First Human Model of In Vitro Candida albicans Persistence within Granuloma for the Reliable Study of Host-Fungi Interactions

BACKGROUND: The balance between human innate immune system and Candida albicans virulence signaling mechanisms ultimately dictates the outcome of fungal invasiveness and its pathology. To better understand the pathophysiology and to identify fungal virulence-associated factors in the context of persistence in humans, complex models are indispensable. Although fungal virulence factors have been extensively studied in vitro and in vivo using different immune cell subsets and cell lines, it is unclear how C. albicans survives inside complex tissue granulomas. METHODOLOGY/PRINCIPAL FINDING: We developed an original model of in vitro human granuloma, reproducing the natural granulomatous response to C. albicans. Persistent granulomas were obtained when the ratio of phagocytes to fungi was high. This in vitro fungal granuloma mimics natural granulomas, with infected macrophages surrounded by helper and cytotoxic T lymphocytes. A small proportion of granulomas exhibited C. albicans hyphae. Histological and time-lapse analysis showed that C. albicans blastoconidia were located within the granulomas before hyphae formation. Using staining techniques, fungal load calculations, as well as confocal and scanning electron microscopy, we describe the kinetics of fungal granuloma formation. We provide the first direct evidence that C. albicans are not eliminated by immunocompetent cells inside in vitro human granulomas. In fact, after an initial candicidal period, the remaining yeast proliferate and persist under very complex immune responses. CONCLUSIONS/SIGNIFICANCE: Using an original in vitro model of human fungal granuloma, we herein present the evidence that C. albicans persist and grow into immunocompetent granulomatous structures. These results will guide us towards a better understanding of fungal invasiveness and, henceforth, will also help in the development of better strategies for its control in human physiological conditions

Recurrent maternal virilization during pregnancy in patients with PCOS: two clinical cases

Abstract Background Maternal virilization during pregnancy is a rare phenomenon. Polycystic ovary syndrome (PCOS), luteoma and luteinic cysts are the most frequent and benign etiologies. This article presents two cases of recurrent maternal virilization during pregnancy. Clinical cases Our reported cases were young women with Afro-Caribbean and Nigerian origins. Data were collected by history-taking, clinical examination, laboratory investigations, transabdominal ultrasonographic examination and Magnetic Resonance Imaging. Both patients were diagnosed with PCOS according to the Rotterdam criteria. During each of their pregnancies they both developed an explosive hirsutism, a deepening in the voice, a clitoromegaly. Gestational diabetes occurred during pregnancies. There was no fetal virilization, despite raising androgen levels, more than tenfold to normal. Improvement of hirsutism and normalization of androgens were described in postpartum. Conclusion Only few cases of maternal virilization during pregnancy were reported in literature and even fewer concern recurrent and bilateral ovarian etiology. Hyperplasia of ovarian theca cells seems to be the most likely explanation, which would suggest that PCOS belongs to a spectrum of abnormal reactivity of the ovary to human Chorionic Gonadotrophin (hCG) stimulation along with luteoma and luteinic cyst of pregnancy.  Insulin resistance could worsen hyperandrogenism but is not enough to explain virilization. Treatment should focus on protecting the fetus of possible virilization as well as its mother, but also on preserving the subsequent fertility in both

Aluminum enhances inflammation and decreases mucosal healing in experimental colitis in mice

The increasing incidence of inflammatory bowel diseases (IBDs) in developing countries has highlighted the critical role of environmental pollutants as causative factors in their pathophysiology. Despite its ubiquity and immune toxicity, the impact of aluminum in the gut is not known. This study aimed to evaluate the effects of environmentally relevant intoxication with aluminum in murine models of colitis and to explore the underlying mechanisms. Oral administration of aluminum worsened intestinal inflammation in mice with 2,4,6-trinitrobenzene sulfonic acid- and dextran sodium sulfate-induced colitis and chronic colitis in interleukin 10-negative (IL10(-/-)) mice. Aluminum increased the intensity and duration of macroscopic and histologic inflammation, colonic myeloperoxidase activity, inflammatory cytokines expression, and decreased the epithelial cell renewal compared with control animals. Under basal conditions, aluminum impaired intestinal barrier function. In vitro, aluminum induced granuloma formation and synergized with lipopolysaccharide to stimulate inflammatory cytokines expression by epithelial cells. Deleterious effects of aluminum on intestinal inflammation and mucosal repair strongly suggest that aluminum might be an environmental IBD risk factor.Mucosal Immunology advance online publication, 16 October 2013; doi:10.1038/mi.2013.78

