Despite numerous observations linking protracted exposure to low-dose (LD) radiation and leukemia occurrence, the effects of LD irradiation on hematopoietic stem cells (HSCs) remain poorly ...documented. Here, we show that adult HSCs are hypersensitive to LD irradiation. This hyper-radiosensitivity is dependent on an immediate increase in the levels of reactive oxygen species (ROS) that also promotes autophagy and activation of the Keap1/Nrf2 antioxidant pathway. Nrf2 activation initially protects HSCs from the detrimental effects of ROS, but protection is transient, and increased ROS levels return, promoting a long-term decrease in HSC self-renewal. In vivo, LD total body irradiation (TBI) does not decrease HSC numbers unless the HSC microenvironment is altered by an inflammatory insult. Paradoxically, such an insult, in the form of granulocyte colony-stimulating factor (G-CSF) preconditioning, followed by LD-TBI facilitates efficient bone marrow transplantation without myeloablation. Thus, LD irradiation has long-term detrimental effects on HSCs that may result in hematological malignancies, but LD-TBI may open avenues to facilitate autologous bone marrow transplantation.
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•HSC hypersensitivity to low-dose (LD) γ-irradiation depends on ROS production•LD irradiation results in persistent oxidative stress and decreased HSC self-renewal•LD total body irradiation (TBI) after an inflammatory insult decreases HSC numbers•LD-TBI facilitates bone marrow transplantation without the need for myeloablation.
Rodrigues-Moreira et al. show that low-dose irradiation induces long-term oxidative stress and decreased self-renewal capacity in hematopoietic stem cells (HSCs). LD total body irradiation after an inflammatory insult decreases HSC numbers but facilitates autologous bone marrow transplantation without myeloablation.
Highly conserved among species and expressed in various types of cells, numerous roles have been attributed to the cellular prion protein (PrPC). In hematopoiesis, PrPC regulates hematopoietic stem ...cell self-renewal but the mechanisms involved in this regulation are unknown. Here we show that PrPC regulates hematopoietic stem cell number during aging and their determination towards myeloid progenitors. Furthermore, PrPC protects myeloid progenitors against the cytotoxic effects of total body irradiation. This radioprotective effect was associated with increased cellular prion mRNA level and with stimulation of the DNA repair activity of the Apurinic/pyrimidinic endonuclease 1, a key enzyme of the base excision repair pathway. Altogether, these results show a previously unappreciated role of PrPC in adult hematopoiesis, and indicate that PrPC-mediated stimulation of BER activity might protect hematopoietic progenitors from the cytotoxic effects of total body irradiation.
The presence of autoantibodies in systemic lupus erythematosus, particularly those of the IgG subclass, have long been associated with disease onset and activity. Here we explored the prevalence of ...autoreactive IgE in SLE and its relevance to disease in French (n = 79) and United States (US) (n = 117) cohorts with a mean age of 41.5 ± 12.7 and 43.6 ± 15.3 years and disease duration of 13.5 ± 8.5 and 16.6 ± 11.9 years, respectively. Our findings show that approximately 65% of all SLE subjects studied produced IgE antibodies to the seven autoantigens tested. This positivity was increased to almost 83% when only those subjects with active disease were considered. SLE subjects who were positive for anti-dsDNA, -Sm, and -SSB/La -specific IgE showed a highly significant association in the levels of these antibodies with disease activity similar to that of the corresponding IgG's. A strong association of IgE autoantibodies with active nephritis was also found in the combined cohort analysis. A test of the predictive value of autoreactive IgE's and IgGs for disease activity (SLE Disease Activity Index (SLEDAI) ≥ 4) revealed that the best predictors were dsDNA-specific IgE and IgG, and that the age of an SLE subject influenced this predictive model. The finding argue that the overall levels of IgE autoantibodies, independently or in combination with IgG autoantibodies, may serve as indicators of active disease.
