Novel point mutations, deletions, and polymorphisms in the cathepsin C gene in nine families from Europe and North Africa with Papillon-Lefèvre syndrome

Two patients with Papillon-Lefèvre syndrome without periodontal involvement of the permanent dentition

Papillon-Lefèvre syndrome (PLS) is a rare autosomal recessive genodermatosis characterized by palmoplantar keratoderma and severe periodontitis leading to premature loss of primary and permanent teeth. PLS is caused by loss-of-function mutations in CTSC, lacking functional cathepsin C, which impairs the activation of neutrophil serine proteases. Precise pathogenesis of periodontal damage is unknown. Patient 1 presented with well-demarcated, transgredient, diffuse, palmoplantar keratoderma and psoriasiform lesions from the age of 2 years. Based on severe and recurrent periodontal inflammation, his dentist had diagnosed PLS at the age of 3 years and provided a strict oral hygiene regimen with repeated adjunct antibiotic therapies. Oral acitretin 10 mg/day along with tretinoin ointment at the age of 9 greatly improved palmoplantar keratoderma. Aged 18 years, the patient exhibited an intact permanent dentition and absence of periodontal disease. Patient 2, a 30-year-old man, suffered from transgredient, diffuse, palmoplantar keratoderma with fissuring from the age of 2 months, marked psoriasiform plaques on elbows and knees, and nail dystrophy. Intriguingly, without specific dental treatment, teeth and dental records were unremarkable. He was referred with a suspected diagnosis of psoriasis. Both patients were otherwise healthy, blood tests and sonography of internal organs were within normal limits. Panel sequencing revealed loss-of-function mutations in CTSC, c.322A>T (p.Lys108Ter) and c.504C>G (p.Tyr168Ter) in patient 1 and homozygous c.415G>T (p.Gly139Ter) in patient 2. The final diagnosis of unusual PLS was made. PLS should be considered in palmoplantar keratoderma lacking periodontitis or tooth loss.

Premedication with a cathepsin C inhibitor alleviates early primary graft dysfunction in mouse recipients after lung transplantation

Neutrophil serine proteases (NSPs), like proteinase 3 (PR3) and neutrophil elastase (NE) are implicated in ischemia-reperfusion responses after lung transplantation (LTx). Cathepsin C (CatC) acts as the key regulator of NSP maturation during biosynthesis. We hypothesized that CatC inhibitors would reduce vascular breakdown and inflammation during reperfusion in pretreated lung transplant recipients by blocking NSP maturation in the bone marrow. An orthotopic LTx model in mice was used to mimic the induction of an ischemia-reperfusion response after 18 h cold storage of the graft and LTx. Recipient mice were treated subcutaneously with a chemical CatC inhibitor (ICatC) for 10 days prior to LTx. We examined the effect of the ICatC treatment by measuring the gas exchange function of the left lung graft, protein content, neutrophil numbers and NSP activities in the bone marrow 4 h after reperfusion. Pre-operative ICatC treatment of the recipient mice improved early graft function and lead to the disappearance of active NSP protein in the transplanted lung. NSP activities were also substantially reduced in bone marrow neutrophils. Preemptive NSP reduction by CatC inhibition may prove to be a viable and effective approach to reduce immediate ischemia reperfusion responses after LTx.

Clinical and molecular analysis in Papillon-Lefèvre syndrome

Papillon-Lefèvre syndrome (PLS; MIM#245000) is a rare recessive autosomal disorder characterized by palmar and plantar hyperkeratosis, and aggressively progressing periodontitis leading to premature loss of deciduous and permanent teeth. PLS is caused by loss-of-function mutations in the CTSC gene, which encodes cathepsin C. PLS clinical expressivity is highly variable and no consistent genotype-phenotype correlation has been demonstrated yet. Here we report the clinical and genetic features of five PLS patients presenting a severe periodontal breakdown in primary and permanent dentition, hyperkeratosis over palms and soles, and recurrent sinusitis and/or tonsillitis. Mutation analysis revealed two novel homozygous recessive mutations (c.947T>C and c.1010G>C) and one previous described homozygous recessive mutation (c.901G>A), with parents carrying them in heterozygous, in three families (four patients). The fourth family presented with the CTSC c.628C>T mutation in heterozygous, which was inherited maternally. Patient carrying the CTSC c.628C>T mutation featured classical PLS phenotype, but no PLS clinical characteristics were found in his carrier mother. All mutations were found to affect directly (c.901G>A, c.947T>C, and c.1010G>C) or indirectly (c.628C>T, which induces a premature termination) the heavy chain of the cathepsin C, the region responsible for activation of the lysosomal protease. Together, these findings indicate that both homozygous and heterozygous mutations in the cathepsin C heavy chain domain may lead to classical PLS phenotype, suggesting roles for epistasis or gene-environment interactions on determination of PLS phenotypes.

