanding of human risk alleles in two prototypical autoimmune diseases - systemic lupus erythematosus (SLE) and type 1 diabetes (T1D) along with spontaneous murine disease models. We compare these risk networks to those reported in murine models of these diseases, focusing on pathways relevant to anergy and central tolerance. We highlight some differences between murine and human environmental and genetic factors that may impact autoimmune disease development and expression and may, in turn, explain some of this discrepancy. Finally, we show that there is substantial overlap between the molecular networks that define these disease states across species. Our synthesis and analysis of the current state of the field are consistent with the idea that the same molecular networks are perturbed in murine and human autoimmune disease. Based on these analyses, we anticipate that murine autoimmune disease models will continue to yield novel insights into how best to diagnose, prognose, prevent and treat human autoimmune diseases.

Prolidase deficiency, a rare inborn error of immunity, clinical phenotypes, immunological features, and proposed treatments in twins

Background

Prolidase deficiency (PD) is an autosomal recessive inborn multisystemic disease caused by mutations in the PEPD gene encoding the enzyme prolidase D, leading to defects in turnover of proline-containing proteins, such as collagen. PD is categorized as a metabolic disease, but also as an inborn error of immunity. PD presents with a range of findings including dysmorphic features, intellectual disabilities, recurrent infections, intractable skin ulceration, autoimmunity, and splenomegaly. Despite symptoms of immune dysregulation, only very limited immunologic assessments have been reported and standard therapies for PD have not been described. We report twin females with PD, including comprehensive immunologic profiles and treatment modalities used.

Case presentation

Patient 1 had recurrent infections in childhood. At age 13, she presented with telangiectasia, followed by painful, refractory skin ulcerations on her lower limbs, where skin biopsy excluded vasculitis. She had typical dysmorphic features of PD. Next-generation sequencing revealed pathogenic compound heterozygous mutations (premature stop codons) in the PEPD gene. Patient 2 had the same mutations, typical PD facial features, atopy, and telangiectasias, but no skin ulceration. Both patients had imidodipeptiduria. Lymphocyte subset analysis revealed low-normal frequency of T_reg cells and decreased frequency of expression of the checkpoint molecule CTLA-4 in CD4⁺ T_EM cells. Analysis of Th1, Th2, and Th17 profiles revealed increased inflammatory IL-17⁺ CD8⁺ T_EM cells in both patients and overexpression of the activation marker HLA-DR on CD4⁺ T_EM cells, reflecting a highly activated proinflammatory state. Neither PD patient had specific antibody deficiencies despite low CD4⁺CXCR5⁺ T_fh cells and low class-switched memory B cells. Plasma IL-18 levels were exceptionally high.

Conclusions

Immunologic abnormalities including skewed frequencies of activated inflammatory CD4⁺ and CD8⁺ T_EM cells, decreased CTLA-4 expression, and defects in memory B cells may be a feature of immune dysregulation associated with PD; however, a larger sample size is required to validate these findings. The high IL-18 plasma levels suggest underlying autoinflammatory processes.

Obstinate leg ulceration secondary to prolidase deficiency, treated with 5% topical proline

Prolidase deficiency is a rare cause of chronic ulceration with less than 100 reported cases in the literature. This article highlights to clinicians the features of this uncommon genodermatosis, the challenge of diagnosis, and treatment options.

Genetic screening of early-onset patients with systemic lupus erythematosus by a targeted next-generation sequencing gene panel

OBJECTIVE

In this study, we aimed to screen 31 genes (C1QA, C1QB, C1QC, C1R, C1S, C2, C3, TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR, DNASE1, DNASE1L3, PRKCD, ACP5, SLC7A7, IFIH1, TMEM173, ISG15, CYBB, FAS, FASLG, KRAS, NRAS, MAN2B1, PEPD, PTPN11, RAG2, and SHOC2), that we have categorized under the umbrella term "monogenic lupus" using a targeted next-generation sequencing (NGS) panel in 24 individuals with early-onset (≤10 years of age) systemic lupus erythematosus (SLE) and in 24 patients with late-onset (>10 years of age) disease.

METHODS

A total of 48 SLE patients (24 with disease onset ≤10 years of age and 24 with disease onset >10 years of age) were included. Patients with late-onset disease have been used as patient controls. Sequencing was carried out using 400 bp kit on the Ion S5 system.

RESULTS

Among the 48 patients, three had one pathogenic variant and 45 patients had at least one rare variant classified as benign, likely benign or variant of unknown significance (VUS). In all three patients with a pathogenic variant, the onset of disease was before 10 years of age. Two patients (they were siblings) carried C1QA homozygote pathogenic allele (p.Gln208Ter, rs121909581), and one patient carried PEPD heterozygote pathogenic allele (p.Arg184Gln, rs121917722).

CONCLUSION

We demonstrated a pathogenic variant in our target gene panel with a frequency of 9.52% in patients with a disease onset ≤10 years of age. All patients with early-onset SLE phenotype, irrespective of a positive family history for SLE or parental consanguinity, should be scanned for a single-gene defect by a targeted gene panel sequencing. With the discovery of many single-gene defects and ongoing efforts to identify novel genes in SLE, similar gene panels including even more genes will possibly become more necessary and practical in the future.

