Defects of monocyte interleukin 12 production and humoral immunity in Whipple's disease

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.

Two consecutive cases of mycotic aneurysms resulting from Whipple disease

Whipple disease is a rare multisystemic infectious process caused by Tropheryma whipplei. Classical clinical manifestations include chronic diarrhea, malabsorption, weight loss, and arthralgias. Cases of endocarditis and isolated involvement of the central nervous system have also been reported. Isolated vascular complications are not common with this disease. Vascular manifestations are mainly described as systemic embolization from underlying endocarditis. We report two consecutive cases of mycotic pseudoaneurysms resulting from Whipple disease treated with successful vascular reconstruction using autologous vein grafting.

Patients with Whipple's disease have a high prevalence of Helicobacter pylori infection

INTRODUCTION

Whipple's disease is a rare systemic infection due to an impaired immunological response against T. whipplei in genetically predisposed individuals. Since we previously noted development of H. pylori related complications in some patients with Whipple's disease, our aim was to study the prevalence of H. pylori infection and H. pylori related disorders in Whipple's disease.

METHODS

Whipple's disease patients diagnosed from Jan-2002 to Dec-2021 and two controls per patient, matched for age, gender, ethnicity and year of H. pylori testing were enrolled.

RESULTS

34 patients with Whipple's disease and 68 controls were enrolled. H. pylori infection (13/34 vs 8/68, p<0.01), H. pylori-related gastritis (p<0.01) and gastric atrophy (p = 0.01) were significantly more common in patients with Whipple's disease than controls. H. pylori infection and Whipple's disease were diagnosed synchronously in 6/13 patients, and during follow-up in the remaining 7. Interestingly, these last 7 patients were all on trimethoprim-sulfamethoxazole long-term therapy. Two patients developed H. pylori-related gastric malignancies during follow-up. No patients on doxycycline developed H. pylori infection.

CONCLUSIONS

H. pylori infection and related disorders are common in patients with Whipple's disease and should always be excluded both at time of diagnosis and during follow-up. These findings should be taken into account when selecting antibiotics for Whipple's disease long-term prophylaxis.

Clinical Manifestations and Diagnosis of Axial Spondyloarthritis

BACKGROUND

Axial spondyloarthritis (axSpA) is a chronic, rheumatic disease characterized by inflammation of the sacroiliac joint, spine, and entheses. Axial spondyloarthritis affects up to 1.4% of adults in the United States and is associated with decreased quality of life, increased mortality, and substantial health care-related costs, imposing a high burden on patients, their caregivers, and society.

SUMMARY OF WORK

Diagnosing axSpA can be difficult. In this review, we seek to help rheumatologists in recognizing and diagnosing axSpA.

MAJOR CONCLUSIONS

A discussion of challenges associated with diagnosis is presented, including use and interpretation of imaging, reasons for diagnostic delays, differences in disease presentation by sex, and differential diagnoses of axSpA.

FUTURE RESEARCH DIRECTIONS

The early diagnosis of axSpA and advances in available therapeutic options have improved patient care and disease management, but delays in diagnosis and treatment remain common. Additional research and education are critical for recognizing diverse axSpA presentations and optimizing management early in the course of disease.

Recent advances in understanding inherited deficiencies in immunity to infections

The immune system is central to our interactions with the world in which we live and importantly dictates our response to potential allergens, toxins, and pathogens to which we are constantly exposed. Understanding the mechanisms that underlie protective host immune responses against microbial pathogens is vital for the development of improved treatment and vaccination strategies against infections. To that end, inherited immunodeficiencies that manifest with susceptibility to bacterial, viral, and/or fungal infections have provided fundamental insights into the indispensable contribution of key immune pathways in host defense against various pathogens. In this mini-review, we summarize the findings from a series of recent publications in which inherited immunodeficiencies have helped illuminate the interplay of human immunity and resistance to infection.

Whipple's endocarditis: a case report of a blood culture-negative endocarditis

Background

Whipple's disease is caused by Tropheryma whipplei and causes a self-limiting gastrointestinal infection. The majority of the population is an asymptomatic carrier, however, in some patients, it causes an invasive infection with for example arthritis, endocarditis, or involvement of the eyes.

Case summary

This case describes a man with long-lasting complaints of progressive dyspnoea caused by heart failure due to total destruction of the aortic and mitral valve as a result of T. whipplei endocarditis, diagnosed with serum polymerase chain reaction. The patient was treated with ceftriaxone and prolonged co-trimoxazole therapy and surgical replacement of the aortic and mitral valve. He was discharged to a rehabilitation centre.

