Proximal gut mucosal epithelial homeostasis in aged IL-1 type I receptor knockout mice after starvation

Prolonged Fasting Induces Histological and Ultrastructural Changes in the Intestinal Mucosa That May Reduce Absorption and Revert after Enteral Refeeding

Background: Malnutrition is usual in patients referred for endoscopic gastrostomy (PEG). Refeeding syndrome is rarely observed in PEG-fed patients, which could possibly be associated with reduced absorption induced by prolonged starvation. Objective: In patients submitted to PEG after a significant period of fasting, the present study aims to: 1. evaluate the histological/ultrastructural initial changes in the intestinal mucosa, potentially associated with reduced absorption, and 2. assess if these changes could reverse with enteral refeeding. Methods: The present study is an observational, prospective, controlled study. Adult patients with ingestion below 50% of daily needs for at least one month and/or diagnosis of malnutrition were enrolled. Duodenal biopsies were taken at baseline and after 3-6 months of PEG feeding, which then underwent histological/ultrastructural analysis. Random healthy individuals were used as controls. Results: A total of 30 patients (16 men/14 women) aged 67.1 ± 13.5 years were included. Malnutrition was found in 40% of patients. Approximately 14 patients completed follow-up during both periods (46.7%). At baseline: duodenal mucosal atrophy was evident in three patients (10%); the median villi length (MVL) was 0.4 mm (0.25-0.6 mm), with it being shorter than the controls, which was 0.6 mm (0.4-0.7 mm) (p = 0.006); ultrastructural changes included focal shortening, bending, and disruption of enterocyte microvilli, the presence of citoplasmatic autophagic vacuoles, dilation and vesiculation of the smooth endoplasmic reticulum, and the presence of dilated intercellular spaces with basement membrane detachment. After refeeding, most patients displayed normal histology (92.9%) and increase MVL (p < 0.001), ultrastructural changes disappeared, and enterocytes resumed a normal appearance, although retaining scarce, small, dense bodies in apical regions from the evolution of previous autophagy. Conclusions: Prolonged fasting induces histological and ultrastructural changes in the intestinal mucosa that may reflect impaired absorption in the early post-PEG period. These changes were reverted after refeeding with enteral nutrition.

Novel insights into perfluorinated compound-induced hepatotoxicity: Chronic dietary restriction exacerbates the effects of PFBS on hepatic lipid metabolism in mice

Perfluorobutane sulfonates (PFBS) have garnered extensive utilization because of their distinctive physicochemical properties. The liver acts as a key target organ for toxicity within the body and is vital for regulating metabolic processes, particularly lipid metabolism. However, there is currently a significant research gap regarding the influences of PFBS on hepatic lipid metabolism, especially in individuals with different dietary statuses. Here, the objective of this research was to examine the effects of PFBS on hepatic function under different dietary conditions. The results suggested that the levels of liver injury biomarkers were significantly upregulated, e.g., transaminase (GPT, GOT), while liver lipid levels were downregulated after exposure to PFBS at concentration of 50 μg/L for 42 days. Moreover, restricted diet further intensified the adverse effects of PFBS on the liver. Metabolomics analysis identified significant alterations in lipid-related metabolites in PFBS-induced hepatotoxicity, PFBS exposure induced a decrease in lysophosphatidylethanolamine and lysophosphatidylcholine. PFBS exposure caused an increase in aldosterone and prostaglandin f2alpha under restricted diet. In PFBS treatment group, histidine metabolism, beta-alanine metabolism, and arginine biosynthesis were the main pathway for PFBS toxicity. Aldosterone-regulated sodium reabsorption as a vital factor in inducing PFBS toxicity in the RD-PFBS treatment group. The analysis of 16S rRNA sequencing revealed that exposure to PFBS resulted in imbalance of gut microbial communities. PFBS exposure induced a decrease in Akkermansia and Lactobacillus, but an increase in Enterococcus. PFBS exposure caused the abundance of Lachnospiraceae_NK4A136_group was significantly elevated under restricted diet. Additionally, disruptions in the expression of genes involved in lipid production and consumption may significantly contribute to lipid imbalance in the liver. This study underscores the importance of recognizing the harmful impact of PFBS on liver function, along with the biotoxicity of contaminant influenced by dietary habits.

IL-1R1 deficiency impairs liver regeneration after 2/3 partial hepatectomy in aged mice

Inflammation has a dual effect: it can protect the body and destroy tissue and cell as well. The purpose of this experiment was to determine the role of IL-1R1 in liver regeneration (LR) after partial hepatectomy (PH) in aged mice. The wild-type (WT, n = 36) and the IL-1R1 knockout (KO, n = 36) 24-month-old C57BL/6J mice underwent two-thirds PH; 33 WT mice underwent sham operation. Liver coefficient was calculated by liver/body weight. The mRNA and protein expressions of genes were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting methods, respectively. Compared with WT mice, liver coefficient was lower in the IL-1R1 KO aged mice at 168 and 192 h (p = 0.039 and p = 0.027). The mRNA transcription of inflammation-related genes and cell cycle-associated genes decreased or delayed. The protein expressions of proliferation-related marker PCNA and proliferation-associated signaling pathway components JNK1, NF-κB and STAT3 reduced or retarded. There was stronger activation of proapoptotic proteins caspase-3, caspase-8 and BAX in the IL-1R1 KO mice at different time points (p < 0.05 or p < 0.01). IL-1R1 KO reduced inflammation and caused impaired liver regeneration after 2/3 partial hepatectomy in aged mice. Maintaining proper inflammation may contribute to regeneration after liver partly surgical resection in the elderly.

