Susceptibility of nucleotide-binding oligomerization domain 2 mutations to Whipple's disease

OBJECTIVES

Whipple's disease (WD) results from infection of the bacteria Tropheryma whipplei (TW). This disease is characterized by macrophage infiltration of intestinal mucosa and primarily affects Caucasian males. Genetic studies of host susceptibility are scarce. Nucleotide-binding oligomerization domain containing protein 2 (NOD2) is an innate immune sensor, resides mainly in monocytes/macrophages and contributes to defence against infection and inflammatory regulation. NOD2 mutations are associated with autoinflammatory diseases. We report the association of NOD2 mutations with TW and WD for the first time.

METHODS

A multicentre, retrospective study of three patients with WD was conducted. Patients received extensive multidisciplinary evaluations and were cared for by the authors. NOD2 and its association with infection and inflammation were schematically represented.

RESULTS

All patients were Caucasian men and presented with years of autoinflammatory phenotypes, including recurrent fever, rash, inflammatory arthritis, gastrointestinal symptoms and elevated inflammatory markers. All patients underwent molecular testing using a gene panel for periodic fever syndromes and were identified to carry NOD2 mutations associated with NOD2-associated autoinflammatory disease. Despite initially negative gastrointestinal evaluations, repeat endoscopy with duodenal tissue biopsy ultimately confirmed WD. After initial ceftriaxone and maintenance with doxycycline and/or HCQ, symptoms were largely controlled, though mild relapses occurred in follow-up.

CONCLUSION

Both NOD2 and TW/WD are intensively involved in monocytes/macrophages. WD is regarded as a macrophage disease. NOD2 leucin-rich repeat-associated mutations in monocytes/macrophages cause functional impairment of these cells and consequently may make the host susceptible for TW infection and WD, especially in the setting of immunosuppression.

IRF4 haploinsufficiency in a family with Whipple's disease

Most humans are exposed to Tropheryma whipplei (Tw). Whipple's disease (WD) strikes only a small minority of individuals infected with Tw (<0.01%), whereas asymptomatic chronic carriage is more common (<25%). We studied a multiplex kindred, containing four WD patients and five healthy Tw chronic carriers. We hypothesized that WD displays autosomal dominant (AD) inheritance, with age-dependent incomplete penetrance. We identified a single very rare non-synonymous mutation in the four patients: the private R98W variant of IRF4, a transcription factor involved in immunity. The five Tw carriers were younger, and also heterozygous for R98W. We found that R98W was loss-of-function, modified the transcriptome of heterozygous leukocytes following Tw stimulation, and was not dominant-negative. We also found that only six of the other 153 known non-synonymous IRF4 variants were loss-of-function. Finally, we found that IRF4 had evolved under purifying selection. AD IRF4 deficiency can underlie WD by haploinsufficiency, with age-dependent incomplete penetrance.

Whipple disease diagnosed with PCR using formalin-fixed paraffin-embedded specimens of the intestinal mucosa

We herein present the case of a 54-year-old Japanese woman with Whipple disease diagnosed with polymerase chain reaction (PCR) using formalin-fixed paraffin-embedded (FFPE) specimens. The patient complained of weight loss, diarrhea and arthralgia. An endoscopic examination revealed swollen villi in the duodenum and ileum. Pathology demonstrated the presence of numerous macrophages filled with diastase-resistant PAS-positive particles. PCR using FFPE specimens amplified a fragment of 16S rDNA from Tropheryma whipplei. After the administration of ceftriaxone followed by trimethoprim/sulfamethoxazole, no signs of recurrence were observed for two years. The use of FFPE specimens for PCR should be considered for the prompt diagnosis and prevention of disease progression.

Whipple's disease. A classic case report and review of the literature

We report the case of a 43-year-old carpenter with abdominal complaints and progressive weight loss. The HLA-B27 positive male had been suffering migratory arthropathy for five years, only partially under control with corticosteroids and methotrexate therapy. Endoscopic investigation showed dark staining of the duodenal mucosa and the ileal mucosa had an erythematous aspect with multiple white spots. Abundant periodic acid Schiff positive macrophages were seen on histologic examination of biopsy samples. This is a classic presentation of Whipple's disease, a rare multisystemic disease caused by the Tropheryma whipplei. Typical symptoms are arthropathy, weight loss, abdominal pain and diarrhea, but also systemic and neurological manifestations may occur. The otherwise lethal disease can be treated with long term antibiotics.

