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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. [ABSTRACT FROM AUTHOR]

Background: Chronic wounds, which are persistent disruptions in skin integrity, represent a significant global health challenge. Various types of ulcers, including venous, arterial, diabetic, pressure, and traumatic ulcers, contribute to personal, professional, and societal burdens. Autologous platelet-rich plasma (PRP) has emerged as a promising therapeutic option by leveraging the growth factors in platelets for tissue regeneration. Methods: This prospective study, conducted from December 2021 to December 2023, enrolled 10 patients with chronic ulcers. The PRP gel was prepared through a systematic process that included blood collection, centrifugation, and activation. Results: The study included 8 males and 2 females, with an average age of 48.8 years. Ulcer etiologies encompassed diabetic foot ulcers, arterial ulcers, and venous ulcers, among others. The initial average surface area of the ulcers was 18.7 cm2. Complete healing was observed in a case of Buerger's disease, while very good healing was achieved in one diabetic foot ulcer, one venous ulcer, and another case of Buerger's disease. Moderate healing was noted in five cases of arterial ulcers, and poor healing was observed in one case of prolidase deficiency. The average surface area post-treatment for all patients was reduced to 8.05 cm2, with no reported pain or adverse effects. Conclusions: Platelet-rich plasma gel emerges as a promising alternative to traditional treatments, potentially lessening the overall impact on healthcare resources and enhancing the quality of life for individuals with chronic ulcers. [ABSTRACT FROM AUTHOR]

Introduction: Prolidase deficiency is a rare autosomal recessive disorder caused by variants in the PEPD gene. Patients usually have multi-organ involvement and a wide range of clinical features including recurrent skin ulcers, dysmorphic facial features, recurrent infections, intellectual disability, and splenomegaly. Studies have shown that patients with prolidase deficiency may have hepatic manifestations including hepatomegaly and abnormal liver enzymes. However, there is no detailed description of liver disease in this patient population. Case Presentation: Here, we present 3 patients with prolidase deficiency with varying extents of hepatic involvement. Conclusion: Prolidase deficiency patients with liver disease should be followed up long term to understand more about the pathophysiology and the impact of liver disease on long-term outcomes.

Introduction: Prolidase deficiency is a rare autosomal recessive disorder caused by variants in the PEPD gene. Patients usually have multi-organ involvement and a wide range of clinical features including recurrent skin ulcers, dysmorphic facial features, recurrent infections, intellectual disability, and splenomegaly. Studies have shown that patients with prolidase deficiency may have hepatic manifestations including hepatomegaly and abnormal liver enzymes. However, there is no detailed description of liver disease in this patient population. Case Presentation: Here, we present 3 patients with prolidase deficiency with varying extents of hepatic involvement. Conclusion: Prolidase deficiency patients with liver disease should be followed up long term to understand more about the pathophysiology and the impact of liver disease on long-term outcomes. [ABSTRACT FROM AUTHOR]

Prolidase deficiency (PD) is a rare autosomal recessive disorder associated with recurrent infections, immune dysregulation, and autoimmunity. PD is characterized by persistent dermatitis, skin fragility, and non‐healing ulcerations on the lower limbs as its main dermatologic characteristics. Herein, we report a boy with PD due to a novel variant in PEPD who had abnormal facies, cognitive impairment, corneal opacity, recurrent infections, and persistent non‐healing leg ulcers. Th17 lymphocyte counts and phosphorylated‐STAT5 expression following IL‐2 stimulation were reduced in our patient as compared to healthy control. [ABSTRACT FROM AUTHOR]

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.