Influences of Short-Term Fasting and Carbohydrate Supplementation on Gut Immunity and Mucosal Morphology in Mice

BACKGROUND

Preoperative carbohydrate (CHO) supplementation has been recommended in enhanced recovery after surgery protocols. However, the effects of CHO supplementation on gut and systemic immunity are not well understood.

METHODS

Mice (n = 60) were randomized to 1 of the following 5 groups: control (ad lib feeding), 12-hour fasting without CHO administration (fasting), and 12 hours of fasting with CHO administration at 2, 4, and 8 hours before sacrifice. Then, lymphocytes were isolated from gut-associated lymphoid tissue, that is, Peyer's patches, the intraepithelial space, and the lamina propria of the small intestine. These lymphocyte numbers and phenotypes were evaluated. IgA levels in respiratory and small-intestinal washings were determined by ELISA. Morphology, proliferation, and apoptosis of the intestinal epithelium were also evaluated histologically.

RESULTS

Although there were no significant differences in IgA levels among the 5 groups, fasting decreased intraepithelial and lamina propria, but not Peyer's patches lymphocyte numbers. CHO at 2 hours prevented lymphocyte loss in intraepithelial, whereas CHO at 4 hours reversed lamina propria lymphocytes numbers. Percentages of lymphocyte phenotypes were similar in each site among the 5 groups. Fasting caused villous atrophy; however, CHO at 2 hours restored villous structure along with maintenance of epithelial cell proliferation rate.

CONCLUSIONS

Only 12 hours of fasting causes marked gut-associated lymphoid tissue cell loss along with gut atrophy. However, CHO at 2 hours preserves gut immunity and morphology not completely but moderately.

Severe burn increased skeletal muscle loss in mdx mutant mice

BACKGROUND

Severe burn causes muscle mass loss and atrophy. The balance between muscle cell death and growth maintains tissue homeostasis. We hypothesize that preexisting cellular structural defects will exacerbate skeletal muscle mass loss after burn. Using a Duchenne muscular dystrophy (mdx) mutant mouse, we investigated whether severe burn caused more damage in skeletal muscle with preexisting muscle disease.

METHODS

The mdx mice and wild-type (WT) mice received 25% total body surface area scald burn. Gastrocnemius (GM), tibialis anterior, and gluteus muscles were obtained at days 1 and 3 after burn. GM muscle function was measured on day 3. Animals without burn served as controls.

RESULTS

Wet tissue weight significantly decreased in tibialis anterior and gluteus in both mdx and WT mice after burn (P < 0.05). The ratio of muscle to body weight decreased in mdx mutant mice (P < 0.05) but not WT. Isometric force was significantly lower in mdx GM, and this difference persisted after burn (P < 0.05). Caspase-3 activity increased significantly after burn in both the groups, whereas HMGB1 expression was higher in burn mdx mice (P < 0.05). Proliferating cell nuclear antigen decreased significantly in mdx mice (P < 0.05). Myogenic markers pax7, myoD, and myogenin increased after burn in both the groups and were higher in mdx mice (P < 0.05).

CONCLUSIONS

More muscle loss occurred in response to severe burn in mdx mutant mice. Cell turnover in mdx mice after burn is differed from WT. Although markers of myogenic activation are elevated in mdx mutant mice, the underlying muscle pathophysiology is less tolerant of traumatic injury.

Histological aspects of the small intestine under variable feed restriction: The effects of short and intense restriction on a growing rabbit model

The objective of this study was to investigate the effect of seven days of feed restriction (between days 42 and 49) on the morphology of the small intestine in experimental rabbit models. Sixty weaned Hyplus rabbits (35 days old) were included in the experiment and split into three groups of 20 rabbits. The first control group (n=20) received feed ad libitum (ADL group), the second (R1) experimental group (n=20) was fed 50 g feed per rabbit per day and the third (R2) experimental group (n=20) received 65 g feed per rabbit per day. Duodenal samples were collected when the rabbits were aged 49, 56, 63 and 70 days. The mean villus height, crypt depth and small intestine length were measured. Significant interactions (P<0.001) between group and age were identified in the villi height and crypt depths. The maximum mean villus height was found in the R2 group in 56-day-old rabbits (643.14 μm), while the minimum was found in the ADL group in 49-day-old rabbits (460.29 μm). The longest (P<0.001) small intestine was measured in the R1 group in 63-day-old rabbits (347.60 cm), while the shortest was measured in the ADL group in 49-day-old rabbits (263.60 cm). The models show that villus height, crypt depth and the length of the small intestine change with the intensity of feed restriction and age.

Gender differences, aging and hormonal status in mucosal injury and repair

As the "baby boomers" age, the percentage of the population over sixty-five years of age is increasing rapidly. Chronic disease management is an important component in the care of the elderly. The effects of aging on different organ systems are also pertinent; such as the weakening homeostatic response to injury in the older individuals. Mucosal surfaces have the largest combined surface area in the body and are the site of important host microbe interactions, especially in the gut which is prone to injury, both from local and systemic insult. This susceptibility has been known to increase with age. Therefore it is important to understand the interplay between aging, injury and recovery at the mucosal surface. Sex hormones play an important role in the maintenance of the mucosal barrier function as well as the mucosa associated immune function in both genders. Menopause in women is a defined time period in which major hormonal changes occur such as a decline in systemic estradiol levels. The differential levels of sex hormones contribute to the sexual dimorphism seen in response to injury at the mucosal surface, prior to and following menopause. Thus the effect of sex hormone and aging on mucosal mechanisms in response to injury is an important area of investigation.