Whipple disease

Whipple disease is a rare disease caused by infection with the bacterium Tropheryma whippelii. Humans are the only known host for the infection. The signs of systemic infection include gastrointestinal problems, weight loss, and arthritis. Signs of central nervous system infection include cognitive changes, supranuclear gaze palsy, altered level of consciousness, and movement disorders. The diagnosis is based on clinical findings as well as microscopic examination of biopsy specimens and, more recently, polymerase chain reaction (PCR) analysis, which has high sensitivity and specificity. Although the organism historically has been difficult to culture, several recent attempts have been successful. Antibiotic treatment is recommended for 1 year while monitoring the clinical signs and cerebrospinal fluid PCR results.

Genome-based design of a cell-free culture medium for Tropheryma whipplei

Empirical approaches have guided the development of bacterial cultures. The availability of sequenced genomes now provides opportunities to define culture media for growth of fastidious pathogens with computer modelling of metabolic networks. A key issue is the possibility of growing host-dependent bacteria in cell-free conditions. The sequenced Tropheryma whipplei genome was analysed to identify specific metabolic deficiencies. We used this information to design a comprehensive medium that allowed three established T whipplei strains from culture with human cells and one new strain from a clinical sample to grow axenically. Genomic information can, therefore, provide sufficient clues for designing axenic media for fastidious and uncultured pathogens.

Sequencing and analysis of the genome of the Whipple's disease bacterium Tropheryma whipplei

BACKGROUND

Whipple's disease is a rare multisystem chronic infection, involving the intestinal tract as well as various other organs. The causative agent, Tropheryma whipplei, is a Gram-positive bacterium about which little is known. Our aim was to investigate the biology of this organism by generating and analysing the complete DNA sequence of its genome.

METHODS

We isolated and propagated T whipplei strain TW08/27 from the cerebrospinal fluid of a patient diagnosed with Whipple's disease. We generated the complete sequence of the genome by the whole genome shotgun method, and analysed it with a combination of automatic and manual bioinformatic techniques.

FINDINGS

Sequencing revealed a condensed 925938 bp genome with a lack of key biosynthetic pathways and a reduced capacity for energy metabolism. A family of large surface proteins was identified, some associated with large amounts of non-coding repetitive DNA, and an unexpected degree of sequence variation.

INTERPRETATION

The genome reduction and lack of metabolic capabilities point to a host-restricted lifestyle for the organism. The sequence variation indicates both known and novel mechanisms for the elaboration and variation of surface structures, and suggests that immune evasion and host interaction play an important part in the lifestyle of this persistent bacterial pathogen.

Molecular techniques in Whipple's disease

Whipple's disease is a systemic infection, caused by the bacterium Tropheryma whipplei, with protean clinical manifestations characterized by fever, weight loss, diarrhea, polyarthritis, skin hyperpigmentation and adenopathy. For a long time, due to the inability to culture the causative organism, diagnosis was based on histologic examination of infected tissues, usually duodenal biopsies, which revealed diastase-resistant periodic acid-Schiff-positive staining. Now, PCR of various tissues or fluid is emerging as a way to diagnose Whipple's disease. However, the presence of T. whipplei DNA in saliva, gastric juice or duodenal biopsies of healthy individuals has led to questions regarding the specificity of the molecular techniques involved. After a series of failures, stable culture was achieved in 2000. Subsequently, the generation of rabbit polyclonal antibodies has led to the detection of the bacterium in tissues by immunohistology. However, culture and immunohistology are very recent techniques and are not yet widely used. Propagation of the bacterium will lead to extensive molecular knowledge of T. whipplei, which will help in the diagnosis and understanding of the epidemiology and pathogenicity of Whipple's disease.

Lack of association with spondyloarthritis and HLA-B27 in Italian patients with Whipple's disease

OBJECTIVE

To examine consecutive patients with Whipple's disease (WD) for the full clinical spectrum of spondyloarthritis.

METHODS

Nine consecutive patients, 8 men, 1 woman, with WD were clinically evaluated and examined for clinical and radiological manifestations of spondyloarthritis by 2 rheumatologists with special interest in spondyloarthritis. The mean age of the patients at the time of study and at the time of their initial diagnosis of WD by duodenal biopsy was 62.4 years (range 42-71) and 54.4 years (range 40-62), respectively. Each patient had an anteroposterior radiographic view of the pelvis and also had HLA typing for class I and II alleles. Pelvis radiographs were read blindly for evidence of sacroiliitis.

RESULTS

All but one patient had rheumatologic manifestations related to WD. The mean interval between the onset of these symptoms and the diagnosis of WD was 6.1 years (range 1-15). One had recurrent polyarthritis, 1 recurrent oligoarthritis, 3 recurrent monoarthritis, 2 recurrent synovitis with pitting edema of the dorsum of hands and/or feet, and 1 isolated De Quervain's tenosynovitis. Of the 5 patients with arthritis, 3 also had episodes of swelling with pitting edema over the dorsum of hands and/or feet together with flexor digit tenosynovitis, 2 also had olecranon bursitis, and 1 tibial tenosynovitis. No patient had clinical or radiological manifestations of spondyloarthritis. None had the HLA-B27.

