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's disease diagnosed using electron microscopy and polymerase chain reaction.

A 50-year-old man presented with bloody diarrhea and 25-kg weight loss over 3 months. Upper and lower endoscopy showed diffuse shaggy white villi in the duodenum and terminal ileum. In addition, capsule endoscopy and double-balloon enteroscopy revealed shaggy white villi in the entire small intestine. Histological examination of biopsy specimens found the lamina propria of the duodenal and intestinal mucosa to be densely infiltrated by rich foamy macrophages that were periodic acid-Schiff-positive. Electron microscopy showed numerous bacilli in the lamina propria. Tropheryma whipplei DNA was detected in the specimens by polymerase chain reaction. Based on these findings, the patient was diagnosed with Whipple's disease. He was treated with a 2-week course of ceftriaxone followed by trimethoprim-sulfamethoxazole. At the 2-month follow up, diffuse white shaggy villi improved dramatically.

-295 T-to-C promoter region IL-16 gene polymorphism is associated with Whipple's disease.

Whipple's disease (WD) is a rare systemic condition caused, in genetically predisposed subjects, by Tropheryma whipplei, a common bacterium widespread in the environment. The relevance of genetic predisposition in WD is shown by the association with HLA alleles DRB1*13 and DQB1*06 and by the demonstration that, in patients with WD, the cytokine genetic profile is skewed toward a Th2 and Treg response. Since IL-16 is involved in hampering the development of a protective macrophagic response against Tropheryma whipplei, we investigated whether the genetic background of IL-16 is different between patients with WD and controls. The -295 T-to-C polymorphism of the promoter region of the IL-16 gene was studied in 90 patients with WD and 152 healthy controls. Levels of serum IL-16 protein were also tested. The frequency of the wild type T allele was significantly higher in patients with WD compared to the controls (155/180 vs. 235/304; p = 0.02 for the Chi(2) test), odds ratio 1.82 [95 % confidence interval (CI) 1.07-3.10]. The TT genotype was found in 65/90 patients with WD and 88/152 controls (p = 0.026). No relationship was found between serum levels of IL-16 and genotypes. Although the functional consequences of this genetic background on levels of IL-16 and on the course of the disease are still unknown, we found, for the first time, that the wild type T allele and the TT genotype of the -295 polymorphism are associated with WD.

Common subclinical hypothyroidism during Whipple's disease.

BACKGROUND: Classic Whipple's disease is caused by T. whipplei and likely involves genetic predispositions, such as the HLA alleles DRB1*13 and DQB1*06, that are more frequently observed in patients. T. whipplei carriage occurs in 2-4% of the general population in France. Subclinical hypothyroidism, characterized by high levels of TSH and normal free tetra-iodothyronine (fT4) dosage, has been rarely associated with specific HLA factors. METHODS: We retrospectively tested TSHus in 80 patients and 42 carriers. In cases of dysthyroidism, we tested the levels of free-T4 and anti-thyroid antibodies, and the HLA genotypes were also determined for seven to eight patients. RESULTS: In this study, 72-74% of patients and carriers were male, and among the 80 patients, 14 (17%) individuals had a high level of TSH, whereas none of the carriers did (p<0. 01). In the 14 patients with no clinical manifestations, the T4 levels were normal, and no specific antibodies were present. Four patients treated with antibiotics, without thyroxine supplementation, showed normal levels of TSHus after one or two years. One patient displayed a second episode of subclinical hypothyroidism during a Whipple's disease relapse five years later, but the subclinical hypothyroidism regressed after antibiotic treatment. HLA typing revealed nine alleles that appeared more frequently in patients than in the control cohort, but none of these differences reached significance due to the small size of the patient group. CONCLUSION: Regardless of the substratum, classic Whipple's disease could lead to subclinical hypothyroidism. We recommend systematically testing the TSH levels in patients with Whipple's disease.

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.

Cytokine genetic profile in Whipple's disease.

Whipple's disease (WD) is a very rare chronic systemic condition characterised by a Th2/T regulatory (Treg) dysregulated immune response versus Tropheryma whipplei, a bacterium widely diffuse in the environment. To investigate whether this Th2/Treg polarised response has a genetic background, we investigated the Th1, Th2, Th17 and Treg cytokine genetic profile of 133 patients with WD. Thanks to the European Consortium on WD (QLG1-CT-2002-01049), the polymorphism of 13 cytokine genes was analysed in 111 German and 22 Italian patients using the polymerase chain reaction with sequence-specific primers (PCR-SSP) technique. The frequencies of the genotypes, haplotypes and functional phenotypes were compared with those obtained in 201 German and 140 Italian controls. Clinical heterogeneity was also considered. Functionally, WD patients may be considered as low producers of TGF-ß1, having an increased frequency of the genotype TGF-ß1+869C/C,+915C/C [12.3 % vs. 3.81 %, odds ratio (OR) = 4.131, p = 0.0002] and high secretors of IL-4, carrying the genotype IL-4-590T/T (5.34 % vs. 1.17 %, OR = 5.09, p = 0.0096). No significant association was found between cytokine polymorphism and clinical variability. Analogously to the recent cellular findings of a Th2/Treg polarised response, we showed that the cytokine genetic profile of WD patients is skewed toward a Th2 and Treg response. This was similar in both German and Italian populations. However, the significant deviations versus the controls are poorer than that expected on the basis of these recent cellular findings.