Human RORγt+ TH17 cells preferentially differentiate from naive FOXP3+Treg in the presence of lineage-specific polarizing factors

RORγt+ TH17 cells are a proinflammatory CD4+ T-cell population associated with autoimmune tissue injury. In mice, priming of TH17 requires TGF-β, which alone directs the priming of FOXP3+ regulatory T cells (Treg), in association with inflammatory cytokines. Priming of human TH17 cells from conventional naive CD4+ T cells under similar conditions, however, has proved difficult to achieve. Here, we report that differentiation of human TH17 cells preferentially occurs from FOXP3+ naive Treg (NTreg) in the presence of IL-2 and IL-1β and is increased by IL-23 and TGF-β. IL-1β–mediated differentiation correlated with IL-1RI expression in stimulated NTreg and was accompanied by induction of RORγt along with down-regulation of FOXP3. IL-17–secreting cells in NTreg cultures cosecreted TNF-α and IL-2 and contained distinct subpopulations cosecreting or not cosecreting IFN-γ and other TH17-associated cytokines. Polarized NTreg contained significant subpopulations of CCR6-expressing cells that were highly enriched in IL-17–secreting cells. Finally, analysis of CCR6 expression with respect to that of IL-1RI identified distinct IL-17–secreting subpopulations that had maintained or lost their suppressive functions. Together our results support the concept that priming of human TH17 from naive CD4+ T cells preferentially takes place from FOXP3+ Treg precursors in the presence of lineage-specific polarizing factors

Human memory FOXP3+ Tregs secrete IL-17 ex vivo and constitutively express the TH17 lineage-specific transcription factor RORγt

Recent studies have suggested a close relationship between CD4+FOXP3+ regulatory T cells (Tregs) and proinflammatory IL-17-producing T helper cells (TH17) expressing the lineage-specific transcription factor RORγt. We report here the unexpected finding that human memory Tregs secrete IL-17 ex vivo and constitutively express RORγt. IL-17-secreting Tregs share some phenotypic and functional features with conventional TH17 cells, expressing high levels of CCR4 and CCR6 and low levels of CXCR3. However, unlike conventional TH17 cells, they express low levels of CD161 and mostly fail to cosecrete IL-22 and TNF-α ex vivo. Ex vivo secretion of IL-17 and constitutive expression of RORγt by human memory Tregs suggest that, in addition to their well-known suppressive functions, these cells likely play additional, as yet undescribed, proinflammatory functions

Impaired blood dendritic cell numbers and functions after aneurysmal subarachnoid hemorrhage.

PREVIOUS PRESENTATION: Portions of this study were presented at the Annual Congress of Société Française d'Anesthésie et de Réanimation in Paris, September 2012. BACKGROUND: Toll-like receptor (TLR) agonists are promising therapy for the prevention of nosocomial infections in critical ill patients. We aimed to analyze the TLR-reactivity of circulating dendritic cells (DC) as assessed by cytokine production after an ex vivo challenge with TLR agonists in aneurysmal subarachnoid hemorrhage (SAH) patients. METHODS AND FINDINGS: A single-center prospective observational study took place in one intensive care unit of a teaching hospital. Blood samples were harvested on days 2, 5 and 10 in 21 severe SAH patients requiring mechanical ventilation and 17 healthy controls. DC production of cytokines (Tumour Necrosis Factor, TNF-α; Interleukin, IL-12; and Interferon, IFN-α) was assessed by intracellular immunostaining on TLR-3, 4, 7/8 and 9 stimulations. SAH patients had decreased numbers of blood myeloid (mDCs) and plasmacytoid DCs (pDCs) on days 2, 5 and 10. Compared with the healthy controls, the frequency of mDCs producing TNF-α after TLR-3 stimulation was decreased in the SAH patients. The frequency of myeloid DCs producing IL-12 after TLR-3 and 4 stimulations was also decreased in the SAH patients. In contrast, the mDCs response to TLR-7/8 was not impaired in the SAH patients. The frequency of pDCs producing TNF-α(+) and IFN-α(+) on TLR-7/8 stimulation were reduced at all of the tested times in the SAH patients, whereas reactivity to TLR-9 was preserved. On day 2, the pDCs from non-survivor patients (n=8) had a decreased ability to produce IFN-α on TLR-9 stimulation compared with the survivors. CONCLUSIONS: These data suggest functional abnormalities of circulating pDCs and mDCs that could be important for immunomodulation after SAH