Prolidase deficiency: a case report and literature review

Recurrent Skin Ulcers with Facial Dysmorphism and Sinopulmonary Infections: Thinking Beyond Hyper-IgE Syndrome

Prolidase deficiency (PD) 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. It occurs due to the mutations in the prolidase gene ( PEPD ) that result in loss of prolidase activity. We reported here a child who had presented with features compatible with hyper-immunoglobulin E syndrome (HIES) like recurrent skin ulcers, recurrent infections, facial dysmorphism, retained primary teeth, and elevated levels of immunoglobulin E levels but with normal flow cytometric assays, which was later diagnosed as PD.

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.

Proline-dependent regulation of collagen metabolism

This review is focused on recent data on the role of proline (Pro) in collagen biosynthesis and cellular metabolism. It seems obvious that one of the main substrates for collagen biosynthesis Pro is required to form collagen molecule. The question raised in this review is whether the Pro for collagen biosynthesis is synthesized "de novo", comes directly from degraded proteins or it is converted from other amino acids. Recent data provided evidence that extracellular Pro (added to culture medium) had significant, but relatively little impact on collagen biosynthesis in fibroblasts (the main collagen synthesized cells) cultured in the presence of glutamine (Gln). However, extracellular Pro drastically increased collagen biosynthesis in the cells cultured in Gln-free medium. It suggests that Pro availability determines the rate of collagen biosynthesis and demand for Pro in fibroblasts is predominantly met by conversion from Gln. The potential mechanism of this process as well as possible implication of this knowledge in pharmacotherapy of connective tissue diseases is discussed in this review.

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.

Biodegradable microspheres for prolidase delivery to human cultured fibroblasts

Prolidase deficiency (PD) is a rare autosomal recessive disorder caused by inadequate levels of the cytosolic exopeptidase prolidase (E.C. 3.4.13.9), for which there is not, as yet, a resolutive cure. We have investigated whether biodegradable microspheres loaded with prolidase could release active enzyme inside cells, to consider this system as a possible therapeutic approach for prolidase deficiency. Poly(lactide-co-glycolide) microspheres were prepared, modifying the classical double emulsion solvent evaporation method to mitigate the burst effect of the enzyme from the microspheres. Ex-vivo experiments were performed, by incubating microencapsulated prolidase with cultured fibroblasts from PD patients and from controls, to determine the amount of active enzyme delivered to the cells. The microparticulate drug delivery system described carried small amounts of active prolidase inside fibroblasts, ensuring a response to the intracellular accumulation of X-Pro dipeptides, the mechanism that is supposed to be responsible for the development of clinical manifestations of this disorder in man. A positive result of the presence of active enzyme inside cells was an improvement in fibroblast shape.

Uncommon leg ulcers in the lower extremity

OBJECTIVE

To determine the prevalence of uncommon ulcers, unrelated to venous or arterial etiology, in patients presenting to vascular clinics.

METHODS

This was a multicenter prospective study of consecutive patients presenting with lower extremity ulceration. The settings were university hospital outpatient centers and venous clinics. A total of 799 limbs in 710 patients with leg ulcers were evaluated. Patients with venous ulcer disease and with evidence of arterial disease with an ankle-brachial index less than 0.7 were excluded from the study. Out of 710 patients, 17 patients with a total of 21 limbs fit the criteria for inclusion. All limbs included in this study underwent physical examination, ankle-brachial index measurements, duplex ultrasonography, and skin biopsies.

RESULTS

The mean age of patients with uncommon ulcers was 65.6 years, and the mean duration was 5.5 years. A total of 2.1% of all leg ulcers seen were due to uncommon etiology unrelated to venous or arterial pathology. Most of these ulcers were located in the medial lower calf (n = 19). In six patients with ulcers, the histology did not reveal any specific cause; five had a neoplasia, three had chronic inflammation, two had sickle cell disease, two had vasculitis, one had rheumatoid arthritis, one had pyoderma gangrenosum, and one had ulcer due to hydroxyurea.

CONCLUSIONS

The prevalence of leg ulcers unrelated to arterial and venous disease that presented with signs and symptoms of chronic venous disease was 2.1%. Their etiology is variable, most often including vasculitis, neoplasia, metabolic disorders, infection, and other rare causes. Early identification of uncommon ulcers may facilitate timely and appropriate management.