Exome sequencing identifies a novel missense variant in CTSC causing nonsyndromic aggressive periodontitis

Cathepsin C (CatC) is a cysteine protease involved in a variety of immune and inflammatory pathways such as activation of cytotoxicity of various immune cells. Homozygous or compound heterozygous variants in the CatC coding gene CTSC cause different conditions that have in common severe periodontitis. Periodontitis may occur as part of Papillon-Lefèvre syndrome (PLS; OMIM#245000) or Haim-Munk syndrome (HMS; OMIM#245010), or may present as an isolated finding named aggressive periodontitis (AP1; OMIM#170650). AP1 generally affects young children and results in destruction of the periodontal support of the primary dentition. In the present study we report exome sequencing of a three generation consanguineous Turkish family with a recessive form of early-onset AP1. We identified a novel homozygous missense variant in exon 2 of CTSC (NM_148170, c.G302C, p.Trp101Ser) predicted to disrupt protein structure and to be disease causing. This is the first described CTSC variant specific to the nonsyndromic AP1 form. Given the broad phenotypic spectrum associated with CTSC variants, reporting this novel variant gives new insights on genotype/phenotype correlations and might improve diagnosis of patients with early-onset AP1.

Autophagic dysfunction in patients with Papillon-Lefèvre syndrome is restored by recombinant cathepsin C treatment

BACKGROUND

Cathepsin C (CatC) is a lysosomal enzyme involved in activation of serine proteases from immune and inflammatory cells. Several loss-of-function mutations in the CatC gene have been shown to be the genetic mark of Papillon-Lefèvre syndrome (PLS), a rare autosomal recessive disease characterized by severe early-onset periodontitis, palmoplantar hyperkeratosis, and increased susceptibility to infections. Deficiencies or dysfunction in other cathepsin family proteins, such as cathepsin B or D, have been associated with autophagic and lysosomal disorders.

OBJECTIVES

Here we characterized the basis for autophagic dysfunction in patients with PLS by analyzing skin fibroblasts derived from patients with several mutations in the CatC gene and reduced enzymatic activity.

METHODS

Skin fibroblasts were isolated from patients with PLS assessed by using genetic analysis. Authophagic flux dysfunction was evaluated by examining accumulation of p62/SQSTM1 and a bafilomycin assay. Ultrastructural analysis further confirmed abnormal accumulation of autophagic vesicles in mutant cells. A recombinant CatC protein was produced by a baculovirus system in insect cell cultures.

RESULTS

Mutant fibroblasts from patients with PLS showed alterations in oxidative/antioxidative status, reduced oxygen consumption, and a marked autophagic dysfunction associated with autophagosome accumulation. These alterations were accompanied by lysosomal permeabilization, cathepsin B release, and NLR family pyrin domain containing 3 (NLRP3) inflammasome activation. Treatment of mutant fibroblasts with recombinant CatC improved cell growth and autophagic flux and partially restored lysosomal permeabilization.

CONCLUSIONS

Our data provide a novel molecular mechanism underlying PLS. Impaired autophagy caused by insufficient lysosomal function might represent a new therapeutic target for PLS.

[Palmoplantar dermatoses: when should genes be considered?]

BACKGROUND

Palmoplantar dermatoses are common. They can be both functionally debilitating and markedly stigmatize the patient because they are so visible. Dermatoses on the hands and feet often go along with palmoplantar hyperkeratosis. Such palmoplantar keratoses (PPK) can be classified into acquired (non-hereditary) and hereditary (monogenetic) PPK.

OBJECTIVES

A considerable proportion of PPK develop on the grounds of gene defects. As these diseases constitute a heterogeneous group of quite uncommon single entities, the treating physician must know when to entertain the diagnosis of a hereditary PPK and which causative genes should be considered.

METHODS

We summarize the common causes of acquired and hereditary PPK based on a review of the latest literature.

RESULTS

The most common causes of acquired PPK are inflammatory dermatoses like psoriasis, lichen planus, or hand and feet eczema. Also irritative-toxic (arsenic poisoning, polycyclic aromatic hydrocarbons) and infectious causes of PPK (human papilloma viruses, syphilis, scabies, tuberculosis, mycoses) are not uncommon. Genetically caused PPK may occur isolated, within syndromes or as a paraneoplastic marker. The clinical/histological classification discerns diffuse, focal, or punctuate forms of PPK with and without epidermolysis. A new classification based on the causative gene defect is starting to replace the traditional clinical classification.

