Starvation-induced proximal gut mucosal atrophy diminished with aging

Physiological and immunological aspects of feed restriction and its beneficial impacts in fattening rabbits' productivity-an updated review

Two feed restriction (FR) regimens are utilized with weaned rabbits including a quantitative FR (amount-limited feed or time-restricted admission to feed) and a qualitative FR (modulation of diet content especially protein and energy). The use of post-weaning FR may help in preventing post-weaning digestive disorders, stimulating compensating growth, improving feed efficiency, and decreasing carcass fat content. Interestingly, FR may contribute to changing meat's chemical composition and its physical quality attributes by regulating the morphological and biochemical characteristics of muscle fibers. Also, FR could enhance the gastrointestinal tract development, its histomorphology, and improve feed digestibility and absorption. Furthermore, FR regimens are involved in establishing gut microbial balance and enhancing the host immunological response. It might be concluded that post-weaning FR is involved in influencing the physiological and immunological aspects of growing rabbits. It might be documented that light to mild FR (i.e., 80-90% AL), early (i.e., at the first 2 weeks post-weaning), and relatively short in duration (i.e., for 2-3 weeks) had no negative effects on live body weight, while severing FR reduced live body weight in comparison with ad libitum rabbits.

METTL14 Regulates Intestine Cellular Senescence through m6A Modification of Lamin B Receptor

N-6-Methyladenosine (m⁶A) modification is involved in multiple biological processes including aging. However, the regulation of m⁶A methyltransferase-like 14 (METTL14) in aging remains unclear. Here, we revealed that the level of m⁶A modification and the expression of METTL14 were particularly decreased in the intestine of aged mice as compared to young mice. Similar results were confirmed in Drosophila melanogaster. Knockdown of Mettl14 in Drosophila resulted in a short lifespan, associated disrupted intestinal integrity, and reduced climbing ability. In human CCD-18Co cells, knockdown of METTL14 accelerated cellular senescence, and the overexpression of METTL14 rescued senescent phenotypes. We also identified the lamin B receptor (LBR) as a target gene for METTL14-mediated m⁶A modification. Knockdown of METTL14 decreased m⁶A level of LBR, resulted in LBR mRNA instability, and thus induced cellular senescence. Our findings suggest that METTL14 plays an essential role in the m⁶A modification-dependent aging process via the regulation of LBR and provides a potential target for cellular senescence.

Age-dependent response to fasting during assessment of metabolizable energy and total tract digestibility in chicken

Fasting is typically used to empty the gastrointestinal tract (GIT) and assess feed metabolizable energy (ME). However, the effects of fasting on energy and nutrient utilization are not well understood. This study aimed to explore the difference in GIT emptying, energy and nutrient utilization of broilers and adult roosters fed corn-soybean meal-based diet upon fasting. In experiment 1, 7 cages of broilers/adult roosters were selected and fasted for 72 h, and excreta were collected from 12 h of fasting and analyzed every 12 h to explore GIT emptying. Results indicated the GIT emptying time of free-feeding broilers or adult roosters is 12 or 24 h, respectively. In experiment 2, 4 treatments were used that consisted of 2 ages of birds (25 d broilers and 30 wk adult roosters) and 2 feeding forms (fed ad libitum or fasted for 36 h before formal feeding). Excreta was collected during refeeding, and the total collection method (TCM) and the index method (IM) were used for data analysis. Compared to non-fasted group, fasting increased the total tract digestibility of ME, gross energy (GE), and ether extract (EE) (by 1.80, 3.50 and 18.56%, respectively, all P < 0.05) in broilers, but decreased the total tract digestibility of nitrogen by 8.10% (P < 0.05). Conversely, fasting increased total tract digestibility of nitrogen in adult roosters (−0.37% vs. 11.65%, P < 0.05). The comparative analysis found that total tract digestibility of nitrogen obtained by TCM was greater than the result calculated by IM (17.76 % vs. −0.37). Similarly, total tract digestibility of GE calculated by TCM was significantly higher than the value observed by IM (P < 0.05). However, the results of total tract digestibility of GE and nitrogen in broilers calculated by TCM were consistent with those obtained by IM. Overall, fasting increases total tract digestibility in broilers and total tract digestibility of nitrogen in adult roosters, respectively. Additionally, total tract digestibility calculated by TCM may be overestimated.

