Lukoševičius, Rokas

Background/Objectives: This study explores the roles of kynurenine and 5-hydroxytryptophan (5-HTP) in modulating gut microbiota and their potential implications for exudative age-related macular degeneration (AMD). By examining the interplay between these metabolites and the microbiome, we aim to uncover novel pathways that may influence the pathogenesis of AMD. Understanding these associations could lead to innovative therapeutic approaches for managing this leading cause of vision loss in the elderly. To investigate the roles of kynurenine and 5-HTP, alongside the composition of the nasopharyngeal microbiota, in patients with exudative AMD. Methods: Blood metabolite profiling was performed using LC–MS–based metabolomics. Metabolites were extracted with cold methanol/water containing internal standards, filtered through a 10 kDa cutoff filter, separated on a ZIC-HILIC HPLC column, and detected using an Orbitrap mass spectrometer. Metabolites were identified using MZmine 2 software. Results: Patients with exudative AMD exhibited a profound systemic shift in tryptophan metabolism, characterized by significantly lower plasma levels of 5-HTP and higher levels of kynurenine compared to control subjects (p < 0.001 for both). Logistic regression analysis confirmed that both metabolites were independent predictors of AMD status; higher kynurenine levels were associated with increased disease probability, while higher 5-HTP levels demonstrated a protective effect. The kynurenine/5-HTP ratio emerged as a robust biomarker, achieving an area under the curve (AUC) of 0.85 with an optimal threshold of 3.43 (74.1% sensitivity, 84.4% specificity). When integrated with age and gender, the diagnostic performance of the model reached an excellent AUC of 0.92. After adjusting for demographic factors, the kynurenine/5-HTP ratio remained a potent independent risk factor, with each unit increase associated with a 6.30-fold increase in the odds of exudative AMD. Conclusions: Exudative AMD is characterized by a shift in tryptophan metabolism toward the kynurenine pathway, with decreased 5-HTP, increased kynurenine, and an elevated kynurenine/5-HTP ratio. This ratio showed a strong independent association with AMD and excellent diagnostic performance, highlighting its potential as a biomarker and its role in disease pathogenesis.

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) share metabolic and inflammatory mechanisms, potentially mediated by the gut microbiota, yet the neurobiological impact of comorbid AD+T2DM microbiota from elderly donors remains unexplored. Fecal microbiota from healthy, AD, T2DM, and AD+T2DM postmenopausal female donors (aged 56-89 years) was transplanted into antibiotic-treated male mice. Behavioral testing, blood profiling, hippocampal neurotrophic gene expression, and 16S rRNA sequencing with taxonomic, functional, and metabolic analyses were performed. Human AD+T2DM microbiota displayed the greatest dysbiosis, characterized by enrichment of pro-inflammatory taxa, depletion of butyrate-producing genera, and loss of neuroprotective metabolic pathways. FMT induced robust engraftment, with AD+T2DM recipients diverging most from controls (PERMANOVA R2 = 0.209, p = 0.001) and healthy recipients (PERMANOVA R2 = 0.111, p = 0.002). Donor age contributed significantly to recipient microbiota variation (R2 = 0.028, p = 0.006), suggesting transmission of aging-associated microbial signatures. Hippocampal neurotrophic gene expression was most suppressed in AD+T2DM recipients (adjusted p value < 0.05) and negatively correlated with disease- and aging-associated taxa and microbial functions (|r| > 0.4, FDR p < 0.05). AD recipients showed reduced olfactory discrimination and increased daytime locomotor activity. Metabolic network analysis revealed depletion of flavonoid, isoflavonoid, and lignan biosynthesis pathways in disease recipients. These findings suggest that microbiota from elderly donors with comorbid AD+T2DM may induce gut-brain axis alterations, linking aging, metabolic dysfunction, and neurodegeneration through convergent taxonomic, functional, and neurotrophic changes. We underscore the potential role of age-associated gut microbial signatures in modulating neurobiological outcomes.

Inflammatory bowel diseases (IBDs), including Crohn’s disease and ulcerative colitis (UC), are characterized by chronic gastrointestinal inflammation and involve complex interactions of genetic, environmental, and immune factors. Enterococcus faecalis, a gut commensal bacterium, has been implicated in IBD pathogenesis. This study investigated the effects of monocolonization with a UC-derived E. faecalis strain on acute dextran sulfate sodium (DSS)-induced colitis in germ-free (GF) mice, focusing on epithelial injury, inflammatory markers, hematologic indices, and bacterial translocation. In DSS-treated mice, monocolonization was associated with modest and mixed effects, including a higher colitis-related disease activity score, reduced anemia, increased fecal albumin and a trend towards reduced fecal calprotectin. Despite translocation of E. faecalis to mesenteric lymph nodes, no systemic dissemination was observed. Histological analysis revealed broadly similar inflammatory patterns between DSS-treated groups, with slightly more epithelial injury observed in colonized mice. These findings suggest that E. faecalis may influence discrete aspects of DSS injury in a strain-dependent and context-specific manner, rather than broadly altering overall disease severity. This study highlights the utility of GF models for examining strain-specific host–microbe interactions and underscores that individual bacterial isolates may exert heterogeneous and selective effects on acute colitis. Further research is needed to elucidate these complex mechanisms.