Prolidase deficiency is an autosomal recessive disease that causes impaired collagen degradation. Altered collagen homeostasis results in the intracellular accumulation of imidodipeptides, which contain proline and hydroxyproline. The many clinical manifestations of prolidase deficiency include dysmorphic facial features, skeletal deformities, hepatosplenomegaly, necrotizing skin ulcers, and recurrent infections. Current clinical knowledge of this genetic disease relies upon few case reports due to its extreme rarity. Diagnosis is dependent on the detection of a pathologic gene variant. Additional diagnostic confirmation may be provided by urine amino acid quantification or reduced in vitro prolidase activity. We present a case of prolidase deficiency caused by a novel variant manifested by skeletal malformations and lifelong multisystemic infections. Genetic testing revealed a homozygous missense variant in the PEPD gene at nucleotide position 200, whereby adenine was replaced by guanine (c.200A > G). The corresponding amino acid change replaced glutamine with arginine at codon 67 (p.Gln67Arg). After boiling the urine sample for hydrolysis, quantitative urine amino acids demonstrated a markedly elevated proline level, confirming the diagnosis. We also provide a discussion of the pathophysiology, clinical manifestations, diagnostic testing, and clinical management of this disease. [ABSTRACT FROM AUTHOR]

Abstract 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 Treg cells and decreased frequency of expression of the checkpoint molecule CTLA-4 in CD4+ TEM cells. Analysis of Th1, Th2, and Th17 profiles revealed increased inflammatory IL-17+ CD8+ TEM cells in both patients and overexpression of the activation marker HLA-DR on CD4+ TEM cells, reflecting a highly activated proinflammatory state. Neither PD patient had specific antibody deficiencies despite low CD4+CXCR5+ Tfh 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+ TEM 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.

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 Treg cells and decreased frequency of expression of the checkpoint molecule CTLA-4 in CD4+ TEM cells. Analysis of Th1, Th2, and Th17 profiles revealed increased inflammatory IL-17+ CD8+ TEM cells in both patients and overexpression of the activation marker HLA-DR on CD4+ TEM cells, reflecting a highly activated proinflammatory state. Neither PD patient had specific antibody deficiencies despite low CD4+CXCR5+ Tfh 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+ TEM 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. [ABSTRACT FROM AUTHOR]

Prolidase deficiency is an extremely rare, autosomal recessive disorder resulting in defective collagen formation. We report a case of prolidase deficiency in a male child, highlighting the dermatologic features. Early diagnosis is important as these patients encounter significant multisystem comorbidities requiring multispecialty care. [ABSTRACT FROM AUTHOR]

Introduction: Prolidase deficiency is a rare multisystemic disease associated with collagen metabolism. Clinical manifestations and age of onset are highly variable. Prolidase deficiency is caused by homozygous variants in the PEPD gene. In this report, three siblings with c.1103T>G (L368R) variant in the PEPD gene are presented. They had features not described in the literature and marked intrafamilial clinical heterogeneity. This is the first family of Syrian ancestral origin with prolidase deficiency., Case Presentation: We performed whole-exome sequencing for the index case, and detected a homozygous c.1103T>G variant, in the PEPD gene. All family members were then screened for the same variant by Sanger sequencing analysis. Two siblings were found to be homozygous, and one of them had not yet developed clinical symptoms., Conclusion: Our data expand the clinical spectrum of prolidase deficiency. It also improves our knowledge of phenotype and genotype relationships of prolidase deficiency patients., Competing Interests: The authors have no conflict of interest to declare., (© 2024 S. Karger AG, Basel.)

Background: We report the Case of Prolidase - deficiency syndrome in a 3-year-old boy suffering from atraumatic compartment syndrome in both hands. Case description: We discuss four areas of controversy. First, what could be the reason for an atraumatic compartment syndrome in both hands?Second, should we operate on a 3-year-old boy or use a conservative approach? Third, would we have chosen an operative approach knowing the underlying condition? Fourth, how should we proceed postoperatively? Conclusion: We chose to operate him and performed a compartment release operation. He was treated interdisciplinary and discharged after fifteen days.

Prolidase (peptidase D), encoded by the PEPD gene, is a ubiquitously expressed cytosolic metalloproteinase, the only enzyme capable of cleaving imidodipeptides containing C-terminal proline or hydroxyproline. Prolidase catalyzes the rate-limiting step during collagen recycling and is essential in protein metabolism, collagen turnover, and matrix remodeling. Prolidase, therefore plays a crucial role in several physiological processes such as wound healing, inflammation, angiogenesis, cell proliferation, and carcinogenesis. Accordingly, mutations leading to loss of prolidase catalytic activity result in prolidase deficiency a rare autosomal recessive metabolic disorder characterized by defective wound healing. In addition, alterations in prolidase enzyme activity have been documented in numerous pathological conditions, making prolidase a useful biochemical marker to measure disease severity. Furthermore, recent studies underscore the importance of a non-enzymatic role of prolidase in cell regulation and infectious disease. This review aims to provide comprehensive information on prolidase, from its discovery to its role in health and disease, while addressing the current knowledge gaps.

