Tropheryma whipplei Increases Expression of Human Leukocyte Antigen-G on Monocytes to Reduce Tumor Necrosis Factor and Promote Bacterial Replication

Tropheryma whipplei pneumonia revealed by Metagenomic next-generation sequencing: Report of two cases

Tropheryma whipplei is the causative agent of Whipple's disease, which is a rare multiorgan systemic disease. We report two cases of Tropheryma whipplei infection, all routine tests were negative and it was finally detected by mNGS. This may help clinicians increase awareness of the diagnosis and treatment of acute severe pneumonia and interstitial pneumonia caused by Tropheryma whipplei.

Whipple Disease Presenting as Isolated Transverse Myelitis with Permanent Neurological Damage in a Patient with Systemic Lupus Erythematosus: A Case Report of a Difficult Diagnosis with a Literature Review

We describe an atypical case of Whipple disease exclusively involving the spinal cord in an adolescent receiving immunosuppressive therapy for systemic lupus erythematosus. The diagnosis was particularly difficult since lupus and Whipple disease can present similar clinical features and the patient's prolonged contact with sewage was initially not mentioned. A literature review of the clinical, imaging, diagnostic, and therapeutic challenges of Whipple disease is also performed.

A Case of Whipple's Disease With Concomitant Esophageal Candidiasis

Whipple's Disease (WD) is a rare disease caused by the infection of Tropheryma whipplei. It can lead to immunosuppression and a multitude of effects on different organ systems, resulting in a constellation of seemingly unrelated findings. Although treatment may appear straightforward, T. whipplei can be difficult to eradicate. We present the case of a 36-year-old male with months of progressively worsening watery diarrhea, migratory arthralgias, and weight loss. He had undergone an extensive evaluation for rheumatologic, oncologic, and infectious disorders without positive findings. Esophagogastroduodenoscopy and colonoscopy revealed esophageal candidiasis, Helicobacter pylori infection, and foamy macrophages in the lamina propria of the duodenum and ileum with positive polymerase chain reaction for T. whipplei. There were no other risk factors for esophageal candidiasis. He received treatment for his esophageal candidiasis and H. pylori infection and was treated for WD with ceftriaxone for 2 weeks, followed by hydroxychloroquine and doxycycline for 1 year. Symptoms resolved after 3 months of therapy. One year later, repeat bidirectional endoscopy was performed. Biopsies were negative for T. whipplei, although there were persistent foamy macrophages. There have been previously reported cases of patients with WD with concomitant esophageal candidiasis, and this association implies a likely state of relative immunosuppression associated with WD, which is thought to be the result of impaired T helper cell 1 activity. This impairment likely contributes to the high rate of relapse. Having a low threshold for repeat evaluation is advisable for recurrent symptoms, but long-term surveillance strategies are not clearly defined.

Current knowledge of the immune reconstitution inflammatory syndrome in Whipple disease: a review

Immune reconstitution inflammatory syndrome (IRIS) is characterized by exaggerated and dysregulated inflammatory responses that occur as a result of reconstitution of adaptive or innate immunity. A wide range of microorganisms have been found to be associated with IRIS, such as human immunodeficiency virus (HIV), Mycobacterium and actinobacteria. Whipple disease (WD) is an infectious disorder caused by the Gram-positive bacterium Tropheryma whipplei (T. whipplei) and IRIS also serves as a complication during its treament. Although many of these pathological mechanisms are shared with related inflammatory disorders, IRIS in WD exhibits distinct features and is poorly described in the medical literature. Novel investigations of the intestinal mucosal immune system have provided new insights into the pathogenesis of IRIS, elucidating the interplay between systemic and local immune responses. These insights may be used to identify monitoring tools for disease prevention and to develop treatment strategies. Therefore, this review synthesizes these new concepts in WD IRIS to approach the feasibility of manipulating host immunity and immune reconstitution of inflammatory syndromes from a newer, more comprehensive perspective and study hypothetical options for the management of WD IRIS.