The duration of food withdrawal affects the intestinal structure, nutrients absorption, and utilization in broiler chicken

Food withdrawal is usually used for accurate feed metabolizable energy (ME) assessment in poultry, but its effects on intestinal structure and the absorption of nutrients are unclear. In this study, broilers were fed ad libitum (CT) or withdrew food for 12 (FH12), 24 (FH24), 36 (FH36), or 48 hours (FH48). We showed that food withdrawal increased the energy assimilation when compared with the CT. Food withdrawal improved the digestibility of ether extract and the level of lipid substances and fatty acid-derived β-hydroxybutyrate in serum. Compared to the CT, food withdrawal did not influence the digestibility of starch. Due to 12 hours or longer food withdrawal duration increased glutamate oxidation and uric acid excretion, the analyzed digestibility of crude protein was underestimated, although the upregulated amino acid transporter genes. In addition, histological analysis showed that short-term food withdrawal (12 hours) increased intestinal villus height, crypt depth, and proliferative cell, whereas prolonged food withdrawal (more than 24 hours) impaired villus structure due to the decreased cell proliferation. Moreover, proteomics analysis revealed upregulated pathways in birds withdrawn food for 36 hours involved in nutrient absorption and amino acid oxidation. In conclusion, food withdrawal changes nutrient absorption and utilization, especially for amino acid and ether extract, and results in increased ME. Both glutamate oxidation and fatty acid incomplete oxidation are involved in energy supply after refeeding. In contrast to short-term food withdrawal, prolonged food withdrawal impairs the intestinal structure and villus renewal. Our findings deserve attention from nutritionists who are analyzing food digestibility.

Heat Stress Directly Affects Intestinal Integrity in Broiler Chickens

A study using pair-feeding technique was conducted to determine whether heat exposure directly or indirectly (via reduced feed intake) increases intestinal mucosal damage and permeability to endotoxin in broiler chickens. Male broiler chickens (Ross 308), 27-d-old, were subjected to one of the three treatments (n=8): 1) thermo-neutral conditions (24°C) with ad libitum feed intake, 2) heat stress conditions (33°C) with ad libitum feed intake, or 3) pair-feeding under thermo-neutral conditions, with the feed intake identical to that of heat-stressed chickens. Using these groups, two experiments were performed to evaluate temporal changes in the intestinal morphology in response to each treatment. In experiment 1, chickens were sacrificed after 24 h of exposure to the treatment conditions, while in experiment 2, chickens were sacrificed after 12 or 72 h of exposure to the treatment conditions. In experiment 1, exposure to heat stress conditions for 24 h significantly decreased both the villus height to crypt depth ratio and number of proliferating cell nuclear antigen (PCNA)-positive cells in the duodenum and increased the plasma endotoxin concentration. These findings were not observed in pair-fed chickens. In experiment 2, intestinal integrity and function were unaffected by 12 h of heat stress. On the other hand, chickens exposed to heat stress for 72 h exhibited significantly damaged intestinal morphology in the duodenum as well as increased plasma endotoxin concentration; these negative effects were not observed in pair-fed chickens. These findings suggest that the intestinal morphology and permeability changes observed in chickens that are heat-stressed for 24–72 h are due to the heat stress conditions and not due to reduced feed intake.

Formula feeding and immature gut microcirculation promote intestinal hypoxia, leading to necrotizing enterocolitis

Major risk factors for necrotizing enterocolitis (NEC) are formula feeding and prematurity; however, their pathogenic mechanisms are unknown. Here, we found that insufficient arginine/nitric oxide synthesis limits blood flow in the intestinal microvasculature, leading to hypoxia, mucosal damage and NEC in the premature intestine after formula feeding. Formula feeding led to increased intestinal hypoxia in pups at postnatal day (P)1 and P5, but not in more mature pups at P9. Accordingly, blood flow in the intestinal microvasculature increased after formula feeding in P9 pups only. mRNA profiling revealed that regulators of arginine/nitric oxide synthesis are at higher levels in endothelial cells of the intestine in P9 than in P1 pups. Importantly, arginine supplementation increased intestinal microvasculature blood flow and prevented NEC, whereas an arginine antagonist exacerbated NEC. Our results suggest that balancing intestinal oxygen demand and supply in the premature intestine by modulating arginine/nitric oxide could be used to prevent NEC.This article has an associated First Person interview with the first author of the paper.