Abstract Prolidase Deficiency (PD) is an autosomal recessive rare disorder caused by loss or reduction of prolidase enzymatic activity due to variants in the PEPD gene. PD clinical features vary among affected individuals: skin ulcerations, recurrent infections, and developmental delay are common. In this study, we describe a 16-year-old boy with a mild PD phenotype comprising chronic eczema, recurrent infections and elevated IgE. Whole exome sequencing analysis revealed three PEPD variants: c.575T>C p.(Leu192Pro) inherited from the mother, and c.692_694del p.(Tyr231del) and c.1409G>A p.(Arg470His), both inherited from the father. The variant p.(Tyr231del) has been previously characterized by high-resolution X-ray structure analysis as altering protein dynamics/flexibility. In order to study the effects of the other two prolidase variants, we performed site directed mutagenesis purification and crystallization studies. A high-resolution X-ray structure could only be obtained for the p.(Arg470His) variant, which showed no significant structural differences in comparison to WT prolidase. On the other hand, the p.(Leu192Pro) variant led to significant protein destabilization. Hence, we conclude that the maternal p.(Leu192Pro) variant was likely causally associated with the proband´s disease, together with the known pathogenic paternal variant p.(Tyr231del). Our results demonstrated the utility of exome sequencing to perform diagnosis in PD cases with mild phenotype.

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. [ABSTRACT FROM AUTHOR]

Abstract is missing (Short communication)

Prolidase catalyzes the cleavage of dipeptides containing proline on their C terminus. The reduction in prolidase activity is the cause of a rare disease named 'Prolidase Deficiency'. Local structural disorder was indicated as one of the causes for diminished prolidase activity. Previous studies showed that heat shock proteins can partially recover prolidase activity in vivo. To analyze this mechanism of enzymatic activity rescue, we compared the crystal structures of selected prolidase mutants expressed in the absence and in the presence of chaperones. Our results confirm that protein chaperones facilitate the formation of more ordered structures by their substrate protein. These results also suggest that the protein expression system needs to be considered as an important parameter in structural studies. Databases: The reported crystal structures and their associated structure factor amplitudes were deposited in the Protein Data Bank under the accession codes 6SRE, 6SRF, and 6SRG, respectively. [ABSTRACT FROM AUTHOR]

The extracellular matrix is essential for brain development, lamination, and synaptogenesis. In particular, the basement membrane below the pial meninx (pBM) is required for correct cortical development. The last step in the catabolism of the most abundant protein in pBM, collagen Type IV, requires prolidase, an exopeptidase cleaving the imidodipeptides containing pro or hyp at the C‐terminal end. Mutations impairing prolidase activity lead in humans to the rare disease prolidase deficiency characterized by severe skin ulcers and mental impairment. Thus, the dark‐like (dal) mouse, in which the prolidase is knocked‐out, was used to investigate whether the deficiency of prolidase affects the neuronal maturation during development of a brain cortex area. Focusing on the cerebellar cortex, thinner collagen fibers and disorganized pBM were found. Aberrant cortical granule cell proliferation and migration occurred, associated to defects in brain lamination, and in particular in maturation of Purkinje neurons and formation of synaptic contacts. This study deeply elucidates a link between prolidase activity and neuronal maturation shedding new light on the molecular basis of functional aspects in the prolidase deficiency. [ABSTRACT FROM AUTHOR]

Prolidase is a ubiquitous enzyme that plays a major role in the metabolism of proline-rich proteins. Prolidase deficiency is a rare autosomal recessive inborn metabolic and multisystemic disease, characterized by a protean association of symptoms, namely intellectual disability, recurrent infections, splenomegaly, skin lesions, auto-immune disorders and cytopenia. To our knowledge, no published review has assembled the different clinical data and research studies over prolidase deficiency. The aim of this study is to summarize the actual state of the art from the descriptions of all the patients with a molecular diagnosis of prolidase deficiency reported to date regarding the clinical, biological, histopathological features, therapeutic options and functional studies.

