Patrícia Gama

Gastric gland cells originate from two proliferative niches: the main rapid one in the isthmus, and the slow secondary one in the base. However, while nutrition is dependent on breastfeeding, the proliferative niches are not established, and proliferation occurs along the gland. Currently, we investigated the influence of early weaning (EW) on shaping gastric proliferative niches and their signaling. Wistar rats were separated into suckling (S) and EW groups on postnatal day (PND) 15 for gastric mucosa collection. BrdU was administered (PND 14 and 15) and as it diluted between daughter‐cells we evaluated migration and differentiation. In parallel EdU incorporation was used to identify cells during S phase. Through these tools, we studied the different profiles of BrdU/EdU dual labeling at 18, 21 and 30 PND. At 18 PND, EW decreased BrdU+ population ( p < 0.0001 vs . S group) in the upper and bottom gland areas ( p < 0.05). The BrdU + /EdU+ cells were concentrated in the upper gland, where we recorded a larger EdU+ population after EW ( p < 0.05). On PND 30, EW decreased BrdU+ cells in the gland ( p < 0.05), whereas EdU+ cells were more numerous in the isthmus. At 18 PND, EW reduced Wnt3 , Notch1 , and Notch2 expressions ( p < 0.05), while increasing Bmp2 . In contrast, at 60 PND, Axin2 , Notch1 , and Notch2 transcripts were elevated after EW ( p < 0.05). Notch1 and Notch2 distribution indicated that EW might shift Notch2 to the upper gland, potentially affecting the fate of progenitor cells in pups. In silico analyses showed that zymogenic cells are in a renewal‐promoting environment, while parietal cells contribute to differentiation and signaling. Therefore, EW restricted the proliferative activity to the isthmus, altering the spatiotemporal expression of genes involved in stemness and differentiation, and reshaped the distribution of Notch receptors, without affecting the distribution of its downstream effector Hes1. These spatially organized molecular landscapes are crucial for proper epithelial renewal and function, and our data suggest that early nutritional disruption reprograms these niches with long‐term consequences.

This study investigates the distribution and role of the stem cell marker Troy (Tnfrsf19) in the gastric mucosa of rats during postnatal development and the effects of early weaning. Troy, previously identified as a reserve stem cell marker in adult gastric tissues, is examined across various developmental stages from birth to adulthood. We showed that Troy+ cells are scattered throughout the gastric gland in early postnatal stages, but they become concentrated in the basal portion of the gland as the rats mature. Additionally, early weaning affects Troy expression at its gene and protein levels, altering its distribution in the gastric mucosa. This suggests that early dietary changes may disrupt the organization and function of the secondary stem cell niche in the stomach, potentially impacting gastric gland homeostasis. We also used in silico analysis to compare the molecular functions of Troy+ zymogenic and parietal cells, finding distinct roles in proliferation and secretion. The results underscore the importance of Troy in gastric development and highlight the long‐term impact of early weaning on gastric tissue organization and cell proliferation dynamics.

Gastrointestinal epithelial cells respond to milk‐born molecules throughout breastfeeding, influencing growth, and development. The rapid renewal of the small intestine depends on the proliferation in the crypt that drives cell fates. We used early weaning model to investigate immediate and late effects of breastfeeding on proliferation, differentiation of jejunal epithelial cells. Wistar rats were either allowed to suckle (S) until 21 postnatal days or submitted to early weaning (EW) at 15 days. By comparing ages (18, 60, and 120 days), we found that EW decreased Ki67 indices and villi height at 18 and 60 days (p < 0.05), and at 120 days they were similar between diets. Proliferative reduction and augmented expression of Cdkn1b (p27 gene) were parallel. In the stem cell niche, EW increased the number and activity (Defa24) of Paneth cells at 18 and 60 days (p < 0.05), and Lgr5 and Ascl2 genes showed inverted responses between ages. Among target cells, EW decreased goblet cell number at 18 and 60 days (p < 0.05) and increased it at 120 days (p < 0.05), whereas enteroendocrine marker genes were differentially altered. EW reduced enterocytes density at 18 days (p < 0.05), and at 120 days this population was decreased (vs. 60 days). Among cell fate crypt‐controlling genes, Notch and Atoh1 were the main targets of EW. Metabolically, intraperitoneal glucose tolerance was immediately reduced (18 days), being reverted until 120 days (p < 0.05). Currently, we showed that breastfeeding has a lifespan influence on intestinal mucosa and on its stem cell compartment. We suggest that, although jejunum absorptive function is granted after early weaning, the long lasting changes in gene expression might prime the mucosa with a different sensitivity to gut disorders that still have to be further explored.

