Human galectin-1 and galectin-3 promote Tropheryma whipplei infection.

Tropheryma whipplei, is an actinobacterium that causes different infections in humans, including Whipple's disease. The bacterium infects and replicates in macrophages, leading to a Th2-biased immune response. Previous studies have shown that T. whipplei harbors complex surface glycoproteins with evidence of sialylation. However, the exact contribution of these glycoproteins for infection and survival remains obscure. To address this, we characterized the bacterial glycoprofile and evaluated the involvement of human ß-galactoside-binding lectins, Galectin-1 (Gal-1) and Galectin-3 (Gal-3) which are highly expressed by macrophages as receptors for bacterial glycans. Tropheryma whipplei glycoproteins harbor different sugars including glucose, mannose, fucose, ß-galactose and sialic acid. Mass spectrometry identification revealed that these glycoproteins were membrane- and virulence-associated glycoproteins. Most of these glycoproteins are highly sialylated and N-glycosylated while some of them are rich in poly-N-acetyllactosamine (Poly-LAcNAc) and bind Gal-1 and Gal-3. In vitro, T. whipplei modulates the expression and cellular distribution of Gal-1 and Gal-3. Although both galectins promote T. whipplei infection by enhancing bacterial cell entry, only Gal-3 is required for optimal bacterial uptake. Finally, we found that serum levels of Gal-1 and Gal-3 were altered in patients with T. whipplei infections as compared to healthy individuals, suggesting that galectins are also involved in vivo. Among T. whipplei membrane-associated proteins, poly-LacNAc rich-glycoproteins promote infection through interaction with galectins. T. whipplei modulates the expression of Gal-1 and Gal-3 both in vitro and in vivo. Drugs interfering with galectin-glycan interactions may provide new avenues for the treatment and diagnosis of T. whipplei infections.

Tropheryma whipplei, the agent of Whipple's disease, affects the early to late phagosome transition and survives in a Rab5- and Rab7-positive compartment.

Tropheryma whipplei, the agent of Whipple's disease, inhibits phago-lysosome biogenesis to create a suitable niche for its survival and replication in macrophages. To understand the mechanism by which it subverts phagosome maturation, we used biochemical and cell biological approaches to purify and characterise the intracellular compartment where Tropheryma whipplei resides using mouse bone-marrow-derived macrophages. We showed that in addition to Lamp-1, the Tropheryma whipplei phagosome is positive for Rab5 and Rab7, two GTPases required for the early to late phagosome transition. Unlike other pathogens, inhibition of PI(3)P production was not the mechanism for Rab5 stabilisation at the phagosome. Overexpression of the inactive, GDP-bound form of Rab5 bypassed the pathogen-induced blockade of phago-lysosome biogenesis. This suggests that Tropheryma whipplei blocks the switch from Rab5 to Rab7 by acting on the Rab5 GTPase cycle. A bio-informatic analysis of the Tropheryma whipplei genome revealed a glyceraldehyde-3-phosphate dehydrogenase (GAPDH) homologous with the GAPDH of Listeria monocytogenes, and this may be the bacterial protein responsible for blocking Rab5 activity. To our knowledge, Tropheryma whipplei is the first pathogen described to induce a "chimeric" phagosome stably expressing both Rab5 and Rab7, suggesting a novel and specific mechanism for subverting phagosome maturation.

Evaluation of arginine metabolism for the analysis of M1/M2 macrophage activation in human clinical specimens.

BACKGROUND: Macrophage heterogeneity reflects their plasticity in response to environmental stimuli. Usually human macrophages are characterized by analysis of surface molecules or cytokine expression while functional assays are established in the mouse system but lacking for various human specimens. METHODS: To evaluate the value of analysis of arginine metabolism for characterization of human macrophage differentiation, we analyzed nitrite production and arginase activity in plasma, duodenal biopsies, and in vitro differentiated macrophages of patients with classical Whipple's disease. RESULTS: We demonstrate that it is feasible to determine the content of urea in supernatants of stimulated duodenal biopsies, arginase activity in fresh duodenal biopsies and plasma samples, and arginase activity and nitrite production in lysates and supernatants of in vitro differentiated macrophages. However, only selected tests are appropriate to define macrophage polarization in human specimens. CONCLUSION: Analysis of arginine metabolism is not suitable for the characterization of in vitro differentiated human macrophages. Besides the measurement of nitrite in duodenal biopsy supernatants, the determination of arginase activity in human plasma seems to be a reasonable functional test to detect enhanced M2 macrophage activation and, thus, is of great value for the analysis of macrophage activity with a minimum of material and costs.