CONCLUSIONS

Knowledge about the large, but heterogeneous group of hereditary PPK is important to adequately counsel and treat patients and their families.

CTSC and Papillon-Lefèvre syndrome: detection of recurrent mutations in Hungarian patients, a review of published variants and database update

Papillon-Lefèvre syndrome (PLS; OMIM 245000) is an autosomal recessive condition characterized by palmoplantar hyperkeratosis and periodontitis. In 1997, the gene locus for PLS was mapped to 11q14-21, and in 1999, variants in the cathepsin C gene (CTSC) were identified as causing PLS. To date, a total of 75 different disease-causing mutations have been published for the CTSC gene. A summary of recurrent mutations identified in Hungarian patients and a review of published mutations is presented in this update. Comparison of clinical features in affected families with the same mutation strongly confirm that identical mutations of the CTSC gene can give rise to multiple different phenotypes, making genotype-phenotype correlations difficult. Variable expression of the phenotype associated with the same CTSC mutation may reflect the influence of other genetic and/or environmental factors. Most mutations are missense (53%), nonsense (23%), or frameshift (17%); however, in-frame deletions, one splicing variant, and one 5' untranslated region (UTR) mutation have also been reported. The majority of the mutations are located in exons 5-7, which encodes the heavy chain of the cathepsin C protein, suggesting that tetramerization is important for cathepsin C enzymatic activity. All the data reviewed here have been submitted to the CTSC base, a mutation registry for PLS at http://bioinf.uta.fi/CTSCbase/.

Identification of novel mutation in cathepsin C gene causing Papillon-Lefèvre Syndrome in Mexican patients

BACKGROUND

Papillon-Lefèvre Syndrome (PLS) is a type IV genodermatosis caused by mutations in cathepsin C (CTSC), with a worldwide prevalence of 1-4 cases per million in the general population. In México, the prevalence of this syndrome is unknown, and there are few case reports. The diagnosis of twenty patients in the state of Sinaloa highlights the need to characterize this syndrome in Mexicans.

METHODS

To understand the basis of PLS in Mexicans, the gene expression, enzymatic activity and mutational analysis of CTSC were assayed in nine PLS patients and their relatives. Frequencies of CTSC gene polymorphisms and HLA alleles were determined in these patients, their relatives, and the population.

RESULTS

Patients showed normal CTSC gene expression, but a deep reduction (up to 85%) in enzymatic activity in comparison to unrelated healthy individuals. A novel loss-of-function mutation, c.203 T > G (p.Leu68Arg), was found in all patients, and some carried the polymorphism c.458C > T (p.Thr153Ile). Allelic frequencies in patients, relatives and controls were 88.89%, 38.24% and 0.25% for G (c.203 T > G); and 11.11%, 8.82% and 9.00% for T (c.458C > T). HLA-DRB1*11 was found significantly more frequent (P = 0.0071) in patients than controls (33.33% vs. 7.32%), with an estimated relative risk of 6.33.

CONCLUSIONS

The novel loss-of function mutation of CTSC gene (c.203 T > G) found in patients correlated with their diminished enzymatic activity, and HLA-DRB1*11 was found to be associated with PLS. The study of more PLS patients may give more insights into the etiology of the disease as well as its prevalence in México.

Cytokine production by leukocytes of Papillon-Lefèvre syndrome patients in whole blood cultures

Papillon-Lefèvre syndrome (PLS) is characterised by aggressively progressive periodontitis combined with palmo-plantar hyperkeratosis. It is caused by "loss of function" mutations in the cathepsin C gene. The hypothesis behind this study is that PLS patients' polymorphonuclear leukocytes (PMNs) produce more proinflammatory cytokines to compensate for their reduced capacity to neutralize leukotoxin and to eliminate Aggregatibacter actinomycetemcomitans. Production of more interleukin (IL)-8 would result in the attraction of more PMNs. The aim of this study was to evaluate the cytokine profile in PLS patients' blood cultures. Blood was sampled from eight PLS patients (one female) from six families (antiinfective therapy completed: six; edentulous: two) with confirmed cathepsin C mutations and deficient enzyme activity. Nine healthy males served as controls. Whole blood cultures were stimulated with highly pure lipopolysaccharide (LPS) from Escherichia coli R515 and IL-1β plus tumor necrosis factor (TNF)-α. Thereafter, release of IL-1β (stimulation: LPS and LPS plus adenosine triphosphate), IL-6, IL-8, interferon-inducible protein (IP)-10, and interferon (IFN)-γ (stimulation: LPS, IL-1β/TNFα) were detected by ELISA. Medians of cytokine release were, with the exception of IP-10, slightly higher for PLS than for controls' cultures. None of these differences reached statistical significance. Increased production of IL-1β, IL-6, IL-8, IP-10, or IFNγ as a significant means to compensate for diminished activity and stability of polymorphonuclear leukocyte-derived proteases could not be confirmed in this study. Cytokine profiles in blood cultures may not be used to identify PLS patients.