Discussion

Tropheryma whipplei is one of the possible microorganisms classified as causing blood culture-negative endocarditis, with predominantly afebrile patients that do not fulfil the Dukes criteria, which makes it difficult to diagnose. Polymerase chain reaction is the cornerstone of the diagnosis. It requires long-term antibiotic treatment up to 12 months. It is recommended by the European Society of Cardiology to discuss treatment in an Endocarditis Team because Whipple's endocarditis has only rarely been described in the literature previously. Whipple's endocarditis has high mortality and relapse rates.

Epidemiology of Whipple's Disease in the USA Between 2012 and 2017: A Population-Based National Study

OBJECTIVE

Prior studies on the epidemiology of Whipple's disease are limited by small sample size and case series design. We sought to characterize the epidemiology of Whipple's disease in the USA utilizing a large population-based database.

METHODS

We queried a commercial database (Explorys Inc, Cleveland, OH), an aggregate of electronic health record data from 26 major integrated healthcare systems in the USA. We identified a cohort of patients with a diagnosis of Whipple's disease based on systemized nomenclature of medical terminology (SNOMED CT) codes. We calculated the overall and age-, race-, ethnicity, and gender-based prevalence of Whipple's disease and prevalence of associated diagnoses using univariate analysis.

RESULTS

A total of 35,838,070 individuals were active in the database between November 2012 and November 2017. Of these, 350 individuals had a SNOMED CT diagnosis of Whipple's disease, with an overall prevalence of 9.8 cases per 1 million. There was no difference in prevalence based on sex. However, prevalence of Whipple's disease was higher in Caucasians, non-Hispanics, and individuals > 65 years old. Individuals with a diagnosis of Whipple's disease were more likely to have associated diagnoses/findings of arthritis, CNS disease, endocarditis, diabetes, malignancy, dementia, vitamin D deficiency, iron deficiency, chemotherapy, weight loss, abdominal pain, and lymphadenopathy.

CONCLUSIONS

To our knowledge, this is the largest study to date examining the epidemiology of Whipple's disease. In this large population-based study, the overall prevalence of Whipple's disease in the USA is 9.8 cases per 1 million people. It affects men and women at similar rates and is more common in Caucasians, non-Hispanics, and people > 65 years old.

Peripheral-blood b-cell subset disturbances in inflammatory joint diseases induced by Tropheryma whipplei

Objective

To look for abnormalities in circulating B-cell subsets in patients with rheumatic symptoms of Whipple’s disease (WD).

Method

Consecutive patients seen between 2010 and 2016 for suspected inflammatory joint disease were identified retrospectively. Results of standardized immunological and serological tests and of peripheral-blood B-cell and T-cell subset analysis by flow cytometry were collected. Patients with criteria suggesting WD underwent PCR testing for Tropheryma whipplei, and those with diagnosis of WD (cases) were compared to those without diagnosis (controls). We used ROC curve analysis to evaluate the diagnostic value of flow cytometry findings for WD.

Results

Among 2917 patients seen for suspected inflammatory joint disease, 121 had suspected WD, including 9 (9/121, 7.4%) confirmed WD. Proportions of T cells and NK cells were similar between suspected and confirmed WD, whereas cases had a lower proportion of circulating memory B cells (IgD^-CD38^low, 18.0%±9.7% vs. 26.0%±14.2%, P = 0.041) and higher ratio of activated B cells over memory B cells (4.4±2.0 vs. 2.9±2.2, P = 0.023). Among peripheral-blood B-cells, the proportion of IgD+CD27- naive B cells was higher (66.2%±18.2% vs. 54.6%±18.4%, P = 0.047) and that of IgD-CD27+ switched memory B cells lower (13.3%±5.7% vs. 21.4%±11.9%, P = 0.023), in cases vs. controls. The criterion with the best diagnostic performance was a proportion of IgD+CD27- naive B cells above 70.5%, which had 73% sensitivity and 80% specificity.

Conclusion

Our study provides data on peripheral-blood B-cell disturbances that may have implications for the diagnosis and pathogenetic understanding of WD.

