Biofilms in the large bowel suggest an apparent function of the human vermiform appendix

Pediatric chronic appendicitis without surgical resection: A case study of endoscopic retrograde appendicitis therapy (ERAT)

INTRODUCTION AND IMPORTANCE

Chronic appendicitis in pediatric patients is rare and challenging to diagnose, typically leading to surgical resection. However, Endoscopic Retrograde Appendicitis Therapy (ERAT) offers a minimally invasive alternative that preserves the appendix, maintaining its immune and digestive functions.

CASE PRESENTATION

A 13-year-old boy with a year-long history of worsening abdominal pain underwent ERAT. The procedure provided symptom relief and preserved the appendix.

CLINICAL DISCUSSION

ERAT successfully treated the appendicitis while preserving the appendix, which plays crucial immune and digestive roles, especially in children.

CONCLUSION

ERAT is a promising, non-surgical alternative for chronic appendicitis in pediatric patients, warranting further study.

Clinical correlates of lifetime and current comorbidity patterns in autoimmune and inflammatory diseases

BACKGROUND

Autoimmune and inflammatory diseases (AIDs) are a heterogeneous group of disorders with diverse etiopathogenic mechanisms. This study explores the potential utility of family history, together with present and past comorbidities, in identifying distinct etiopathogenic subgroups. This approach may facilitate more accurate diagnosis, prognosis and personalized therapy.

METHODS

We performed a multiple correspondence analysis on patients' comorbidities, followed by hierarchical principal component clustering of clinical data from 48 healthy volunteers and 327 patients with at least one of 19 selected AIDs included in the TRANSIMMUNOM cross-sectional study.

RESULTS

We identified three distinct clusters characterized by: 1) the absence of comorbidities, 2) polyautoimmunity, and 3) polyinflammation. These clusters were further distinguished by specific comorbidities and biological parameters. Autoantibodies, allergies, and viral infections characterized the polyautoimmunity cluster, while older age, BMI, depression, cancer, hypertension, periodontal disease, and dyslipidemia characterized the polyinflammation cluster. Rheumatoid arthritis patients were distributed across all three clusters. They had higher DAS28 and prevalence of extra-articular manifestations when belonging to the polyinflammation and polyautoimmunity clusters, and also lower ACPA and RF seropositivity and higher pain scores within the polyinflammation cluster. We developed a model allowing to classify AID patients into comorbidity clusters.

CONCLUSIONS

In this study, we have uncovered three distinct comorbidity profiles among AID patients. These profiles suggest the presence of distinct etiopathogenic mechanisms underlying these subgroups. Validation, longitudinal stability assessment, and exploration of their impact on therapy efficacy are needed for a comprehensive understanding of their potential role in personalized medicine.

Appendiceal periappendicitis and ulcerative colitis: Relationship and research advances

The prevalence of ulcerative colitis (UC) has been increasing in China, reaching about 11.6 per 100000. The diagnostic process for this disease is extremely lengthy and complex, significantly impacting the patient's health. UC typically starts in the rectum and sigmoid colon, and when patients with distal colitis also present with appendiceal periappendicitis, this condition is considered a "skip lesion" of UC. This phenomenon may be related to the appendix's role as an immune organ and its immunological connection to the pathogenesis of UC. Appendiceal periappendicitis combined with rectal inflammation can facilitate the diagnosis of UC. However, there is still no consensus on the pathogenesis, treatment prognosis, and clinical significance of appendiceal periappendicitis. This paper reviews the recent literature and provides a comprehensive analysis of appendiceal periapp-endicitis.

Endoscopic retrograde appendicitis therapy

Endoscopic retrograde appendicitis therapy (ERAT) is a novel and minimally invasive technological alternative for the management of acute or chronic appendicitis. Through endoscopic appendiceal intubation, obstructions such as appendiceal feces and parasites within the appendiceal lumen can be effectively eliminated, leading to patient recovery. Additionally, in cases where the orifices are swollen or complicated appendicitis is present, a stent may be inserted following appendiceal flushing. Due to the utilization of endoscopy for accessing the orifices of the appendix in order to alleviate appendiceal obstruction, patients were able to avoid undergoing appendectomy and experienced a reduced likelihood of recurrence when compared to antibiotic therapy. Additionally, the ERAT provided alternative options for individuals with appendicitis and comorbidities. Recent advancements in techniques, such as the "mother-baby" endoscopic system and the use of microbubble contrast agents, have expanded the range of indications and the eligible patient populations. The objective of this review is to present a comprehensive overview of the development, procedural aspects, therapeutic principles, treatment efficacy, therapeutic applications, and potential complications associated with ERAT.

Prior Appendicectomy and Gut Microbiota Re-Establishment in Adults after Bowel Preparation and Colonoscopy

Emerging evidence suggests that the human vermiform appendix is not a vestigial organ but rather an immunological organ of biological relevance. It is hypothesised that the appendix acts as a bacterial 'safe house' for commensal gut bacteria and facilitates re-inoculation of the colon after disruption through the release of biofilms. To date, no studies have attempted to explore this potential mechanistic function of the appendix. We conducted a pre-post intervention study in adults (n = 59) exploring re-establishment of the gut microbiota in those with and without an appendix after colonic disruption via bowel preparation and colonoscopy. Gut microbiota composition was measured one week before and one month after bowel preparation and colonoscopy using 16S rRNA sequencing. We observed between group differences in gut microbiota composition between those with (n = 45) and without (n = 13) an appendix at baseline. These differences were no longer evident one-month post-procedure, suggesting that this procedure may have 'reset' any potential appendix-related differences between groups. Both groups experienced reductions in gut microbiota richness and shifts in beta diversity post-procedure, with greater changes in those without an appendix, and there were five bacterial genera whose re-establishment post-procedure appeared to be moderated by appendicectomy status. This small experimental study provides preliminary evidence of a potential differential re-establishment of the gut microbiota after disruption in those with and without an appendix, warranting further investigation into the potential role of the appendix as a microbial safe house.

Appendectomy and appendicitis do not increase colorectal cancer risk: evidence from Mendelian randomization

Background

Acute appendicitis (AA) is one of the most prevalent acute abdominal diseases and appendectomy is the definitive treatment of appendicitis. However, whether appendicitis and appendectomy cause colorectal cancer (CRC) is controversial. The results of observational studies are contradictory, but randomized controlled trials (RCT) cannot be conducted.

