The association of serum prolidase activity with developmental dysplasia of the hip

Investigation of Igf-1, Igf-Bp3 and Igf-Bp5 levels in umbilical cord blood of infants with developmental dysplasia of the hip

BACKGROUND

IGF-1 (insulin-like growth factor-1) is an important regulator of bone formation. Its deficiency has been associated with fetal growth disorders and hip dysplasia. The aim of this study was to evaluate whether IGF-1, IGF-BP3 (insulin like growth factorbinding protein 3), and IGF-BP5 levels in the umbilical cord blood can be predictive for early diagnosis of DDH.

METHODS

Umbilical cord blood samples were collected from 860 mothers with pregnancies at high risk for DDH between October 2020 and January 2021. Mothers at 37-42 weeks of gestation, with risk factors for DDH, who delivered healthy infants were included. Blood samples were collected during delivery. Each eligible infant was medically followed up and underwent a hip ultrasound in the postnatal 2nd or 3rd month. Infants diagnosed with DDH were matched with a healthy cohort in terms of sex, birth weight, maternal age, and gestational week, and the IGF-1, IGF-BP3 and IGF-BP5 levels were studied and compared.

RESULTS

Evaluation was made of 20 infants diagnosed with DDH and 60 healthy infants. Of the total 80 infants, 72.5% were female.The umbilical cord blood levels of IGF-1 and IGF-BP3 were similar in both groups. The IGF-BP5 values were significantly lower in the DDH patient group. Except for DDH diagnosis, the other categorical variables of the study did not appear to influence the levels of any of the IGFs.

DISCUSSION

Umbilical blood samples could potentially help diagnose DDH. The levels of IGF-BP5 were shown to be significantly lower in infants with DDH.

Fluoride increases the susceptibility of developmental dysplasia of the hip via increasing capsular laxity triggered by cell apoptosis and oxidative stress in vivo and in vitro

The etiology of developmental dysplasia of the hip (DDH) is multifactorial, including breech presentation and hip capsular laxity. In particular, hip laxity is the main contributor to DDH by changing the ratio and distribution of collagens. Also, fluoride (F) affects collagens from various tissue besides bone and tooth. To investigate the association of DDH and excessive F intake, we conducted this research in lab on cell and animal model simultaneously. We established animal model of combination of DDH and F toxicity. The incidence of DDH in each group was calculated, and hip capsules were collected for testing histopathological and ultrastructural changes. The primary fibroblasts were further extracted from hip capsule and treated with F. The expression of collagen type I and III was both examined in vivo and in vitro, and the level of oxidative stress and apoptosis was also tested identically. We revealed that the incidence of DDH increased with F concentration. Furthermore, the oxidative stress and apoptosis levels of hip capsules and fibroblasts both increased after F exposure. Therefore, this study shows that excessive F intake increases susceptibility to DDH by altering hip capsular laxity in vivo and in vitro respectively. We believe that F might be a risk factor for DDH by increasing hip laxity induced by triggering fibroblast oxidative stress and apoptosis.

Greater presence of receptors for relaxin in the ligamentum teres of female infants who undergo open reduction for developmental dysplasia of the hip

BACKGROUND

While many factors involved in the etiology of developmental dysplasia of the hip (DDH), one of which is the hormone relaxin. Relaxin concentrations in patients with DDH may lead to pathodynamic changes during hip development by altering the physiological nature of the ligament, as well as by long-term exposure to relaxin during pregnancy. Our objective in this study was to determine the number of relaxin receptors in the ligamentum teres and their role in causing DDH.

METHODS

We identified 26 infants between birth and 3 years of age who had undergone open reduction for DDH between 2010 and 2012. 12 hips of 12 miss abortus fetus between 20 to 35 weeks of gestation were used as control group. Specimens obtained from two groups were stained with Relaxin-2 antibody, and the amount of staining for relaxin receptors was determined using an ordinal H score.

RESULTS

The mean (SD) H scores of infants with DDH were significantly higher than those of controls: 215 (59) versus 52 (48); P = 0.00; 95% CI. Statistically significant difference between the two groups in terms of gender was not found.

CONCLUSION

As a result, increased number of relaxin receptors in the ligamentum teres could be a risk factor for DDH.

LEVEL OF EVIDENCE

Level 2, Prospective comparative study.