[The rich diversity of Whipple's disease]

Whipple's disease (WD) is a rare, chronic multiorgan disease which can caused by Tropheryma whipplei, a ubiquitous gram positive bacterium. Detection of T. whipplei is mostly performed histologically using periodic acid-Schiff (PAS) staining in affected tissues to visualize characteristic PAS-positive macrophages and by the polymerase chain reaction (PCR). Clinically, WD is often characterized by gastrointestinal symptoms (diarrhea, colic-like abdominal pain and weight loss). Arthritis is a common presentation of WS, often leading to a misdiagnosis of seronegative rheumatoid arthritis and as a consequence to immunosuppressive therapy. The clinical presentation of WD is highly polymorphic affecting different organ systems (e. g. cardiac or neurological manifestation) and making an appropriate clinical diagnosis and even the diagnostic process itself difficult. This article reports on three cases presenting with completely different leading symptoms (initially misdiagnosed as seronegative rheumatoid arthritis, spondyloarthritis and adult onset of Still's disease, respectively) that illustrate the rich diversity of WD. The cases were chosen to draw attention to the fact that although WD is mainly associated with the field of gastroenterology and gastrointestinal (GI) involvement is common, it may appear without GI symptoms. In cases of a clinical suspicion of WD, diagnostic efforts should be made to detect the bacterium in the affected organ. The German S2k guidelines on GI infections and WD published in January 2015 summarized the current state of the art for WD. The currently recommended primary treatment is antibiotics that can infiltrate the cerebrospinal fluid, e. g. ceftriaxone, followed by cotrimoxazole, which should be maintained over several months.

Non-neoplastic histiocytic and dendritic cell disorders in lymph nodes

Benign and malignant proliferations of histiocytes and dendritic cells may be encountered in lymph nodes. Reactive histiocytic and dendritic cell infiltrates occur in response to diverse stimuli and in addition to causing lymphadenopathy, may be present unexpectedly in lymph nodes excised for other indications. This review summarizes the pathogenesis and histopathological features of the various non-neoplastic histiocytic and dendritic cell infiltrates that can occur in lymph nodes.

Architectural and functional alterations of the small intestinal mucosa in classical Whipple's disease

Classical Whipple's disease (CWD) affects the gastrointestinal tract and rather elicits regulatory than inflammatory immune reactions. Mechanisms of malabsorption, diarrhea, and systemic immune activation are unknown. We here analyzed mucosal architecture, barrier function, and immune activation as potential diarrheal trigger in specimens from 52 CWD patients. Our data demonstrate villus atrophy and crypt hyperplasia associated with epithelial apoptosis and reduced alkaline phosphatase expression in the duodenum of CWD patients. Electrophysiological and flux experiments revealed increased duodenal permeability to small solutes and macromolecules. Duodenal architecture and permeability ameliorated upon antibiotic treatment. Structural correlates for these alterations were concordant changes of membranous claudin-1, claudin-2, claudin-3, and tricellulin expression. Tumor necrosis factor-α and interleukin-13 were identified as probable mediators of epithelial apoptosis, and altered tight junction expression. Increased serum markers of microbial translocation and their decline following treatment corroborated the biological significance of the mucosal barrier defect. Hence, mucosal immune responses in CWD elicit barrier dysfunction. Diarrhea is caused by loss of absorptive capacity and leak flux of ions and water. Downregulation of tricellulin causes increased permeability to macromolecules and subsequent microbial translocation contributes to systemic inflammation. Thus, therapeutic strategies to reconstitute the mucosal barrier and control inflammation could assist symptomatic control of CWD.

Clinical Manifestations, Treatment, and Diagnosis of Tropheryma whipplei Infections

Whipple's disease is a rare infectious disease that can be fatal if left untreated. The disease is caused by infection with Tropheryma whipplei, a bacterium that may be more common than was initially assumed. Most patients present with nonspecific symptoms, and as routine cultivation of the bacterium is not feasible, it is difficult to diagnose this infection. On the other hand, due to the generic symptoms, infection with this bacterium is actually quite often in the differential diagnosis. The gold standard for diagnosis used to be periodic acid-Schiff (PAS) staining of duodenal biopsy specimens, but PAS staining has a poor specificity and sensitivity. The development of molecular techniques has resulted in more convenient methods for detecting T. whipplei infections, and this has greatly improved the diagnosis of this often missed infection. In addition, the molecular detection of T. whipplei has resulted in an increase in knowledge about its pathogenicity, and this review gives an overview of the new insights in epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of Tropheryma whipplei infections.