Methods

Data of appendectomy, AA, and CRC were obtained from the IEU Open GWAS project. We selected several Genome-wide association studies (GWAS) summary statistics for CRC: statistics for colon cancer (CC) were obtained from MRC-IEU and Neale lab, respectively; statistics for rectum cancer (RC) were obtained from MRC-IEU and FinnGen, respectively; statistics for CRC were provided by Sakaue S et al. Mendelian randomization (MR) was used to evaluate the causal relationships between exposure and outcomes. Inverse variance weighting (IVW) was the most important analysis method. Meta-analysis was used to summarize the results of IVW to increase the reliability and sensitivity analysis was used to evaluate the robustness of the results.

Results

According to the results of IVW, appendectomy did not increase risk of CC: MRC-IEU (OR:1.009, 95%CI:0.984-1.035, P=0.494), Neale lab (OR:1.016, 95%CI:0.993-1.040, P=0.174); Appendectomy also did not increase risk of RC: MRC-IEU(OR:0.994, 95%CI:0.974-1.014, P=0.538), FinnGen(OR:2.791, 95%CI:0.013-580.763, P=0.706); Appendectomy also did not increase risk of CRC: Sakaue S(OR:1.382, 95%CI:0.301-6.352, P=0.678). Appendicitis did not increase risk of CC: MRC-IEU(OR:1.000, 95%CI:0.999-1.001, P=0.641), Neale lab(OR:1.000, 95%CI:1.000-1.001, P=0.319); Appendicitis also did not increase risk of RC: MRC-IEU(OR:1.000, 95%CI:0.999-1.000, P=0.361), FinnGen(OR:0.903, 95%CI:0.737-1.105, P=0.321); Appendicitis also did not increase risk of CRC: Sakaue S (OR:1.018, 95%CI:0.950-1.091, P=0.609). The results of Meta-analysis also showed appendectomy (P=0.459) and appendicitis (P=0.999) did not increase the risk of CRC.

Conclusions

Appendectomy and appendicitis do not increase the risk of colorectal cancer. More clinical trials are needed in the future to verify the causal relationships.

Early colonic-preparation and salvage laparoscopic appendectomy (ECSLA)- innovative protocol for the management of magnets ingestion

BACKGROUND

Ingestion of magnets carries risks for significant morbidity. We propose a new protocol designed to reduce the need for surgery, shorten length of stay, and decrease morbidity.

METHODS

The Early Colonic-preparation and Salvage Laparoscopic Appendectomy (ECSLA) protocol includes initiating colonoscopy preparation upon admission in asymptomatic patients if magnets are not amenable to removal by gastroscopy, and laparoscopic magnets retrieval via appendectomy if surgery is eventually needed. The protocol was initiated in May 2023. A retrospective study of all cases of ingested magnets in children in our institution during July 2020 - January 2024 was conducted to retrieve and analyze demographic, clinical, imaging, management, and outcome data.

RESULTS

During the 3.5-year study period, 13 cases of ingested multiple magnets were treated, including 7 cases since initiation of ECLSA protocol, with no complications. Since initiation of ECSLA protocol, Early colonic preparation resulted in spontaneous passage of magnets (two cases) and successful colonocsopic removal (three cases), with two cases in which magnets were retrieved via gastroscopy upon admission, and no patients needing surgical intervention. Length of stay (LOS) was short (1-3 days).

CONCLUSIONS

The ECSLA protocol is a promising tool for preventing surgical intervention and complications and for possibly shortening LOS in children who have ingested multiple magnets.

Contrast-Enhanced Ultrasound-Guided Endoscopic Retrograde Appendicitis Treatment-A Pilot Study on the Diagnostic and Therapeutic Efficacy in Uncomplicated Appendicitis

OBJECTIVE

To determine the diagnostic and therapeutic value of contrast-enhanced ultrasound-guided endoscopic retrograde appendicitis treatment (ERAT) in patients with uncomplicated appendicitis.

METHODS

A retrospective analysis was performed on clinical and ultrasound data collected from 105 pediatric patients with uncomplicated appendicitis between January 2020 and December 2023. The ultrasound findings before and after treatment, as well as postoperative follow-up and recurrence rates, were summarized and analyzed.

RESULTS

Successful intubation was achieved in 96 patients (91.4%). The conventional ultrasound appendix visualization rate was 39.6% (38/105), while the appendix visualization rate after contrast-enhanced ultrasound-guidance was 75% (72/105). Contrast-enhanced ultrasound revealed various appendiceal morphologic changes in 89 patients, such as twisting, tortuosity, stiffness, rough inner wall, dilated diameter, and narrowing of the lumen. Additionally, local filling defects, which indicated the presence of fecal stones or debris deposition, were noted in 68 patients. No leakage of the contrast agent occurred. Post-treatment evaluation showed improvement in appendiceal diameter, lumen, and filling defects (P < .01). The follow-up rate was 82 of 89 patients (92.1%), all of whom recovered well without a recurrence. The recurrence rate was 7.9% (7/89). Among the patients with recurrences, five patients resolved after medical treatment and two patients recovered after surgical treatment.

CONCLUSION

Contrast-enhanced ultrasound-guided ERAT for uncomplicated appendicitis is safe and effective. Specifically, the appendix is increased, which facilitates an evaluation of therapeutic effectiveness. ERAT serves as a valuable supplementary modality to determine the need for surgical treatment of acute appendicitis, which is of significant clinical value.

Appendectomy and Risk of Advanced Colorectal Neoplasia in Inflammatory Bowel Disease: A Nationwide Population-based Cohort Study

BACKGROUND

The aim of this study was to examine the association between appendectomy and advanced colorectal neoplasia (aCRN) in patients with inflammatory bowel disease (IBD).

METHODS

Inflammatory bowel disease patients diagnosed in Denmark in the period 1977 to 2017 were identified from the Danish National Patient Registry. Inflammatory bowel disease patients who underwent appendectomy were matched with up to 10 IBD patients without appendectomy and followed until aCRN, death, or emigration. Absolute risks of aCRN were calculated, treating death and bowel resections as competing risks. Stratified Cox regression was used to calculate adjusted hazard ratios (aHRs) of aCRN, comparing IBD patients with appendectomy to IBD patients without appendectomy.

RESULTS

We identified 3789 IBD patients with appendectomy and 37 676 IBD patients without appendectomy. A total of 573 patients (1.4%) developed aCRN, with an absolute risk of aCRN at 20 years of 4.9% (95% confidence interval [CI], 2.9%-7.7%) for ulcerative colitis (UC) patients with appendectomy after UC diagnosis compared with 2.8% (95% CI, 2.3%-3.3%) for UC patients without appendectomy. Appendectomy after UC was associated with an increased rate of aCRN 5 to 10 years (aHR, 2.5; 95% CI, 1.1-5.5) and 10 to 20 years after appendectomy (aHR, 2.3; 95% CI, 1.0-5.5). Appendectomy prior to UC diagnosis was not associated with an increased rate of aCRN, and Crohn's disease was not associated with the rate of aCRN, regardless of timing or histological diagnosis of the appendix specimen.

