The genetic bases of Alzheimer’s disease (AD) and frontotemporal dementia (FTD) have been comprehensively studied, which is not the case for atypical cases not classified into these diagnoses. In the present study, we aim to contribute to the molecular understanding of the development of non-AD and non-FTD dementia due to hyperammonemia caused by mutations in urea cycle genes. The analysis was performed by pooled whole-exome sequencing (WES) of 90 patients and by searching for rare pathogenic variants in autosomal genes for enzymes or transporters of the urea cycle pathway. The survey returned two rare pathogenic coding mutations leading to citrullinemia type I: rs148918985, p.Arg265Cys, C>T; and rs121908641, p.Gly390Arg, G>A in the argininosuccinate synthase 1 (ASS1) gene. The p.Arg265Cys variant leads to enzyme deficiency, whereas p.Gly390Arg renders the enzyme inactive. These variants found in simple or compound heterozygosity can lead to the late-onset form of citrullinemia type I, associated with high ammonia levels, which can lead to cerebral dysfunction and thus to the development of dementia. The presence of urea cycle disorder-causing mutations can be used for the early initiation of antihyperammonemia therapy in order to prevent the neurotoxic effects.

Adenomyosis and endometriosis are distinct gynecological disorders characterized by ectopic growth of endometrial tissue. Their etiology remains unclear, but stem cells have been implicated in both. The aim of this study was to investigate and compare the quantity of NOTCH1+ and CD117+ stem cells in endometriosis and adenomyosis lesions. Immunohistochemical staining of ectopic endometrium biopsies using antibodies against NOTCH1 and CD117 was performed. The quantity and spatial distribution of endometrial stromal cells positive for these markers were determined and compared between endometriosis and adenomyosis lesions. Additionally, their quantities were compared between endometriosis lesion types. Mann–Whitney U test showed that the median percentages of both NOTCH1+ and CD117+ cells in the endometriosis lesions were significantly higher than those in the adenomyosis lesions (2.26% vs. 0.13%, p = 0.002 and 0.44% vs. 0.26%, p = 0.016, respectively). Spearman’s test showed a positive correlation between NOTCH1+ and CD117+ cells in endometriosis lesions (R = 0.45, p = 0.027) but no significant correlation in adenomyosis lesions (R = −0.11, p = 0.69). The quantity of both stem cell types was highest in extragenital endometriotic lesions. Unlike adenomyosis, endometriosis lesions are associated with higher quantities of NOTCH1+ and CD117+ stem cells and a coordinated increase in their number. These findings support the distinct origin of the two conditions.

Background/Objectives: Senescent cells contribute to endometrial remodeling during the implantation window, but their spatial organization within the stroma remains poorly understood. This study aimed to characterize the distribution of senescent (p16-positive) cells in the functional layer of the endometrium and to evaluate their spatial relationships with immune cell subsets. Methods: Endometrial biopsies from 68 women undergoing IVF were collected during the mid-luteal phase (LH+7, corresponding to the implantation window). Samples were analyzed by immunohistochemistry for p16 and immune markers (CD3, CD4, CD8, CD14, CD68, CD56, CD79α). Images from adjacent serial sections were digitally aligned, and senescent cell density, clustering, and nearest-neighbor distances to immune cells were quantified using HALO Image Analysis software (v3.4). Ratios of senescent-to-immune cell abundance were also calculated to account for stromal variability. Results: Senescent cells were heterogeneously dispersed within the stroma, with occasional high-density clusters. Quantitative analysis revealed that their abundance was lower than that of monocytes, macrophages, and total T cells, but higher than that of T-helper and B cells. Across patients, median senescent-to-immune cell ratios were approximately 1, indicating comparable abundances, except for CD4⁺ and CD79α⁺ subsets, where ratios were significantly elevated. Nearest-neighbor analysis showed that macrophages and monocytes localized in closest proximity to senescent cells (45 ± 20 μm and 45 ± 25 μm), while T-helper and NK cells were positioned at greater distances from senescent cells (102 ± 42 μm and 53 ± 23 μm, respectively). B cells showed the greatest separation (211 ± 66 μm). Correlation analysis confirmed density-driven proximity for most immune subsets, with CD4⁺ and CD56⁺ cells as exceptions, displaying limited spatial association with senescent cells. Conclusions: Senescent cells in the endometrium during the implantation window display heterogeneous distribution and selective spatial associations with immune subsets. Their preferential distancing from T-helper and NK cells suggests impaired local immune–senescence crosstalk, highlighting spatial profiling of senescent cells as a potential diagnostic marker of endometrial receptivity.