Peripheral T-Cell Reactivity to Heat Shock Protein 70 and Its Cofactor GrpE from Tropheryma whipplei Is Reduced in Patients with Classical Whipple's Disease

Classical Whipple's disease (CWD) is characterized by the lack of specific Th1 response toward Tropheryma whipplei in genetically predisposed individuals. The cofactor GrpE of heat shock protein 70 (Hsp70) from T. whipplei was previously identified as a B-cell antigen. We tested the capacity of Hsp70 and GrpE to elicit specific proinflammatory T-cell responses. Peripheral mononuclear cells from CWD patients and healthy donors were stimulated with T. whipplei lysate or recombinant GrpE or Hsp70 before levels of CD40L, CD69, perforin, granzyme B, CD107a, and gamma interferon (IFN-γ) were determined in T cells by flow cytometry. Upon stimulation with total bacterial lysate or recombinant GrpE or Hsp70 of T. whipplei, the proportions of activated effector CD4⁺ T cells, determined as CD40L⁺ IFN-γ⁺, were significantly lower in patients with CWD than in healthy controls; CD8⁺ T cells of untreated CWD patients revealed an enhanced activation toward unspecific stimulation and T. whipplei-specific degranulation, although CD69⁺ IFN-γ⁺ CD8⁺ T cells were reduced upon stimulation with T. whipplei lysate and recombinant T. whipplei-derived proteins. Hsp70 and its cofactor GrpE are immunogenic in healthy individuals, eliciting effective responses against T. whipplei to control bacterial spreading. The lack of specific T-cell responses against these T. whipplei-derived proteins may contribute to the pathogenesis of CWD.

Whipple's disease

In recent years, it has become apparent that Tropheryma whipplei not only causes a chronic multisystemic infection which is often preceded by arthropathies for many years, well known as 'classical' Whipple's disease, but also clinically becomes manifest with localized organ affections and acute (transient) infections in children. T. whipplei is found ubiquitously in the environment and colonizes in some healthy carriers. In this review, we highlight new aspects of this enigmatic infectious disorder.

Tropheryma whipplei infection and Whipple's disease

Recent advances in medical microbiology, epidemiology, cellular biology, and the availability of an expanded set of diagnostic methods such as histopathology, immunohistochemistry, PCR, and bacterial culture have improved our understanding of the clinical range and natural course of Tropheryma whipplei infection and Whipple's disease. Interdisciplinary and transnational research activities have contributed to the clarification of the pathogenesis of the disorder and have enabled controlled trials of different treatment strategies. We summarise the current knowledge and new findings relating to T whipplei infection and Whipple's disease.

Systematic review: Whipple's disease (Tropheryma whipplei infection) and its unmasking by tumour necrosis factor inhibitors

BACKGROUND

The classical form of Whipple's disease (WD), clinically characterised by arthropathy, diarrhoea and weight loss, is rare. Recently, other more frequent forms of Tropheryma whipplei infection have been recognised. The clinical spectrum includes an acute, self-limiting disease in children, localised forms affecting cardiac valves or the central nervous system without intestinal symptoms, and asymptomatic carriage of T. whipplei which is found in around 4% of Europeans. Genomic analysis has shown that T. whipplei represents a host-dependent or opportunistic bacterium. It has been reported that the clinical course of T. whipplei infection may be influenced by medical immunosuppression.

AIM

To identify associations between immunomodulatory treatment and the clinical course of T. whipplei infection.

METHODS

A PubMed literature search was performed and 19 studies reporting on immunosuppression, particularly therapy with tumour necrosis factor inhibitors (TNFI) prior to the diagnosis in 41 patients with Whipple?s disease, were evaluated.

RESULTS

As arthritis may precede the diagnosis of WD by many years, a relevant percentage (up to 50% in some reports) of patients are treated with immunomodulatory drugs or with TNFI. Many publications report on a complicated Whipple?s disease course or T. whipplei endocarditis following medical immunosuppression, particularly after TNFI. Standard diagnostic tests such as periodic acid-Schiff stain used to diagnose Whipple?s disease often fail in patients who are pre-treated by TNFI.

CONCLUSIONS

In cases of doubt, Whipple?s disease should be excluded before therapy with TNFI. The fact that immunosuppressive therapy contributes to the progression of T. whipplei infection expands our pathogenetic view of this clinical entity.