CONCLUSIONS

Although appendectomy may have a positive effect on the clinical course of UC, our study suggests that this may come at the expense of a higher risk of aCRN.

Is non-operative treatment of acute appendicitis possible: A narrative review

Introduction

Acute appendicitis (AA) represents the most frequent surgical emergency. Perforation was long considered the ultimate outcome of AA, prompting appendectomy; which remains the standard treatment. New data have clarified the role of the appendix, justifying conservative treatment. This narrative review aims to summarize the evidence regarding the non-operative treatment (NOT) of AA in adults.

Methods

The literature search was performed via the PubMed Medline database. Our criteria-based selection resulted in a total of 48 articles for review.

Results

Recent trials and meta-analyses have assessed NOT, which support primary antibiotic treatment of uncomplicated AA. Although it has a significant recurrence and failure rate, NOT does not appear to increase the risk of appendicular perforation. Moreover, NOT compared with appendectomy, seems to be associated with less morbidity, lower cost of care and preserved quality of life.

Conclusion

First-line NOT seems to be a reasonable approach for the treatment of uncomplicated CT-confirmed AA. Careful patient screening would definitely enhance the success rate.

Maintenance of caecal homeostasis by diverse adaptive immune cells in the rhesus macaque

Objectives

The caecum bridges the small and large intestine and plays a front-line role in discriminating gastrointestinal antigens. Although dysregulated in acute and chronic conditions, the tissue is often overlooked immunologically.

Methods

To address this issue, we applied single-cell transcriptomic-V(D)J sequencing to FACS-isolated CD45+ caecal patch/lamina propria leukocytes from a healthy (5-year-old) female rhesus macaque ex vivo and coupled these data to VDJ deep sequencing reads from haematopoietic tissues.

Results

We found caecal NK cells and ILC3s to co-exist with a spectrum of effector T cells partially derived from SOX4 + recent thymic emigrants. Tolerogenic Vγ8Vδ1-T cells, plastic CD4+ T helper cells and GZMK + EOMES + and TMIGD2 + tissue-resident memory CD8+ T cells were present and differed metabolically. An IL13 + GATA3 + Th2 subset expressing eicosanoid pathway enzymes was accompanied by IL1RL1 + GATA3 + regulatory T cells and a minor proportion of IgE+ plasma cells (PCs), illustrating tightly regulated type 2 immunity devoid of ILC2s. In terms of B lymphocyte lineages, caecal patch antigen-presenting memory B cells sat alongside germinal centre cells undergoing somatic hypermutation and differentiation into IGF1 + PCs. Prototypic gene expression signatures decreased across PC clusters, and notably, expanded IgA clonotypes could be traced in VDJ deep sequencing reads from additional compartments, including the bone marrow, supporting that these cells contribute a steady stream of systemic antibodies.

Conclusions

The data advance our understanding of caecal immunological function, revealing processes involved in barrier maintenance and molecular networks relevant to disease.

Beyond a vestigial organ: effects of the appendix on gut microbiome and colorectal cancer

The role of appendectomy in the pathogenesis of colorectal cancer (CRC) is a recent topic of contention. Given that appendectomy remains one of the most commonly performed operations and a first-line management strategy of acute appendicitis, it is inherently crucial to elucidate the association between prior appendectomy and subsequent development of CRC, as there may be long-term health repercussions. In this review, we summarize the data behind the relationship of CRC in post-appendectomy patients, discuss the role of the microbiome in relation to appendectomy and CRC pathogenesis, and provide an appraisal of our current understanding of the function of the appendix. We seek to piece together the current landscape surrounding the microbiome and immunological changes in the colon post-appendectomy and suggest a direction for future research involving molecular, transcriptomic, and immunologic analysis to complement our current understanding of the alterations in gut microbiome.

Prior Appendectomy Is Associated With a Milder Clinical Course in Crohn's Disease: A Nationwide Population-based Cohort Study

BACKGROUND

Appendectomy may affect the clinical course of Crohn's disease (CD), but rigorous evidence is sparse and contradicting. The aim of this study was to examine the association between appendectomy and the clinical course of CD.

METHODS

All patients diagnosed with CD in Denmark in the period from 1977 to 2017 were identified from the Danish National Patient Registry. Patients with appendectomy were matched with up to 10 comparators with CD and no appendectomy; and rates of CD-related hospital admissions were compared between CD patients with and without appendectomy using incidence rate ratios (IRRs). We used stratified Cox regression analysis to calculate adjusted hazard ratios (aHRs) of initiating treatment with biologics or undergoing intestinal resections.

RESULTS

In all, 21 189 CD patients (1936 with appendectomy and 19 253 without) were identified and followed for a median of 13.6 years. Crohn's disease patients who had undergone appendectomy experienced a lower rate of CD-related hospital admissions (appendectomy before CD: IRR = 0.83; 95% confidence interval [CI], 0.81-0.85; appendectomy after CD: IRR = 0.85; 95% CI, 0.81-0.88) compared with CD patients without appendectomy. For patients with appendectomy before CD diagnosis, the rate of initiating biologics was lower compared with CD patients with no appendectomy (aHR1-<5 years = 0.61; 95% CI, 0.46-0.81; aHR5-<10 years 0.47; 95% CI, 0.33-0.66; aHR10-20 years = 0.61; 95% CI, 0.47-0.79), as was the risk of undergoing colorectal resections (aHR1-<5 years = 0.94; 95% CI, 0.77-1.15; aHR5-<10 years 0.63; 95% CI, 0.47-0.85; aHR10-20 years = 0.75; 95% CI, 0.54-1.04). Rates of small bowel resections were comparable for CD patients with or without appendectomy prior to CD. Appendectomy performed after CD did not influence the rate of initiating treatment with biologics or undergoing intestinal resections.

CONCLUSION

The clinical course of CD is milder for those who have previously undergone appendectomy.

Housing of electrosynthetic biofilms using a roll-up carbon veil electrode increases CO2 conversion and faradaic efficiency in microbial electrosynthesis cells

Electrode-driven microbial electron transfer enables the conversion of CO2 into multi-carbon compounds. The electrosynthetic biofilms grow slowly on the surface and are highly susceptible to operational influences, such as hydrodynamic shear stress. In this study, a cylindrical roll-up carbon felt electrode was developed as a novel strategy to protect biofilms from shear stress within the reactor. The fabricated electrode allowed hydrogen bubble formation inside the structure, which enabled microbes to uptake hydrogen and convert CO2 to multi-carbon organic compounds. The roll-up electrode exhibited faster start-up and biofilm formation than the conventional linear shape carbon felt. The acetate yield and cathodic faradaic efficiency increased by 80% and 34%, respectively, and the bioelectrochemical stability was improved significantly. The roll-up structure increased biofilm development per unit electrode surface by three to five-fold. The roll-up configuration improved biofilm formation on the electrode, which enhanced the performance of microbial electrosynthesis-based CO2 valorization.