Schlafen 12 Interaction with SerpinB12 and Deubiquitylases Drives Human Enterocyte Differentiation

BACKGROUND/AIMS

Human enterocytic differentiation is altered during development, fasting, adaptation, and bariatric surgery, but its intracellular control remains unclear. We hypothesized that Schlafen 12 (SLFN12) regulates enterocyte differentiation.

METHODS

We used laser capture dissection of epithelium, qRT-PCR, and immunohistochemistry to evaluate SLFN12 expression in biopsies of control and fasting human duodenal mucosa, and viral overexpression and siRNA to trace the SLFN12 pathway in human Caco-2 and HIEC6 intestinal epithelial cells.

RESULTS

Fasting human duodenal mucosa expressed less SLFN12 mRNA and protein, accompanied by decreases in enterocytic markers like sucrase-isomaltase. SLFN12 overexpression increased Caco-2 sucrase-isomaltase promoter activity, mRNA, and protein independently of proliferation, and activated the SLFN12 putative promoter. SLFN12 coprecipitated Serpin B12 (SERPB12). An inactivating SLFN12 point mutation prevented both SERPB12 binding and sucrase-isomaltase induction. SERPB12 overexpression also induced sucrase-isomaltase, while reducing SERPB12 prevented the SLFN12 effect on sucrase-isomaltase. Sucrase-isomaltase induction by both SLFN12 and SERPB12 was attenuated by reducing UCHL5 or USP14, and blocked by reducing both. SERPB12 stimulated USP14 but not UCHL5 activity. SERPB12 coprecipitated USP14 but not UCHL5. Moreover, SLFN12 increased protein levels of the sucrase-isomaltase-promoter-binding transcription factor cdx2 without altering Cdx2 mRNA. This was prevented by reducing UCHL5 and USP14. We further validated this pathway in vitro and in vivo. SLFN12 or SERPB12 overexpression induced sucrase-isomaltase in human non-malignant HIEC-6 enterocytes.

CONCLUSIONS

SLFN12 regulates human enterocytic differentiation by a pathway involving SERPB12, the deubiquitylases, and Cdx2. This pathway may be targeted to manipulate human enterocytic differentiation in mucosal atrophy, short gut or obesity.

Aging effects on intestinal homeostasis associated with expansion and dysfunction of intestinal epithelial stem cells

Intestinal epithelial stem cells (IESCs) are critical to maintain intestinal epithelial function and homeostasis. We tested the hypothesis that aging promotes IESC dysfunction using old (18-22 months) and young (2-4 month) Sox9-EGFP IESC reporter mice. Different levels of Sox9-EGFP permit analyses of active IESC (Sox9-EGFP^Low), activatable reserve IESC and enteroendocrine cells (Sox9-EGFP^High), Sox9-EGFP^Sublow progenitors, and Sox9-EGFP^Negative differentiated lineages. Crypt-villus morphology, cellular composition and apoptosis were measured by histology. IESC function was assessed by crypt culture, and proliferation by flow cytometry and histology. Main findings were confirmed in Lgr5-EGFP and Lgr5-LacZ mice. Aging-associated gene expression changes were analyzed by Fluidigm mRNA profiling. Crypts culture from old mice yielded fewer and less complex enteroids. Histology revealed increased villus height and Paneth cells per crypt in old mice. Old mice showed increased numbers and hyperproliferation of Sox9-EGFP^Low IESC and Sox9-EGFP^High cells. Cleaved caspase-3 staining demonstrated increased apoptotic cells in crypts and villi of old mice. Gene expression profiling revealed aging-associated changes in mRNAs associated with cell cycle, oxidative stress and apoptosis specifically in IESC. These findings provide new, direct evidence for aging associated IESC dysfunction, and define potential biomarkers and targets for translational studies to assess and maintain IESC function during aging.