Prolidase is a metallopeptidase that cleaves iminodipeptides containing a proline (Pro) or hydroxyproline (Hyp) residue at their C‐terminal end. The disease prolidase deficiency (PD) is a rare recessive human disorder characterized by reduced prolidase activity. PD manifests itself by a wide range of severe clinical symptoms, most commonly as skin ulceration, recurrent infections of the respiratory tract, and mental retardation. Several mutations in the PEPD gene have been identified that are responsible for the loss or the reduction of prolidase activity. In contrast, the structural basis of enzyme inactivation has so far remained elusive. In this study, we present high resolution crystal structures of a number of human prolidase (HsProl) variants, in which single amino acids are either substituted by others or deleted. The observed implications of the mutations on the three‐dimensional structure of HsProl are reported and discussed and related to their enzymatic activity. The resulting structures may be divided into four groups depending on the presumed effect of the corresponding mutations on the reaction mechanism. The four possible inactivation mechanisms, which could be elucidated, are disruption of the catalytic Mn2(OH−)‐center, introduction of chain disorder along with the displacement of important active site residues, rigidification of the active site, and flexibilization of the active site. Database: All refined structure coordinates as well as the corresponding structure factor amplitudes have been deposited in the PDB under the accession numbers 5MBY, 5MBZ, 5MC0, 5MC1, 5MC2, 5MC3, 5MC4, 5MC5, 6H2P, 6H2Q. [ABSTRACT FROM AUTHOR]

Prolidase deficiency (PD) is a rare autosomal recessive disorder characterized mainly by skin lesions of the legs and feet, respiratory infections and mental retardation, and impaired immune system. To date, no effective PD treatment has been developed. The PD case are caused by homozygous mutation in PEPD gene. The peripheral blood mononuclear cells from a patient carrying homozygous in-frame mutation of the PEPD gene were reprogrammed using the CytoTune-iPS2.0 Sendai Reprogramming Kit. The homozygous in-frame mutation in PEPD will cause the abnormal protein variant. The established human induced pluripotent cell line will enable proper in vitro disease modelling of PD., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Prolidase deficiency is a rare autosomal recessive disorder characterized by cutaneous ulcers, facial dysmorphism, recurrent infections, and intellectual disability. We report a unique case of a 6‐year‐old boy with prolidase deficiency and Crohn's disease who presented with lower extremity ulcers. Cutaneous ulcers due to prolidase deficiency are historically resistant to treatment, and we report success with the novel use of topical tacrolimus. [ABSTRACT FROM AUTHOR]

Prolidase deficiency (PD) is a multisystem disorder caused by mutations in the PEPD gene, which encodes a ubiquitously expressed metallopeptidase essential for the hydrolysis of dipeptides containing C-terminal proline or hydroxyproline. PD typically presents in childhood with developmental delay, skin ulcers, recurrent infections, and, in some patients, autoimmune features that can mimic systemic lupus erythematosus. The basis for the autoimmune association is uncertain, but might be due to self-antigen exposure with tissue damage, or indirectly driven by chronic infection and microbial burden. In this study, we address the question of causation and show that Pepd-null mice have increased antinuclear autoantibodies and raised serum IgA, accompanied by kidney immune complex deposition, consistent with a systemic lupus erythematosus-like disease. These features are associated with an accumulation of CD4 and CD8 effector T cells in the spleen and liver. Pepd deficiency leads to spontaneous T cell activation and proliferation into the effector subset, which is cell intrinsic and independent of Ag receptor specificity or antigenic stimulation. However, an increase in KLRG1+ effector CD8 cells is not observed in mixed chimeras, in which the autoimmune phenotype is also absent. Our findings link autoimmune susceptibility in PD to spontaneous T cell dysfunction, likely to be acting in combination with immune activators that lie outside the hemopoietic system but result from the abnormal metabolism or loss of nonenzymatic prolidase function. This knowledge provides insight into the role of prolidase in the maintenance of self-tolerance and highlights the importance of treatment to control T cell activation., (Copyright © 2023 The Authors.)