Enhanced Th17 responses in the appendix of children with complex compared to simple appendicitis are associated with microbial dysbiosis

Introduction

Appendicitis is one of the most common causes of acute abdominal surgery in children. The clinical course of appendicitis ranges from simple to complex appendicitis. The mechanisms underlying the heterogeneity of appendicitis in children remain largely unclear. Dysregulated T cell responses play an important role in several inflammatory diseases of the intestine, but the extend of T cell dysregulation in appendicitis in children is less well known.

Methods

To characterize appendiceal T cells in simple and complex appendicitis we performed in-depth immunophenotyping of appendiceal-derived T cells by flow cytometry and correlated this to appendiceal-derived microbiota analyses of the same patient.

Results

Appendix samples of twenty children with appendicitis (n = 8 simple, n = 12 complex) were collected. T cells in complex appendicitis displayed an increased differentiated phenotype compared to simple appendicitis, including a loss of both CD27 and CD28 by CD4+ T cells and to a lesser extent by CD8+ T cells. Frequencies of phenotypic tissue-resident memory CD69+CD4+ T cells and CD69+CD8+ T cells were decreased in children with complex compared to simple appendicitis, indicating disruption of local tissue-resident immune responses. In line with the increased differentiated phenotype, cytokine production of in particular IL-17A by CD4+ T cells was increased in children with complex compared to simple appendicitis. Furthermore, frequencies of IL-17A+ CD4+ T cells correlated with a dysregulation of the appendiceal microbiota in children with complex appendicitis.

Conclusion

In conclusion, disruption of local T cell responses, and enhanced pro-inflammatory Th17 responses correlating to changes in the appendiceal microbiota were observed in children with complex compared to simple appendicitis. Further studies are needed to decipher the role of a dysregulated network of microbiota and Th17 cells in the development of complex appendicitis in children.

Intra-abdominal Surgery and Intestinal Syndromes After Pelvic Radiation Therapy

Purpose

To determine the effects of intra-abdominal surgery on the intensities of 5 radiation-induced intestinal syndromes in survivors of pelvic cancer.

Methods and Materials

The analysis included 623 women born in 1927 or later who had survived cancer. They all had received external radiation therapy toward the pelvic area to treat gynecologic cancers. Information from 344 women who did not undergo irradiation, matched for age and residency, was also included. Main outcome measures after the surgical procedures were the intensity scores for 5 radiation-induced intestinal syndromes: urgency-tenesmus syndrome, fecal-leakage syndrome, excessive mucus discharge, excessive gas discharge, and blood discharge. The scores were based on symptom frequencies obtained from patient-reported outcomes and on factor loadings obtained from a previously reported factor analysis. Follow-up was 2 to 15 years after radiation therapy.

Results

Among survivors of cancer, intra-abdominal surgery increased the intensity of the urgency-tenesmus syndrome, the fecal-leakage syndrome, excessive gas discharge, and blood discharge but had a negligible effect on mucus discharge. Intra-abdominal surgery had an especially negative effect on the urgency-tenesmus syndrome. Although the combination of appendectomy with 1 or more other intra-abdominal surgeries resulted in the highest score for all syndromes, appendectomy alone had weak to no effect. In women who did not undergo irradiation, a similar pattern was seen, albeit with much lower scores.

Conclusions

We found intra-abdominal surgery to be a risk factor among survivors of gynecologic cancer, increasing the intensity score of 4 out of 5 radiation-induced intestinal syndromes. During radiation therapy, it may be worthwhile to pay extra attention to the dose of unwanted ionizing radiation to the intestines if the patient previously has undergone intra-abdominal surgery.

Clinical efficacy and safety of endoscopic retrograde appendicitis treatment for acute appendicitis: A systematic review and meta-analysis

OBJECTIVES

To assess the efficacy and safety of endoscopic retrograde appendicitis treatment (ERAT) for acute appendicitis (AA) by conducting a meta-analysis of clinical randomized trials (RCTs).

METHODS

Eight electronic databases were searched. Study quality was assessed using the Cochrane risk of bias tool. RevMan5.3 and STATA14 software were used to for statistical analysis.

RESULTS

Twenty-six RCTs with 2236 subjects were analyzed. First, operative time, length of hospital stay and duration of bed rest were shorter in the ERAT groups than in the control groups, with the pooled MD and 95 % CI being -13.22(-20.09, -6.35)(p = 0.0002), -2.13 (-2.47, -1.80)(p < 0.00001) and -3.15 (-3.76, -2.53)(p < 0.00001), respectively. Second, patients in the ERAT groups had a lower incidence of complications than the control groups, with a pooled RR and 95 % CI of 0.25(0.18, 0.35)(p < 0.00001). Third, patients who received ERAT returned to normal temperature faster than the control groups, the pooled MD and 95 % CI was -3.39(-4.36, -2.42)(p<0.00001). Finally, the result showed that the recurrence rate in the ERAT groups was approximately twice that of control groups, with the pooled RR and 95 % CI being 2.10(1.02, 4.32)(p < 0.00001).

CONCLUSIONS

ERAT results in fewer complications and shorter recovery time. And compared to appendectomy, ERAT reduces operative time and intraoperative bleeding. However, the recurrence of acute appendicitis after ERAT remains a concern. And more multicenter and large-scale RCTs are needed to confirm the benefits of ERAT.

SYSTEMATIC REVIEW REGISTRATION

We have registered on the PROSPERO [https://www.crd.york.ac.uk/PROSPERO/], and the registration number is CRD42023420171.

B cell immune profiles in dysbiotic vermiform appendixes of pancreatic cancer patients

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest solid tumors and is resistant to immunotherapy. B cells play an essential role in PDAC progression and immune responses, both locally and systemically. Moreover, increasing evidence suggests that microbial compositions inside the tumor, as well as in the oral cavity and the gut, are important factors in shaping the PDAC immune landscape. However, the gut-associated lymphoid tissue (GALT) has not previously been explored in PDAC patients. In this study, we analyzed healthy vermiform appendix (VA) from 20 patients with PDAC and 32 patients with colon diseases by gene expression immune profiling, flow cytometry analysis, and microbiome sequencing. We show that the VA GALT of PDAC patients exhibits markers of increased inflammation and cytotoxic cell activity. In contrast, B cell function is decreased in PDAC VA GALT based on gene expression profiling; B cells express significantly fewer MHC class II surface receptors, whereas plasma cells express the immune checkpoint molecule HLA-G. Additionally, the vermiform appendix microbiome of PDAC patients is enriched with Klebsiella pneumoniae, Bifidobacterium animalis, and Adlercreutzia equolifaciens, while certain commensals are depleted. Our findings may suggest impaired B cell function within the GALT of PDAC patients, which could potentially be linked to microbial dysbiosis. Additional investigations are imperative to validate our observations and explore these potential targets of future therapies.