The small intestine mucosa is lined by specialized cells that form the crypt‐villus axis, which expands its surface. Among the six intestinal epithelial cell types, the Paneth cell is located at the base of the crypt, and it contains numerous granules in its cytoplasm, composed of antimicrobial peptides, such as defensins and lysozyme, and growth factors, such as epidermal growth factor, transforming growth factor‐α, and Wnt ligands. Together, these elements act in the defense against microorganisms, regulation of intestinal microbiota, maintenance, and regulation of stem cell identity. Pathologies that target Paneth cells can disturb such defense activity, but they also affect the maintenance of the stem cell niche. In that way, Crohn's disease, necrotizing enterocolitis, and graft‐versus‐host disease promote a reduction of Paneth cell population, and, consequently, secretion of their products into the lumen of the crypts, making the affected organism predisposed to infections and dysbiosis. Additionally, the emergence of new intestinal cells is also decreased. This review aims to address the main characteristics of Paneth cells, highlighting their multiple functions and the importance of their preservation to ensure bowel homeostasis.

The gastric mucosa is disturbed when breastfeeding is interrupted, and such early weaning (EW) condition permanently affects the differentiation of zymogenic cells. The aim of the study was to evaluate the immediate and long-term effects of EW on gastric cell proliferation, considering the molecular markers for cell cycle, inflammation, and metaplasia. Overall, we investigated the lifelong adaptation of gastric growth. Wistar rats were divided into suckling-control (S) and EW groups, and gastric samples were collected at 18, 30, and 60 days for morphology, RNA, and protein isolation. Inflammation and metaplasia were not identified, but we observed that EW promptly increased Ki-67-proliferative index (PI) and mucosa thickness (18 days). From 18 to 30 days, PI increased in S rats, whereas it was stable in EW animals, and such developmental change in S made its PI higher than in EW. At 60 days, the PI decreased in S, making the indices similar between groups. Spatially, during development, proliferative cells spread along the gland, whereas, in adults, they concentrate at the isthmus-neck area. EW pushed dividing cells to this compartment (18 days), increased PI at the gland base (60 days), but it did not interfere in expression of cell cycle molecules. At 18 days, EW reduced Tgfβ2, Tgfβ3, and Tgfbr2 and TβRII and p27 levels, which might regulate the proliferative increase at this age. We demonstrated that gastric cell proliferation is immediately upregulated by EW, corroborating previous results, but for the first time, we showed that such increased PI is stable during growth and aging. We suggest that suckling and early weaning might use TGFβs and p27 to trigger different proliferative profiles during life course.

During postnatal development, colostrum and breastmilk are sequentially the first sources of nutrition with protein components and bioactive molecules that confer protection and immunostimulatory function to the gut. Caseins, whey proteins, secretory immunoglobulin A (sIgA), mucins, tryptophan, and growth factors are among milk‐borne elements that are directly important in the control of mucosa development and protection. Consequently, breastfeeding is associated with the low incidence of gastrointestinal inflammation and with the decrease in respiratory diseases during postnatal period. The novel coronavirus (SARS‐CoV‐2) binds to angiotensin II‐converting enzyme (ACE2) on the cell membrane, allowing virus entrance, replication, and host commitment. ACE2 is expressed by different cell types, which include ciliated cells in the lungs and enterocytes in the intestine. Such cells are highly active in metabolism, as they internalize molecules to be processed and used by the organism. The disruption of ACE2 impairs leads to intestinal inflammation and decreased synthesis of serotonin, affecting motility. By reviewing the effects of SARS‐CoV‐2 in the gastrointestinal and respiratory tracts in infants, and gut responses to breastfeeding interruption, we suggest that it is important to maintain breastfeeding during SARS‐CoV‐2 infection, as it might be essential to protect newborns from gastrointestinal‐associated disorders and relieve disease symptoms.

