Contrast-Enhanced Multispectral Optoacoustic Tomography for Functional Assessment of the Gastrointestinal Tract

Real-time imaging and functional assessment of the intestinal tract and its transit pose a significant challenge to conventional clinical diagnostic methods. Multispectral optoacoustic tomography (MSOT), a molecular-sensitive imaging technology, offers the potential to visualize endogenous and exogenous chromophores in deep tissue. Herein, a novel approach using the orally administered clinical-approved fluorescent dye indocyanine green (ICG) for bedside, non-ionizing evaluation of gastrointestinal passage is presented. The authors are able to show the detectability and stability of ICG in phantom experiments. Furthermore, ten healthy subjects underwent MSOT imaging at multiple time points over eight hours after ingestion of a standardized meal with and without ICG. ICG signals can be visualized and quantified in different intestinal segments, while its excretion is confirmed by fluorescent imaging of stool samples. These findings indicate that contrast-enhanced MSOT (CE-MSOT) provides a translatable real-time imaging approach for functional assessment of the gastrointestinal tract.

Prostaglandin E2 directly inhibits the conversion of inducible regulatory T cells through EP2 and EP4 receptors via antagonizing TGF-β signalling

Regulatory T (Treg) cells are essential for control of inflammatory processes by suppressing effector T-cell functions. The actions of PGE2 on the development and function of Treg cells, particularly under inflammatory conditions, are debated. In this study, we employed pharmacological and genetic approaches to examine whether PGE2  had a direct action on T cells to modulate de novo differentiation of Treg cells. We found that TGF-β-induced Foxp3 expression and iTreg cell differentiation in vitro is markedly inhibited by PGE2 , which was mediated by the receptors EP2 and EP4. Mechanistically, PGE2 -EP2/EP4 signalling interrupts TGF-β signalling during iTreg differentiation. Moreover, EP4 deficiency in T cells impaired iTreg cell differentiation in vivo. Thus, our results demonstrate that PGE2 negatively regulates iTreg cell differentiation through a direct action on T cells, highlighting the potential for selectively targeting the PGE2 -EP2/EP4 pathway to control T cell-mediated inflammation.

What is the optimum time to start antiretroviral therapy in people with HIV and tuberculosis coinfection? A systematic review and meta-analysis

BACKGROUND

HIV and tuberculosis are frequently diagnosed concurrently. In March 2021, World Health Organization recommended that antiretroviral therapy (ART) should be started within two weeks of tuberculosis treatment start, at any CD4 count. We assessed whether earlier ART improved outcomes in people with newly diagnosed HIV and tuberculosis.

METHODS

We did a systematic review by searching nine databases for trials that compared earlier ART to later ART initiation in people with HIV and tuberculosis. We included studies published from database inception to 12 March 2021. We compared ART within four weeks versus ART more than four weeks after TB treatment, and ART within two weeks versus ART between two and eight weeks, and stratified analysis by CD4 count. The main outcome was death; secondary outcomes included IRIS and AIDS-defining events. We pooled effect estimates using random effects meta-analysis.

RESULTS AND DISCUSSION

We screened 2468 abstracts, and identified nine trials. Among people with all CD4 counts, there was no difference in mortality by earlier ART (≤4 week) versus later ART (>4 week) (risk difference [RD] 0%, 95% confidence interval [CI] -2% to +1%). Among people with CD4 count ≤50 cells/mm3 , earlier ART (≤4 weeks) reduced risk of death (RD -6%, -10% to -1%). Among people with all CD4 counts earlier ART (≤4 weeks) increased the risk of IRIS (RD +6%, 95% CI +2% to +10%) and reduced the incidence of AIDS-defining events (RD -2%, 95% CI -4% to 0%). Results were similar when trials were restricted to the four trials which permitted comparison of ART within two weeks to ART between two and eight weeks. Trials were conducted between 2004 and 2014, before recommendations to treat HIV at any CD4 count or to rapidly start ART in people without TB. No trials included children or pregnant women. No trials included integrase inhibitors in ART regimens.

DISCUSSION

Earlier ART did not alter risk of death overall among people living with HIV who had TB disease. For logistical and patient preference reasons, earlier ART initiation for everyone with TB and HIV may be preferred to later ART.

Establishment and Culture of Human Intestinal Organoids Derived from Adult Stem Cells

Human intestinal organoids derived from adult stem cells are miniature ex vivo versions of the human intestinal epithelium. Intestinal organoids are useful tools for the study of intestinal physiology as well as many disease conditions. These organoids present numerous advantages compared to immortalized cell lines, but working with them requires dedicated techniques. The protocols described in this article provide a basic guide to establishment and maintenance of human intestinal organoids derived from small intestine and colon biopsies. Additionally, this article provides an overview of several downstream applications of human intestinal organoids. © 2020 The Authors. Basic Protocol 1: Establishment of human small intestine and colon organoid cultures from fresh biopsies Basic Protocol 2: Mechanical splitting, passage, and expansion of human intestinal organoids Alternate Protocol: Differentiation of human intestinal organoids Basic Protocol 3: Cryopreservation and thawing of human intestinal organoids Basic Protocol 4: Immunofluorescence staining of human intestinal organoids Basic Protocol 5: Generation of single-cell clonal intestinal organoid cultures Support Protocol 1: Production of Wnt3A conditioned medium Support Protocol 2: Production of Rspo1 conditioned medium Support Protocol 3: Extraction of RNA from intestinal organoid cultures.