A child with anorexia nervosa presenting with severe infection with cytopenia and hemophagocytosis: a case report

Background

Patients with anorexia nervosa in the acute phase have physical complications, such as infectious disease. Although hemophagocytic syndrome due to infection is a rare complication in anorexia nervosa, early identification for hemophagocytosis is important for avoiding a life-threatening condition.

Case presentation

We report a case of a 12-year-old girl with anorexia nervosa presenting with infection with cytopenia and hemophagocytosis during initial nutritional therapy. She developed pyrexia, abdominal pain, and diarrhea during inpatient treatment. Although intravenous antibiotics were administered, the symptoms persisted. Acinetobacter baumannii was detected in blood culture. Hemophagocytosis was present in the bone marrow. Gamma globulin therapy was effective, with improvement in symptoms and cytopenia.

Conclusions

Although our case did not fulfill the criteria of hemophagocytic syndrome, clinicians should consider severe infection in anorexia nervosa with cytopenia and hemophagocytosis.

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.

Increased prevalence of antibodies against dietary proteins in children and young adults with cerebral palsy

OBJECTIVES

Undernourishment is common in children with cerebral palsy (CP), but the reasons are unknown. We previously reported elevated levels of immunoglobulin (Ig) A and IgG antibodies against gliadin (AGA) and tissue transglutaminase (tTG) in 99 children and young adults with CP without characteristic findings of gluten enteropathy in small bowel biopsies. Our aim was to perform a case-control study of IgG antibodies against other dietary antigens, AGA, anti-tTG, and IgE antibodies against wheat and gluten.

METHODS

Sera from 99 cases with CP and 99 healthy, age- and sex-matched controls were analysed with fluorescence enzyme-linked immunosorbent assay for detection of IgG antibodies against β-lactoglobulin, casein, egg white, IgG- and IgA-AGA, IgA-anti-tTG, and IgE antibodies against gluten and wheat.

RESULTS

Compared with controls, the odds ratio in cases with CP for having elevated levels of IgG antibodies against β-lactoglobulin was 17.0 (95% confidence interval [CI] 2.3-128), against casein 11.0 (95% CI 2.6-46.8), and against egg white 7.0 (95% CI 1.6-30.8). The IgE responses for wheat/gluten were generally low. The tetraplegic and dyskinetic CP subtypes had significantly higher frequencies of elevated levels for all of the tested antibodies except IgG against egg white, and IgA-anti-tTG. A significantly lower weight was seen in cases with CP with positive versus negative serology.

CONCLUSIONS

Elevated levels of IgG against dietary antigens were more frequent in the CP group compared with controls, and particularly in the tetraplegic and dyskinetic CP subtypes with the most severe neurologic handicap and undernourishment. Hypothetically, malnourishment may cause increased intestinal permeability and thus immunization against dietary antigens.

Intestinal mucosal atrophy and adaptation

Mucosal adaptation is an essential process in gut homeostasis. The intestinal mucosa adapts to a range of pathological conditions including starvation, short-gut syndrome, obesity, and bariatric surgery. Broadly, these adaptive functions can be grouped into proliferation and differentiation. These are influenced by diverse interactions with hormonal, immune, dietary, nervous, and mechanical stimuli. It seems likely that clinical outcomes can be improved by manipulating the physiology of adaptation. This review will summarize current understanding of the basic science surrounding adaptation, delineate the wide range of potential targets for therapeutic intervention, and discuss how these might be incorporated into an overall treatment plan. Deeper insight into the physiologic basis of adaptation will identify further targets for intervention to improve clinical outcomes.

Home enteral nutrition in children: a 14-year multicenter survey

BACKGROUND/OBJECTIVES

The practice of home enteral nutrition (HEN) represents a relevant aspect of the clinical management of both malnourished children and well-nourished children unable to be fed using an oral diet. The aim of this study was to estimate in an Italian paediatric population over a 14-year period (1996-2009), the clinical relevance and results over time of HEN activity.

SUBJECTS/METHODS

HEN-computerized database and medical/dietetic charts were evaluated for patients aged at start of HEN <18 years and HEN duration >1 month.