Prolidase deficiency in an infant with an incidental finding of methaemoglobinaemia

A 4-week-old boy presented to the hospital with symptoms of diarrhoea and vomiting initially thought to be due to cow's milk allergy. He was discharged with extensively hydrolysed formula. The patient represented with worsening of symptoms with metabolic acidosis and was screened and treated for sepsis. However, his condition deteriorated further and he developed methaemoglobinaemia. He was transferred to the high dependency unit and was given two doses of methylene blue. Further investigations were carried out, including rapid trio exome sequencing, which identified a homozygous pathogenic Peptidase D (PEPD) variant (c.978G>A, p.(Trp326*)). This was consistent with a diagnosis of prolidase deficiency.

Osteoarticular Manifestations of Prolidase Deficiency and Disability: Case Reports of Two Moroccan Sisters

Prolidase deficiency (PD) is a rare autosomal recessive disorder that has symptoms such as chronic skin ulcers, dysmorphic facies, cognitive retardation, hematological anomalies, splenomegaly, and chronic infections. Bone and joint abnormalities were referred occasionally and included the signs and symptoms of prolidase deficiency, but were not deeply investigated in PD patients. We report a case of two PD Moroccan sisters with osteoarticular deformities, some of them were never described before: toes deformities and equinovalgus with fusion and dislocation of a tarsal bone in radiography x-rays.

Quantitative analysis of the natural history of prolidase deficiency: description of 17 families and systematic review of published cases

PURPOSE

Prolidase deficiency is a rare inborn error of metabolism causing ulcers and other skin disorders, splenomegaly, developmental delay, and recurrent infections. Most of the literature is constituted of isolated case reports. We aim to provide a quantitative description of the natural history of the condition by describing 19 affected individuals and reviewing the literature.

METHODS

Nineteen patients were phenotyped per local institutional procedures. A systematic review following PRISMA criteria identified 132 articles describing 161 patients. Main outcome analyses were performed for manifestation frequency, diagnostic delay, overall survival, symptom-free survival, and ulcer-free survival.

RESULTS

Our cohort presented a wide variability of severity. Autoimmune disorders were found in 6/19, including Crohn disease, systemic lupus erythematosus, and arthritis. Another immune finding was hemophagocytic lymphohistiocytosis (HLH). Half of published patients were symptomatic by age 4 and had a delayed diagnosis (mean delay 11.6 years). Ulcers were present initially in only 30% of cases, with a median age of onset at 12 years old.

CONCLUSION

Prolidase deficiency has a broad range of manifestations. Symptoms at onset may be nonspecific, likely contributing to the diagnostic delay. Testing for this disorder should be considered in any child with unexplained autoimmunity, lower extremity ulcers, splenomegaly, or HLH.

Prolidase - A protein with many faces

Prolidase is a metal-dependent peptidase specialized in the cleavage of dipeptides containing proline or hydroxyproline on their C-termini. Prolidase homologues are found in all kingdoms of life. The importance of prolidase in human health is underlined by a rare hereditary syndrome referred to as Prolidase Deficiency. A growing number of studies highlight the importance of prolidase in various other human conditions, including cancer. Some recent studies link prolidase's activity-independent regulatory role to tumorigenesis. Furthermore, the enzyme or engineered variants have some applications in biotechnology. In this short review, we aim to highlight different aspects of the protein the importance of which is increasingly recognized over the last years.

Systemic lupus erythematosus in a girl with PTEN variant and transaldolase deficiency: a novel phenotype

Genetic defect of phosphatase and tensin homolog (PTEN) gene might play a role in B cell hyperactivity and result in the development of systemic lupus erythematosus (SLE), while transaldolase deficiency has a spectrum of clinical features including autoimmune endocrinopathy. Herein, we identified a novel phenotype in a girl presenting with clinical and laboratory findings consistent with SLE. Exome sequencing identified pathogenic heterozygous variant in PTEN gene (NM_000314: exon 6: c.518G > C: p. R173P) and homozygous variant in TALDO1 gene (NM_006755: exon 6: c.793C del: p. Q265f). Our report highlights the association of PTEN mutation and autoimmunity and the possibility that transaldolase deficiency may be indirectly involved in the development of SLE.

Prolidase deficiency in two dermatological patients in western Sicily

Prolidase deficiency is a rare disorder inherited through an autosomal recessive gene. The hallmark of the disorder are iminodipeptiduria, chronic skin ulcers, recurring infections, mental retardation and characteristic facial appearance, although prolidase deficiency can occur with no clinical manifestation. The primary biological function of the enzyme involves the metabolism of collagen degradation products and the recycling of proline for collagen resynthesis. We describe two patients with prolidase deficiency and review the different clinical manifestations suggesting the pathogenetic mechanism through few hypotheses.