Pratarmė. Mieli studentai, Gastroenterologija yra viena įdomiausių ir greičiausiai besiplėtojančių medicinos sričių. Dėl mokslo ir technologijų pažangos XXI a. gastroenterologija apima vis platesnį kepenų ir virškinamojo kanalo ligų, gydymo metodų spektrą. Tai neabejotinai viena įvairiapusiškiausių specialybių, kur akivaizdi klinikinių įgūdžių, molekulinių ir ultragarsinių tyrimų bei sudėtingų endoskopinių intervencijų sąsaja. Uždegiminės žarnyno ligos, retos virškinamojo kanalo ligos, mikrobiotos ir kepenų transplantacija yra tik nedidelė dalis sričių, kurios yra patikėtos gydytojams gastroenterologams. Šis Lietuvos sveikatos mokslų universiteto Medicinos akademijos Medicinos fakulteto Gastroenterologijos klinikos (toliau - Gastroenterologijos klinika) kolektyvo parengtas vadovėlis yra skirtas studentams, siekiantiems susipažinti su gastroenterologijos pagrindais. Jau beveik 30 metų Gastroenterologijos klinika aktyviai dalyvauja rengiant tarptautines diagnostikos ir gydymo gaires, yra prestižinių tarptautinių mokslo projektų ir konsorciumų dalyvė, o 2020 m. klinika tapo ir asocijuota Europos retų kepenų ligų tinklo nare. Mūsų klinikos mokslinių tyrimų rezultatai yra publikuojami prestižiniuose mokslo leidiniuose: Nature, Lancet, New England Journal of Medicine, Nature Genetics ir kituose. Rengdami šį vadovėlį stengėmės perteikti visą klinikos sukauptą ilgametę pedagoginę ir klinikinę patirtį bei naujausius mokslo pasiekimus. Tikimės, kad šis vadovėlis ne tik suteiks Jums pagrindinių žinių apie gastroenterologiją, bet ir paskatins rinktis šią specialybę rezidentūros studijose. Autorių vardu prof. Juozas Kupčinskas

Introduction: Over recent decades, the study of the bacterial microbiome has gained increasing attention due to its vital role in human health. The development of the gut microbiome is especially critical during infancy, as it supports nutrient absorption, metabolic regulation, and immune system maturation. Several perinatal factors, including delivery mode, gestational age, and health status, have been shown to influence micro -biome establishment. Preterm and low-birth-weight infants, in particular, face heightened vulnerability to disruptions in microbiome development, which may contribute to adverse health outcomes. Aims & Methods: This study aimed to analyze the longitudinal development of the gut microbiome in preterm, low-birth-weight neonates over the first two months of life and to identify microbial patterns and alterations associated with delivery mode, gestational age, and clinical conditions. The study cohort included 115 low-birth-weight preterm infants and 99full-term, normal-weight controls. Stool samples from preterm infants were collected at multiple time points between day 1 and day 61 of life and grouped into six age categories for analysis. In total, 819 stool samples were examined. DNA was extracted and amplified targeting the V3–V4 region of the 16S rRNA gene, followed by sequencing on the Illumina MiSeq platform. Microbiome data were analyzed using bioinformatic and statistical tools to assess taxonomic composition, alpha diversity, and beta diversity. Results: Significant differences in microbiome profiles were associated with gestational age, mode of delivery, postnatal age, maternal medication, and the presence of necrotizing enterocolitis (NEC). Bacterial com-munities began to stabilize between days 26 and 35. A total of 56 bacterial genera — including Bifidobacterium, Clostridium, Escherichia-Shigella, Gemella, Klebsiella, Lactobacillus, and Streptococcus — showed a positive correlation with infants’ age in days, while 31 genera — including Bacillus, Cutibacterium, Flavobacterium, Macrococcus, Pseudomonas, and Staphylococcus — were negatively correlated. Eighteen bacterial genera were associated with the mode of delivery at various time points. Genera such as Fusobacterium, Bacteroides, Entero-coccus, Streptococcus, Gemella, and Corynebacterium were more commonly associated with vaginal birth, while Staphylococcus, Rahnella, Yokenella, Millisia, Negativicoccus, Finegoldia, Haemophilus, Acinetobacter, Conservatibacter, Serratia, Stenotrophomonas, and Peptoniphilus were associated with Caesarean section delivery. Moderate differences in early-life microbiome composition were also ob -served between low-birth-weight preterm and full-term infants. Conclusion: Gut microbiome development in preterm, low-birth-weight newborns is strongly influenced by clinical and perinatal factors, particularly during the first month of life. Mode of delivery, gestational maturity, and disease presence such as NEC contribute to microbial variability and delayed community stabilization. These findings highlight the importance of early-life monitoring and tailored interventions to support healthy microbiome development in vulnerable neonates.