RESULTS

During the study period, we recorded 757 HEN programs. HEN began at a median age of 2 years for a median duration of 8.1 months. The complication rate was 14.8%. In the second period of the survey (2003-2009), the main changes concerned the underlying diseases requiring HEN, choice of formula feeding and access route. In 2009, the estimated overall prevalence of HEN was 3.47 and the incidence 2.45 per 100 000 inhabitants from 0 to 18 years of age.

CONCLUSIONS

The epidemiological data of this study demonstrate that HEN concerns a growing number of Italian children and families. Some aspects of HEN clinical management should be modified to reach the recommended standards.

Alanyl-glutamine promotes intestinal epithelial cell homeostasis in vitro and in a murine model of weanling undernutrition

Alanyl-glutamine (Ala-Gln) has recently been shown to enhance catch-up growth and gut integrity in undernourished children from Northeast Brazil. We hypothesized that the intestinal epithelial effects of Ala-Gln in malnourished weanling mice and mouse small intestinal epithelial (MSIE) cells would include modulation of barrier function, proliferation, and apoptosis. Dams of 10-day-old suckling C57BL/6 pups were randomized to a standard diet or an isocaloric Northeast Brazil "regional basic diet," moderately deficient in protein, fat, and minerals. Upon weaning to their dam's diet on day of life 21, pups were randomized to Ala-Gln solution or water. At 6 wk of age, mice were killed, and jejunal tissue was collected for morphology, immunohistochemistry, and Ussing chamber analysis of transmucosal resistance and permeability. Proliferation of MSIE cells in the presence or absence of Ala-Gln was measured by MTS and bromodeoxyuridine assays. MSIE apoptosis was assessed by annexin and 7-amino-actinomycin D staining. Pups of regional basic diet-fed dams exhibited failure to thrive. Jejunal specimens from undernourished weanlings showed decreased villous height and crypt depth, decreased transmucosal resistance, increased permeability to FITC-dextran, increased claudin-3 expression, and decreased epithelial proliferation and increased epithelial apoptosis (as measured by bromodeoxyuridine and cleaved caspase-3 staining, respectively). Undernourished weanlings supplemented with Ala-Gln showed improvements in weight velocity, villous height, crypt depth, transmucosal resistance, and epithelial proliferation/apoptosis compared with unsupplemented controls. Similarly, Ala-Gln increased proliferation and reduced apoptosis in MSIE cells. In summary, Ala-Gln promotes intestinal epithelial homeostasis in a mouse model of malnutrition-associated enteropathy, mimicking key features of the human disease.

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

BACKGROUND

Previous studies have shown that starvation induces small bowel atrophy, and that atrophy diminishes with aging. In this experiment, we assessed whether starvation-induced atrophy of proximal gut mucosa is associated with the Interleukin-1 receptor (IL-1R) signaling pathway in aged mice.

MATERIALS AND METHODS

Thirty 26-month-old IL-1R knockout mice and age-matched wild-type C57BL/6 mice were randomly divided into two groups: ad libitum fed and fasted. Mice were euthanized 12 or 48 hours after starvation. The proximal small bowel was harvested for morphologic analysis. Gut epithelial cell proliferation was detected using immunohistochemical staining for proliferating cell nuclear antigen (PCNA), and apoptosis was identified using terminal deoxyuridine nick-end labeling (TUNEL) staining.

RESULTS

Aged IL-1R knockout mice were larger than aged-matched wild-type mice (P < 0.05). Proximal gut mucosal height and mucosal cell number were not different between aged IL-1R knockout and wild-type groups. The apoptosis index in gut epithelial cells was higher in fed IL-1R knockout versus wild-type mice (P < 0.05), while there was no significant difference in cell proliferation between both groups. Mucosal atrophy was induced in both aged IL-1R knockout and wild-type groups by starvation (P < 0.05), however, aged IL-1R knockout mice experienced greater loss in proximal gut weight, mucosal length, and corresponding cell number than did wild-type mice at the 12-h time point (P < 0.05). The apoptosis index in gut epithelial cells significantly increased in both groups after starvation (P < 0.05). Starvation decreased cell proliferation in IL-1R knockout mice (P < 0.05), but not in wild-type mice.

CONCLUSIONS

The response in aged IL-1R knockout mice differs from wild-type mice in that starvation increases atrophy and is associated with decreased cell proliferation rather than increased apoptosis.