Flow Cytometry Contributions for the Diagnosis and Immunopathological Characterization of Primary Immunodeficiency Diseases With Immune Dysregulation

Almost 70 years after establishing the concept of primary immunodeficiency disorders (PIDs), more than 320 monogenic inborn errors of immunity have been identified thanks to the remarkable contribution of high-throughput genetic screening in the last decade. Approximately 40 of these PIDs present with autoimmune or auto-inflammatory symptoms as the primary clinical manifestation instead of infections. These PIDs are now recognized as diseases of immune dysregulation. Loss-of function mutations in genes such as FOXP3, CD25, LRBA, IL-10, IL10RA, and IL10RB, as well as heterozygous gain-of-function mutations in JAK1 and STAT3 have been reported as causative of these disorders. Identifying these syndromes has considerably contributed to expanding our knowledge on the mechanisms of immune regulation and tolerance. Although whole exome and whole genome sequencing have been extremely useful in identifying novel causative genes underlying new phenotypes, these approaches are time-consuming and expensive. Patients with monogenic syndromes associated with autoimmunity require faster diagnostic tools to delineate therapeutic strategies and avoid organ damage. Since these PIDs present with severe life-threatening phenotypes, the need for a precise diagnosis in order to initiate appropriate patient management is necessary. More traditional approaches such as flow cytometry are therefore a valid option. Here, we review the application of flow cytometry and discuss the relevance of this powerful technique in diagnosing patients with PIDs presenting with immune dysregulation. In addition, flow cytometry represents a fast, robust, and sensitive approach that efficiently uncovers new immunopathological mechanisms underlying monogenic PIDs.

Serum prolidase activity in systemic sclerosis

Systemic sclerosis, also known as scleroderma, is a complex systemic inflammatory autoimmune disease that targets the vasculature and connective tissue-producing cells and components of the innate and adaptive immune systems. The disease is characterized by a hardening of the skin and an increased synthesis of collagen . Prolidase is a specific imidodipeptidase involved in collagen degradation. The aim of this study was to search the serum prolidase activity (SPA) in the two subtypes of systemic sclerosis: diffuse and limited cutaneous systemic sclerosis. For this purpose, 35 patients diagnosed with systemic sclerosis (24 diffuse and 11 limited) and 41 healthy control subjects were included in the study. SPA was determined using Myara's method, which is a modification of Chinard's method. SPA did not differ between the scleroderma patients and controls (p = 0.467). However, SPA was significantly lower in diffuse form than in both limited form and control subjects (p = 0.021 and p = 0.024, respectively). SPA also did not differ between the limited form and control subjects (p = 0.145). Scleroderma is characterized by excessive deposition of collagen and tissue fibrosis due to the reduced collagen degradation. SPA is reduced in scleroderma patients, especially in diffuse form. Circulating autoantibodies, oxidative stress, and decreased physical activity may contribute to this process.

Prolidase Deficiency in a Mexican-American Patient Identified by Array CGH Reveals a Novel and the Largest PEPD Gene Deletion

Prolidase deficiency (PD) is a rare genetic disorder caused by mutations in the peptidase D (PEPD) gene, affecting collagen degradation. Features include lower extremity ulcers, facial dysmorphism, frequent respiratory infections, and intellectual disability, though there is significant intra- and interfamilial variability. Twenty-eight mutations have been previously reported, all either small deletions/duplications or point mutations discovered by enzyme or DNA assays. PD has been reported in patients of various ethnic backgrounds, but never in the Mexican-American population. We describe the first Mexican-American patient with PD, who presented with typical facial features, developmental delay, microcephaly, and xerosis. Chromosome microarray analysis (CMA) revealed a homozygous deletion in the region of 19q13.11, estimated to be between 124.79 and 195.72 kb in size, representing the largest PEPD gene deletion reported to date and the first discovered by CMA.

A Rare Cause of Lower Extremity Ulcers: Prolidase Deficiency

Prolidase deficiency is an autosomal recessive disorder, which is associated with chronic skin ulcers, a characteristic facial appearance, mental retardation, and recurrent infections. This study describes 4 patients with recurrent leg ulcerations and abnormal facies who were first clinically suspected of prolidase deficiency and then biochemically confirmed. Two siblings and 2 other patients were admitted to our clinic at different times, and they had some common features such as chronic leg and foot ulcers recalcitrant to treatment, consanguineous parents, facial dysmorphism, mental retardation, and widespread telangiectasias. Physical examination and detection of low prolidase level in blood finally led us to the diagnose of ulcers secondary to prolidase deficiency. Prolidase deficiency is a rare genodermatosis and must be considered in the differential diagnosis of recurrent leg and foot ulcers that develop at an early age.

Lack of prolidase causes a bone phenotype both in human and in mouse

The degradation of the main fibrillar collagens, collagens I and II, is a crucial process for skeletal development. The most abundant dipeptides generated from the catabolism of collagens contain proline and hydroxyproline. In humans, prolidase is the only enzyme able to hydrolyze dipeptides containing these amino acids at their C-terminal end, thus being a key player in collagen synthesis and turnover. Mutations in the prolidase gene cause prolidase deficiency (PD), a rare recessive disorder. Here we describe 12 PD patients, 9 of whom were molecularly characterized in this study. Following a retrospective analysis of all of them a skeletal phenotype associated with short stature, hypertelorism, nose abnormalities, microcephaly, osteopenia and genu valgum, independent of both the type of mutation and the presence of the mutant protein was identified. In order to understand the molecular basis of the bone phenotype associated with PD, we analyzed a recently identified mouse model for the disease, the dark-like (dal) mutant. The dal/dal mice showed a short snout, they were smaller than controls, their femurs were significantly shorter and pQCT and μCT analyses of long bones revealed compromised bone properties at the cortical and at the trabecular level in both male and female animals. The differences were more pronounce at 1 month being the most parameters normalized by 2 months of age. A delay in the formation of the second ossification center was evident at postnatal day 10. Our work reveals that reduced bone growth was due to impaired chondrocyte proliferation and increased apoptosis rate in the proliferative zone associated with reduced hyperthrophic zone height. These data suggest that lack of prolidase, a cytosolic enzyme involved in the final stage of protein catabolism, is required for normal skeletogenesis especially at early age when the requirement for collagen synthesis and degradation is the highest.