Correlation between the presence of a cecal appendix and reduced diarrhea severity in primates: new insights into the presumed function of the appendix

Increased severity or recurrence risk of some specific infectious diarrhea, such a salmonellosis or Clostridium difficile colitis, have been reported after an appendectomy in human patients. While several other mammals also possess an appendix, the suspected protective function against diarrhea conferred by this structure is known only in humans. From a retrospective collection of veterinary records of 1251 primates attributed to 45 species, including 13 species with an appendix and 32 without, we identified 2855 episodes of diarrhea, 13% of which were classified as severe diarrhea requiring a therapeutic medication or associated with a fatal issue. We identified a lower risk of severe diarrhea among primate species with an appendix, especially in the early part of life when the risk of diarrhea is maximal. Moreover, we observed a delayed onset of diarrhea and of severe diarrhea in species possessing an appendix. Interestingly, none of the primates with an appendix were diagnosed, treated or died of an acute appendicitis during the 20 years of veterinarian follow-up. These results clarify the function of the appendix among primates, as protection against diarrhea. This supports its presumed function in humans and is congruent with the existence of a selective advantage conferred by this structure.

The evolving role of methanogenic archaea in mammalian microbiomes

Methanogenic archaea (methanogens) represent a diverse group of microorganisms that inhabit various environmental and host-associated microbiomes. These organisms play an essential role in global carbon cycling given their ability to produce methane, a potent greenhouse gas, as a by-product of their energy production. Recent advances in culture-independent and -dependent studies have highlighted an increased prevalence of methanogens in the host-associated microbiome of diverse animal species. Moreover, there is increasing evidence that methanogens, and/or the methane they produce, may play a substantial role in human health and disease. This review addresses the expanding host-range and the emerging view of host-specific adaptations in methanogen biology and ecology, and the implications for host health and disease.

The appendix and ulcerative colitis - an unsolved connection

The appendix is thought to have a role in the pathogenesis of ulcerative colitis, but the nature and basis of this association remains unclear. In this Perspective, we consider the biology of the appendix with respect to its immunological function and the microbiome, and how this relates to evidence that supports the involvement of the appendix in ulcerative colitis. In experimental models, removal of the inflamed appendix prevents colitis, and in human observational studies, appendectomy is associated with protection against ulcerative colitis. Further, among people who develop ulcerative colitis, appendectomy before diagnosis might influence the course and outcomes of the disease - some evidence suggests that it protects against colectomy but could increase the risk of colorectal cancer. Appendectomy after onset of ulcerative colitis seems to have disparate consequences. Clinical trials to understand whether appendectomy has a role in the treatment of ulcerative colitis are ongoing. Major questions about the role of the appendix in the pathogenesis of ulcerative colitis remain unanswered, and further research is needed to establish whether the connection is clinically relevant.

A Systematic Review and Meta-Analysis: A Prior Appendectomy Does Not Increase the Risk of Severe Clostridioides difficile Infection or Recurrence

BACKGROUND AND OBJECTIVES

There is conflicting evidence regarding the association between a prior appendectomy and severity of Clostridioides difficile infection. The aim of this study was to perform a systematic review and meta-analysis to evaluate this association.

PATIENTS AND METHODS

Comprehensive review of multiple databases was performed up to May 2022. The primary outcome assessed was the rate of severe Clostridioides difficile infection in patients with a prior appendectomy compared to patients with an appendix. The secondary outcomes assessed were recurrence, mortality, and colectomy rates associated with Clostridioides difficile infection in patients with a prior appendectomy compared to patients with an appendix.

RESULTS

Eight studies with 666 patients with a prior appendectomy and 3580 patients without an appendectomy were included. The odds ratio of severe Clostridioides difficile infection in patients who underwent prior appendectomy was 1.03 (95% CI 0.6-1.78, p = 0.92). The odds ratio of recurrence in patients who underwent prior appendectomy was 1.29 (95% CI 0.82-2.02, p = 0.28). The odds ratio of colectomy due to Clostridioides difficile infection in patients who underwent prior appendectomy was 2.16 (95% CI 1.27-3.67, p = 0.004). The odds ratio of mortality due to Clostridioides difficile infection in patients with a prior appendectomy was 0.92 (95% CI 0.62-1.37, p = 0.68).

CONCLUSION

Patients with appendectomy are not at increased risk for developing severe Clostridioides difficile infection or recurrence. Further prospective studies are needed to establish these associations.

Impaired cecal motility and secretion alongside expansion of gut-associated lymphoid tissue in the Nlgn3R451C mouse model of autism

Individuals with Autism Spectrum Disorder (ASD; autism) commonly present with gastrointestinal (GI) illness in addition to core diagnostic behavioural traits. The appendix, or cecum in mice, is important for GI homeostasis via its function as a key site for fermentation and a microbial reservoir. Even so, the role of the appendix and cecum in autism-associated GI symptoms remains uninvestigated. Here, we studied mice with an autism-associated missense mutation in the post-synaptic protein neuroligin-3 (Nlgn3R451C), which impacts brain and enteric neuronal activity. We assessed for changes in cecal motility using a tri-cannulation video-imaging approach in ex vivo preparations from wild-type and Nlgn3R451C mice. We investigated cecal permeability and neurally-evoked secretion in wild-type and Nlgn3R451C tissues using an Ussing chamber set-up. The number of cecal patches in fresh tissue samples were assessed and key immune populations including gut macrophages and dendritic cells were visualised using immunofluorescence. Nlgn3R451C mice displayed accelerated cecal motor complexes and reduced cecal weight in comparison to wildtype littermates. Nlgn3R451C mice also demonstrated reduced neurally-evoked cecal secretion in response to the nicotinic acetylcholine receptor agonist 1,1-dimethyl-4-phenylpiperazinium (DMPP), but permeability was unchanged. We observed an increase in the number of cecal patches in Nlgn3R451C mice, however the cellular morphologies of key immune populations studied were not significantly altered. We show that the R451C nervous system mutation leads to cecal dysmotility, impaired secretion, and neuro-immune alterations. Together, these results suggest that the R451C mutation disrupts the gut-brain axis with GI dysfunction in autism.

