Association between altered tryptophan metabolism, plasma aryl hydrocarbon receptor agonists, and inflammatory Chagas disease

Introduction

Chagas disease causes a cardiac illness characterized by immunoinflammatory reactions leading to myocardial fibrosis and remodeling. The development of Chronic Chagas Cardiomyopathy (CCC) in some patients while others remain asymptomatic is not fully understood, but dysregulated inflammatory responses are implicated. The Aryl hydrocarbon receptor (AhR) plays a crucial role in regulating inflammation. Certain tryptophan (Trp) metabolites have been identified as AhR ligands with regulatory functions.

Methods results and discussion

We investigated AhR expression, agonist response, ligand production, and AhR-dependent responses, such as IDO activation and regulatory T (Treg) cells induction, in two T. cruzi-infected mouse strains (B6 and Balb/c) showing different polymorphisms in AhR. Furthermore, we assessed the metabolic profile of Trp catabolites and AhR agonistic activity levels in plasma samples from patients with chronic Chagas disease (CCD) and healthy donors (HD) using a luciferase reporter assay and liquid chromatography-mass spectrophotometry (LC-MS) analysis. T. cruzi-infected B6 mice showed impaired AhR-dependent responses compared to Balb/c mice, including reduced IDO activity, kynurenine levels, Treg cell induction, CYP1A1 up-regulation, and AhR expression following agonist activation. Additionally, B6 mice exhibited no detectable AhR agonist activity in plasma and displayed lower CYP1A1 up-regulation and AhR expression upon agonist activation. Similarly, CCC patients had decreased AhR agonistic activity in plasma compared to HD patients and exhibited dysregulation in Trp metabolic pathways, resulting in altered plasma metabolite profiles. Notably, patients with severe CCC specifically showed increased N-acetylserotonin levels in their plasma. The methods and findings presented here contribute to a better understanding of CCC development mechanisms and may identify potential specific biomarkers for T. cruzi infection and the severity of associated heart disease. These insights could be valuable in designing new therapeutic strategies. Ultimately, this research aims to establish the AhR agonistic activity and Trp metabolic profile in plasma as an innovative, non-invasive predictor of prognosis for chronic Chagas disease.

The high identity of the Trypanosoma cruzi Group-I of trans-sialidases points them as promising vaccine immunogens

Trans-sialidase (TS) superfamily of proteins comprises eight subgroups, being the proteins of Group-I (TS-GI) promising immunogens in vaccine approaches against Trypanosoma cruzi. Strikingly, TS-GI antigenic variability among parasite lineages and their influence on vaccine development has not been previously analyzed. Here, a search in GenBank detects 49 TS-GI indexed sequences, whereas the main infecting human different parasite discrete typing units (DTU) are represented. In silico comparison among these sequences indicate that they share an identity above 92%. Moreover, the antigenic regions (T-cell and B-cell epitopes) are conserved in most sequences or present amino acid substitutions that scarcely may alter the antigenicity. Additionally, since the generic term TS is usually used to refer to different immunogens of this broad family, a further in silico analysis of the TS-GI-derived fragments tested in preclinical vaccines was done to determine the coverage and identity among them, showing that overall amino acid identity of vaccine immunogens is high, but the segment coverage varies widely. Accordingly, strong H-2K, H-2I, and B-cell epitopes are dissimilarly represented among vaccine TS-derived fragments depending on the extension of the TG-GI sequence used. Moreover, bioinformatic analysis detected a set of 150 T-cell strong epitopes among the DTU-indexed sequences that strongly bind human HLA-I supertypes. In all currently reported experimental vaccines based on TS-GI fragments, mapping these 150 epitopes showed that they are moderately represented. However, despite vaccine epitopes do not present all the substitutions observed in the DTUs, these regions of the proteins are equally recognized by the same HLAs.  Interestingly, the predictions regarding global and South American population coverage estimated in these 150 epitopes are similar to the estimations in experimental vaccines when the complete sequence of TS-GI is used as an antigen. In silico prediction also shows that a number of these MHC-I restricted T-cell strong epitopes could be also cross-recognized by HLA-I supertypes and H-2Kb or H-2Kd backgrounds, indicating that these mice may be used to improve and facilitate the development of new TS-based vaccines and suggesting an immunogenic and protective potential in humans. Further molecular docking analyses were performed to strengthen these results. Taken together, different strategies that would cover more or eventually fully of these T-cell and also B-cell epitopes to reach a high level of coverage are considered.