Role of dendritic cells in the pathogenesis of Whipple's disease

Accumulation of Tropheryma whipplei-stuffed macrophages in the duodenum, impaired T. whipplei-specific Th1 responses, and weak secretion of interleukin-12 (IL-12) are hallmarks of classical Whipple's disease (CWD). This study addresses dendritic cell (DC) functionality during CWD. We documented composition, distribution, and functionality of DC ex vivo or after in vitro maturation by fluorescence-activated cell sorting (FACS) and by immunohistochemistry in situ. A decrease in peripheral DC of untreated CWD patients compared to healthy donors was due to reduced CD11c(high) myeloid DC (M-DC). Decreased maturation markers CD83, CD86, and CCR7, as well as low IL-12 production in response to stimulation, disclosed an immature M-DC phenotype. In vitro-generated monocyte-derived DC from CWD patients showed normal maturation and T cell-stimulatory capacity under proinflammatory conditions but produced less IL-12 and failed to activate T. whipplei-specific Th1 cells. In duodenal and lymphoid tissues, T. whipplei was found within immature DC-SIGN(+) DC. DC and proliferating lymphocytes were reduced in lymph nodes of CWD patients compared to levels in controls. Our results indicate that dysfunctional IL-12 production by DC provides suboptimal conditions for priming of T. whipplei-specific T cells during CWD and that immature DC carrying T. whipplei contribute to the dissemination of the bacterium.

Widespread colonization of the lung by Tropheryma whipplei in HIV infection

RATIONALE

Lung infections caused by opportunistic or virulent pathogens are a principal cause of morbidity and mortality in HIV infection. It is unknown whether HIV infection leads to changes in basal lung microflora, which may contribute to chronic pulmonary complications that increasingly are being recognized in individuals infected with HIV.

OBJECTIVES

To determine whether the immunodeficiency associated with HIV infection resulted in alteration of the lung microbiota.

METHODS

We used 16S ribosomal RNA targeted pyrosequencing and shotgun metagenomic sequencing to analyze bacterial gene sequences in bronchoalveolar lavage (BAL) and mouths of 82 HIV-positive and 77 HIV-negative subjects.

MEASUREMENTS AND MAIN RESULTS

Sequences representing Tropheryma whipplei, the etiologic agent of Whipple's disease, were significantly more frequent in BAL of HIV-positive compared with HIV-negative individuals. T. whipplei dominated the community (>50% of sequence reads) in 11 HIV-positive subjects, but only 1 HIV-negative individual (13.4 versus 1.3%; P = 0.0018). In 30 HIV-positive individuals sampled longitudinally, antiretroviral therapy resulted in a significantly reduced relative abundance of T. whipplei in the lung. Shotgun metagenomic sequencing was performed on eight BAL samples dominated by T. whipplei 16S ribosomal RNA. Whole genome assembly of pooled reads showed that uncultured lung-derived T. whipplei had similar gene content to two isolates obtained from subjects with Whipple's disease.

CONCLUSIONS

Asymptomatic subjects with HIV infection have unexpected colonization of the lung by T. whipplei, which is reduced by effective antiretroviral therapy and merits further study for a potential pathogenic role in chronic pulmonary complications of HIV infection.

Whipple's Disease: Our Own Experience and Review of the Literature

Whipple's disease is a chronic infectious systemic disease caused by the bacterium Tropheryma whipplei. Nondeforming arthritis is frequently an initial complaint. Gastrointestinal and general symptoms include marked diarrhoea (with serious malabsorption), abdominal pain, prominent weight loss, and low-grade fever. Possible neurologic symptoms (up to 20%) might be associated with worse prognosis. Diagnosis is based on the clinical picture and small intestinal histology revealing foamy macrophages containing periodic-acid-Schiff- (PAS-) positive material. Long-term (up to one year) antibiotic therapy provides a favourable outcome in the vast majority of cases. This paper provides review of the literature and an analysis of our 5 patients recorded within a 20-year period at a tertiary gastroenterology centre. Patients were treated using i.v. penicillin G or amoxicillin-clavulanic acid + i.v. gentamicin for two weeks, followed by p.o. doxycycline (100 mg per day) plus p.o. salazopyrine (3 g per day) for 1 year. Full remission was achieved in all our patients.

Whipple disease a century after the initial description: increased recognition of unusual presentations, autoimmune comorbidities, and therapy effects

Although Whipple disease was described over a century ago, it remains challenging to recognize. To better understand the presentation of Whipple disease, we undertook a clinicopathologic study of our experience since implementation of the Whipple immunohistochemical stain. Twenty-three biopsy specimens from 15 patients were identified, and an association with immunomodulatory conditions was noted. Whipple disease involved the small intestine (19), brain (2), breast (1), and retroperitoneum (1). Whipple disease was suspected by 3 clinicians and by the majority of pathologists (9). Alternative clinical impressions included lymphoma, celiac disease, Crohn vasculitis, sepsis, an inflammatory process, liposarcoma, rheumatoid arthritis, seizure disorder, cerebrovascular accident, xanthoma, and central nervous system neoplasm. The nonspecific nature of the disease presentation likely contributed to the extended period between onset of symptoms and a definitive diagnosis, which ranged from at least 1 year to over 10 years. One patient died of unknown causes, and both patients with detailed follow-up had clinically persistent disease. We also describe Whipple disease with therapy effects, including partial and complete histologic treatment effects. Awareness of the unusual clinicopathologic presentations of Whipple disease is essential for timely diagnosis of this potentially lethal disease.

