Lipid components of bile increase the protective effect of conjugated bile salts against antifungal drugs

TUDCA modulates drug bioavailability to regulate resistance to acute ER stress in Saccharomyces cerevisiae

Cells counter accumulation of misfolded secretory proteins in the endoplasmic reticulum (ER) through activation of the Unfolded Protein Response (UPR). Small molecules termed chemical chaperones can promote protein folding to alleviate ER stress. The bile acid tauroursodeoxycholic acid (TUDCA) has been described as a chemical chaperone. While promising in models of protein folding diseases, TUDCA's mechanism of action remains unclear. Here, we found TUDCA can rescue growth of yeast treated with the ER stressor tunicamycin (Tm), even in the absence of a functional UPR. In contrast, TUDCA failed to rescue growth on other ER stressors. Nor could TUDCA attenuate chronic UPR associated with specific gene deletions or overexpression of a misfolded mutant secretory protein. Neither pretreatment with nor delayed addition of TUDCA conferred protection against Tm. Importantly, attenuation of Tm-induced toxicity required TUDCA's critical micelle forming concentration, suggesting a mechanism where TUDCA directly sequesters drugs. Indeed, in several assays, TUDCA-treated cells closely resembled cells treated with lower doses of Tm. In addition, we found TUDCA can inhibit dyes from labeling intracellular compartments. Thus, our study challenges the model of TUDCA as a chemical chaperone and suggests that TUDCA decreases drug bioavailability, allowing cells to adapt to ER stress.

Interplay between Bile Acids and Intestinal Microbiota: Regulatory Mechanisms and Therapeutic Potential for Infections

Bile acids (BAs) play a crucial role in the human body's defense against infections caused by bacteria, fungi, and viruses. BAs counteract infections not only through interactions with intestinal bacteria exhibiting bile salt hydrolase (BSH) activity but they also directly combat infections. Building upon our research group's previous discoveries highlighting the role of BAs in combating infections, we have initiated an in-depth investigation into the interactions between BAs and intestinal microbiota. Leveraging the existing literature, we offer a comprehensive analysis of the relationships between BAs and 16 key microbiota. This investigation encompasses bacteria (e.g., Clostridioides difficile (C. difficile), Staphylococcus aureus (S. aureus), Escherichia coli, Enterococcus, Pseudomonas aeruginosa, Mycobacterium tuberculosis (M. tuberculosis), Bacteroides, Clostridium scindens (C. scindens), Streptococcus thermophilus, Clostridium butyricum (C. butyricum), and lactic acid bacteria), fungi (e.g., Candida albicans (C. albicans) and Saccharomyces boulardii), and viruses (e.g., coronavirus SARS-CoV-2, influenza virus, and norovirus). Our research found that Bacteroides, C. scindens, Streptococcus thermophilus, Saccharomyces boulardii, C. butyricum, and lactic acid bacteria can regulate the metabolism and function of BSHs and 7α-dehydroxylase. BSHs and 7α-dehydroxylase play crucial roles in the conversion of primary bile acid (PBA) to secondary bile acid (SBA). It is important to note that PBAs generally promote infections, while SBAs often exhibit distinct anti-infection roles. In the antimicrobial action of BAs, SBAs demonstrate antagonistic properties against a wide range of microbiota, with the exception of norovirus. Given the intricate interplay between BAs and intestinal microbiota, and their regulatory effects on infections, we assert that BAs hold significant potential as a novel approach for preventing and treating microbial infections.

Alterations of Fungal Microbiota in Patients With Cholecystectomy

Increasing evidence suggests a high risk of gastrointestinal postoperative comorbidities (such as colorectal cancer) in patients with postcholecystectomy (PC). Although previous studies implicated the role of fungi in colon carcinogenesis, few reports focused on the fungal profile in patients with PC. We enrolled 104 subjects, including 52 patients with PC and 52 non-PC controls (CON), for fecal collection to detect the fungal composition by an internal transcribed spacer (ITS) 1 rDNA sequencing. Data showed that Candida (C.) glabrata and Aspergillus (A.) Unassigned were enriched, and Candida albicans was depleted in patients with PC. In addition, postoperative duration was the main factor to affect the fungal composition. Machine learning identified that C. glabrata, A. Unassigned, and C. albicans were three biomarkers to discriminate patients with PC from CON subjects. To investigate the fungal role in colon carcinogenesis, the subjects of the PC group were divided into two subgroups, namely, patients with PC without (non-CA) and with precancerous lesions or colorectal cancer (preCA_CRC), by histopathological studies. C. glabrata was found to be gradually accumulated in different statuses of patients with PC. In conclusion, we found fungal dysbiosis in patients with cholecystectomy, and the postoperative duration was a potent factor to influence the fungal composition. The accumulation of C. glabrata might be connected with carcinogenesis after cholecystectomy.