Dysregulated Network of Immune, Endocrine and Metabolic Markers is Associated to More Severe Human Chronic Chagas Cardiomyopathy

Individuals who are infected with Trypanosoma cruzi develop chronic Chagas cardiomyopathy (CCC), which is a complication involving a series of immune pathogenetic mechanisms, although an association between immune and metabolic alterations was more recently proposed. Accordingly, we investigated the immuno-metabolic response in chagasic patients and their possible influence on CCC pathogenesis. To this end, T. cruzi-seropositive (asymptomatic or with CCC) and sero-negative individuals were studied. Serum tumour necrosis factor (TNF)-α, interleukin (IL)-6, adipocytokines and the expression of their receptors in peripheral blood mononuclear cell (PBMC) were evaluated, together with other factors influencing the immune response. CCC patients showed major metabolic and hormonal abnormalities, in parallel with increased IL-6 and leptin serum levels. TNF-α receptor s, leptin and adiponectin receptors (ObR and Adipo-Rs respectively), as well as PPAR-γ expression in PBMCs from CCC patients were compatible with a counteracting response leading to an unfavourable immune-metabolic profile. These results suggest that persistently increased levels of immune-metabolic pro-inflammatory mediators along with the adverse endocrine anti-inflammatory response of CCC individuals, may contribute to the underlying mechanisms dealing with myocardial tissue damage.

Recent advances in stem and germ cell research: implications for the derivation of pig pluripotent cells

Pluripotent stem cells have the unique capacity to contribute to all the tissues of an adult animal after transfer into a host embryo. How pluripotency is acquired during early development and how it is maintained in stem cells have attracted the interest of many scientists for over three decades. Much progress in our understanding of how stem cells arise in culture and the signals required for homoeostasis has enabled the derivation of pluripotent cells in multiple species. Here, we discuss recent developments in stem cell biology that will impact the generation of pluripotent cells from different embryonic origins and will contribute to increase our capacity for generating transgenic animals.

Renal transplantation program in Cuba

Kidney transplantation has been performed in Cuba since 1970. In 1979, compatible living-related donors were introduced into our renal transplantation program. There are 43 hospitals distributed around the country with a multidisciplinary group that attends cadaveric donors with encephalic death. The donor rate in Cuba oscillates between 15 and 18 per million; 90% of them are from cadaveric donors. This program includes 47 dialysis centers throughout the country with 2300 patients as supported by a National Coordinating Center at The Nephrology Institute. Cuba is one of the first countries in our region with this experience.

Cytokines and cell adhesion receptors in the regulation of immunity to Trypanosoma cruzi

Pathophysiology of Chagas' disease is not completely defined, although innate and adaptative immune responses are crucial. In acute infection some parasite antigens can activate macrophages, and this may result in pro-inflammatory cytokine production, nitric oxide synthesis, and consequent control of parasitemia and mortality. Cell-mediated immunity in Trypanosoma cruzi infection is also modulated by cytokines, but in addition to parasite-specific responses, autoimmunity can be also triggered. Importantly, cytokines may also play a role in the cell-mediated immunity of infected subjects. Finally, leukocyte influx towards target tissues is regulated by cytokines, chemokines, and extracellular matrix components which may represent potential therapeutic targets in infected patients. Here we will discuss recent findings on the role of cytokines, chemokines and extracellular matrix components in the regulation of innate and adaptive immunity during T. cruzi infection.

Improved outcome of Trypanosoma cruzi infection in rats following treatment in early life with suspensions of heat-killed environmental Actinomycetales

The well-established model of Chagas' disease in "l" rats was used to evaluate the effects of three injections of heat-killed Gordonia bronchialis, Rhodococcus coprophilus or saline on Trypanosoma cruzi parasitaemia and acute and chronic myocarditis, sequelae of the infection. Two vaccinating injections were given prior to challenge with T. cruzi, and the third, immunotherapeutic, injection was given 7 days after challenge. Treatment with either actinomycete significantly reduced acute parasitaemia (p<0.04), modified cellular infiltration during acute myocarditis and limited chronic myocarditis (p<0.03) in comparison with the saline-treated control animals. Immunological investigations showed that both bacterial preparations achieved their results through different mechanisms. The relevance of our findings to human Chagas' disease is discussed.