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. [ABSTRACT FROM AUTHOR]

Prolidase gene (PEPD) encodes prolidase enzyme, which is responsible for hydrolysis of dipeptides containing proline or hydroxyproline at their C-terminal end. Mutations in PEPD gene cause, in human, prolidase deficiency (PD), a rare autosomal recessive disorder. PD patients show reduced or absent prolidase activity and a broad spectrum of phenotypic traits including various degrees of mental retardation. This is the first report correlating PD and brain damages using as a model system prolidase deficient mice, the so called dark-like (dal) mutant mice. We focused our attention on dal postnatal brain development, revealing a panel of different morphological defects in the cerebral and cerebellar cortices, such as undulations of the cerebral cortex, cell rarefaction, defects in cerebellar cortex lobulation, and blood vessels overgrowth. These anomalies might be ascribed to altered angiogenic process and loss of pial basement membrane integrity. Further studies will be directed to find a correlation between neuroarchitecture alterations and functional consequences.

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. [ABSTRACT FROM AUTHOR]

Prolidase deficiency is a rare inborn disorder of collagen metabolism characterized by chronic recurrent skin ulceration. A seven-year-old girl and her younger sibling with clinical features and laboratory criteria fulfilling the diagnosis of prolidase deficiency are presented in view of rarity of the condition.

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-doublestranded 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. [ABSTRACT FROM AUTHOR]

Abstract: Prolidase deficiency (PD) is a rare inborn disorder of collagen metabolism characterized by chronic recurrent cutaneous ulceration. We report a novel 3bp insertion in the 12th exon of the PEPD gene in two Kashmiri siblings with prolidase deficiency phenotype. This mutation results in addition of an extra alanine residue at the amino-acid position number 304 of prolidase peptide. The structural analysis showed that this Ala insertion is located at the helix (a.a. 300–320), which contains several important hydrogen bonds between residues essential for structural folding for the enzyme activity. In silico analysis suggests that this insertion mutation might distort or bend the helical feature to affect the hydrogen-bond network between residues of neighboring secondary structures and deform the metal-binding geometry of the enzyme. Although approximately 70 PEPD gene mutations and polymorphisms have been reported in various ethnic groups, we however report, for the first time, the identification of insertion mutation in human the PEPD gene. [Copyright &y& Elsevier]

Abstract: Background: Prolidase is a metallo-exopeptidase hydrolyzing X-Pro and X-Hyp dipeptides. Its absence or reduced level is typical in prolidase deficiency (PD) patients, and altered prolidase activity was reported in various diseases. Therefore, standardized and accurate measurement of prolidase activity is essential for PD diagnosis, as well as to elucidate the pathophysiology of other disorders. Methods: Human recombinant prolidase was used to optimize a spectrophotometric enzyme activity assay. Kinetic parameters and Mn2+ affinity were evaluated. The method was validated on blood and fibroblasts from PD patients. Results: An activation step consisting in prolidase incubation with 1mmol/l MnCl2 and 0.75mmol/l reduced glutathione at 50°C for 20min was necessary to obtain the maximum activity and to accurately determine, for the recombinant enzyme, Vmax (489U/mg), K m (5.4mM) and Mn2+ affinity (54mM−1). The method applied to PD diagnosis revealed an intra-assay CV=8% for blood and 9% for fibroblasts lysates. The inter-assay CV was 21% for blood and 20% for cell lysates. Conclusion: We optimized a faster spectrophotometric method to measure the activity when the enzyme is fully activated, this is crucial to allow a reliable evaluation of prolidase activity from different sources. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Abstract: Prolidase loaded chitosan nanoparticles were set up in order to suggest an innovative therapeutic approach for Prolidase Deficiency (PD), a rare autosomal inherited disorder of the connective tissue. The satisfactory drug loading efficiency (42.6±2.1%) as well as the suitable physical characteristics (mean diameter of 365.5±35.1nm and a positive zeta-potential of 17.94±0.12mV) was achieved. In order to verify the compatibility of the chitosan nanoparticles with cells, the influence of the nanoparticles on the growth and the viability (MTT assay) of cultured skin fibroblasts were determined: the nanoparticles showed a good biocompatibility up to 5μg of chitosan/10,000 fibroblasts. Uptake of chitosan nanoparticles by fibroblasts was verified by confocal microscopy using FITC-labelled chitosan nanoparticles. The ex vivo experiments were performed by incubating different amounts of prolidase loaded chitosan nanoparticles with skin human fibroblasts from PD patients for scheduled times. The restored prolidase activity was quantitatively monitored by a capillary electrophoretic method and confirmed by cells morphological observations. Standing from the nanoparticles internalization, the enzymatic activity was progressively restored reaching the best value (about 66%) after 5 days of co-incubation. Moreover, prolidase loaded chitosan nanoparticles permitted to restore prolidase activity in PD fibroblasts for a prolonged period of time (8 days). [Copyright &y& Elsevier]