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.

An atypical case of Whipple's disease: case report and review of the literature.

We report the case of a 57-year-old man, presenting with bilateral panuveitis, bilateral sacroiliitis, intermittent pyrexia and a pulmonary nodule. The patient had been under immunosuppressive treatment for 2 years for Behçet's disease. However, he did not fulfill the diagnostic criteria of Behçet's disease. Blood analysis showed a very high C reactive protein (CRP at 34 mg/dl). In view of severe intra-ocular inflammation, the anterior chamber was punctured. Polymerase chain reaction (PCR) on the aqueous humour and on the blood revealed the presence of Tropheryma whippelii DNA, an agent responsible for Whipple's disease. The patient was treated with ceftriaxone followed by trimethoprim-sulfamethoxazol for 1 year with good clinical and biological evolution. This case illustrates the difficulty to diagnose an atypical Whipple's disease. In cases of uveitis with atypical signs and/or not responding to the treatment, the internist must consider to perform an analysis of the ocular fluids.

Whipple disease: intestinal infiltrating cells exhibit a transcriptional pattern of M2/alternatively activated macrophages.

Whipple disease (WD) is a rare systemic disease caused by Tropheryma whipplei and is characterized by the presence of foamy macrophages with periodic acid-Schiff-positive inclusions in tissues such as lamina propria. For the first time, we report the gene-expression profile of macrophages in intestinal lesions from a patient with WD. Microarray and real-time polymerase chain reaction revealed that genes encoding CCL18, cathepsins, scavenger receptor, interleukin-10, and lipid metabolites were up-regulated in intestinal lesions. This transcriptional pattern corresponds to that of M2/alternatively activated macrophages. Our results suggest that the T helper 2 response in the intestinal environment may account for the pathophysiological properties of WD.

IL-16 is critical for Tropheryma whipplei replication in Whipple's disease.

Whipple's disease (WD) is a rare systemic disease caused by Tropheryma whipplei. We showed that T. whipplei was eliminated by human monocytes but replicated in monocyte-derived macrophages (Mphi) by inducing an original activation program. Two different host molecules were found to be key elements for this specific pattern. Thioredoxin, through its overexpression in infected monocytes, was involved in bacterial killing because adding thioredoxin to infected Mphi inhibited bacterial replication. IL-16, which was up-regulated in Mphi, enabled T. whipplei to replicate in monocytes and increased bacterial replication in Mphi. In addition, anti-IL-16 Abs abolished T. whipplei replication in Mphi. IL-16 down-modulated the expression of thioredoxin and up-regulated that of IL-16 and proapoptotic genes. In patients with WD, T. whipplei replication was higher than in healthy subjects and was related to high levels of circulating IL-16. Both events were corrected in patients who successfully responded to antibiotics treatment. This role of IL-16 was not reported previously and gives an insight into the understanding of WD pathophysiology.

Whipple's disease: immunospecific and quantitative immunohistochemical study of intestinal biopsy specimens.

Whipple's disease may be diagnosed by periodic acid-Schiff (PAS) staining, electron microscopy, or polymerase chain reaction of intestinal biopsy specimens. The aim of this study was to evaluate the diagnostic value of immunohistochemistry and the quantification of infected cells in intestinal Whipple's disease. A total of 29 duodenal biopsy specimens from 15 patients with untreated and treated Whipple's disease were examined and compared with biopsy specimens from control patients with normal intestinal mucosa or various pathologic processes. Percentages of staining surfaces with PAS stain and antibodies directed against CD68, a macrophage marker, or the Whipple bacillus, Tropheryma whipplei, were studied quantitatively using a computerized system of image analysis. Positive detection of T. whipplei was obtained using immunohistochemistry in all 15 patients with Whipple's disease. No bacteria were detected in any of the negative controls. The use of quantitative image analysis showed a massive intestinal macrophagic infiltration before (20.3%) and after (13.4%) antibiotic therapy completion as compared with controls (2.1%). The 2 detection methods for T. whipplei, PAS stain and immunohistochemistry, were quantitatively similar before therapy (19.9% versus 17.5%), but the immunodetection-based surface area was significantly lower than the PAS staining surface area after therapy (2.8% versus 7.9%). Our findings indicate that immunohistochemistry is highly specific and sensitive and is applicable as a diagnostic method on intestinal tissue specimens to detect T. whipplei during active infection or in retrospective studies.