The aim of this study was to investigate the association between the endometrial microbiome and local immune cell composition during the implantation window. We conducted a single-center prospective observational study including endometrial samples from 58 women without endometrial pathology. All samples were obtained during the mid-secretory phase (day 5 post-ovulation). Endometrial stromal CD3⁺ T cells, CD4⁺ T helpers, CD56⁺ NK cells and CD68⁺ macrophages were identified by immunohistochemistry and quantified as a percentage of stromal cells using HALO image analysis software. Microbiome composition was assessed by 16S rRNA gene sequencing (V4–V5 region). Lactobacillus dominance (LD) was defined as the genus with the highest centered log-ratio value within each sample. Endometrial immune cell composition showed a median 2.28% CD3⁺ T cells of stromal cells, 1.75% CD56⁺ NK cells, 1.44% CD68⁺ macrophages and 0.29% CD4⁺ T helpers. Lactobacillus-dominated microbiota was identified in 51.7% (30/58) of samples. Correlation analysis showed that Lactobacillus-related taxa were negatively associated with NK/T ratios and positively with T helper-related ratios. LD samples exhibited reduced NK cell abundance (1.17% vs. 2.12%, p = 0.006, q = 0.023) and a lower NK/T ratio (0.52 vs. 1.05, p = 0.004, q = 0.023) compared to non-LD samples. This study provides evidence for a link between microbial composition and local immune regulation in the endometrium.

Endometrial senescence and the endometrial microbiota have both been implicated in the regulation of endometrial receptivity, yet their relationship remains poorly understood. The aim of this study was to investigate associations between p16-positive endometrial cells and microbiota composition during the implantation window and to determine whether these relationships differ according to implantation outcome. Endometrial senescence was assessed by p16 immunohistochemistry and digital image analysis, whereas microbial composition was characterized by 16S rRNA gene sequencing in endometrial biopsies collected from 68 women prior to undergoing transfer of a single euploid embryo, which was performed within six months of biopsy under the same hormonal preparation protocol. No significant differences in luminal epithelial or stromal p16 abundance were observed according to subsequent implantation outcome. Although senescence was not directly associated with implantation success, stromal p16 expression demonstrated multiple associations with the endometrial microbiota. Increased stromal p16-positivity was associated with lower relative abundance of Lactobacillus and higher abundance of Delftia. Notably, in exploratory subgroup analyses more pronounced associations were observed in women who achieved pregnancy, including a negative correlation between stromal p16 expression and Lactobacillus abundance (ρ = −0.48, p = 0.005) and positive correlation with Delftia abundance (ρ = 0.42, p = 0.016). Species-level analyses revealed implantation outcome-specific associations involving Lactobacillus iners and Limosilactobacillus vaginalis. In addition, stromal p16 expression was associated with differences in microbial co-occurrence networks, indicating broader effects on microbial community organization. Together, these findings suggest that stromal, but not luminal, senescence is closely linked to endometrial microbiota composition and microbial community organization during the window of implantation. The observation that the strongest senescence–microbiota associations occurred in women who subsequently achieved successful implantation supports the hypothesis that coordinated senescence–microbiota relationships may represent a previously underrecognized feature of the receptive endometrial microenvironment.

The genetic bases of Alzheimer's disease (AD) and frontotemporal dementia (FTD) have been comprehensively studied, which is not the case for atypical cases not classified into these diagnoses. In the present study, we aim to contribute to the molecular understanding of the development of non-AD and non-FTD dementia by surveying rare pathogenic variants. The analysis was performed on 91 patients, the DNA samples of which were pooled and then subjected to whole exome sequencing. Among detected variants two are rare pathogenic and show significant difference in frequency between the analyzed pool and gnomAD Bulgarian control exomes. The rs373478202, G>T, B9D1 variant, most likely present in heterozygous state; is causative for the autosomal recessive ciliopathy- Joubert syndrome, which involves specific CNS malformation. The rs148918985, C>T, ASS1 variant leads to arginosuccinate enzyme deficiency and in compound heterozygosity with other rare pathogenic variant detected in the same gene causes the late-onset form of citrullinemia type I. This disorder causes high ammonia levels, which can lead to cerebral dysfunction. In conclusion, the detected rare pathogenic variants suggest that, in certain cases, the development of non-AD and non-FTD dementia can be mediated by structural alterations in neuronal cilia or by hyperammoniemia.