Macrophage-related diseases of the gut: a pathologist's perspective

The resident macrophages of the gastrointestinal tract represent the largest population of macrophages in the human body and are usually located in the subepithelial lamina propria. This strategic location guarantees a first-line defense to the huge numbers of potentially harmful bacteria and antigenic stimuli that are present in the intestinal lumen. In non-inflamed mucosa, macrophages phagocytose and kill microbes in the absence of an inflammatory response. However, in the event of an epithelial breach and/or microbial invasion, new circulating monocytes and lymphocytes will be recruited to the damaged area of the gut, which will result in the secretion of proinflammatory mediators and engage a protective inflammatory response. Although macrophages are usually not conspicuous in normal mucosal samples of the gut, they can easily be detected when they accumulate exogenous particulate material or endogenous substances or when they become very numerous. These events will mostly occur in pathologic conditions, and this review presents an overview of the diseases which are either mediated by or affecting the resident macrophages of the gut.

Regulatory T cells in patients with Whipple's disease

Classical Whipple's disease (CWD) is caused by chronic infection with Tropheryma whipplei that seems to be associated with an underlying immune defect. The pathognomonic hallmark of CWD is a massive infiltration of the duodenal mucosa with T. whipplei-infected macrophages that disperse systemically to many other organ systems. An alleviated inflammatory reaction and the absence of T. whipplei-specific Th1 reactivity support persistence and systemic spread of the pathogen. In this article, we hypothesized that regulatory T cells (T(reg)) are involved in immunomodulation in CWD, and we asked for the distribution, activation, and regulatory capacity of T(reg) in CWD patients. Whereas in the lamina propria of CWD patients before treatment numbers of T(reg) were increased, percentages in the peripheral blood were similar in CWD patients and healthy controls. However, peripheral T(reg) of CWD patients were more activated than those of controls. Elevated secretion of IL-10 and TGF-β in the duodenal mucosa of CWD patients indicated locally enhanced T(reg) activity. Enhanced CD95 expression on peripheral memory CD4(+) T cells combined with reduced expression of IFN-γ and IL-17A upon polyclonal stimulation by CD4(+) cells from untreated CWD patients further hinted to T(reg) activity-related exhaustion of effector CD4(+) T cells. In conclusion, increased numbers of T(reg) can be detected within the duodenal mucosa in untreated CWD, where huge numbers of T. whipplei-infected macrophages are present. Thus, T(reg) might contribute to the chronic infection and systemic spread of T. whipplei in CWD but in contrast prevent mucosal barrier defect by reducing local inflammation.

Specific and nonspecific B-cell function in the small intestines of patients with Whipple's disease

Whipple's disease is a chronic multisystemic infection caused by Tropheryma whipplei that is characterized by arthritis, weight loss, and diarrhea. The immunological defects in the duodenal mucosa, the site of major replication of the agent underlying the pathogenesis of Whipple's disease, are poorly understood. Mucosal immunoglobulins are essential for the defense against intestinal pathogens; therefore, we analyzed the B-cell response in duodenal specimens and sera of Whipple's disease patients. Whereas systemic immunoglobulin production was affected only marginally, duodenal biopsy specimens of Whipple's disease patients contained reduced numbers of immunoglobulin-positive plasma cells and secreted less immunoglobulin compared to healthy controls but showed a weak secretory IgA response toward T. whipplei. This T. whipplei-specific intestinal immune response was not observed in controls. Thus, we were able to demonstrate that general mucosal immunoglobulin production in Whipple's disease patients is impaired. However, this deficiency does not completely abolish T. whipplei-specific secretory IgA production that nonetheless does not protect from chronic infection.

Interleukin 12 a key immunoregulatory cytokine in infection applications

Interleukin 12 (termed IL-12p70 and commonly designated IL-12) is an important immunoregulatory cytokine that is produced mainly by antigen-presenting cells. The expression of IL-12 during infection regulates innate responses and determines the type of adaptive immune responses. IL-12 induces interferon-γ (IFN-γ) production and triggers CD4⁺ T cells to differentiate into type 1 T helper (Th1) cells. Studies have suggested that IL-12 could play a vital role in treating many diseases, such as viral and bacterial infections and cancers. The unique heterodimeric structure, which IL-12 shares with its family members including IL-23, IL-27, and IL-35, has recently brought more attention to understanding the mechanisms that regulate the functions of IL-12. This article describes the structure and biological activities of IL-12 in both the innate and adaptive arms of the immune system, and discusses the applications of IL-12 in treating and preventing infections.