A case of prolidase deficiency accompanying leg ulcers

Prolidase deficiency (PD) is a rare autosomal recessive disorder that has symptoms such as skin ulcers, characteristic facies, mental retardation, skeletal deformities, hematological anomalies, splenomegaly, and chronic infections. Deficiency of prolidase leads to the increased excretion of proline in urine, which causes impaired collagen synthesis and delay in wound healing. This case reports a 40-year-old female who has had cutaneous ulcers since the age of 7 years. We also recognized borderline intellectual functioning as well as hematologic abnormalities and splenomegaly. We present this rare case to draw attention to consider prolidase deficiency in the differential diagnosis of leg ulcers.

Systemic Prolidase Activity and Oxidative Stress in Keratoconus

AIM

Our aim was to evaluate the serum prolidase activity, total antioxidant capacity (TAC) and total oxidant status (TOS) in patients with keratoconus.

MATERIAL AND METHOD

A total 69 keratoconus patients and 72 control subjects with similar age and gender were evaluated within the scope of this study. The keratoconus group was divided into four stages with the modified Krumeich classification. Serum prolidase activity, TAC and TOS were measured and compared between the patient and control groups.

RESULTS

The median serum prolidase enzyme activity value was 528.3 (684.1-416.7) U/L in the keratoconus group and 606.2 (812.9-482.3) U/L in the control group. The difference between the groups was statistically significant (p = 0.027). The median TAC value was 1.24 (1.37-1.05) mmol/L in the keratoconus group and 1.29 (1.38-1.18) mmol/L in the control group. The median TOS value was 2 (4-1) μmol/L in the keratoconus group and 3 (4-2) μmol/L in the control group. There was no statistically significant difference between the two groups in terms of TAC or TOS (p = 0.113 and p = 0.366, respectively). There was a positive correlation between TAC and TOS in keratoconus group but not in the control group (r = 0.670, p = 0.001 and r = 0.141, p = 0.241, respectively). No significant relationship was seen between the keratoconus group stages and serum prolidase activity, TAS or TOS (p = 0.894, p = 0.155 and p = 0.381, respectively).

CONCLUSION

In conclusion, a significant relationship was found between decreased serum prolidase activity and keratoconus but there was no significant relationship between keratoconus and serum TAC or TOS.

Paediatric-onset systemic lupus erythematosus

Paediatric-onset systemic lupus erythematosus (SLE) is usually more severe than its adult counterpart. In particular, there is a higher incidence of renal and central nervous system involvement. Specific measures to assess disease activity and damage have been implemented. The disease is very rare before the fifth birthday and therefore the onset of an SLE picture in the first years of life should lead to the suspicion of the presence of one of the rare monogenic diseases that causes SLE or of one of those congenital diseases that has been showed to be closely associated with the SLE.

Prolidase deficiency breaks tolerance to lupus-associated antigens

AIM

Prolidase deficiency is a rare autosomal recessive disease in which one of the last steps of collagen metabolism, cleavage of proline-containing dipeptides, is impaired. Only about 93 patients have been reported with about 10% also having systemic lupus erythematosus (SLE).

METHODS

We studied a large extended Amish pedigree with four prolidase deficiency patients and three heterozygous individuals for lupus-associated autoimmunity. Eight unaffected Amish children served as normal controls. Prolidase genetics and enzyme activity were confirmed. Antinuclear antibodies (ANA) were determined using indirect immunofluorescence and antibodies against extractable nuclear antigens were determined by various methods, including double immunodiffusion, immunoprecipitation and multiplex bead assay. Serum C1q levels were determined by enzyme-linked immunosorbent assay.

RESULTS

Two of the four homozygous prolidase deficiency subjects had a positive ANA. One had anti-double-stranded DNA, while another had precipitating anti-Ro. By the simultaneous microbead assay, three of the four had anti-Sm and anti-chromatin. One of the three heterozygous subjects had a positive ANA and immunoprecipitation of a 75 000 molecular weight protein. The unaffected controls had normal prolidase activity and were negative for autoantibodies.

CONCLUSIONS

Prolidase deficiency may be associated with the loss of immune tolerance to lupus-associated autoantigens even without clinical SLE.