Disruption of the Expression of the Placental Clock and Melatonin Genes in Preeclampsia

Circadian rhythms have been described in numerous tissues of living organisms and are necessary for homeostasis. The understanding of their role in normal and pathological pregnancy is only just emerging. It has been established that clock genes are expressed in the placenta of animals and humans, but the rhythmicity of placenta immune cells is not known. Macrophages from healthy placenta of women at term were isolated and the expression of clock genes BMAL1, CLOCK, PER2, CRY2, and NR1D1 was assessed by qRT-PCR every 4 h over 24 h. Raw data were treated with cosinor analysis to evaluate the significance of the oscillations. Placental macrophages exhibited significant circadian expression of clock genes but one third of placental macrophages lost clock gene rhythmicity; the clock gene oscillations were restored by co-culture with trophoblasts. We wondered if melatonin, a key hormone regulating circadian rhythm, was involved in the oscillations of placental cells. We showed that macrophages and trophoblasts produced melatonin and expressed MT2 receptor. In women who developed preeclampsia during pregnancy, circadian oscillations of placental macrophages were lost and could not be rescued by coculture with trophoblasts from healthy women. Moreover, production and oscillations of melatonin were altered in preeclamptic macrophages. For the first time to our knowledge, this study shows circadian rhythms and melatonin production by placental macrophages. It also shows that preeclampsia is associated with a disruption of the circadian rhythm of placental cells. These results represent a new scientific breakthrough that may contribute to the prevention and treatment of obstetrical pathologies.

Functional, transcriptional, and microbial shifts associated with healthy pulmonary aging in rhesus macaques

Older individuals are at increased risk of developing severe respiratory infections. However, our understanding of the impact of aging on the respiratory tract remains limited as samples from healthy humans are challenging to obtain and results can be confounded by variables such as smoking and diet. Here, we carry out a comprehensive cross-sectional study (n = 34 adult, n = 49 aged) to define the consequences of aging on the lung using the rhesus macaque model. Pulmonary function testing establishes similar age and sex differences as humans. Additionally, we report increased abundance of alveolar and infiltrating macrophages and a concomitant decrease in T cells were in aged animals. scRNAseq reveals shifts from GRZMB to IFN expressing CD8⁺ T cells in the lungs. These data provide insight into age-related changes in the lungs’ functional, microbial, and immunological landscape that explain increased prevalence and severity of respiratory diseases in the elderly.

Rhoades et al. describe age-associated functional, microbial, and immunological changes in the lung using the rhesus macaque model. These data will support further studies aimed at designing and testing interventions to mitigate the impact of age-associated shifts in the lung environment to reduce age-related pulmonary disease in the elderly.

Immunomodulatory Potential of Non-Classical HLA-G in Infections including COVID-19 and Parasitic Diseases

Human Leukocyte Antigen-G (HLA-G), a polymorphic non-classical HLA (HLA-Ib) with immune-regulatory properties in cancers and infectious diseases, presents both membrane-bound and soluble (sHLA-G) isoforms. Polymorphism has implications in host responses to pathogen infections and in pathogenesis. Differential expression patterns of HLA-G/sHLA-G or its polymorphism seem to be related to different pathological conditions, potentially acting as a disease progression biomarker. Pathogen antigens might be involved in the regulation of both membrane-bound and sHLA-G levels and impact immune responses during co-infections. The upregulation of HLA-G in viral and bacterial infections induce tolerance to infection. Recently, sHLA-G was found useful to identify the prognosis of Coronavirus disease 2019 (COVID-19) among patients and it was observed that the high levels of sHLA-G are associated with worse prognosis. The use of pathogens, such as Plasmodium falciparum, as immune modulators for other infections could be extended for the modulation of membrane-bound HLA-G in COVID-19-infected tissues. Overall, such information might open new avenues concerning the effect of some pathogens such as parasites in decreasing the expression level of HLA-G to restrict pathogenesis in some infections or to influence the immune responses after vaccination among others.