Long-chain unsaturated fatty acids are involved in the viability and itraconazole susceptibility of Aspergillus fumigatus

The prevalence of invasive aspergillosis with azole resistance is increasing, but the mechanisms underlying the development of resistance and treatment strategies are still limited. The present work is focused on finding a relationship between long-chain unsaturated fatty acids (LCUFAs), Aspergillus fumigatus development, and antifungal resistance. The effects of LCUFAs on antifungal agents in vitro were determined, and the stearic acid desaturase gene (sdeA) of A. fumigatus was characterized. In in vitro antifungal tests, LCUFAs antagonized the antifungal activity of itraconazole by extracting it from media, thereby preventing it from entering cells. The OA auxotrophic phenotype caused by an sdeA deletion confirmed that SdeA was required for OA biosynthesis in A. fumigatus. Furthermore, several low-level sdeA-overexpressing mutants with impaired vegetative growth phenotypes were successfully constructed. Additionally, an sdeA-overexpressing mutant, OEsdeA-5, showed lowered sensitivity levels to itraconazole. Moreover, RNA sequencing of OEsdeA-5 revealed that the altered gene-expression pattern. Through targeted metabolomics, decreased palmitic acid and stearic acid contents, accompanied by higher palmitoleic acid, margaroleic acid, and OA production levels, were found in OEsdeA-5. This study provides a novel insight of understanding of azole resistance and a potential target for drug development.

Contamination of single fluid-filled intragastric balloons with orogastric fluid is not associated with hyperinflation: an ex-vivo study and systematic review of literature

BACKGROUND

Spontaneous hyperinflation is reported to the Food and Drug Administration as a complication of intragastric balloons. It is postulated that orogastric contamination of the intragastric balloon may cause this phenomenon. We sought to investigate the effects of intentional balloon contamination with gastric contents on intragastric balloon perimeter and contents, whether methylene blue plays a role in preventing spontaneous hyperinflation, and review the available literature on spontaneous hyperinflation.

METHODS

Four pairs of balloons with different combinations of sterile saline, orogastric contaminants, and methylene blue were incubated in a 37 °C water bath for six months to simulate physiological conditions with serial measurements of balloon perimeter. Our findings were compared against a systematic review across multiple databases to summarize the available literature.

RESULTS

Balloon mean perimeter decreased from 33.5 cm ± 0.53 cm to 28.5 cm ± 0.46 cm (p < 0.0001). No significant differences were seen with the methylene blue group. Only 11 cases were found reported in the literature.

CONCLUSIONS

Despite contaminating intragastric balloons with gastric aspirates, hyperinflation did not occur, and other factors may be in play to account for this phenomenon, when observed. Rates of hyperinflation remain under-reported in the literature. Further controlled experiments are needed.

Prediction of negative food effect induced by bile micelle binding on oral absorption of hydrophilic cationic drugs

The purpose of the present study was to quantitatively predict the negative food effect induced by bile micelle binding on the oral absorption of hydrophilic cationic drugs. The intrinsic membrane permeability and bile micelle unbound fraction of 12 model drugs (7 tertiary amines, 3 quaternary ammoniums, and 2 neutral drugs) were calculated from the experimental Caco-2 permeability data (P_app) under fasted and fed conditions. From these input data, the fraction of a dose absorbed (Fa) was predicted using the gastrointestinal unified theoretical framework, a mechanism-based oral absorption model. The predicted Fa ratio (fed/fasted) was then compared with the in vivo fed/fasted area under the plasma concentration-time curve ratio (AUCr). The AUCr values of tertiary amines and neutral drugs were appropriately predicted (absolute average fold error (AAFE) = 1.19), whereas those of quaternary ammoniums were markedly underestimated (AAFE = 4.70). The P_app ratio (fed/fasted) predicted AUCr less quantitatively (AAFE = 1.30 for tertiary amines and neutral drugs). The results of the present study would lead to a better understanding of negative food effect on oral drug absorption.

Antibiotic-induced alterations in taurocholic acid levels promote gastrointestinal colonization of Candida albicans

Candida albicans is a fungal pathogen that poses a significant public health risk due to high incidence and mortality rates among immunocompromised patients. Candida albicans infections begin with successful gastrointestinal (GI) colonization; however, the mechanisms behind this colonization remain to be elucidated. In this study, we investigated the role of taurocholic acid (TCA) on growth and GI colonization of C. albicans. Our results indicate that cefoperazone-treated mice susceptible to C. albicans infection had significantly increased levels of TCA in the gut contents. In addition, an increase in TCA levels directly correlates with higher C. albicans load in the fecal and gut contents of antibiotic-treated infected mice. Using in vitro assays, we also demonstrated that TCA enhances the growth of C. albicans and its ability to develop filamentous hyphae. Furthermore, TCA significantly increased the ability of C. albicans to attach to mammalian cells. These results demonstrate that antibiotic treatment alters TCA levels in the gut and potentially enhances GI colonization of C. albicans.