Obesity adversely affects the outcome of antireflux operations

BACKGROUND

We hypothesized that obesity was associated with long-term failure of antireflux procedures, and that in obese patients antireflux operations were easier to perform via thoracotomy, and therefore likely to have a higher success rate than transabdominal (laparoscopic or open) antireflux procedures. The aims of this study was to determine the impact of obesity on the success of antireflux operations, and to compare the success rates of transthoracic and laparoscopic approaches in obese patients with gastroesophageal reflux.

METHODS

The records of 224 consecutive patients undergoing antireflux surgery by two surgeons in a university-based tertiary care center were reviewed and patients contacted for follow-up assessment. The patients were classified into groups based on the type of operation performed and the calculated body mass index (BMI): normal (BMI 30). Recurrences were documented by symptoms responsive to acid-suppressive medication and radiologic or pH probe studies.

RESULTS

Among the 224 patients included in this study, 187 underwent laparoscopic Nissen fundoplications (LNF) and 37 underwent Belsey Mark IV(BM4) procedures. The mean follow-up period was 37 months. The three groups included 89 (39.7%) patients classified as having normal weight, 87 (38.8%) as overweight and 48 (21.4%) as obese. Normal, overweight, and obese patients were similar in terms of age, gender, hiatal hernia size, degree of esophagitis, and comorbid conditions. A total of 26 recurrences occurred, giving an overall recurrence rate of 11.6%. There were 4 recurrences in the normal group (4.5%), 7 in the overweight group (8.0%; p not significant vs normal), and 15 in the obese group (31%; p < 0.001 vs normal; p <.001 vs overweight). The recurrence rate was similar between LNF and BM4 in each BMI subgroup, although in aggregate, the recurrence rate after BMW was greater than after LNF (10/37 vs 16/187; p < 0.02).

CONCLUSIONS

Obesity adversely affects the long-term success of antireflux operations. Although athoracotomy provides optimal exposure of the hiatal structures in obese patients, a transthoracic approach was associated with a higher recurrence rate than LNF. Given the high failure rate of antireflux operations in obese patients, intensive efforts at sustained weight loss should be made before consideration of surgery.

SpoIIB localizes to active sites of septal biogenesis and spatially regulates septal thinning during engulfment in bacillus subtilis

A key step in the Bacillus subtilis spore formation pathway is the engulfment of the forespore by the mother cell, a phagocytosis-like process normally accompanied by the loss of peptidoglycan within the sporulation septum. We have reinvestigated the role of SpoIIB in engulfment by using the fluorescent membrane stain FM 4-64 and deconvolution microscopy. We have found that spoIIB mutant sporangia display a transient engulfment defect in which the forespore pushes through the septum and bulges into the mother cell, similar to the situation in spoIID, spoIIM, and spoIIP mutants. However, unlike the sporangia of those three mutants, spoIIB mutant sporangia are able to complete engulfment; indeed, by time-lapse microscopy, sporangia with prominent bulges were found to complete engulfment. Electron micrographs showed that in spoIIB mutant sporangia the dissolution of septal peptidoglycan is delayed and spatially unregulated and that the engulfing membranes migrate around the remaining septal peptidoglycan. These results demonstrate that mother cell membranes will move around septal peptidoglycan that has not been completely degraded and suggest that SpoIIB facilitates the rapid and spatially regulated dissolution of septal peptidoglycan. In keeping with this proposal, a SpoIIB-myc fusion protein localized to the sporulation septum during its biogenesis, discriminating between the site of active septal biogenesis and the unused potential division site within the same cell.

The large window ductus: a surgical trap

A rare window type of patent ductus arteriosus is reported that was large (15 mm in maximal transverse dimension) but had virtually no length and hence was externally invisible. The smaller aortic isthmus (4 mm in diameter), which was intrapericardial, was mistaken for the ductus and was inadvertently clip-occluded, leading to death. After a specific diagnosis is made, the large window ductus should be patched on cardiopulmonary bypass with a transpulmonary approach.