Exogenous lipase administration alters gut microbiota composition and ameliorates Alzheimer's disease-like pathology in APP/PS1 mice.

Alzheimer's disease (AD) represents the most common form of dementia in the elderly with no available disease modifying treatments. Altered gut microbial composition has been widely acknowledged as a common feature of AD, which potentially contributes to progression or onset of AD. To assess the hypothesis that Candida rugosa lipase (CRL), which has been shown to enhance gut microbiome and metabolite composition, can rebalance the gut microbiome composition and reduce AD pathology, the treatment effects in APPswe/PS1de9 (APP/PS1) mice were investigated. The analysis revealed an increased abundance of Acetatifactor and Clostridiales vadin BB60 genera in the gut; increased lipid hydrolysis in the gut lumen, normalization of peripheral unsaturated fatty acids, and reduction of neuroinflammation and memory deficits post treatment. Finally, we demonstrated that the evoked benefits on memory could be transferred via fecal matter transplant (FMT) into antibiotic-induced microbiome-depleted (AIMD) wildtype mice, ameliorating their memory deficits. The findings herein contributed to improve our understanding of the role of the gut microbiome in AD's complex networks and suggested that targeted modification of the gut could contribute to amelioration of AD neuropathology.

Novel, natural allosteric inhibitors and enhancers of Candida rugosa lipase activity.

Candida rugosa lipase (CRL) is an enzyme commonly used in medicinal and biotechnological applications. Allosteric modulators of CRL could aid in modifying lipase-related diseases as well as improving biotechnological processes. Thus, a combinatorial approach of computational in-silico and high-throughput in-vitro screening was used to identify allosteric modulators of CRL. The screening of natural product libraries resulted in 132 compounds of which 53 were tested in-vitro. Subsequently, four inhibitors and three enhancers were identified of which rutin and cynaroside represented the strongest inhibitors of CRL activity (IC50: 227 ± 26 µM and 446 ± 15 µM, respectively) and NP-008496 the strongest enhancer (EC50: 425 ± 18 µM). All three compounds were predicted to bind the same allosteric site suggesting a common mechanism. Therefore, the present study demonstrated a reliable work-flow, identified an allosteric site of CRL and determined inhibitors and enhancers with numerous potential medical and biotechnological applications.

Candida rugosa lipase alters the gastrointestinal environment in wild-type mice.

Diet and commercially available supplements can significantly impact the gut microbial composition; however, the effects of supplements often lack scientific data demonstrating the effects on healthy and diseased individuals. Hence, it was investigated, whether a frequently used supplement in humans, Candida rugosa lipase (CRL), gets delivered active beyond the stomach in the intestinal tract of C57BL/6 J mice and its impact on the gut microbial community and environment. We showed for the first time the movement of CRL in an active state through the mouse digestive tract by determination of intestinal CRL activity and free fatty acids concentrations. The short- and long-term administration of CRL resulted in significant alterations of the gut microbiome, favoring the growth of, for instance, Verrucomicrobia but also other species associated with normal body mass index (BMI) or butyrate expression, both considered beneficial. In addition, we showed that these changes persisted after supplementation and that gut barrier integrity was unaffected by the treatment. In conclusion, CRL can be delivered in an active state beyond the stomach and supplementation altered the murine gut microbiome favoring beneficial bacterial species, which may be of relevance in humans in healthy but also potentially in disease states.

A fast, miniaturised in-vitro assay developed for quantification of lipase enzyme activity.

The discovery of allosteric modulators is a multi-disciplinary approach, which is time- and cost-intensive. High-throughput screening combined with novel computational tools can reduce these factors. Thus, we developed an enzyme activity assay, which can be included in the drug discovery work-flow subsequent to the in-silico library screening. While the in-silico screening yields in the identification of potential allosteric modulators, the developed in-vitro assay allows for the characterisation of them. Candida rugosa lipase (CRL), a glyceride hydrolysing enzyme, has been selected for the pilot development. The assay conditions were adjusted to CRL's properties including pH, temperature and substrate specificity for two different substrates. The optimised assay conditions were validated and were used to characterise Tropolone, which was identified as an allosteric modulator. In conclusion, the assay is a reliable, reproducible, and robust tool, which can be streamlined with in-silico screening and incorporated in an automated high-throughput screening workflow.

Oxytocin analysis from human serum, urine, and saliva by orbitrap liquid chromatography-mass spectrometry.

Oxytocin (OT) is a neurohormone that has gained interest recently due to its emerging role in cognition and social/emotional behaviors, including possibly depression and autism. OT is commonly measured using enzyme- or radio-based immunoassays (RIA, ELISA), which lack specificity or are complicated to perform and involve hazardous radioactive material. We have developed a high resolution accurate-mass (HRAM) liquid chromatography-mass spectrometry (LC-MS) method that separates interferences and selectively and accurately quantitates native OT from human serum, urine, and saliva after solid phase extraction. The doubly protonated OT ion m/z 562.25503 was selected for quantitation due its high signal intensity. With our method lower limit of detection (LLOD) of 5-25 pg/mL, we measured native OT in serum from pregnant women (16-24 pg/mL) and rats (350 pg/mL), and in serum, urine, and saliva from a healthy male after intranasal (IN) OT application of 100 IU and 20 IU and from a healthy post-menopausal female after IN OT application of 100 IU. Peak levels were detected in serum, urine, and saliva 15-30 minutes after each dose then decreased to below detection limits 1-2 hours thereafter. We were unable to detect native OT in serum from non-pregnant/non-lactating/non-medicated women due to levels known to occur below 5 pg/mL. The fast elimination of OT we found is in excellent agreement with the pharmacokinetics of OT in other studies. The effects on the central nervous system occurring after IN OT administration remains to be determined.