Abstract: The first aim of this work was to perform site-directed PEGylation of the enzyme prolidase at sulphydril groups by methoxy-polyethylene glycol-maleimide (Mal-PEG, Mw 5000Da) in order to obtain a safe conjugation product more stable than the native enzyme. Prolidase is a cytosolic aminoacyl-l-proline hydrolase whose deficiency causes the onset of rare autosomal recessive disorder called prolidase deficiency (PD). The second purpose of this work was to investigate whether biodegradable chitosan nanoparticles loaded with PEGylated prolidase could be effective in releasing active enzyme inside fibroblasts as a possible therapeutic approach for PD. The SDS-PAGE analysis and the ESI-MS spectra confirmed the presence of the PEGylated prolidase: in particular the main conjugation product (m/z =about 65,000Da) corresponded to the enzyme with two residues of Mal-PEG. In this study it was demonstrated the lack of toxicity (MTT assay) and the prolonged activity (40.6±2.6% after 48h of incubation at 37°C) of the PEGylated enzyme. The PEGylated prolidase loaded chitosan nanoparticles had spherical shape, narrow size distribution (271.6±45.5nm), a positive zeta-potential (15.93±0.26mV) with a good preparation yield (54.6±3.6%) and protein encapsulation efficiency (44.8±4.6%). The ex vivo evaluation of prolidase activity on PD fibroblasts individuated a good level of prolidase activity replaced (about 72% after only 2 days of incubation) up to 10 days with improved morphological cell features. [Copyright &y& Elsevier]

Abstract: Background: Prolidase and prolinase activity is known to be enhanced significantly in some diseases. Recently, the effect of amino acids on prolidase and prolinase activity in normal and prolidase-deficient human erythrocytes was investigated. It was reported that both enzymes were enhanced by glycine and alanine in the presence of MnCl2. Methods: Erythrocytes were isolated from heparinized blood from normal human and a patient with prolidase deficiency. Effects of various sulfur amino acids on prolidase and prolinase activities against iminodipeptides in the presence of 1 or 0.1 mmol/l MnCl2 were investigated. Results: Prolinase activity against prolylglycine in normal and prolidase-deficient erythrocyte lysates was inhibited by l-methionine, NAc-l-methionine and d,l-methionine in a concentration-dependent manner, but d-methionine enhanced the activity in low concentrations (0–20 mmol/l). d,l-Homocysteine inhibited the activity more strongly than other sulfur amino acids tested in a concentration-dependent manner. On the other hand, prolidase activity against glycylproline was enhanced by l-methionine, d-methionine, d,l-methionine, d,l-homocysteine thiolactone and d,l-ethionine. The rates of enhancement by these sulfur amino acids were in the following order: d,l-ethionine> d,l-methionine, d-methionine, d,l-homocysteine thiolactone> l-methionine (10 mmol/l). Conclusion: The prolinase activity in normal and prolidase-deficient erythrocyte lysates was inhibited by l-methionine, d,l-ethionine and d,l-homocysteine. On the other hand, prolidase activity in their erythrocyte lysates was enhanced by d,l-ethionine, d-methionine and l-methionine. These results indicate the effects of these sulfur amino acids on prolidase and prolinase activities were different. [Copyright &y& Elsevier]