Serum prolidase activity in psoriasis patients

This study aimed to evaluate serum prolidase activity and the effects of gender, body mass index (BMI), disease severity and duration, and therapy type on prolidase activity in patients with psoriatic as well as the relationship between serum NO· and prolidase levels in these patients. The study included 29 clinically documented plaque patients with psoriasis and 24 healthy volunteers. Data such as age, sex, BMI, duration and severity of disease, and type of therapy were assessed. NO· levels were determined by the Griess reaction. Serum prolidase assay is based on a colorimetric determination of proline by Chinard's reagent. We did not determine any difference in serum NO· levels of psoriatic patients when compared to controls. Serum prolidase levels in psoriasis patients were significantly higher than those in controls. There was no significant difference in prolidase activity between male and female. No statistically significant correlations were found between serum prolidase levels and BMI, PASI and disease duration. When compared between topical treatment group and systemic treatment group, there was no significant difference in serum prolidase activity. In conclusion, patients with psoriasis exhibit higher serum prolidase activity independent of gender, BMI, disease severity or duration, type of treatments or NO· level. However, further studies are needed to verify these findings as well as altered collagen synthesis in patients with psoriasis.

Prolidase deficiency associated with systemic lupus erythematosus (SLE): single site experience and literature review

INTRODUCTION

Prolidase deficiency (PD) is a rare autosomal recessive disorder which may have a wide spectrum of clinical features. These features include a characteristic facies, cognitive impairment, rashes or skin ulceration, splenomegaly, recurrent infections involving mainly the respiratory system, and iminodipeptiduria. The disorder is caused by a mutation in the PEPD gene.

OBJECTIVE

To describe a cohort of unrelated PD patients from Northern Israel whose inborn error of metabolism was associated with systemic lupus erythematosus (SLE) and to identify in the medical literature all PD cases mimicked by and/or associated with SLE.

METHODS

Three patients with PD associated with SLE were clinically, biochemically and genetically investigated. These patients were from 3 unrelated consanguineous families residing in Northern Israel. A computer-assisted (PubMed) search of the medical literature from 1975 to 2011 was performed using the following key words: Prolidase deficiency, SLE, and systemic lupus erythematosus.

RESULTS

An association between PD and SLE was found in 10 PD patients. These 10 patients included three from our cohort of 23 PD patients, and seven out of just under 70 PD patients previously reported in the literature.

CONCLUSION

The present findings underscore the relatively high incidence of the association between SLE and PD, suggesting that this association may not be coincidental. The phenotypic similarities between SLE and PD might suggest that the PEPD gene constitutes a modifier gene or a genetic risk factor in the causation of SLE.

Dilatation of the ascending aorta is associated with low serum prolidase activity

The pathogenesis of ascending aortic aneurysm (AAA) involves many factors; elastin degradation could lead to initial dilation, and changes in the collagen structure predispose the aneurysm to rupture. Prolidase is an enzyme that catalyzes the final step of collagen breakdown by liberating free proline for collagen recycling. The enzyme activity may be a step-limiting factor in the regulation of collagen biosynthesis. Consequently, in this study we sought to determine serum prolidase activity in AAAs. Eighty consecutive patients with the diagnosis of hypertension or chest pain, referred for echocardiographic examination in the outpatient cardiology clinic, were included in the study. The subjects were grouped into three categories according to the aortic diameter; control group without aortic dilatation (<or= 3.7 cm, n = 20), medium (3.8-4.3 cm, n = 36), and large (>or= 4.4 cm, n = 24) group. We assessed the association of serum prolidase activity with the presence and severity of AAAs, clinical characteristics and laboratory parameters. Serum prolidase activity was significantly higher in the patients without aortic dilatation (1386.3 +/- 320.5 U/L) compared to medium group (1212.0 +/- 282.5 U/L) and large group (1072.2 +/- 192.3 U/L): control group vs. medium group (P = 0.023) and control group vs. large group (P < 0.001). Ascending aortic diameter was inversely correlated with serum prolidase activity and in multivariate analysis, serum prolidase activity was the only independent predictor of aortic dilatation (beta = -0.44, P = 0.006). In conclusion, the presence of AAAs is associated with low serum prolidase activity.

Prolidase deficiency: it looks like systemic lupus erythematosus but it is not

Three siblings with recalcitrant leg ulceration, splenomegaly, photosensitive rash, and autoantibodies were suspected of having prolidase deficiency. Urine was checked for iminodipeptiduria, fibroblasts were cultured and analyzed for prolidase activity, and DNA was extracted for identifying the causative mutation. Glycyl proline was found as the dominant dipeptide in the urine. The activity of proline dipeptidase in fibroblasts was 2.5% of control fibroblasts. Sequence analysis of the PEPD gene revealed a homozygous nonsense C-->G transition at nucleotide 768. In conclusion, prolidase deficiency was diagnosed in siblings with skin ulceration autoantibodies and a lupus-like disease. A novel nonsense mutation was found, associated with the severe outcome of our patients.