Observational studies are widely used in pharmacoepidemiology. Several designs can be used, in particular self-controlled designs (case-crossover and self-controlled case series). These designs offer ...the advantage of controlling for time-invariant confounders, which may not be collected in electronic healthcare databases. They are particularly useful in pharmacoepidemiology involving healthcare database. To be valid, they require the presence of some characteristics (key validity assumptions), and in such situations, these designs should be preferred. We aimed at describing the appropriate use and reporting of the key validity assumptions in self-controlled design studies.
Articles published between January 2011 and December 2014, and describing a self-controlled study design involving electronic healthcare databases were retrieved. The appropriate use (fulfilment of key assumptions) was studied in terms of major (abrupt onset event, rare or recurrent event, and intermittent exposure) and minor assumptions (those for which the design can be adapted).
Among the 107 articles describing a self-controlled design, 35/53 (66%) case-crossover studies, and 48/55 (87%) self-controlled case series fulfilled the major validity assumptions for use of the design; 4/35 and 14/48 respectively did not fulfill the minor assumptions. Overall, 31/53 (58%) case-crossover studies and 34/55 (62%) self-controlled case series fulfilled both major and minor assumptions. The reporting of the methodology or the results was appropriate, except for power calculation.
Self-controlled designs were not appropriately used in34% and 13% of the articles we reviewed that described a case-crossover or a self-controlled case series design, respectively. We encourage better use of these designs in situations in which major validity assumptions are fulfilled (i.e., for which they are recommended), accounting for situations for which the design can be adapted.
Background/aims
Jackhammer esophagus (JE) is a hypercontractile esophageal motor disorder defined by at least two swallows with a distal contractile integral (DCI) >8000 mm Hg.s.cm during ...high‐resolution manometry (HRM). The relationship between symptoms and hypercontractility and the response to therapies have been poorly evaluated. The aim of this study was to determine the clinical presentation, manometric diagnosis, and therapeutic results in a large cohort of JE patients.
Methods
Patients with JE diagnosed among the HRM tests performed in nine academic French centers from 01/01/2010 to 08/31/2016 were included. Patient charts were reviewed to collect clinical and therapeutic data.
Results
Among the 16 264 HRM tests performed during this period, 227 patients (60.8 ± 13.8 years, 151 male) had JE (1.7%). Dysphagia was the most frequent symptom (74.6%), followed by regurgitation (37.1%) and chest pain (36.6%); 4.7% of the patients were asymptomatic. The diagnostic workup was heterogeneous, and only a minority of patients had esophageal biopsies. None of the individual symptoms were significantly associated with any of the manometric parameters defined, except for dysphagia, which was significantly associated with the mean of all DCIs >8000 mm Hg.s.cm (P = .04). Additionally, the number of symptoms was not associated with any manometric parameter. Medical treatment and endoscopic treatments had poor efficacy and a high relapse rate.
Conclusion
Jackhammer esophagus is a rare motility disorder. Diagnostic workup is heterogeneous and should be standardized. Symptoms are poorly associated with manometric parameters. The medical treatments and endoscopic therapies currently used are inefficient.
Human and murine skin wounding commonly results in fibrotic scarring, but the murine wounding model wound-induced hair neogenesis (WIHN) can frequently result in a regenerative repair response. Here, ...we show in single-cell RNA sequencing comparisons of semi-regenerative and fibrotic WIHN wounds, increased expression of phagocytic/lysosomal genes in macrophages associated with predominance of fibrotic myofibroblasts in fibrotic wounds. Investigation revealed that macrophages in the late wound drive fibrosis by phagocytizing dermal Wnt inhibitor SFRP4 to establish persistent Wnt activity. In accordance, phagocytosis abrogation resulted in transient Wnt activity and a more regenerative healing. Phagocytosis of SFRP4 was integrin-mediated and dependent on the interaction of SFRP4 with the EDA splice variant of fibronectin. In the human skin condition hidradenitis suppurativa, phagocytosis of SFRP4 by macrophages correlated with fibrotic wound repair. These results reveal that macrophages can modulate a key signaling pathway via phagocytosis to alter the skin wound healing fate.