Prolidase is a critical enzyme for complete gliadin digestion in Tenebrio molitor larvae

Prolidase is a proline-specific metallopeptidase that cleaves imidodipeptides with C-terminal Pro residue. Prolidase was purified and characterized from the Tenebrio molitor larval midgut. The enzyme was localized in the soluble fraction of posterior midgut tissues, corresponding to a predicted cytoplasmic localization of prolidase according to the structure of the mRNA transcript. Expression of genes encoding prolidase and the major digestive proline-specific peptidase (PSP)-dipeptidyl peptidase 4-were similar. The pH optimum of T. molitor prolidase was 7.5, and the enzyme was inhibited by Z-Pro, indicating that it belongs to type I prolidases. In mammals, prolidase is particularly important in the catabolism of a proline-rich protein-collagen. We propose that T. molitor larval prolidase is a critical enzyme for the final stages of digestion of dietary proline-rich gliadins, providing hydrolysis of imidodipeptides in the cytoplasm of midgut epithelial cells. We propose that the products of hydrolysis are absorbed from the luminal contents by peptide transporters, which we have annotated in the T. molitor larval gut transcriptome. The origin of prolidase substrates in the insect midgut is discussed in the context of overall success of grain feeding insects.

Serum prolidase activity and oxidative-antioxidative status in patients with developmental dysplasia of the hip and its relationship with radiographic severity

BACKGROUND

We aimed to investigate serum prolidase activity and to investigate its association with oxidative-antioxidative status in patients with developmental dysplasia of the hip (DDH).

METHODS

Oxidative status parameters, including lipid hydroperoxide (LOOH), total oxidant status (TOS), and the oxidative stress index (OSI), and antioxidative status parameters, free sulfhydryl groups (Total -SH), and total antioxidative capacity (TAC), as well as serum prolidase activity were assessed in patients with DDH (n = 93), and in healthy controls (n = 82). The severity of dysplasia was evaluated according to the Tonnis grading system.

RESULTS

Serum prolidase activity and the oxidant parameters (LOOH, TOS, and OSI) were significantly higher and the antioxidant parameters (Total -SH and TAC) were significantly lower in patients with DDH compared to the controls (P < 0.005 for all). Serum prolidase activity was positively correlated with the Tonnis grade of DDH and LOOH, TOS, and OSI levels (P < 0.001 for all), but inversely correlated with total -SH and TAC levels (P < 0.001 for all).

CONCLUSION

Increased levels of serum prolidase activity, LOOH, TOS, and OSI, and decreased levels of total -SH and TAC, may be associated with DDH, and these parameters may be useful adjunctive tools to assess the severity of DDH.

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 review of environmental factors implicated in human developmental dysplasia of the hip

PURPOSE

Developmental dysplasia of the hip (DDH) is common, and the term encompasses a spectrum of anatomical abnormalities of the hip in which the femoral head displaces from the acetabulum. These abnormalities may be congenital or develop during infancy and/or childhood. Neither the prenatal and postnatal factors that predispose to hip instability nor the determinants of its resolution or persistence are well characterised. A multifactorial pathogenesis of DDH is commonly accepted and identified risk factors include a family history, being first born, breech presentation, female gender, high birth weight and oligohydramnios 1. Further to genetic factors, a number of nutritional, hormonal and mechanical influences on ligament laxity have been hypothesised.

METHODS

A comprehensive search was conducted using NICE Healthcare Databases Advanced Search and Google Scholar engines, and the terms "nutrition", "environmental", "risk factors", "CDH" and "DDH". Wherever possible, evidence from randomised controlled trials, systematic reviews and expert review articles published in the medical and veterinary literature was considered.

RESULTS

The relationship between a number of hormones and biochemical markers of nutritional status and the development of DDH has been repeatedly hypothesised upon in the last 45 years. Of those most frequently cited are calcium, vitamins C and D, and relaxin hormone. The evidence for these potential risk factors is provided mainly by canine studies, with a paucity of consistent or strong evidence in humans.

CONCLUSIONS

DDH is common and remains a leading cause of hip osteoarthritis in young adults. Neonatal clinical screening programmes for this condition have been in practice since the 1950s, albeit with varying levels of sensitivity. This review summarises current understanding of some of the most frequently cited nongenetic hypothesised risk factors, the significance of which remain to be determined.

Serum prolidase enzyme activity and oxidative status in patients with Behçet's disease

OBJECTIVES

To assess serum prolidase enzyme activity and oxidative stress in patients with Behçet's disease (BD).

METHODS

The study population consisted of BD patients (n = 42) and healthy participants (n = 29). BD patients were classified as active (n = 18) or inactive (n = 24) according to disease activity. Serum prolidase enzyme activity, total antioxidant status (TAS), total oxidative status (TOS), oxidative stress index (OSI), and malondialdehyde (MDA) levels were measured.

RESULTS

In BD patients with active disease, serum prolidase activity was significantly higher compared with the inactive and control participants. Serum prolidase activity was also significantly higher in all BD patients in comparison with controls. Serum prolidase activity was also positively correlated with OSI, C-reactive protein, and active BD. MDA, TOS, and OSI levels were all significantly higher in the BD group when compared with the healthy control participants. Serum TAS levels were significantly lower in BD patients in comparison with healthy controls.

CONCLUSION

High prolidase activity may indicate critical biological activities relevant to pathological events in BD, and this activity may be a biological indicator of disease. Further studies are needed to verify these findings.