A broad spectrum of developmental delay in a large cohort of prolidase deficiency patients demonstrates marked interfamilial and intrafamilial phenotypic variability

Prolidase deficiency (PD) is a rare, pan-ethnic, autosomal recessive disease with a broad phenotypic spectrum. Seventeen causative mutations in the PEPD gene have been reported worldwide. The purpose of this study is to characterize, clinically and molecularly, 20 prolidase deficient patients of Arab Moslem and Druze origin from 10 kindreds residing in northern Israel. All PD patients manifested developmental delay and facial dysmorphism. Typical PD dermatological symptoms, splenomegaly, and recurrent respiratory infections presented in varying degrees. Two patients had systemic lupus erythematosus (SLE), and one a novel cystic fibrosis phenotype. Direct DNA sequencing revealed two novel missense mutations, A212P and L368R. In addition, a previously reported S202F mutation was detected in 17 patients from seven Druze and three Arab Moslem kindreds. Patients homozygous for the S202F mutation manifest considerable interfamilial and intrafamilial phenotypic variability. The high prevalence of this mutation among Arab Moslems and Druze residing in northern Israel, and the presence of an identical haplotype along 500,000 bp in patients and their parents, suggests a founder event tracing back to before the breakaway of the Druze from mainstream Moslem society.

Biotechnological applications of recombinant microbial prolidases

Prolidase is a metallopeptidase that is ubiquitous in nature and has been isolated from mammals, bacteria and archaea. Prolidase specifically hydrolyzes dipeptides with a prolyl residue in the carboxy terminus (NH(2)-X-/-Pro-COOH). Currently, the only solved structure of prolidase is from the hyperthermophilic archaeon Pyrococcus furiosus. This enzyme is of particular interest because it can be used in many biotechnological applications. Prolidase is able to degrade toxic organophosphorus (OP) compounds, namely, by cleaving the P-F and P-O bonds in the nerve agents, sarin and soman. Applications using prolidase to detoxify OP nerve agents include its incorporation into fire-fighting foams and as biosensors for OP compound detection. Prolidases are also employed in the cheese-ripening process to improve cheese taste and texture. In humans, prolidase deficiency (PD) is a rare autosomal recessive disorder that affects the connective tissue. Symptoms of PD include skin lesions, mental retardation and recurrent respiratory infections. Enzyme replacement therapies are currently being studied in an effort to optimize enzyme delivery and stability for this application. Previously, prolidase has been linked to collagen metabolism and more recently is being associated with melanoma. Increased prolidase activity in melanoma cell lines has lead investigators to create cancer prodrugs targeting this enzyme. Thus, there are many biotechnological applications using recombinant and native forms of prolidase and this review will describe the biochemical and structural properties of prolidases as well as discuss their most current applications.

The association of serum prolidase activity with the presence and severity of coronary artery disease

OBJECTIVES

Prolidase is a cytosolic exopeptidase that cleaves iminodipeptides with carboxy-terminal proline or hydroxyproline and plays major role in collagen turnover. Collagen is the essential content in atherosclerotic plaque playing a key role in the stability/instability of and progression of coronary artery disease (CAD). Consequently, in this study we sought to determine serum prolidase activity and markers of oxidative stress such as lipid hydroperoxide and total free sulfhydryl in CAD.

DESIGN AND METHODS

We have evaluated 199 patients with CAD and 122 control cases with clinical, electrocardiographic, and laboratory investigation. We have measured serum prolidase activity and serum total free sulfhydryl levels spectrophotometrically. Serum lipid hydroperoxide levels were determined with ferrous ion oxidation-xylenol orange method. We assessed the association of serum prolidase activity with the presence and severity of CAD and clinical characteristics, and laboratory parameters.

RESULTS

Serum prolidase activity (52.5+/-5.6 vs. 46.7+/-5.1 U/l, respectively, P<0.001) and serum lipid hydroperoxide levels were significantly increased in patients with CAD compared with control cases whereas, serum total free sulfhydryl levels were significantly decreased in patients with CAD compared with control cases. Serum prolidase activity and total free sulfhydryl levels were independent predictors of the presence of CAD [(chi=75.532, ss=0.212, P=0.003) and (chi=25.969, ss=-30.486, P=0.019), respectively] and Gensini score [(beta=0.276, P<0.001) and (beta=-0.274, P<0.001), respectively]. Independent predictors of serum prolidase activity were serum high-density lipoprotein cholesterol (beta=-0.138, P=0.023) and urea levels (beta=0.146, P=0.036), and Gensini score (beta=0.317, P<0.001).

CONCLUSION

Findings of this study have shown that serum prolidase activity is significantly associated with the presence and severity of CAD, and elevated serum prolidase activity might be an independent predictor of coronary atherosclerosis.

Understanding systemic lupus erythematosus physiopathology in the light of primary immunodeficiencies

INTRODUCTION

Associations between systemic lupus erythematosus (SLE) and primary immunodeficiencies (PIDs) were analyzed to gain insight into the physiopathology of SLE. Some PIDs have been consistently associated with SLE or lupus-like manifestations: (a) homozygous deficiencies of the early components of the classical complement pathway in the following decreasing order: in C1q, 93% of affected patients developed SLE; in C4, 75%; in C1r/s, 57%; and in C2, up to 25%; (b) female carriers of X-linked chronic granulomatous disease allele; and (c) IgA deficiency, present in around 5% of juvenile SLE.