Appendiceal Mucinous Neoplasms: From Clinic to Pathology and Prognosis

Appendiceal mucinous neoplasms have been classified differently over time causing confusion when comparing results between working groups in this field and establishing a prognosis of the disease. A historical perspective of the different classification systems of these tumors is essential for the understanding of the evolution of concepts and histopathological definitions that have led up to the present moment. We carried out a systematic review of the pathological classifications of appendiceal mucinous tumors and how they have included the new criteria resulting from clinical and pathological research. The latest classifications by PSOGI and AJCC 8th edition Cancer Staging have made a great effort to incorporate the new pathological descriptions and develop prognostic groups. The introduction of these new classification systems has posed the challenge of verifying how they adapt to our casuistry and which one defines best the prognosis of our patients. We reclassified our series of patients treated for mucinous appendiceal tumors with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy following the PSOGI and the AJCC 8th edition criteria and concluded that both classifications correspond well with the OS and DFS of these patients, with some advantage relative to the PSOGI classification due to a better histopathological description of the different groups.

It's all relative: analyzing microbiome compositions, its significance, pathogenesis and microbiota derived biofilms: Challenges and opportunities for disease intervention

Concept of microorganisms has largely been perceived from their pathogenic view point. Nevertheless, it is being gradually revisited in terms of its significance to human health and now appears to be the most dominant force that shapes the immune system of the human body and also determines an individual's predisposition to diseases. Human inhabits bacterial diversity (which is predominant among all microbial communities in human body) occupying 0.3% of body mass, known as microbiota. On birth, a part of microbiota that child obtains is essentially a mother's legacy. So, the review was initiated with this critical topic of microbiotal inheritance. Since, each body site has distinct physiological specifications; therefore, they contain discrete microbiome composition that has been separately discussed along with dysbiosis-induced pathologies originating in different body organs. Factors affecting microbiome composition and may cause dysbiosis like antibiotics, delivery, feeding method etc. as well as the strategies that immune system adopts to prevent dysbiosis have been highlighted. We also tried to bring into attention the topic of dysbiosis induced biofilms, that enables cohort to survive stresses, evolve, disseminate and infection resurgence that is still in dormancy. Eventually, we put spotlight on microbiome significance in medical therapeutics. We didn't merely confine article to gut microbiota, that is being studied more extensively. Numerous community forms at diverse body sites are inter-related, and being exposed to awfully variable perturbations appear to be challenging to evaluate perturbation risks holistically. All aspects have been elaborately discussed to achieve a global depiction of human microbiota in order to meet urgent necessity for protocol standardisation. Demonstrates that environmental challenges (antibiotic use, alterations in diet, stress, smoking etc.) might cause dysbiosis i.e. transition of healthy microbiome composition to the one in which pathogenic microorganisms become more abundant, and eventually results in an infected state.

Appendicitis is associated with an increased risk of systemic lupus erythematosus: a nationwide, population-based, case-control study

OBJECTIVE

To examine the association between appendicitis and the risk of systemic lupus erythematosus (SLE).

METHODS

Using claims data from the 2003-2013 Taiwanese National Health Insurance Research Database, we selected 6054 patients with newly diagnosed SLE from 2007 to 2012 and 36,324 age-, sex- and year of SLE diagnosis date-matched (1:6) non-SLE controls. After controlling for potential confounders, a multivariable conditional logistic regression model was used to calculate the adjusted odds ratio (aOR) with 95% confidence interval (CI) for the association of appendicitis history with SLE. Sensitivity analyses were conducted using various definitions of appendicitis. Subgroup analyses were conducted to examine possible modification effects by age, gender, level of urbanization, income and Charlson Comorbidity Index (CCI).

RESULTS

The average age of patients was 38 years old in both groups. The proportion of females was 86.5%. 75 (1.2%) of SLE cases and 205 (0.6%) of non-SLE controls had appendicitis history before the index date. After adjusting for potential confounding factors, appendicitis was associated with a higher risk of SLE (aOR, 1.84; 95% CI, 1.34-2.52), and such association remained robust after variation of appendicitis definition. No significant modification effects were found for the association between appendicitis and SLE by age, gender, urbanization level, income and CCI.

CONCLUSION

This nationwide, population-based case-control study demonstrates an association between appendicitis and incident SLE. Lack of individual smoking status is a major limitation. Key Points • Appendicitis was significantly associated with an increased risk of SLE. • Such association remained robust using various definitions of appendicitis.

Typical and Atypical Presentations of Appendicitis and Their Implications for Diagnosis and Treatment: A Literature Review

Appendicitis, an acute inflammation of the appendix, affects all demographic groups and exhibits various incidences and clinical manifestations. While acute appendicitis typically presents with colicky periumbilical abdominal pain that localizes to the right lower quadrant, atypical presentations are more common in children, geriatric, and pregnant patient populations, leading to delays in diagnosis. Clinical evaluation, clinical scoring systems, and inflammatory markers are commonly used, but their limitations have led to the increased use of diagnostic imaging in patients suspected of appendicitis. Acute appendicitis is managed by non-operative and operative management, depending on whether it is uncomplicated or complicated. Developing diagnostic pathways to improve outcomes and reduce complications is crucial. Although medical advancements have been made, diagnosing and managing appendicitis can be challenging, mainly when patients are present atypically. This literature review aims to comprehensively review typical and atypical presentations of appendicitis and their current implications for diagnosis and treatment modalities in pediatric, adult, pregnant, and geriatric patient populations.

Maturation state of colonization sites promotes symbiotic resiliency in the Euprymna scolopes-Vibrio fischeri partnership

BACKGROUND

Many animals and plants acquire their coevolved symbiotic partners shortly post-embryonic development. Thus, during embryogenesis, cellular features must be developed that will promote both symbiont colonization of the appropriate tissues, as well as persistence at those sites. While variation in the degree of maturation occurs in newborn tissues, little is unknown about how this variation influences the establishment and persistence of host-microbe associations.

RESULTS

The binary symbiosis model, the squid-vibrio (Euprymna scolopes-Vibrio fischeri) system, offers a way to study how an environmental gram-negative bacterium establishes a beneficial, persistent, extracellular colonization of an animal host. Here, we show that bacterial symbionts occupy six different colonization sites in the light-emitting organ of the host that have both distinct morphologies and responses to antibiotic treatment. Vibrio fischeri was most resilient to antibiotic disturbance when contained within the smallest and least mature colonization sites. We show that this variability in crypt development at the time of hatching allows the immature sites to act as a symbiont reservoir that has the potential to reseed the more mature sites in the host organ when they have been cleared by antibiotic treatment. This strategy may produce an ecologically significant resiliency to the association.