Iron loading: a risk factor for Whipple's disease?

Because of impairment of microbial iron acquisition ability, some potential pathogens can cause disease only in iron loaded hosts. Tropheryma whippelii, the etiologic agent of Whipple's disease, is a possible example. Whipple's disease is non-contagious, occurs mainly in middle-aged white males, and displays many, but not all, of the complications of hereditary haemochromatosis. Tropheryma whippelii is a gastrointestinal commensal that causes disease in persons who have a Th1-Th2 imbalance. Host susceptibility may be exacerbated by iron loading. Consideration should be given to have patients evaluated for levels of interferon-gamma and interleukin-4 as well as for serum ferritin and transferrin iron saturation.

Smooth muscle distribution in the extrahepatic bile duct: histologic and immunohistochemical studies of 122 cases.

The distribution of smooth muscle fibers in the extrahepatic bile duct (EBD) wall is not well characterized. We analyzed 101 consecutive Whipple's operation specimens and 21 autopsy specimens for the pattern of smooth muscle distribution in EBD using the Masson-trichrome stain and the desmin immunohistochemical stain. The patterns were categorized as continuous, interrupted, scattered, and no muscle layer. EBDs were divided into lower, middle, and upper portions, and the distribution pattern of smooth muscle fibers was analyzed separately in each portion. Because most surgically resected specimens contained the middle and lower EBDs with only a portion of the upper EBD, only the length of the middle and lower EBDs (common bile duct, CBD) was measured. The mean length of CBD in surgically resected specimens was 6.4 +/- 1.4 cm (men, 6.6 +/- 1.3 cm; women, 6.1 +/- 1.5 cm). The mean length of CBD in autopsy specimens was 6.8 +/- 1.0 cm. The predominant patterns of the lower third of the EBD were interrupted (49%) and continuous (43%). The predominant patterns of the middle third of the EBD were scattered (63%) and interrupted (23%). Those of the upper third of the EBD were no muscle fiber (58%) and scattered (39%). In conclusion, different patterns of smooth muscle distribution were observed in different portions of the EBD. Because scattered muscle fibers or no muscle fibers were the main features of the upper third of the EBD, understanding of this pattern may be helpful for assessment of the depth of invasion or staging of carcinoma of the upper third of the EBD.

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

BACKGROUND & AIMS: Whipple's disease (WD) is a systemic infection in which the causative bacteria typically accumulate within macrophages. The aim of this study was to test whether this macrophage dysfunction is the cause or result of previously shown T-cell defects. METHODS: In vitro production of interleukin (IL)-12, IL-10, tumor necrosis factor alpha, interferon gamma (IFN-gamma), and transforming growth factor beta (TGF-beta) from purified monocytes and peripheral blood mononuclear cells, cytokine expression on duodenal biopsy specimens, and serum cytokine and immunoglobulin (Ig) levels were tested in 9 patients with WD. RESULTS: Reduced monocyte IL-12 production and decreased IFN-gamma secretion by peripheral blood mononuclear cells in vitro were found, as well as reduced immunohistological staining for IL-12 and IFN-gamma, but no decrease in other cytokines in patients with WD. A similar but less severe defect in 2 relatives with WD argued for a genetic basis of this abnormality. Serum IgG2, an IFN-gamma-dependent Ig subclass, and serum TGF-beta levels were reduced in patients with WD. CONCLUSIONS: The described monocyte defects in WD may result in a secondary reduction of IFN-gamma production and IgG2 serum levels. This provides a rationale for additive immunotherapy in patients with antibiotic-refractory WD.

[Whipple's disease with reactive (AA) amyloidosis]. / Morbus Whipple mit reaktiver (AA-)Amyloidose.