DISCUSSION

In the first two groups, disturbances of cellular waste-disposal have been proposed as the main mechanisms of pathogenesis. On the other hand and very interestingly, there are PIDs systematically associated with several autoimmune manifestations in which SLE has not been described, such as autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED), immunodysregulation polyendocrinopathy enteropathy X-linked (IPEX), and autoimmune lymphoproliferative syndrome (ALPS), suggesting that mechanisms considered as critical players for induction and maintenance of tolerance to autoantigens, such as (1) AIRE-mediated thymic negative selection of lymphocytes, (2) Foxp3+ regulatory T cell-mediated peripheral tolerance, and (3) deletion of auto-reactive lymphocytes by Fas-mediated apoptosis, could not be relevant in SLE physiopathology. The non-description of SLE and neither the most characteristic SLE clinical features among patients with agammaglobulinemia are also interesting observations, which reinforce the essential role of B lymphocytes and antibodies for SLE pathogenesis.

CONCLUSION

Therefore, monogenic PIDs represent unique and not fully explored human models for unraveling components of the conundrum represented by the physiopathology of SLE, a prototypical polygenic disease.

Molecular characterisation of six patients with prolidase deficiency: identification of the first small duplication in the prolidase gene and of a mutation generating symptomatic and asymptomatic outcomes within the same family

Prolidase deficiency (PD) is a rare autosomal recessive connective tissue disorder caused by mutations in the prolidase gene. The PD patients show a wide range of clinical outcomes characterised mainly by intractable skin ulcers, mental retardation and recurrent respiratory infections. Here we describe five different PEPD mutations in six European patients. We identified two new PEPD mutant alleles: a 13 bp duplication in exon 8, which is the first reported duplication in the prolidase gene and a point mutation resulting in a change in amino acid E412, a highly conserved residue among different species. The E412K substitution is responsible for the first reported phenotypic variability within a family with severe and asymptomatic outcomes.

A nonsense mutation of PEPD in four Amish children with prolidase deficiency

Encoded by the peptidase D (PEPD) gene located at 19q12-q13.11, prolidase is a ubiquitous cytosolic enzyme that catalyzes hydrolysis of oligopeptides with a C-terminal proline or hydroxyproline. We describe here four Amish children with a severe phenotype of prolidase deficiency in the Geauga settlements of Ohio as the first report of prolidase deficiency in the Amish population as well as in the United States. The patients presented with infection, hepatosplenomegaly, or thrombocytopenia, in contrast to most cases previously reported in the literature, presenting with skin ulcers. All four patients had typical facial features, classic skin ulcers, and multisystem involvement. Recurrent infections, asthma-like chronic reactive airway disease, hyperimmunoglobulins, hepatosplenomegaly with mildly elevated aspartate transaminase (AST), anemia, and thrombocytopenia were common and massive imidodipeptiduria was universal. Prolidase activity in our patients is nearly undetectable. Direct sequencing of PCR-amplified genomic DNA for all of the exons from the four patients revealed the same homozygous single nucleotide mutation c.793 T > C in exon 11, resulting in a premature stop-codon at amino acid residue 265 (p.R265X). It is speculated that the severe phenotype in these patients might be associated with the type of the PEPD gene mutation.

A homozygous missense mutation in PEPD encoding peptidase D causes prolidase deficiency associated with hyper-IgE syndrome

BACKGROUND

Prolidase deficiency is a complex disease characterized by various skin manifestations accompanied by mental retardation, facial dysmorphism and susceptibility to pyogenic infections.

METHODS

We assessed a patient presenting a peculiar phenotype combining manifestations of prolidase deficiency with features typical of hyper-IgE syndrome. Mutation analysis was performed using direct PCR amplification and PCR restriction fragment length polymorphism analysis.

RESULTS

We identified a novel homozygous recessive mutation in the PEPD gene, which was found to segregate in the family of the patient with the disease and was not found in a panel of DNA samples representative of all major Druze families living in northern Israel.

DISCUSSION

Our results suggest that prolidase deficiency associated with hyper-IgE syndrome, a rare disorder, can be caused by mutations in PEPD.

The role of emerging techniques in the investigation of prolidase deficiency: From diagnosis to the development of a possible therapeutical approach

The aim of the present article is to review the efforts performed in the past two decades by numerous research groups for the development of methods that allow a correct diagnosis of prolidase deficiency (PD), a rare autosomal recessive disorder and for the rationalization of a possible therapeutic intervention on these patients. In particular, the interest of the reader is focused on the application of capillary electrophoresis (i) for the detection of biological markers that reflect the pathological feature of the disease and (ii) for the determination of the efficiency of a carrier system in delivering prolidase inside cells in a possible therapy based on enzyme replacement.

Abnormal apoptosis in chronic granulomatous disease and autoantibody production characteristic of lupus

OBJECTIVES

Patients with chronic granulomatous disease and carrier mothers of patients with chronic granulomatous disease are predisposed to developing various forms of lupus. This disorder is a neutrophil defect in intracellular killing. Abnormal apoptosis has been described. We hypothesized that abnormal apoptosis occurring in neutrophils of patients made them more immunogenic.

METHODS

Human patients with chronic granulomatous disease were examined for abnormalities of neutrophil apoptosis by flow cytometry. To model the effect of abnormal apoptosis, a murine model was used. Apoptotic cells from either wild type or mice with chronic granulomatous disease were injected into either wild type or chronic granulomatous disease mice and autoantibodies were determined by ELISA.