Introduction: Microscopic colitis (MC) refers to two pathologies – Collagenous colitis (CC) and Lymphocytic colitis (LC) that cause chronic watery diarrhoea, urgency, incontinence leading to significantly decreased quality of life 1.It is thought that MC develops due to a pathological immune response to intestinal luminal antigens in genetically predisposed individuals, with microbiota playing an important role2, 3. However, the pathogenesis of MC is still unclear. Aims & Methods: The aim of this study was to identify and characterize changes in bacterial composition of MC patients in terminal ileum and different colonic segments and determine its relation to the clinical course of disease. Biopsies from terminal ileum and six segments of the colon were collected during diagnostic colonoscopies. DNA extraction was performed using All Prep DNA/RNA Micro Kit (Qiagen) following the manufacturer’s instructions. To determine bacterial composition, sequencing of the 16S rRNA variable region V3-V4 was conducted using the 27F and 338R polymerase chain re-action primers and sequenced on a MiSeq (2×250 bp; Illumina, Hayward, CA). Bioinformatic analysis was performed using DADA2, and taxonomic classification was carried out with the RDP classifier. Results: Biopsy samples from 20 active CC patients, 20 active LC patients, and 50 controls demonstrated distinct microbial profiles across different intestinal segments, as revealed by beta-diversity and differential com-positional analyses. Compared with controls, CC patients had consistent alterations in three bacterial families throughout the entire colon, with Erysipelato clostridiaceae and Coriobacteriaceae decreased and Pasteurellaceae increased. Additionally, 35 families had segment-specific changes, and 25 families displayed altered abundance in the terminal ileum.LC patients exhibited a consistent increase in Erisypelotrichaceae across the entire colon, with 38 other families showing segmental changes, and12 families displaying altered abundance in the terminal ileum. Com-paring LC and CC revealed a significantly different bacterial profile. LC showed lower abundance across many families, particularly in the right colon and terminal ileum. After sample collection, 15 CC patients and 12 LC patients received budesonide, with 3 CC and 2 LC patients having incomplete response. Beta diversity analysis revealed significant differences in the ascending colon and left side of the colon of CC patients based on response to budesonide. Patients with incomplete response to budesonide had an increased abundance of the genus Paucibacter. Similar tendencies were not observed in LC.1 CC patient exhibited a quiescent disease course, 6 reached a sustained remission after treatment, 7 had a relapsing and 6 had a chronic active dis-ease. Significant differences in beta diversity were observed in transverse, descending colon and rectum. Beta diversity of the descending colon had a medium correlation with disease behaviour. In the LC group 6 patients had a quiescent disease, 8 had a sustained remission after treatment, 3 exhibited a relapsing and 4 had a chronic active disease. No significant correlation between microbiota and disease behaviour was observed in LC. Conclusion: This study showed significant differences in bacterial com-position between CC, LC and controls in the terminal ileum and colon. In both CC and LC, bacterial alterations were not consistent throughout the entire colon but varied between different colonic segments. Microbiome differences based on response to budesonide and disease behaviour were observed in CC, but not LC.

