Tropheryma whipplei, Helicobacter pylori, and Intestinal Protozoal Co-Infections in Italian and Immigrant Populations: A Cross-Sectional Study

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.

Uptake of Tropheryma whipplei by Intestinal Epithelia

Background: Tropheryma whipplei (TW) can cause different pathologies, e.g., Whipple’s disease and transient gastroenteritis. The mechanism by which the bacteria pass the intestinal epithelial barrier, and the mechanism of TW-induced gastroenteritis are currently unknown. Methods: Using ex vivo disease models comprising human duodenal mucosa exposed to TW in Ussing chambers, various intestinal epithelial cell (IEC) cultures exposed to TW and a macrophage/IEC coculture model served to characterize endocytic uptake mechanisms and barrier function. Results: TW exposed ex vivo to human small intestinal mucosae is capable of autonomously entering IECs, thereby invading the mucosa. Using dominant-negative mutants, TW uptake was shown to be dynamin- and caveolin-dependent but independent of clathrin-mediated endocytosis. Complementary inhibitor experiments suggested a role for the activation of the Ras/Rac1 pathway and actin polymerization. TW-invaded IECs underwent apoptosis, thereby causing an epithelial barrier defect, and were subsequently subject to phagocytosis by macrophages. Conclusions: TW enters epithelia via an actin-, dynamin-, caveolin-, and Ras-Rac1-dependent endocytosis mechanism and consecutively causes IEC apoptosis primarily in IECs invaded by multiple TW bacteria. This results in a barrier leak. Moreover, we propose that TW-packed IECs can be subject to phagocytic uptake by macrophages, thereby opening a potential entry point of TW into intestinal macrophages.

Prevalence and detection of Tropheryma whipplei in the stools of Korean patients with diarrhea using real-time PCRs

BACKGROUND

The prevalence of Tropheryma whipplei varies depending on age, region, and underlying disease. We estimated the prevalence of T. whipplei in the stools of Korean patients with diarrhea using real-time PCR (RT-PCR) and compared three RT-PCR targets, rpoB, hsp65, and Dig15.

METHODS

A total of 1404 nucleic acid samples extracted from the stools of Korean patients with diarrhea were tested using an initial RT-PCR targeting T. whipplei-specific regions of 16S-23S rRNA intergenic spacer. Subsequently, the samples positive for the initial RT-PCR were tested using the follow-up RT-PCRs targeting rpoB, hsp65, and Dig15 and analyzed by sequencing to confirm the presence of T. whipplei. We estimated the prevalence of T. whipplei and compared them according to gender and age. We also compared the performance of three targets in the follow-up RT-PCRs.

RESULTS

T. whipplei was detected in 1.4% of all samples (20 of 1404), and there were no differences according to gender and age. In pediatric samples (≤ 19 years), T. whipplei was detected higher in children aged 6-19 than in those aged 1-5 (2.7% vs. 0.7%, P = 0.01). Sensitivities of the rpoB, hsp65, and Dig15 RT-PCR were 50.0%, 85.0%, and 95.0%, respectively; specificities were 100.0%, 100.0%, and 84.6%, respectively.

CONCLUSIONS

This is the first study that estimated the prevalence of T. whipplei in the stools of Korean patients with diarrhea. This study demonstrated the presence of T. whipplei in stools of Koreans, even though the bacterium was detected low. The RT-PCRs targeting hsp65 and Dig15 showed reliable performance, and a multiplex PCR including these targets is expected to be useful for T. whipplei detection.

Design of a Multi-Epitope Vaccine against Tropheryma whipplei Using Immunoinformatics and Molecular Dynamics Simulation Techniques

Whipple’s disease is caused by T. whipplei, a Gram-positive pathogenic bacterium. It is considered a persistent infection affecting various organs, more likely to infect males. There is currently no licensed vaccination available for Whipple’s disease; thus, the development of a chimeric peptide-based vaccine against T. whipplei has the potential to be tremendously beneficial in preventing Whipple’s disease in the future. The present study aimed to apply modern computational approaches to generate a multi-epitope-based vaccine that expresses antigenic determinants prioritized from the core proteome of two T. whipplei whole proteomes. Using an integrated computational approach, four immunodominant epitopes were found from two extracellular proteins. Combined, these epitopes covered 89.03% of the global population. The shortlisted epitopes exhibited a strong binding affinity for the B- and T-cell reference set of alleles, high antigenicity score, nonallergenic nature, high solubility, nontoxicity, and excellent binders of DRB1*0101. Through the use of appropriate linkers and adjuvation with a suitable adjuvant molecule, the epitopes were designed into a chimeric vaccine. An adjuvant was linked to the connected epitopes to boost immunogenicity and efficiently engage both innate and adaptive immunity. The physiochemical properties of the vaccine were observed favorable, leading toward the 3D modeling of the construct. Furthermore, the vaccine’s binding confirmation to the TLR-4 critical innate immune receptor was also determined using molecular docking and molecular dynamics (MD) simulations, which shows that the vaccine has a strong binding affinity for TLR4 (−29.4452 kcal/mol in MM-GBSA and −42.3229 kcal/mol in MM-PBSA). Overall, the vaccine described here has a promising potential for eliciting protective and targeted immunogenicity, subject to further experimental testing.