Background: Gastric glands grow and cells reach differentiation at weaning in rats. By considering that early weaning (EW) can affect the timing of development, we aimed to compare molecular and cellular markers of differentiation in pups and adults. Methods: Wistar rats were separated into suckling-control (S) and EW groups at 15 days. Stomachs were collected at 15, 18, and 60 days for RNA and protein extraction, and morphology. Results: After EW, the expression of genes involved in differentiation (Atp4b, Bhlha15 and Pgc) augmented (18 days), and Atp4b and Gif were high at 60 days. EW increased the number of zymogenic cells (ZC) in pups and adults and augmented mucous neck cells only at 18 days, whereas parietal and transition cells (TC) were unchanged. Conclusions: EW affected the gastric mucosa mostly in a transient manner as the changes in gene expression and distribution of differentiated cells that were detected in pups were not fully maintained in adults, except for the size of ZC population. We concluded that though most of EW effects were immediate, such nutritional change in the infancy might affect part of gastric digestive functions in a permanent manner, as some markers were kept unbalanced in the adulthood.

Background: Cachexia is a multifactorial and multiorgan syndrome associated with cancer and other chronic diseases and characterized by severe involuntary body weight loss, disrupted metabolism, inflammation, anorexia, fatigue, and diminished quality of life. This syndrome affects around 50% of patients with colon cancer and is directly responsible for the death of at least 20% of all cancer patients. Systemic inflammation has been recently proposed to underline most of cachexia‐related symptoms. Nevertheless, the exact mechanisms leading to the initiation of systemic inflammation have not yet been unveiled, as patients bearing the same tumour and disease stage may or may not present cachexia. We hypothesize a role for gut barrier disruption, which may elicit persistent immune activation in the host. To address this hypothesis, we analysed the healthy colon tissue, adjacent to the tumour.Methods: Blood and rectosigmoid colon samples (20 cm distal to tumour margin) obtained during surgery, from cachectic (CC = 25) or weight stable (WSC = 20) colon cancer patients, who signed the informed consent form, were submitted to morphological (light microscopy), immunological (immunohistochemistry and flow cytometry), and molecular (quantification of inflammatory factors by Luminex® xMAP) analyses.Results: There was no statistical difference in gender and age between groups. The content of plasma interleukin 6 (IL‐6) and IL‐8 was augmented in cachectic patients relative to those with stable weight (P = 0.047 and P = 0.009, respectively). The number of lymphocytic aggregates/field in the gut mucosa was higher in CC than in WSC (P = 0.019), in addition to those of the lamina propria (LP) eosinophils (P < 0.001) and fibroblasts (P < 0.001). The area occupied by goblet cells in the colon mucosa was decreased in CC (P = 0.016). The M1M2 macrophages percentage was increased in the colon of CC, in relation to WSC (P = 0.042). Protein expression of IL‐7, IL‐13, and transforming growth factor beta 3 in the colon was significantly increased in CC, compared with WSC (P = 0.02, P = 0.048, and P = 0.048, respectively), and a trend towards a higher content of granulocyte‐colony stimulating factor in CC was also observed (P = 0.061). The results suggest an increased recruitment of immune cells to the colonic mucosa in CC, as compared with WSC, in a fashion that resembles repair response following injury, with higher tissue content of IL‐13 and transforming growth factor beta 3.Conclusions: The changes in the intestinal mucosa cellularity, along with modified cytokine expression in cachexia, indicate that gut barrier alterations are associated with the syndrome.

Neonatal- Maternal Separation (NMS) deprives mammals from breastfeeding and maternal care, influencing growth during suckling- weaning transition. In the gastric mucosa, Mist1 (encoded by Bhlha15 gene) and moesin organize the secretory apparatus for pepsinogen C in zymogenic cells. Our current hypothesis was that NMS would change corticosterone activity through receptors (GR), which would modify molecules involved in zymogenic cell differentiation in rats. We found that NMS increased corticosterone levels from 18 days onwards, as GR decreased in the gastric mucosa. However, as nuclear GR was detected, we investigated receptor binding to responsive elements (GRE) and observed an augment in NMS groups. Next, we demonstrated that NMS increased zymogenic population (18 and and 30 days), and targeted Mist1 and moesin. Finally, we searched for evolutionarily conserved sequences that contained GRE in genes involved in pepsinogen C secretion, and found that the genomic regions of Bhlha15 and PgC contained sites highly likely to be responsive to glucocorticoids. We suggest that NMS triggers GR- GRE to enhance the expression and to prime genes that organize cellular architecture in zymogenic population for PgC function. As pepsinogen C- pepsin is essential for digestion, disturbance of parenting through NMS might alter functions of gastric mucosa in a permanent manner.