Over the past decades, bacterial microbiome studies have become increasingly important. The development of the gut microbiome has been shown to play an essential role in human health, and to be especially decisive in infants [1]. It influences nutrient absorption, metabolism regulation, and immune system development. Various factors have been proposed to modulate the development of the microbiome and therefore shape the growth and health of newborns [2]. Premature babies are often lowweight and even more sensitive to health issues. This study aims to analyse the development of the microbiome in preterm neonates over the first two months of life and look for patterns and alterations associated with several factors, like delivery mode, gestation time and necrotizing enterocolitis (NEC). A total of 78 preterm newborns were included in the study, with stool samples being taken at several timepoints from each baby. In total 515 samples were collected. The timepoints varied between ages of one and 61 days and were grouped in six age groups during the analysis. Genomic DNA was extracted from stool samples, and the bacterial V3–V4 hypervariable region of the 16S rRNA gene was amplified and sequenced on the Illumina MiSeq platform. The data were processed using bioinformatical tools and analysed bioinformatically and statistically to access microbiome composition, abundancies, alpha- and beta-diversities. The analysis revealed significant differences in the bacterial profiles across different timepoints, gestational ages, delivery modes, and in relation to the development of NEC. Alpha diversity indices increased over time; however, fewer or no significant differences were observed between the later timepoints. Consistent patterns emerged from both PCoA and PERMANOVA analyses. Notably, NEC was associated with distinct bacterial. Additionally, the abundance of several bacterial taxa correlated with gestational age. The bacterial profile of premature, low-birth-weight newborns varies according to factors such as age, delivery mode, gestational age, and the presence of disease. Comparing these microbiome dynamics in low-birth-weight infants with those in full-term newborns could provide valuable insights into the development of neonatal diseases such as necrotizing enterocolitis.

Introduction Collagenous colitis (CC) and Lymphocytic colitis (LC) are forms of microscopic colitis (MC) that cause chronic watery diarrhoea, urgency, incontinence leading to significantly decreased quality of life (1). The pathogenesis of MC is not fully understood; however, the leading theory suggests that MC develops as a pathological immune response to intestinal luminal antigens in genetically predisposed individuals (2). Although the gut microbiota is thought to play an important part in this process, its exact role has not been fully explored to this day (3). Aim The aim of this study was to identify and characterize changes in bacterial composition of MC patients in terminal ileum and different colonic segments. Methods Biopsies from terminal ileum and six segments of the colon were collected during diagnostic colonoscopies. DNA extraction was performed using AllPrep DNA/RNA Micro Kit (Qiagen) following the manufacturer’s instructions. To determine bacterial composition, sequencing of the 16S rRNA variable region V3-V4 was conducted. Sequencing data were processed using DADA2, and taxonomic classification was carried out with the RDP classifier. Results In this study, biopsy samples from 20 active CC patients, 20 active LC patients, and 50 controls revealed distinct microbial profiles across different segments of the colon. When comparing CC patients with controls, three bacterial families showed consistent alterations throughout the entire colon, with Erysipelatoclostridiaceae and Coriobacteriaceae decreased and Pasteurellaceae increased. Additionally, 35 families had segment-specific changes, and 25 families displayed altered abundance in the terminal ileum. In contrast, LC patients exhibited a consistent increase in Erisypelotrichaceae across the entire colon, with 38 other families showing segmental changes, and 12 families displaying altered abundance in the terminal ileum. The comparison between LC and CC highlighted a significantly different bacterial profile, with LC showing lower abundance across many families, particularly in the terminal ileum. This segmental dysbiosis pattern, more pronounced in the proximal colon, may contribute to the distinctive pathophysiology in microscopic colitis subtypes. Conclusions This study showed significant differences in bacterial composition between CC, LC and controls in the terminal ileum and colon. Bacterial alterations were not consistent throughout the entire colon but varied between different colonic segments.

The rapid emergence of multidrug-resistant bacterial species poses a critical threat by reducing the efficacy of antibiotics and complicating infection treatment. Bacteriocins, such as klebicin KvarM, have emerged as promising alternatives to traditional antibiotics due to their targeted antimicrobial activity. In this study, we evaluated the therapeutic potential of Eudragit-coated klebicin KvarM in a mouse model of Klebsiella pneumoniae intestinal colonization, assessing both its antimicrobial effectiveness and impact on commensal gut microbiota.

Išradime aprašytas storosios žarnos vėžio (SŽV) nustatymo būdas. Šis būdas apima biologinio mėginio paėmimą, laisvai cirkuliuojančios DNR išskyrimą iš biologinio mėginio (kraujo plazmos), Staphylococcaceae ir Staphylococcus hominis bakterijų sekų nustatymą laisvai cirkuliuojančioje DNR naudojant naujos kartos sekoskaitą, Staphylococcaceae ir Staphylococcus hominis bakterijų sekų santykinio skaičiaus biologiniame mėginyje paliginimo su referentinėmis reikšmėmis (atitinkamai 9,0 proc. ir 0.3 proc.), jei Staphylococcaceae ir Staphylococcus hominis bakterijų sekų santykinis skaičius paciento biologiniame mėginyje viršija referentinę reikšmę, pacientui nustatomas SŽV. Būdas pasižymi aukštu jautrumu ir specifiškumu, todėl jis yra perspektyvi alternatyva ankstyvajai SŽV diagnostikai.