Introduction

Metabolic dysfunction-associated steatotic liver disease (MASLD) is closely related to the metabolic syndrome of chronic liver disease and its pathogenesis involves a variety of cell types of metabolic disorders and inflammatory response, however, treatment is limited. Mas is a G protein-coupled receptor highly expressed by myeloid cells. It may play a key role in regulating myeloid-associated inflammation and metabolic homeostasis in the process of MASLD. However, its specific mechanism of action in MASLD remains unclear.

Aims & Methods

This study aims to explore the regulatory mechanism of MAS in myeloid cells in the occurrence and development of MASLD. In this study, liver tissues of patients with MASLD and animal models of MASLD induced by high-fat diet (HFD) were analyzed. In this study, myeloid-specific Mas1 knockout (Lysm^creMas1^f/f) mice were constructed. Single-cell RNA sequencing and multi-omics analysis were used to explore the role and mechanism of myeloid Mas in HFD-induced MASLD mice.

Results

The study found that the expression of MAS protein on myeloid cells in the livers of MASLD patients and MASLD animal models was significantly increased. Mononuclear phagocyte system（MPs）undergo metabolic disorders in the MASLD model, with elevated glycolysis levels, increased lactic acid production, and at the same time, the expression of cellular senescence markers (such as p16 and p21) is upregulated, and the secretion of inflammatory factors is increased. Single-cell multi-omics analysis revealed that myeloid MAS1 knockout activated the FN1⁺CCR2⁺monocytes first. Pseudo-temporal analysis showed that the FN1⁺CCR2⁺ monocytes had spatiotemporal metabolic responses with the macrophages, significantly involving the activation of glycolysis and inflammatory senescence by myeloid MAS. Non-target metabolomics of MASLD patients also revealed elevated glycolytic metabolism and increased lactic acid secretion. Mass spectrometry revealed that Mas specifically bound to the key glycolytic protein pyruvate kinase M2 (PKM2) and activated the lactylation of transcription factor Spi1-K208 site mediated by PKM2. The lactylation of Spi1-K208 promoted the transcription of senescence-associated secretory phenotype (SASP) -related proteins. Myeloid Mas1 knockout inhibited the nuclear translocation of PKM2 and blocked the lactylation of Spi1, inhibiting the transcriptional initiation of SASP. Screening of over 100,000 small molecule compounds through a virtual drug library revealed that Theaflavin 3,3'-digallate (TFDG) might reduce the protein expression of Mas and PKM2, and block the binding of the MAS-PKM2 complex. We synthesized macrophage membrane to encapsulat PLGA nanoparticles loaded with TFDG (MM@NP-TFDG) and found that MM@NP-TFDG effectively reduced the expression level of Mas-PKM2 complex protein expression in the MASLD mouse model, inhibited the glycolytic - inflammatory senescence axis of FN1⁺CCR2⁺ monocytes and macrophages, and alleviated liver inflammation and tissue damage. While the lipid deposition in the liver is reduced and the fatty acid oxidation is enhanced.

Conclusion

This study reveals that myeloid MAS1 protein participates in the occurrence and development of MASLD by regulating PKM2-mediated Spi1 lactylation and reprogramming the metabolic-inflammatory senescence axis of MPs during the process of MASLD. This discovery provides new potential targets for the treatment of MASLD patients and is expected to offer new clinical treatment strategies for MASLD patients.

Disclosure

The authors declare no conflict of interest.

Introduction

There is a widespread agreement that age is a significant predictor of impaired response to nutritional support. For the same amount of protein and energy provided, the increase in weight and fat-free mass is significantly lower in older persons. This is generally attributed to anabolic resistance, and impaired absorption is usually considered non-existent/irrelevant. Nevertheless, in older rats gradual changes of the intestinal mucosa were observed, including reductions in villus height/width and density, which reduce absorption. Despite this, the aging influence on human intestinal mucosa is a matter of debate, and the lack of knowledge is partially explained by the exclusion criteria of older patients from most research protocols.