CONCLUSION

In Italian Caucasian patients with WD there was no association with spondyloarthritis and HLA-B27.

Diagnostic value of the detection of t(14;18) chromosome translocation in malignant hematological and immunopathological diseases using polymerase chain reaction

The majority of the t(14;18) chromosome translocations that occur in non-Hodgkin centroblastic-centrocytic follicular lymphoma can be detected by various methods. During the translocation process the bcl-2 gene located on chromosome 18 (18q21) is translocated to the JH region of the immunoglobulin gene of chromosome 14 (14q32). The most frequent type of bcl-2 translocations is the mbr type, whereas the immunoglobulin gene breaks mainly at the JH1-6 exons. About one of the 10(5) cells bearing the translocation can already be detected by using nested polymerase chain reaction (PCR). Eight patients suffering from follicular lymphoma were included in this study, which considered the usefulness of the PCR method. The results are in good agreement with those obtained by conventional diagnostic methods. Translocation can be detected, however, in patients with non-malignant diseases such as Sjögren's syndrome (about 5% of the patients) and in a patient with Whipple disease. In addition, translocation was detected in lymphocytes of peripheral blood of a healthy donor. Since lymphomas are detected in patients with Sjögren's syndrome with a relative high frequency, an early diagnosis of the translocation could improve the treatment of the disease. Nevertheless, a diagnosis of lymphoma is valid only in cases of bone marrow translocation-positivity.

Dermatomyositis and Whipple's disease

A 14-year-old boy presented with a 3-year history of a skin rash typical of juvenile dermatomyositis, and a 2-month history of mild proximal weakness, myalgia, and weight loss. A quadriceps biopsy showed perifascicular fibre atrophy, focal necrosis and regeneration, immunohistochemical labelling for HLA-1 on the surface of the fibres, and focal C5-9 deposition in capillaries. Macrophages with diastase-resistant, PAS-positive cytoplasm were present. Ultrastructural studies showed electron dense and membranous debris. The patient's symptoms responded to intravenous immunoglobulin and oral prednisolone. Four months after discontinuing prednisolone, the patient developed cardiac failure, ventricular tachycardia, and a recurrence of his rash. The 16S ribosomal RNA specific for Tropheryma whippelii was identified by polymerase chain reaction (PCR) analysis in skeletal and cardiac muscle. The myalgia and skin rash responded to prednisolone and oral co-trimoxazole, and the tachycardia is controlled by oral verapamil. This patient appears to have a novel association of juvenile dermatomyositis and Whipple's disease.

[The presence of t(14;18) chromosome translocation in various types of diseases]

Chromosome translocation of t(14;18) can be detected in most cases of centroblastic/centrocytic follicular lymphomas. They are causative factors of lymphomas but the translocation is present in different other types of diseases although the translocation does not belong to the features of these illnesses. Our present work shows the appearance of t(14;18) translocation in lymphocytes of two patients of Sjögren's syndrome, one that of Whipple disease as well as one of healthy donors' lymphocytes using polymerase chain reaction technique presented in one of our previous publication. The translocation occurred in the mbr of bcl-2 gene in all cases showed and the bcl-2 gene was coupled with the immunoglobulin heavy chain gene. These results are definitively positive concerning the fact of translocation as it has been proved by sequencing of the amplification products showed in our earlier and present paper. Because relatively high percentages of Sjögren's syndrome patients develop later on lymphoma, the early detection of the translocation could result in a more successful diagnosis as well as treatment of the disease. The question arises, however, what role the translocation plays in illnesses such as the Whipple disease or what kind of consequences can be drawn from the appearance of the t(14;18) translocation in lymphocytes of healthy donors.

Whipple's disease: comparison of histology with diagnosis based on polymerase chain reaction in four consecutive cases

BACKGROUND

Polymerase chain reaction (PCR) based detection of species specific sequences of the 16S rRNA gene of Tropheryma whippelii is a recently described method for diagnosis of Whipple's disease.

AIMS

Comparison of histology with PCR in mucosal samples of patients with Whipple's disease before, during, and after treatment. Detection of T whippelii in peripheral blood mononuclear cells as a non-invasive test for infection.

METHODS

Four consecutive patients with histologically proven Whipple's disease were studied prospectively.