CONCLUSIONS

The data presented here provide evidence that the evolution of the squid-vibrio association has been selected for a nascent organ with a range of host tissue maturity at the onset of symbiosis. The resulting variation in physical and chemical environments results in a spectrum of host-symbiont interactions, notably, variation in susceptibility to environmental disturbance. This "insurance policy" provides resiliency to the symbiosis during the critical period of its early development. While differences in tissue maturity at birth have been documented in other animals, such as along the infant gut tract of mammals, the impact of this variation on host-microbiome interactions has not been studied. Because a wide variety of symbiosis characters are highly conserved over animal evolution, studies of the squid-vibrio association have the promise of providing insights into basic strategies that ensure successful bacterial passage between hosts in horizontally transmitted symbioses. Video Abstract.

Non-culture-based studies of the appendiceal microbiota: a systematic review

Aims: To review studies examining the appendiceal microbiota and microbial changes in acute appendicitis. Methods: After a systematic literature search, 11 studies examining the appendiceal microbiota (414 samples) using non-culture-based methods were included. Results: The appendiceal microbiota showed decreased α-diversity compared with fecal microbiota. Inflamed and uninflamed appendices showed differences in β-diversity, and there was an increased abundance of oral-associated bacteria in inflamed versus uninflamed appendices. Conclusion: The appendiceal microbiota exhibits lower α-diversity than the fecal microbiota, with an increased abundance of oral-associated bacteria. Compared with uninflamed appendices, the appendix microbiota in acute appendicitis also showed increased abundance of oral-associated bacteria, but no bacterial profile unique to either complicated or uncomplicated appendicitis was found.

Microbiome Structure and Mucosal Morphology of Jejunum Appendix and Colon of Rats in Health and Dysbiosis

Gut microbiota contributes to human health. Plenty of studies demonstrate that antibiotics can disrupt gut ecosystem leading to dysbiosis. Little is known about the microbial variation of appendix and its up/downstream intestine after antibiotic treatment. This study aimed to investigate the microbiome and mucosal morphology of jejunum, appendix, and colon of rats in health and dysbiosis. A rodent model of antibiotic-induced dysbiosis was employed. Microscopy was used to observe mucosal morphological changes. 16S rRNA sequencing was performed for identifying bacterial taxa and microbiome structure. The appendices of dysbiosis were found enlarged and inflated with loose contents. Microscopy revealed the impairment of intestinal epithelial cells. High-throughput sequencing showed the Operational Taxonomic Units changed from 361 ± 33, 634 ± 18, 639 ± 19 in the normal jejunum, appendix, colon to 748 ± 98, 230 ± 11, 253 ± 16 in the disordered segments, respectively. In dysbiosis, Bacteroidetes translocated inversely from the colon and appendix (0.26%, 0.23%) to the jejunum (13.87% ± 0.11%); the relative abundance of all intestinal Enterococcaceae increased, while Lactobacillaceae decreased. Several bacterial clusters were found correlated to the normal appendix, whereas nonspecific clusters correlated to the disordered appendix. In conclusion, species richness and evenness reduced in the disordered appendix and colon; similar microbiome patterns were shared between the appendix and colon regardless of dysbiosis; site-specific bacteria were missing in the disordered appendix. Appendix is likely a transit region involving in upper and lower intestinal microflora modulation. The limitation of this study is all the data were derived from rats. We must be cautious about translating the microbiome results from rats to humans.

Altered gastrointestinal tract structure and microbiome following cerebral malaria infection

Cerebral malaria (CM) is the most severe form of malaria with the highest mortality rate and can result in life-long neurological deficits and ongoing comorbidities. Factors contributing to severity of infection and development of CM are not fully elucidated. Recent studies have indicated a key role of the gut microbiome in a range of health conditions that affect the brain, but limited microbiome research has been conducted in the context of malaria. To address this knowledge gap, the impact of CM on the gut microbiome was investigated in mice. C57BL/6J mice were infected with Plasmodium berghei ANKA (PbA) parasites and compared to non-infected controls. Microbial DNA from faecal pellets collected daily for 6-days post-infection were extracted, and microbiome comparisons conducted using 16S rRNA profiling. We identified significant differences in the composition of bacterial communities between the infected and the non-infected groups, including a higher abundance of the genera Akkermansia, Alistipes and Alloprevotella in PbA-infected mice. Furthermore, intestinal samples were collected post-cull for morphological analysis. We determined that the caecal weight was significantly lower, and the small intestine was significantly longer in PbA-infected mice than in the non-infected controls. We concluded that changes in microbial community composition were primarily driven by the infection protocol and, to a lesser extent, by the time of infection. Our findings pave the way for a new area of research and novel intervention strategies to modulate the severity of cerebral malaria disease.

Issues for patchy tissues: defining roles for gut-associated lymphoid tissue in neurodevelopment and disease

Individuals diagnosed with neurodevelopmental conditions such as autism spectrum disorder (ASD; autism) often experience tissue inflammation as well as gastrointestinal dysfunction, yet their underlying causes remain poorly characterised. Notably, the largest components of the body's immune system, including gut-associated lymphoid tissue (GALT), lie within the gastrointestinal tract. A major constituent of GALT in humans comprises secretory lymphoid aggregates known as Peyer's patches that sense and combat constant exposure to pathogens and infectious agents. Essential to the functions of Peyer's patches is its communication with the enteric nervous system (ENS), an intrinsic neural network that regulates gastrointestinal function. Crosstalk between these tissues contribute to the microbiota-gut-brain axis that altogether influences mood and behaviour. Increasing evidence further points to a critical role for this signalling axis in neurodevelopmental homeostasis and disease. Notably, while the neuroimmunomodulatory functions for Peyer's patches are increasingly better understood, functions for tissues of analogous function, such as caecal patches, remain less well characterised. Here, we compare the structure, function and development of Peyer's patches, as well as caecal and appendix patches in humans and model organisms including mice to highlight the roles for these essential tissues in health and disease. We propose that perturbations to GALT function may underlie inflammatory disorders and gastrointestinal dysfunction in neurodevelopmental conditions such as autism.

Association between prior appendectomy and the risk and course of Crohn's disease: A systematic review and meta-analysis

BACKGROUND AND AIMS

The appendix has an important immune function in both health and disease, and appendectomy may influence microbial ecology and immune function. This meta-analysis aims to assess the association between appendectomy and the risk and course of Crohn's disease (CD).

METHODS

PubMed, EMBASE, and the Cochrane Library were used to identify all studies published until June 2022. Data from studies evaluating the association between appendectomy and CD were reviewed.