Aims & Methods

We aimed to evaluate potential histological and ultrastructural changes associated with aging that may reflect reduced absorption in older people.
The present single-center study is observational and prospective. Younger (18-45 years) and older (≥70 years) adults referred for upper endoscopy for reasons unrelated with intestinal alterations were included and underwent duodenal biopsies. Those biopsies were analyzed for histological, histomorphometric and ultrastructural changes. Histologic analysis was performed using optical microscopy with hematoxylin–eosin staining observed by two pathologists, including one expert gastrointestinal pathologist. All samples were analyzed for the presence of mucosal atrophy according to the adapted Marsh–Oberhuber classification and histomorphometric evaluation of duodenal villi length in micrometers, with at least two villi being measured through the use of an automatic scale. For transmission electron microscopy, duodenal fragments were fixed in 3% glutaraldehyde in cacodylate buffer (0.1 M, pH 7.4) overnight at 4 °C. The fixed fragments were rinsed and post-fixed in 1.0% osmium tetroxide for 1 h in the same buffer and dehydrated in graded ethanol passages. The fragments were embedded in a mixture of Epon and Araldite after two 15-min passages in propylene oxide. Thin sections, cut on a ultramicrotome with a diamond knife, were stained on the grid with uranyl acetate and lead citrate and examined with a electron microscope.

Results

A total of 84 patients were included (38 men/46 women), 33 with 18-45 years and 50 with ≥70 years. There were no duodenal endoscopic or microscopic changes apart from mucosal atrophy that was evident in one older adult. The median villi length was 0.35 mm (0.23-0.43 mm) in older persons, lower than in younger adults (0.65 mm; 0.37-0.79 mm) (p<0.01). On ultrastructural evaluation, the enterocytes of older group showed several changes suggesting compromise of the normal cell physiology. These changes were not observed in younger adults, who displayed normal cell architecture with regular microvilli structure and normal organelles.

Conclusion

Aging is associated with histological, histomorphometric and ultrastructural changes in the intestinal mucosa that can be linked with reduced absorptive capacity. Besides anabolic resistance, this could be a reason for the reduced response to nutritional support found in older citizens.

References

1. Soenen S, Rayner CK, Jones KL, et al. The ageing gastrointestinal tract. Curr Opin Clin Nutr Metab Care. 2016 Jan;19(1):12-8.
2. Patel BA, Patel N, Fidalgo S, et al. Impaired colonic motility and reduction in tachykinin signalling in the aged mouse. Exp Gerontol 2014; 53:24 – 30.
3. Saffrey MJ. Aging of the mammalian gastrointestinal tract: a complex organ system. Age 2014; 36:9603.
4. Ren WY, Wu KF, Li X, et al. Age-related changes in small intestinal mucosa epithelium architecture and epithelial tight junction in rat models. Aging Clin Exp Res 2014; 26:183 – 191.
5. Thomson AB. Small intestinal disorders in the elderly. Best Pract Res Clin Gastroenterol. 2009;23(6):861-74.
6. Nalapareddy K, Zheng Y, Geiger H. Aging of intestinal stem cells. Stem Cell Reports. 2022 Apr 12;17(4):734-740.

Introduction

The vacuum-assisted closure stent (VAC-stent) is a novel approach for managing esophageal defects, combining endoscopic vacuum therapy (EVT) and metal stent support to promote effective tissue healing [1].
We present a case of esophageal perforation following circumferential Endoscopic Submucosal Dissection (ESD), successfully managed with a VAC-Stent (video 1).

Aims & Methods

We report a case of a 59-year-old man with a 40mm lesion involving 75% of the esophageal circumference (Paris 0-IIa + Is), arising in Barrett’s esophagus (Prague C4M5) and consistent with adenocarcinoma, who was referred to our unit. CT scans excluded metastatic disease, and after multidisciplinary consultation, ESD was planned.