A novel mutation in the cathepsin C gene in a Pakistani family with Papillon-Lefevre syndrome

BACKGROUND

Papillon-Lefevre syndrome (PLS; OMlM 245000) is an autosomal recessive disease caused by mutations in cathepsin C (CTSC) gene and is characterized by palmoplantar keratoderma, psoriasiform lesion over the extensor surfaces and gingivitis followed by loss of teeth. CTSC gene is expressed in several tissues including the skin and cells of the immune system. In the skin, CTSC plays a role in differentiation and desquamation, whereas in the immune system, it activates serine proteases.

OBJECTIVES

We analysed the molecular basis of PLS in a Pakistani family.

METHODS

Genomic DNA was isolated from the sample according to standard techniques. All exons of the CTSC gene with adjacent sequences of exon-intron borders were amplified by PCR and directly sequenced.

RESULTS

We identified a novel deletion mutation designated c.2ldelG (Leu7PhefsX57) in exon 1 of the CTSC gene, which probably results in the absence of CTSC protein.

CONCLUSION

Our data further expand the spectrum of mutations in the CTSC gene underlying PLS.

Evidence for a founder mutation in the cathepsin C gene in three families with Papillon-Lefèvre syndrome

BACKGROUND

Papillon-Lefèvre syndrome (PLS; OMIM 245000) is a rare autosomal recessive disorder. Clinically, PLS is characterized by hyperkeratosis involving the palms, soles, elbows and knees which is followed later on by periodontitis, destruction of alveolar bone and loss of primary and permanent teeth. The condition is caused by mutations in the cathepsin C (CTSC) gene.

METHODS

We analyzed the DNA of members from 3 consanguineous families for mutations in the CTSC gene by direct sequencing analysis. We then performed haplotype analysis.

RESULTS

We identified an identical recurrent missense mutation, R272P, in all 3 families. Microsatellite marker analysis around the CTSC gene revealed the same haplotype on the mutation-carrying allele in all 3 families.

CONCLUSION

The presence of this common mutation in families from 2 different geographical areas provides evidence for a founder effect for CTSC mutations in PLS.

Cephalometric findings in patients with Papillon-Lefèvre syndrome

INTRODUCTION

Literature regarding oral conditions in patients with Papillon-Lefèvre syndrome (PLS) often covers the periodontal aspects, but no literature was found describing specific craniofacial findings in this group. The aim of this retrospective study was to investigate the cephalometric findings of patients with PLS.

METHODS

Lateral cephalograms of 8 patients with PLS were traced, and hard- and soft-tissue variables were analyzed.

RESULTS

Class III skeletal relationship was evident (ANB angle, 2 degrees +/- 3.1 degrees ; Wits appraisal, -9.1 mm +/- 3.7 mm). Other findings include maxillary retrognathia, decreased lower facial height, retroclined mandibular incisors, and upper lip retrusion.

CONCLUSIONS

Patients affected with PLS have a Class III skeletal pattern. These findings can be of clinical value not only for diagnosis, but also for proper treatment planning.

Functional Cathepsin C mutations cause different Papillon-Lefèvre syndrome phenotypes

AIM

The autosomal-recessive Papillon-Lefèvre syndrome (PLS) is characterized by severe aggressive periodontitis, combined with palmoplantar hyperkeratosis, and is caused by mutations in the Cathepsin C (CTSC) gene. This study aimed to identify CTSC mutations in different PLS phenotypes, including atypical forms and isolated pre-pubertal aggressive periodontitis (PAP).

MATERIAL AND METHODS

Thirteen families with different phenotypes were analysed by direct sequencing of the entire coding region and the regulatory regions of CTSC. The function of novel mutations was tested with enzyme activity measurements.