RESULTS

Our studies found that human and murine neutrophils carrying the gp91 form of chronic granulomatous disease had impaired exposure of phosphatidyl serine on the surface. Other markers of apoptosis were largely normal. Injection of apoptotic neutrophils from gp91 knockout mice into gp91 knockout mice led to the development of characteristic autoantibodies of lupus.

CONCLUSIONS

Humans with chronic granulomatous disease may be at an increased risk of developing lupus due to abnormal apoptosis and abnormal clearance of apoptotic cells.

Determination of prolidase activity using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Proline-containing peptides of the X-proline type are cleaved by the dipeptidase prolidase. The classical method of prolidase assay relied on the colorimetric estimation of the liberated proline with ninhydrin using acidic media and heat. This method, however, gave inconsistent results due to the nonspecificity of the ninhydrin color reaction. We report here a method for the detection of the liberated proline using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Human sera were incubated with a mixture containing the dipeptide glycyl-proline in Tris-HCl supplemented with manganese at 37 degrees C for 24h. The samples were precipitated with trifluoroacetic acid and centrifuged. An aliquot of the supernatant was mixed with an equal volume of ferulic acid solution. An aliquot from this mixture was spotted on a stainless steel mass spectrometry grid and analyzed using MALDI-TOF mass spectrometry. The activity of the enzyme was determined by the complete disappearance of the glycyl-proline peak with the concomitant appearance of the proline peak and can be expressed in terms of the ratio of the area beneath the proline to the area beneath the glycyl-proline peak. Subjects homozygous for prolidase deficiency had a ratio ranging from 0.006 to 0.04 while obligatory heterozygotes had a ratio ranging from around 1.1 to 2.4. Normal subjects had ratios ranging from 9 to 239. Using this method we have unambiguously identified subjects with homozygous or heterozygous prolidase deficiency. In addition to the advantage of rapid sample preparation time, this method is highly specific, reproducible, and sensitive.

Rheumatic disease mimics in childhood

Aches and pains in children can arise from multiple problems, varying from a reaction to minor intercurrent infection that rapidly improves to the presence of severe skeletal lesions such as malignancy; they can also be part of a skeletal dysplasia. All cases require a good history (including family history), a full examination, and basic blood tests, which include the erythrocyte sedimentation rate, hemoglobin, white count, platelets, rheumatoid factor, and antinuclear factor. Other tests need be performed only when suspicion has been aroused. Recognition of unusual syndromes is important; no child should be labeled as having juvenile idiopathic arthritis unless there is a clear history with the presence of soft tissue swelling in appropriate sites and other causes for joint pain have been excluded. The conditions that most frequently mimic systemic onset juvenile arthritis are infections, which may have been partially treated, inflammatory bowel disease, malignancy, familial Mediterranean Fever, and the rarer connective tissue diseases, in particular systemic lupus erythematosus. Bacterial infection should be suspected in a child who is feverish and toxic, with a single hot swollen joint that has limited movement and is often rigidly guarded. Should such a child have already received antibiotics, general symptoms may well be minimal, so one is left with the history and a swollen and painful joint. Aspiration for investigation of the synovial fluid as well as blood tests should be undertaken immediately to establish the nature of any underlying infection.

Genetics of systemic lupus erythematosus. Clinical implications

Rheumatic diseases have long been recognized as having complex inheritance patterns. It has recently been estimated that over 100 genes may be implicated in the SLE disease process. Identification of these genes has led to a greater understanding of the etiopathogenesis of SLE and is beginning to lead to new types of interventions directed at correcting aberrant biological processes.

The genes of systemic autoimmunity

Autoimmune diseases include a wide spectrum of disorders, which have been divided into systemic and organ-specific disorders. Lupus, the prototypic systemic autoimmune disease, is characterized by female predominance, multiorgan pathology, and autoantibodies, primarily directed against nuclear antigens. The disease is heterogeneous, with variable organ involvement, serology, and clinical course. Susceptibility to lupus is inherited as a polygenic trait with added contributions from environmental and stochastic variance. Concerted efforts have recently been made by several laboratories to define the genetic basis of this disease in predisposed mice and humans. The identification of the Fas/FasL defects in lpr and gld lupus mice was the first example of spontaneous mutations of apoptosis-promoting genes being associated with systemic autoimmunity. This research was instrumental in clarifying the roles of these genes in tolerance and immunoregulation, and in extrapolating these results to other autoimmune diseases, as well as cancer and transplantation. To these findings have been added those from transgenic and gene knockout mouse studies that have helped to define the systemic autoimmunity-inducing or -modifying effects of specific genes in normal background and lupus-congenic mice. In addition, the findings from genome-wide searches have begun to identify predisposing loci (and ultimately genes) for the spontaneous lupus-like diseases in various mouse strains and in humans. The emerging picture is that multiple genetic contributions can independently lead to systemic autoimmunity in mice, which reinforces the view that human lupus may be similarly composed of diverse genotypes. This complexity underscores the importance of defining the predisposing alleles and mechanisms of action, an undertaking that is certainly feasible given current technologies and future advances in the definition of mammalian genomes.