Results

Circumferential ESD was performed using a triple-tunnel approach. After the resection, muscular tears were closed with through-the-scope (TTS) clips, and pre-emptive Endoscopic Vacuum Therapy (EVT) was applied to enhance granulation and healing.
Due to rising inflammatory markers and fever onset, an esophagogastroduodenoscopy (EGD) was performed on the 3rd Post-Operative Day (POD). The EGD revealed two <5mm perforations 4cm apart, and a VAC-stent was placed to bridge the defects. At the follow-up EGD on the 9th POD, a single defect remained, and a new VAC-Stent was placed. The patient showed progressive clinical improvement and successfully resumed a liquid diet. By the 15th POD, the perforations had healed.
The patient was discharged in good clinical condition on the 18th POD.
At the EGD on the 30th POD, homogeneous healing tissue was observed, with no stricture detected at the resection site.
Histological analysis of the ESD specimen revealed moderately differentiated adenocarcinoma with submucosal invasion: pT1b (sm1) pNX G2, with R0 resection achieved and no high-risk pathological features. An oncological and endoscopic follow-up was planned.

Conclusion

Our case demonstrates that the VAC-Stent is a safe and effective method for treating perforations following esophageal ESD. In cases of circumferential ESD, VAC-stent use may also help prevent strictures.

References

[1]. Dell’Anna G, Fanti L, Fanizza J, et al. VAC-Stent in the Treatment of Post-Esophagectomy Anastomotic Leaks: A New “Kid on the Block” Who Marries the Best of Old Techniques—A Review. Journal of Clinical Medicine 2024; 13: 3805. doi:10.3390/jcm13133805

Introduction

Pathological esophageal acid exposure may persist in patients with Barrett’s esophagus (BE) despite standard proton pump inhibitor (PPI) therapy and symptom control, although current guidelines recommend at least standard-dose PPI for all patients with BE.¹

Aims & Methods

Aim was to evaluate the role of esophageal function testing in assessing acid exposure in BE patients on PPI therapy and in predicting neoplastic progression. We conducted a multicenter retrospective study including asymptomatic BE patients (defined by GerdQ total score <8 and a score of 0 on the first GerdQ item) who underwent high-resolution manometry and 24-hour pH impedance monitoring while on various PPI regimens. Maximal PPI therapy included esomeprazole 40 mg, pantoprazole 40 mg, rabeprazole 20 mg, or lansoprazole 30 mg, all administered twice daily. All other regimens were considered standard dosing. Index upper endoscopy with biopsies was performed under the same therapeutic regimen. Histologically, presence and degree of neoplasia (all confirmed by a second pathologist) was recorded. Acid exposure time (AET) <4% was defined as adequate acid control; AET >6% as pathological reflux. Predictors of pathological reflux and neoplasia were assessed using logistic regression analysis.

Results

A total of 135 patients (2016-2025) were included (mean age 58 ± 15 years; 73% male). Median BE length was C1 (range 0–3 cm) and M2 (range 1–5 cm), with 41% (n=56) classified as having long-segment BE. Sixty-seven patients (50%) were on standard-dose PPI. Pathological reflux was identified in 37 patients (27%), of whom 25 (67%) were on standard-dose therapy. Fourteen patients (10%) had borderline AET values (4–6%). Among the 84 patients (62%) with adequate acid control, 33 (39%) were taking standard-dose PPI. On multivariable analysis, standard-dose PPI (OR 3.04; 95% CI 1.34–6.89; p=0.008) and type III esophagogastric junction morphology (OR 2.52; 95% CI 1.01–5.01; p=0.047), consistent with manometric hiatal hernia, were independently associated with pathological reflux. Non-dysplastic BE was found in 112 patients, while 13 (10%) had neoplasia at index endoscopy (8 low-grade dysplasia, 3 high-grade dysplasia, 2 intramucosal adenocarcinoma). Pathological reflux was the only independent predictor of neoplasia (OR 10.41; 95% CI 2.65–41.26; p<0.001).

Table 1. Logistic regression analysis for factors associated with neoplasia on index endoscopy.

Conclusion

Nearly one-third of asymptomatic BE patients exhibit pathological reflux on pH-monitoring despite PPI treatment, predominantly among those on standard-dose and with manometric hiatal hernia. Nonetheless, adequate acid control is achieved in over one-third of patients on standard PPI therapy. Pathological reflux is associated with a 10-fold increased risk of neoplasia.

References

1. Shaheen NJ, Falk GW, Iyer PG, et al. Diagnosis and Management of Barrett's Esophagus: An Updated ACG Guideline. Am J Gastroenterol. 2022;117(4):559-587.