Impaired immune functions of monocytes and macrophages in Whipple's disease

BACKGROUND & AIMS

Whipple's disease is a chronic multisystemic infection caused by Tropheryma whipplei. Host factors likely predispose for the establishment of an infection, and macrophages seem to be involved in the pathogenesis of Whipple's disease. However, macrophage activation in Whipple's disease has not been studied systematically so far.

METHODS

Samples from 145 Whipple's disease patients and 166 control subjects were investigated. We characterized duodenal macrophages and lymphocytes immunohistochemically and peripheral monocytes by flow cytometry and quantified mucosal and systemic cytokines and chemokines indicative for macrophage activation. In addition, we determined duodenal nitrite production and oxidative burst induced by T whipplei and by other bacteria.

RESULTS

Reduced numbers of duodenal lymphocytes, increased numbers of CD163(+) and stabilin-1(+), reduced numbers of inducible nitric synthase+ duodenal macrophages, and increased percentages of CD163(+) peripheral monocytes indicated a lack of inflammation and a M2/alternatively activated macrophage phenotype in Whipple's disease. Incubation with T whipplei in vitro enhanced the expression of CD163 on monocytes from Whipple's disease patients but not from control subjects. Chemokines and cytokines associated with M2/alternative macrophage activation were elevated in the duodenum and the peripheral blood from Whipple's disease patients. Functionally, Whipple's disease patients showed a reduced duodenal nitrite production and reduced oxidative burst upon incubation with T whipplei compared with healthy subjects.

CONCLUSIONS

The lack of excessive local inflammation and alternative activation of macrophages, triggered in part by the agent T whipplei itself, may explain the hallmark of Whipple's disease: invasion of the intestinal mucosa with macrophages incompetent to degrade T whipplei.

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.

[Whipple's disease]

Whipple's disease is a chronic, multisystemic, curable, bacterial infection that usually affects middle-aged men. It has a wide range of clinical manifestations. In the historical presentation, weight loss and diarrhoea are the most common symptoms and are preceded in three-quarters of cases by arthritis for a mean of six years. Long-term, unexplained, seronegative oligoarthritis or polyarthritis of large joints with a palindromic or relapsing course is typical. In most patients, periodic acid-Schiff staining of proximal small bowel biopsy specimens reveals inclusions within the macrophages, corresponding to bacterial structures. However, patients may have no gastrointestinal symptoms, negative jejunum biopsy results and even negative PCR tests. Even in the absence of gastrointestinal symptoms, Whipple's disease should be considered in case of negative blood culture endocarditis, unexplained central neurological manifestations or unexplained arthritis. Identification of the causative bacterium, Tropheryma whipplei, has led to the development of PCR as a diagnostic tool, particularly useful in patients in the early stages of the disease or with atypical disease. The recent cultivation of T. whipplei and the complete sequencing of its genome should improve our understanding and treatment of the disease. The future development of an assay for detection of specific antibodies in the serum and generalization of the immunohistochemical detection of antigenic bacterial structures may allow earlier diagnosis, thereby preventing the development of the severe late systemic and sometimes fatal forms of the disease.

Whipple's disease: new aspects of pathogenesis and treatment

100 years after its first description by George H Whipple, the diagnosis and treatment of Whipple's disease is still a subject of controversy. Whipple's disease is a chronic multisystemic disease. The infection is very rare, although the causative bacterium, Tropheryma whipplei, is ubiquitously present in the environment. We review the epidemiology of Whipple's disease and the recent progress made in the understanding of its pathogenesis and the biology of its agent. The clinical features of Whipple's disease are non-specific and sensitive diagnostic methods such as PCR with sequencing of the amplification products and immunohistochemistry to detect T whipplei are still not widely distributed. The best course of treatment is not completely defined, especially in relapsing disease, neurological manifestations, and in cases of immunoreconstitution after initiation of antibiotic treatment. Patients without the classic symptoms of gastrointestinal disease might be misdiagnosed or insufficiently treated, resulting in a potentially fatal outcome or irreversible neurological damage. Thus, we suggest procedures for the improvement of diagnosis and an optimum therapeutic strategy.