RESULTS

In 11 of 13 families, 12 different pathogenic CTSC mutations were found in 10 typical PLS patients, three atypical cases and one PAP patient. Out of four novel mutations, three result in protein truncation and are thus considered to be pathogenic. The homozygous c.854C>T nucleotide exchange (p.P285L) was associated with an almost complete loss of enzyme activity. The observed phenotypic heterogeneity could not be associated with specific genotypes.

CONCLUSIONS

The phenotypic variability of the PLS associated with an identical genetic background may reflect the influence of additional genetic or environmental factors on disease characteristics. CTSC mutation analyses should be considered for differential diagnosis in all children suffering from severe aggressive periodontitis.

The role of cathepsin C in Papillon-Lefèvre syndrome, prepubertal periodontitis, and aggressive periodontitis

We have previously reported that loss-of-function mutations in the cathepsin C gene (CTSC) result in Papillon-Lefèvre syndrome, an autosomal recessive condition characterized by palmoplantar keratosis and early-onset, severe periodontitis. Others have also reported CTSC mutations in patients with severe prepubertal periodontitis, but without any skin manifestations. The possible role of CTSC variants in more common types of non-mendelian, early-onset, severe periodontitis ("aggressive periodontitis") has not been investigated. In this study, we have investigated the role of CTSC in all three conditions. We demonstrate that PLS is genetically homogeneous and the mutation spectrum that includes three novel mutations (c.386T>A/p.V129E, c.935A>G/p.Q312R, and c.1235A>G/p.Y412C) in 21 PLS families (including eight from our previous study) provides an insight into structure-function relationships of CTSC. Our data also suggest that a complete loss-of-function appears to be necessary for the manifestation of the phenotype, making it unlikely that weak CTSC mutations are a cause of aggressive periodontitis. This was confirmed by analyses of the CTSC activity in 30 subjects with aggressive periodontitis and age-sex matched controls, which demonstrated that there was no significant difference between these two groups (1,728.7 +/- SD 576.8 micro moles/mg/min vs. 1,678.7 +/- SD 527.2 micro moles/mg/min, respectively, p = 0.73). CTSC mutations were detected in only one of two families with prepubertal periodontitis; these did not form a separate functional class with respect to those observed in classical PLS. The affected individuals in the other prepubertal periodontitis family not only lacked CTSC mutations, but in addition did not share the haplotypes at the CTSC locus. These data suggest that prepubertal periodontitis is a genetically heterogeneous disease that, in some families, just represents a partially penetrant PLS.

Infections in patients with inherited defects in phagocytic function

Patients with defects in phagocytic function are predisposed to intracellular microorganisms and typically have early dissemination of the infection. Recognition of the underlying disorder and aggressive antimicrobial therapy has been beneficial for the patients. Improved understanding of the pathophysiology has also affected patient management by allowing specific, targeted immunomodulatory intervention. The disorders described in this review are not common but have had a significant impact on our understanding of the role of phagocytic cells in host defense. Conversely, understanding the role of the neutrophil and macrophage in infection has benefited not just the patients described in this review but also other patients with similar disease processes.

Mutation analysis of the cathepsin C gene in Indian families with Papillon-Lefèvre syndrome

BACKGROUND

PLS is a rare autosomal recessive disorder characterized by early onset periodontopathia and palmar plantar keratosis. PLS is caused by mutations in the cathepsin C (CTSC) gene. Dipeptidyl-peptidase I encoded by the CTSC gene removes dipeptides from the amino-terminus of protein substrates and mainly plays an immune and inflammatory role. Several mutations have been reported in this gene in patients from several ethnic groups. We report here mutation analysis of the CTSC gene in three Indian families with PLS.

METHODS

Peripheral blood samples were obtained from individuals belonging to three Indian families with PLS for genomic DNA isolation. Exon-specific intronic primers were used to amplify DNA samples from individuals. PCR products were subsequently sequenced to detect mutations. PCR-SCCP and ASOH analyses were used to determine if mutations were present in normal control individuals.

RESULTS

All patients from three families had a classic PLS phenotype, which included palmoplantar keratosis and early-onset severe periodontitis. Sequence analysis of the CTSC gene showed three novel nonsense mutations (viz., p.Q49X, p.Q69X and p.Y304X) in homozygous state in affected individuals from these Indian families.

CONCLUSIONS

This study reported three novel nonsense mutations in three Indian families. These novel nonsense mutations are predicted to produce truncated dipeptidyl-peptidase I causing PLS phenotype in these families. A review of the literature along with three novel mutations reported here showed that the total number of mutations in the CTSC gene described to date is 41 with 17 mutations being located in exon 7.