Prolidase is a Mn2+-dependent dipeptidase that cleaves imidodipeptides containing C-terminal proline or hydroxyproline. In humans, a lack of prolidase activity causes prolidase deficiency, a rare autosomal recessive disease, characterized by a wide range of clinical outcomes, including severe skin lesions, mental retardation, and infections of the respiratory tract. In this study, recombinant prolidase was produced as a fusion protein with an N-terminal histidine tag in eukaryotic and prokaryotic hosts and purified in a single step using immobilized metal affinity chromatography. The enzyme was characterized in terms of activity against different substrates, in the presence of various bivalent ions, in the presence of the strong inhibitor Cbz-Pro, and at different temperatures and pHs. The recombinant enzyme with and without a tag showed properties mainly indistinguishable from those of the native prolidase from fibroblast lysate. The protein yield was higher from the prokaryotic source, and a detailed long-term stability study of this enzyme at 37 °C was therefore undertaken. For this analysis, an ‘on-column’ digestion of the N-terminal His tag by Factor Xa was performed. A positive effect of Mn2+ and GSH in the incubation mixture and high stability of the untagged enzyme are reported. Poly(ethylene glycol) and glycerol had a stabilizing effect, the latter being the more effective. In addition, no significant degradation was detected after up to 6 days of incubation with cellular lysate. Generation of the prolidase in Escherichia coli, because of its high yield, stability, and similarity to native prolidase, appears to be the best approach for future structural studies and enzyme replacement therapy. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: Objectives: : The purpose of this study was to investigate the effect of various amino acids and their metabolites on the activities of prolidase I and II from human erythrocytes compared to those in a patient with prolidase deficiency. Design and methods: : Prolidase I and II from human erythrocytes were purified by using column chromatography. Prolidase activity against various iminodipeptides was determined by spectrophotometry using Chinard''s method. Results: : The activities of prolidase I and II against glycylproline and methionylproline were enhanced by glycine, l- and d-isoforms of alanine and serine and d-isoforms of valine, leucine and isoleucine. l-isoforms of branched amino acids inhibited the activity of prolidase I. On the other hand, the activity of prolidase II was enhanced by all of these l-branched amino acids. The patient''s prolidase activity was also enhanced by all the l- and d-branched amino acids. Conclusion: : The activities of prolidase I and II against various iminodipeptides were prominently enhanced by glycine, but the effect of l-valine differed between the two enzymes. Enzymatic properties of the patient''s prolidase were essentially the same as those of prolidase II. [Copyright &y& Elsevier]

Abstract: Prolidase deficiency (PD) is a recessive disorder of the connective tissue caused by mutations in the prolidase, a specific peptidase, cleaving the dipeptides with a C-terminal prolyl and hydroxyprolyl residue. PD is a complex syndrome characterized mainly by intractable skin lesions, recurrent respiratory infections and mental retardation. The relation between prolidase biological functions and the disease is still largely unknown. We studied the effect of a prolidase inhibitor, N-benzyloxycarbonyl-l-proline (Cbz-Pro), in vitro on prolidase from human fibroblasts and in vivo on murine erythrocytes prolidase. A 90% inhibition was detected incubating cellular extracts at 1:1 ratio of Gly-Pro substrate: Cbz-Pro inhibitor. Pulse experiments performed incubating human fibroblasts with 6 mM Cbz-Pro revealed that the inhibitor uptake was completed in about 1 min. The Cbz-Pro uptake was saturable and pH dependent. Long-term incubation of fibroblasts with Cbz-Pro caused mitochondria depolarization and increased cellular death as reported for long-term culture of fibroblasts from PD patients. An inhibitory effect of Cbz-Pro has also been shown in vivo. Our results demonstrated that Cbz-Pro is a potent inhibitor of prolidase in cultured fibroblasts and it can be used in vivo to better characterize the prolidase enzyme and further investigate PD physiopathology. [Copyright &y& Elsevier]