Human multilineage-differentiating stress enduring (Muse) cells are nontumorigenic endogenous pluripotent-like stem cells that can be easily obtained from various adult or fetal tissues. Regenerative ...effects of Muse cells have been shown in some disease models. Muse cells specifically home in damaged tissues where they exert pleiotropic effects. Exposition of the small intestine to high doses of irradiation (IR) delivered after radiotherapy or nuclear accident results in a lethal gastrointestinal syndrome (GIS) characterized by acute loss of intestinal stem cells, impaired epithelial regeneration and subsequent loss of the mucosal barrier resulting in sepsis and death. To date, there is no effective medical treatment for GIS. Here, we investigate whether Muse cells can prevent lethal GIS and study how they act on intestinal stem cell microenvironment to promote intestinal regeneration.
Human Muse cells from Wharton's jelly matrix of umbilical cord (WJ-Muse) were sorted by flow cytometry using the SSEA-3 marker, characterized and compared to bone-marrow derived Muse cells (BM-Muse). Under gas anesthesia, GIS mice were treated or not through an intravenous retro-orbital injection of 50,000 WJ-Muse, freshly isolated or cryopreserved, shortly after an 18 Gy-abdominal IR. No immunosuppressant was delivered to the mice. Mice were euthanized either 24 h post-IR to assess early small intestine tissue response, or 7 days post-IR to assess any regenerative response. Mouse survival, histological stainings, apoptosis and cell proliferation were studied and measurement of cytokines, recruitment of immune cells and barrier functional assay were performed.
Injection of WJ-Muse shortly after abdominal IR highly improved mouse survival as a result of a rapid regeneration of intestinal epithelium with the rescue of the impaired epithelial barrier. In small intestine of Muse-treated mice, an early enhanced secretion of IL-6 and MCP-1 cytokines was observed associated with (1) recruitment of monocytes/M2-like macrophages and (2) proliferation of Paneth cells through activation of the IL-6/Stat3 pathway.
Our findings indicate that a single injection of a small quantity of WJ-Muse may be a new and easy therapeutic strategy for treating lethal GIS.
Background
Alongside the recent worldwide expansion of hypervirulent
Klebsiella pneumoniae
(KP) infections, the available literature regarding cases of community acquired pneumonias (KP-CAP) remains ...scarce but reports a strikingly high and early mortality. We performed a retrospective multicenter study (7 ICU in France) between 2015 and 2019, comparing prognosis and severity of KP-CAP versus
Streptococcus pneumoniae -
CAP (SP-CAP).
Methods
For each KP-CAP, three SP-CAP admitted in ICUs within the same center and within the same 6-month window were selected. When available, KP strains were studied, and bacterial virulence was genetically assessed for virulence factors. The primary outcome was in-hospital mortality. Associations between clinical outcomes and type of infection were tested using univariate and multivariate logistic regressions, adjusted for pairing variables.
Results
Twenty-seven KP-CAP and 81 SP-CAP were included. Respective in-hospital mortality rates were 59% (
n
= 16) and 17% (
n
= 14,
p
< 0.001), despite adequate antibiotic therapy. KP-CAP median time from admission to death was 26.9 h IQR 5.75–44 h and were significantly associated with higher rates of multiple organ failures (93% vs. 42%,
p
< 0.001), disseminated intravascular coagulation (12% vs. 1.3%,
p
= 0.046), septic shock (median lactate on ICU admission 4.60 vs. 2.90 mmol/L,
p
= 0.030) and kidney failure (KDIGO-3: 87% vs. 44%,
p
< 0.001). Interestingly, alcoholism was the only identified predisposing factor of KP-CAP. Severity on ICU admission (2-fold higher for KP-CAP) was the only factor associated with mortality in a multivariate analysis.
Conclusion
We described a strong association between KP-CAP infection and higher and earlier mortality when compared to SP-CAP. Moreover, alcoholism was the sole predisposing factor associated with KP-CAP infection. These findings should raise awareness of clinicians involved in the management of severe CAP about this microbiological etiology. Future prospective studies are needed to confirm these results and to design strategies to improve the prognosis of such infections.
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