[Tropheryma whipplei infection. Colonization, self-limiting infection and Whipple's disease]. / Infektionen mit Tropheryma whipplei. Besiedlung, selbstlimitierte Infektion und Morbus Whipple.

Whipple's disease is a multisystemic infection caused by the ubiquitous bacterium Tropheryma whipplei. Immunological host factors enable classical Whipple's disease; however, T. whipplei can be found in three other clinical conditions: healthy colonization, self-limiting infections, and isolated endocarditis. The genetic predisposition of the host rather than the genotype of the bacterium influences the infection. Modern diagnostic methods elucidate the many facets of Whipple's disease. In particular, isolated T. whipplei-induced infective endocarditis can only be diagnosed after valve resection. The sole treatment of Whipple's disease evaluated prospectively comprises intravenous induction therapy with ceftriaxone or meropenem, followed by continuation therapy with oral TMP-SMX. In the case of Immune reconstitution inflammatory syndrome (IRIS) or inflammatory lesions of the CNS in the setting of Whipple's disease, additional treatment with corticosteroids should be considered to avoid severe tissue damage.

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.

Type I interferon induction is detrimental during infection with the Whipple's disease bacterium, Tropheryma whipplei.

Macrophages are the first line of defense against pathogens. Upon infection macrophages usually produce high levels of proinflammatory mediators. However, macrophages can undergo an alternate polarization leading to a permissive state. In assessing global macrophage responses to the bacterial agent of Whipple's disease, Tropheryma whipplei, we found that T. whipplei induced M2 macrophage polarization which was compatible with bacterial replication. Surprisingly, this M2 polarization of infected macrophages was associated with apoptosis induction and a functional type I interferon (IFN) response, through IRF3 activation and STAT1 phosphorylation. Using macrophages from mice deficient for the type I IFN receptor, we found that this type I IFN response was required for T. whipplei-induced macrophage apoptosis in a JNK-dependent manner and was associated with the intracellular replication of T. whipplei independently of JNK. This study underscores the role of macrophage polarization in host responses and highlights the detrimental role of type I IFN during T. whipplei infection.

The HLA alleles DRB1*13 and DQB1*06 are associated to Whipple's disease.

BACKGROUND & AIMS: Whipple's disease is a systemic, chronic, relapsing disorder caused by a combination of environmental (Tropheryma whipplei) and unknown host factors. Because it is a rare disease, the association between HLA type and Whipple's disease has been studied in only small numbers of patients; these studies have led to conflicting results. We aimed to investigate whether disease phenotype and outcome are associated with HLA type in 122 patients with Whipple's disease. METHODS: Genomic DNA was collected from 103 German, 11 Italian, and 8 Austrian patients with Whipple's disease, along with 62 healthy Austrian workers exposed to T whipplei (14 stool samples contained the bacterium). HLA class I and II alleles were identified by polymerase chain reaction analysis. Patient genotypes were compared with those of healthy German and Austrian populations; data for Italian controls were obtained from the Pavia HLA bone marrow donors' bank. RESULTS: HLA-DRB1*13 and DQB1*06 alleles occurred significantly more frequently in patients with Whipple's disease but not in healthy individuals who had been exposed to T Whipplei. The cumulative odds ratios for disease were 2.23 for the DRB1*13 allele (P < .0001) and 2.25 for the DQB1*06 allele (P < .0001). CONCLUSIONS: DRB1*13 and DQB1*06 alleles were found to be risk factors in the largest HLA study ever performed in patients with Whipple's disease.

Advances in Tropheryma whipplei research: the rush to find biomarkers for Whipple's disease.

Whipple's disease (WD) is a systemic chronic infection, caused by the Gram-positive bacterium Tropheryma whipplei. There are several clinical traits linked to WD: histological lesions in the GI tract in association with diverse clinical manifestations (classic WD), endocarditis with negative blood cultures, and isolated neurological infection. WD is rare, predominantly affects middle-aged men and is fatal without treatment. The most recent strategy for diagnosing WD uses the results of diastase-resistant periodic acid Schiff staining and PCR in parallel, both performed on involved organ/tissue biopsy (small intestine, cardiac valve and cerebrospinal fluid). The generation of rabbit polyclonal antibodies has enabled the detection of the bacterium in tissues by immunohistochemical staining. However, the diagnosis of WD remains an invasive procedure. The recent achievement of stable bacterial culture and sequencing of the T. whipplei genome has opened a framework for the development of a biomarker platform. Several studies in different fields have been performed, for example, transcriptomics, immunoproteomics and comparative proteomics. Biomarker candidates have been proposed for the development of less invasive procedures for diagnosing WD.

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.