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.

Nutrition 1: a vital consideration in the management of skin wounds

Nutrition is a provocative subject in tissue repair, particularly in relation to the skin which consists of many different tissues fulfilling various essential functions. This article, the first in a two-part series, will discuss the structure of the human skin and its variations, with indications as to the individual requirements of the cells in fulfilling their normal role in skin physiology and in repair systems. Nutrient gradients seem to play a major role in normal skin physiology and repair systems following injury. The second part will discuss in more detail the importance of major nutrient factors and their inter-relationships in tissue repair. It is clear that much of our available knowledge is derived from experimental studies in animals. Their relevance in human wound healing may be equivocal as the human skin is unique in the animal kingdom.

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.

Therapeutic apheresis exchange in two patients with prolidase deficiency

BACKGROUND

Prolidase deficiency is a rare genetic disorder for which a cure has not yet been found.

OBJECTIVES

To assess the effectiveness of apheresis exchange as a new therapeutic approach.

METHODS

Apheresis exchanges were repeated monthly for four consecutive months, in parallel, on two patients, replacing prolidase-deficient red blood cells with normal filtered cells. Prolidase activity and urinary dipeptides were determined at regular intervals.

RESULTS

The constant presence of active prolidase inside cells allowed a continuous, although partial, degradation of imidodipeptides, with a concomitant improvement of skin ulceration.

CONCLUSIONS

Apheresis exchange could be a reasonable way of obtaining a clinical improvement in these patients.

Transient beneficial effect of GH replacement therapy and topical GH application on skin ulcers in a boy with prolidase deficiency

A diagnostic examination for short stature in a boy with chronic ulcers of the feet due to prolidase deficiency, a rare disorder associated with intractable ulcers of the skin, led to the diagnosis of growth hormone (GH) deficiency. Replacement treatment with r-hGH associated with the topical application of a GH-containing ointment when the boy was 13 years old resulted in complete but transitory healing of the ulcers, which can probably be attributed to the growth-promoting effects of GH on dermal connective tissue.

Prolidase deficiency associated with pathologic myopia

Deficiency of prolidase, a key enzyme in proline metabolism, is extremely rare and is usually associated with skin lesions, recurrent infections, characteristic facies, mental retardation, and splenomegaly. These clinical features are largely due to inhibition of normal recycling of proline, which causes an alteration in the metabolism of collagen and other proline-rich proteins. The case of a 25-year-old with all the recognized characteristics of prolidase deficiency is reported. Pathologic myopia, which has not been hitherto described in association with prolidase deficiency, is added to the clinical spectrum of this rare disorder.

Prolidase deficiency and systemic lupus erythematosus

Two children with prolidase deficiency, an inborn error of proline metabolism, developed clinical and immunological abnormalities consistent with a diagnosis of systemic lupus erythematosus (SLE). The first child died from septicaemia, and SLE was only diagnosed during his terminal illness. As a result of this diagnosis his cousin, who was already known to have prolidase deficiency, was investigated further and a diagnosis of SLE confirmed. Following treatment with oral prednisolone her clinical condition has improved, although she has a persistently raised erythrocyte sedimentation rate (ESR) and florid facial rash. Both prolidase deficiency and SLE are associated with disturbances in immune function and have clinical features in common. It is likely that prolidase deficiency is a risk factor for the development of SLE. Additionally, patients with SLE should-where there is a family history or presentation in childhood-be specifically investigated for prolidase deficiency, since standard immunological or haematological investigations will not identify the characteristic biochemical abnormalities.

Prolidase deficiency: a multisystemic hereditary disorder

Prolidase deficiency is a rare hereditary disorder with a wide spectrum of clinical manifestations including skin ulcers, eczematous eruptions, characteristic facies, mental retardation, splenomegaly, and susceptibility to infections. We report two new cases of prolidase deficiency. Our patients had the typical manifestations of prolidase deficiency. One also had lupus erythematosus. Prolidase activity was either normal or half-normal in all family members. The skin disease in our patients did not respond to topical glycine/proline ointment or to oral vitamin C.