RESULTS

In untreated patients biopsy specimens taken from regions with PAS positive macrophages gave a positive result with PCR for T whippelii; however, a PCR signal was also found in tissue biopsy specimens from mucosal regions with negative histology. In two of the patients the PCR performed with nucleic acids extracted from peripheral blood mononuclear cells was positive. After treatment with sulfamethoxazole/trimethoprim the PCR became negative after one month in two patients and after two months in the third patient treated, whereas PAS positive macrophages were found throughout the treatment period in two patients and disappeared in only one of them thereafter.

CONCLUSIONS

Detection of T whippelii specific sequences based on the PCR is useful to confirm the diagnosis, is able to detect a positive signal in samples taken from histologically negative mucosal areas, and can be used to monitor treatment. The PCR can sometimes be positive in peripheral blood mononuclear cells, but this cellular compartment cannot be taken as a substitute for duodenal biopsy specimens in the diagnosis of Whipple's disease.

The identification of uncultured microbial pathogens

Clinicians have long been aware of human diseases that are associated with visible but uncultured microorganisms. Without the ability to cultivate these organisms, they have remained unidentified. Environmental microbiologists have also discovered on the basis of recent advances in the field of molecular phylogeny that culture-based methods for detecting microorganisms are biased and insensitive. A culture-independent experimental approach is described for the identification of microbial pathogens. This approach incorporates fundamental aspects of 16S rRNA-based molecular phylogeny as well as nucleic acid amplification technology. From its application to Whipple's disease, one can speculate as to the potential insights a highly sensitive, culture-independent method may provide into the diversity and natural ecology of human microbial pathogens.

Impact of molecular biology in gastroenterology

Molecular biology has become an integral part of basic and clinical gastroenterology. A broad spectrum of infectious, inherited and malignant gastrointestinal diseases can now be studied by molecular methods, including polymerase chain reaction, hybridization and DNA sequence analyses. Recent progress in the molecular analysis of Whipple's disease and colorectal cancer, two major problems in clinical gastroenterology, is presented in greater detail. The implications of new molecular data for the understanding of the pathobiology of these disease entities and their clinical management are discussed.

Genetics of the spondarthropathies

Recent investigation of the possible role of bacteria in the pathogenesis of AS has provided very interesting data. What is at present lacking is a clear demonstration that the findings point to the actual mechanisms involved in the initiation of the disorder. Rapid progress in three related areas of research gives hope that, in the relatively near future, the genetic basis for susceptibility to AS will be elucidated. These are the demonstration of the detailed structure of an HLA class I molecule, of the primary amino acid structure of B27 heavy chain with its subtypes, and of the nature of the interaction between foreign proteins and MHC molecules which leads to antibody and cytotoxic cell responses. It is just possible that the B27 molecules have a disease-promoting capability because of some structural characteristic independent of their antigen binding site. However, it may perhaps be considered more likely that it is the propensity of the specific antigen-binding site itself to bind to a particular group of antigenic peptides that will explain the susceptibility of B27-positive individuals to several clinical disorders. The ability to study the properties of antigenic epitopes which preferentially bind to the very variable binding site of different MHC molecules raises the possibility of revealing the antigenic structures which bind to B27 molecules in patients with AS. This could in turn lead to the source of these antigens in the environment. There has been a tendency to assume that one simple model will explain all the B27-associated disorders but it may be preferable to keep an open mind about the possibility that the mechanisms involved in AS, in the bacteria-induced acute arthropathies and in acute anterior uveitis may not be identical. At the same time, there is a need to continue further direct investigation of the role of microbiological agents in AS both in vitro and in vivo, as ultimately it is most likely that, by blocking the effects of such agents as may be shown to be involved, progress in our ability to influence the progress of the disease in a fundamental way will be achieved. There is still little information as to how the tissues involved in AS come to be the particular targets of the pathological process and currently proposed theories of pathogenesis have not yet provided very satisfactory answers to this problem.

Genetic aspects of the spondyloarthropathies

Family studies and investigation of the HLA associations have in recent years added to our understanding of the spondyloarthropathies. In regard to ankylosing spondylitis it is likely that B27 itself is the major susceptibility gene but that additional genes may play a secondary role. Heterogeneity of the B27 antigen has been demonstrated but has not yet been shown to be relevant to disease susceptibility. Haplotypes including Cw6 are related to susceptibility to psoriasis and psoriatic arthritis and although the risk for the arthropathy is increased in B27-positive individuals, there is some uncertainty regarding the association with other B locus antigens and further work is needed. There is also uncertainty as to whether B27-associated disorders occur randomly within families, or whether particular disorders cluster in certain families and further evidence in this field would be of considerable interest. Genetic studies, as here outlined, have not as yet had a major impact in clinical medicine but it is anticipated that a deeper understanding of the mechanisms of HLA-linked susceptibility genes and in particular of how they interact with environmental agents, will improve our ability to treat and possibly prevent the relevant diseases.