Possible case of CNS Whipple's disease in an adolescent with AIDS

An adolescent with HIV/AIDS presented subacutely with progressive encephalopathy, spastic quadraplegia, and diarrhea. His brain biopsy was suggestive of central nervous system Whipple's disease, a disease rarely described in HIV patients. Due to overlapping, nonspecific symptoms associated with several opportunistic infections and to the difficulty in culturing the causative organism Tropheryma whipplei, Whipple's disease may be more common than previously suspected, and it is an important consideration in patients with AIDS.

Whipple disease

PURPOSE OF REVIEW

The availability of and advantages in molecular technology and immunology have led to an improved understanding of the etiology and pathogenesis of Whipple disease. As this rare infection represents a model disease reflecting the input of novel findings into clinical medicine and therapy, this review intends to highlight newer findings and put them in context.

RECENT FINDINGS

Sequencing of 16S rRNA allowed the phylogeny of the bacterium to be determined. The culture and subsequent genome analysis have led to improved diagnosis and monitoring of the disease, for example by PCR or immunohistochemistry. New experimental approaches hint of defects in T-cell and macrophage immunity in patients. Antibiotic therapy will soon be based on data from the first prospective therapy study.

SUMMARY

Within a few years the findings from molecular genetics and immunology as well as concerted research activities from the European Consortium on Whipple Disease which established a data and material bank could be translated into clinical medicine. Thus, for patients with Whipple disease an improved basis for diagnosis and therapy have been achieved.

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's disease: current problems]

Whipple's disease is a rare multisystemic infectious disease of bacterial origin characterized by variable clinical manifestations, and an insidious and chronic relapsing course. Untreated disease can be even fatal. The presence of the characteristic (though not specific) triad of weight loss, chronic diarrhea and arthralgias may raise its suspicion. When chronic intermittent fever and lymphadenopathy are associated, the suspicion is substantial. Recognition of the causative agent, Tropheryma whippelii with unique characteristics was essential. Despite the presumed ubiquitous presence of the bacteria the disease probably occurs only in cases of immunological host susceptibility. Presence of the bacteria living and multiplying especially in macrophages has suggested alterations of the mononuclear-phagocytic system. (Whipple's disease is commonly mentioned as a macrophage disorder.) Clinical manifestations are quite diverse. While it has traditionally been regarded as a gastrointestinal disease, currently is considered to be a systemic disorder. In cases of suspected infection the approach of first choice is upper gastrointestinal endoscopy. Small, whitish-yellow diffusely distributed plaques alternating with an erythematous, erosive, friable mucosa in the postbulbar region of the duodenum or in the jejunum can appear. Histological samples indicate tissue infiltration of macrophages with intracellular bacterial invasion. The hallmark of Whipple's disease is the presence of PAS positive macrophages in the lamina propria of duodenal biopsy specimens, still the diagnosis needs to be confirmed with the detection of bacteria by PCR. The selection of antibiotics and duration of treatment still remains largely empiric.

Murine model of infection by Tropheryma whipplei

We developed an animal model reproducing several aspects of Whipple's disease. Immunocompetent mice were persistently infected with Tropheryma whipplei, its etiological agent, and developed liver granulomas. SCID mice were infected similarly but did not develop tissue lesions. The delayed clearance of T. whipplei suggests a protective role for innate immunity.

Reduced Peripheral and MucosalTropheryma whipplei-Specific Th1 Response in Patients with Whipple’s Disease

Whipple's disease is a rare infectious disorder caused by Tropheryma whipplei. Major symptoms are arthropathy, weight loss, and diarrhea, but the CNS and other organs may be affected, too. The incidence of Whipple's disease is very low despite the ubiquitous presence of T. whipplei in the environment. Therefore, it has been suggested that host factors indicated by immune deficiencies are responsible for the development of Whipple's disease. However, T. whipplei-specific T cell responses could not be studied until now, because cultivation of the bacteria was established only recently. Thus, the availability of T. whipplei Twist-Marseille(T) has enabled the first analysis of T. whipplei-specific reactivity of CD4(+) T cells. A robust T. whipplei-specific CD4(+) Th1 reactivity and activation (expression of CD154) was detected in peripheral and duodenal lymphocytes of all healthy (16 young, 27 age-matched, 11 triathletes) and disease controls (17 patients with tuberculosis) tested. However, 32 Whipple's disease patients showed reduced or absent T. whipplei-specific Th1 responses, whereas their capacity to react to other common Ags like tetanus toxoid, tuberculin, actinomycetes, Giardia lamblia, or CMV was not reduced compared with controls. Hence, we conclude that an insufficient T. whipplei-specific Th1 response may be responsible for an impaired immunological clearance of T. whipplei in Whipple's disease patients and may contribute to the fatal natural course of the disease.