A 59-year-old man had been known for two years to have a clearly elevated blood sedimentation reaction and intermittent arthralgia in the hand. His general condition had progressively deteriorated over the last six months, with weight loss, recurrent vomiting and constipation. At first malignant lymphoma had been suspected because numerous lymph nodes were enlarged. But a lymph-node biopsy revealed massive macrophages with PAS-positive inclusion material, diagnosed as Whipple's disease. The patient died suddenly of a heart attack on the day of diagnosis. At necropsy generalized amyloidosis with marked cardiac involvement was found. Immunohistochemically the amyloid deposits gave a strongly positive reaction to anti-AA, while other amyloid syndromes were excluded using appropriate anti-sera. This was therefore a case of reactive (AA) amyloidosis in the presence of Whipple's disease.

Enteric protein loss in various gastrointestinal diseases determined by intestinal alpha 1-antitrypsin clearance.

Intestinal protein loss was measured by means of faecal alpha 1-antitrypsin clearance (alpha 1 ATC) in patients with various gastrointestinal diseases. In healthy controls and in patients with various gastrointestinal diseases there is a remarkable intraindividual fluctuation of the faecal protein loss from day to day. Alpha 1 AT clearance calculated from a three-day stool collection is usually sufficient to indicate enteric protein loss in Crohn's disease, ulcerative colitis, celiac sprue, and Whipple's disease. However, in two patients with intermittent diarrhea coinciding with edema and hypalbuminemia excessive enteric protein loss was observed on one day during a two week stool sampling period only. In one of these patients suction biopsies showed histologically intestinal lymphangiectasia of a 10 cm segment of the upper jejunum. The alpha 1 ATC is a suitable and cheap method to determine enteric protein loss without the use of radioactive tracers and therefore can be used in clinics without departments of nuclear medicine. In contrast to the conventional Gordon test the use of the endogenous marker alpha 1 AT facilitates the determination of faecal protein loss over long time periods, which might be of value in the diagnosis of intermittent occurring enteric protein loss. Furthermore, the endogenous marker alpha 1 AT is of use in following the course of illness and in monitoring the efficacy of therapy in patients with enteric protein loss.

Periodic acid-Schiff-negative granulomatous lymphadenopathy in patients with Whipple's disease. Localization of the Whipple bacillus to noncaseating granulomas by electron microscopy.

The diagnosis of Whipple's disease in a 58-year-old man was based on the finding of periodic acid-Schiff (PAS)-positive foamy macrophages on duodenal biopsy and demonstration of the typical bacilliform bodies by electron microscopy. The patient also had generalized peripheral lymphadenopathy with lymph node biopsy showing PAS-negative noncaseating granulomas. Electron microscopic examination of the lymph node specimen demonstrated a small number of typical bacilliform bodies with localization specifically to the granulomas in the lymph node. This finding of bacilliform bodies within PAS-negative noncaseating granulomas has not been reported previously. Localization of the Whipple bacillus specifically to noncaseating granulomas suggests that some patients with the disease may manifest a delayed hypersensitivity reaction to the bacillus.

[Oxalic acid resorption in patients with resection of the small intestine, jejunoileal bypass, Crohn disease and chronic pancreatitis]. / Oxalsäureresorption bei Patienten mit Dünndarmresektion, jejunoilealem Bypass, Morbus Crohn und chronischer Pankreatitis.

The enteric absorption of oxalic acid with 14C-labelled oxalic acid was determined in patients with small bowel resection, jejunoileal bypass, Crohn's disease and chronic pancreatitis in comparison to the control group. Extreme hyperoxaluria were found in small bowel resections above 100 cm, after bypass operations and in ileocolitis Crohn with signs of clinical activity. Small bowel resections and relapses of Crohn's disease increase the absorption of oxalic acid. The significance of 14C-oxalic acid absorption test is the recognition of enteric hyperoxaluria.

Limitations of the usefulness of the d-xylose absorption test.

The results of the conventional 5-hour d-xylose absorption test were surveyed in 38 subjects with disease of the jejunal mucosa, giardiasis or bacterial overgrowth, or no small-bowel disorder. The test was in error in 20-40% of cases, depending on the disease category, and the error for the entire group was 30%. We conclude that the test yields little guidance for diagnosis or therapy of clinical problems and is superfluous when a jejunal biopsy can be obtained.