Daytime variation in SARS-CoV-2 infection and cytokine production

S. Ray and A. Reddy recently anticipated the implication of circadian rhythm in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the causative agent of the coronavirus disease (Covid-19). In addition to its key role in the regulation of biological functions, the circadian rhythm has been suggested as a regulator of viral infections. Specifically, the time of day of infection was found critical for illness progression, as has been reported for influenza, respiratory syncytial and parainfluenza type 3 viruses. We analyzed circadian rhythm implication in SARS-CoV-2 virus infection of isolated human monocytes, key actor cells in Covid-19 disease, from healthy subjects. The circadian gene expression of BMAL1 and CLOCK genes was investigated with q-RTPCR. Monocytes were infected with SARS-CoV-2 virus strain and viral infection was investigated by One-Step qRT-PCR and immunofluorescence. Interleukin (IL)-6, IL-1β and IL-10 levels were also measured in supernatants of infected monocytes. Using Cosinor analysis, we showed that BMAL1 and CLOCK transcripts exhibited circadian rhythm in monocytes with an acrophase and a bathyphase at Circadian Time (CT)6 and CT17. After 48 h, the amount of SARS-CoV-2 virus increased in the monocyte infected at CT6 compared to CT17. The high virus amount at CT6 was associated with significant increased release in IL-6, IL-1β and IL-10 compared to CT17. Our results suggest that time day of SARS-CoV-2 infection affects viral infection and host immune response. They support consideration of circadian rhythm in SARS-CoV-2 disease progression and we propose circadian rhythm as a novel target for managing viral progression.

Phenotypic diversity of Tropheryma whipplei clinical isolates

Tropheryma whipplei is a bacterial pathogen responsible for a wide range of infections in humans, covering asymptomatic carriage, acute infections, chronic isolated infections and classic Whipple's disease. Although the bacterium is commonly found in the environment, it very rarely causes disease. Genetic comparison of clinical isolates has revealed that main variations were found in region encoding T. whipplei surface glycoproteins called WiSP. However, no association has been made between the genetic diversity and the clinical manifestations of the infection. In this study we evaluated the phenotypic diversity of 26 clinical isolates from different origins and taken from patient with different infection outcomes. MRC5 and macrophages cells were infected, and bacterial uptake, survival and the pro-and anti-inflammatory potential of the different clinical isolates was assessed. No significant difference of phagocytosis was found between the different isolates; however, we found that bacterial replication was increased for bacteria expressing high molecular weight WiSP. In addition, we found that the expression of the genes coding for IL-1β and TGF-β was significantly higher when MRC5 cells were stimulated with isolates from chronic infections compared to isolates from localized infections while no significant differences were observed in macrophages. Overall, our study revealed that, as previously observed at the genetic level, phenotypic diversity of T. whipplei isolates is associated with the expression of different WiSP, which may result in subtle differences in host responses. Other host factors or genetic predisposition may explain the range of clinical manifestations of T. whipplei infections.

Tumor Necrosis Factor Inhibitors Exacerbate Whipple's Disease by Reprogramming Macrophage and Inducing Apoptosis

Tropheryma whipplei is the agent of Whipple’s disease, a rare systemic disease characterized by macrophage infiltration of the intestinal mucosa. The disease first manifests as arthralgia and/or arthropathy that usually precede the diagnosis by years, and which may push clinicians to prescribe Tumor necrosis factor inhibitors (TNFI) to treat unexplained arthralgia. However, such therapies have been associated with exacerbation of subclinical undiagnosed Whipple’s disease. The objective of this study was to delineate the biological basis of disease exacerbation. We found that etanercept, adalimumab or certolizumab treatment of monocyte-derived macrophages from healthy subjects significantly increased bacterial replication in vitro without affecting uptake. Interestingly, this effect was associated with macrophage repolarization and increased rate of apoptosis. Further analysis revealed that in patients for whom Whipple’s disease diagnosis was made while under TNFI therapy, apoptosis was increased in duodenal tissue specimens as compared with control Whipple’s disease patients who never received TNFI prior diagnosis. In addition, IFN-γ expression was increased in duodenal biopsy specimen and circulating levels of IFN-γ were higher in patients for whom Whipple’s disease diagnosis was made while under TNFI therapy. Taken together, our findings establish that TNFI aggravate/exacerbate latent or subclinical undiagnosed Whipple’s disease by promoting a strong inflammatory response and apoptosis and confirm that patients may be screened for T. whipplei prior to introduction of TNFI therapy.