RESULTS

A total of 28 studies were included in the final analysis, comprising 22 case-control and 6 cohort studies. A positive relationship between prior appendectomy and the risk of developing CD was observed in both case-control studies (odds ratio [OR]: 1.59, 95% confidence interval [CI]: 1.22-2.08) and cohort studies (relative risk [RR]: 2.28, 95% CI: 1.66-3.14). The elevated risk of CD persisted 5 years post-appendectomy (RR = 1.24, 95% CI: 1.12-1.36). The risk of developing CD was similarly elevated regardless of the presence (RR = 1.64, 95% CI: 1.17-2.31) or absence (RR = 2.77, 95% CI: 1.84-4.16) of appendicitis in patients. Moreover, significant differences were found in the proportion of terminal ileum lesions (OR = 1.63; 95% CI: 1.38-1.93) and colon lesions (OR = 0.70; 95% CI: 0.5-0.84) between CD patients with appendectomy and those without appendectomy.

CONCLUSIONS

The risk of developing CD following an appendectomy is significant and persists 5 years postoperatively. Moreover, the elevated risk of CD may mainly occur in the terminal ileum.

Application value of high-frequency ultrasonography in endoscopic retrograde appendicitis therapy for pediatric acute appendicitis

BACKGROUND

Endoscopic retrograde appendicitis therapy (ERAT) is a new method of treating acute appendicitis that has emerged in recent years in children, but the application of radiological examination in the diagnosis and treatment of pediatric diseases is greatly limited. Therefore, high-frequency ultrasonography imaging has attracted more and more attention because of its advantages such as non-invasiveness, no radiation, and a simpler procedure. This study aims to explore the application value of high-frequency ultrasonography in ERAT for pediatric acute appendicitis.

METHODS

A retrospective analysis was conducted on 136 children admitted to our hospital from January 2020 to October 2021 who were definitively diagnosed with acute appendicitis and underwent endoscopic retrograde intra-appendiceal irrigation treatment under the guidance of high-frequency ultrasonography. They were divided into the preschool age group (< 6 years) and school age group (≥ 6 years) according to age. Before the operation and at 1-2 days after ERAT, the external diameter of the appendix, as well as the thickness of the intestinal wall, mucosal layer, and muscular layer in each group were measured by high-frequency ultrasonography and recorded in detail. During the operation, a stent was placed under real-time guidance, and the situation in the cavity was observed. The clinical data of the two groups of children before and after the operation were collected, and the recurrence status after treatment was followed up.

RESULTS

Endoscopic treatment was completed in 131 patients with a success rate of 96.32%. There was no significant difference between the two groups in appendix diameter, intestinal wall, or muscular layer after the operation when compared to those before the operation (p > 0.05), but there was a significant difference in the mucosal thickness after operation when compared to before the operation (p < 0.05). Abdominal pain in the two groups was significantly relieved immediately after the operation, and the white blood cell count returned to normal, with a significant difference before and after the ERAT operation (p < 0.05).

CONCLUSION

Endoscopic intra-appendiceal irrigation under the guidance of high-frequency ultrasonography is a real-time and convenient method that is safe and effective in treating pediatric acute appendicitis.

The Appendix Orchestrates T-Cell Mediated Immunosurveillance in Colitis-Associated Cancer

BACKGROUND & AIMS

Although appendectomy may reduce colorectal inflammation in patients with ulcerative colitis (UC), this surgical procedure has been suggested to be associated with an increased risk of colitis-associated cancer (CAC). Our aim was to explore the mechanism underlying the appendectomy-associated increased risk of CAC.

METHODS

Five-week-old male BALB/c mice underwent appendectomy, appendicitis induction, or sham laparotomy. They were then exposed to azoxymethane/dextran sodium sulfate (AOM/DSS) to induce CAC. Mice were killed 12 weeks later, and colons were taken for pathological analysis and immunohistochemistry (CD3 and CD8 staining). Human colonic tumors from 21 patients with UC who underwent surgical resection for CAC were immunophenotyped and stratified according to appendectomy status.

RESULTS

Whereas appendectomy significantly reduced colitis severity and increased CAC number, appendicitis induction without appendectomy led to opposite results. Intratumor CD3+ and CD8+ T-cell densities were lower after appendectomy and higher after appendicitis induction compared with the sham laparotomy group. Blocking lymphocyte trafficking to the colon with the anti-α4β7 integrin antibody or a sphingosine-1-phosphate receptor agonist suppressed the inducing effect of the appendectomy on tumors' number and on CD3+/CD8+ intratumoral density. CD8+ or CD3+ T cells isolated from inflammatory neo-appendix and intravenously injected into AOM/DSS-treated recipient mice increased CD3+/CD8+ T-cell tumor infiltration and decreased tumor number. In UC patients with a history of appendectomy, intratumor CD3+ and CD8+ T-cell densities were decreased compared with UC patients without history of appendectomy.

CONCLUSIONS

In UC, appendectomy could suppress a major site of T-cell priming, resulting in a less efficient CAC immunosurveillance.

Exploring the value of microorganisms in the appendix for inferring postmortem interval in Sprague-Dawley rats using high-throughput sequencing

Various microorganisms play an important role in daily functions in the body and continue to flourish after death. Our prior investigation using frozen cadavers revealed that the appendix, rather than the transverse colon, was a superior sampling site for intestinal bacteria because the appendiceal flora had higher diversity than that in the transverse colon in the majority of experimental periods after death. We sought to explore out more about whether the appendicular flora is significantly related to postmortem interval (PMI) at natural temperatures following the host's death. In this work, we employed high-throughput sequencing to evaluate the contents of rats' appendices within 2 weeks after death and then utilized the random forest algorithm to build a PMI prediction model after completing basic visual analyses on the sequencing data. The findings revealed that Firmicutes was the absolute dominant species of appendicular flora; alpha-diversity of appendix flora first increased and then decreased, with the highest point appearing at 36 h after death; and the primary metabolic functions were carbohydrate metabolism, amino acid metabolism, as well as cofactors and vitamin metabolism. Finally, a random forest regression model for PMI prediction was built by the training data at the family level, with the mean absolute error of 10.27 h for prediction within 14 days postmortem, and the test set data subsequently proved the model's reliability. Changes in appendicular flora were strongly related to the PMI following rats' deaths, so we have reason to believe that the appendicular flora is valuable in predicting PMI.

Pathogenic Mechanisms of the Severe Acute Respiratory Syndrome Coronavirus 2 and Potential Direct and Indirect Counteractions by Intermittent Fasting

The coronavirus disease 2019 (COVID-19) pandemic created an unprecedented burden on human health and on the function and interaction of societies across the globe. Public health preventive measures, vaccines, and antivirals were key components of the world-wide response to the health emergency. Due to the uncoordinated and variably successful response to COVID-19 and the ability of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to rapidly mutate, SARS-CoV-2 continues to create considerable difficulty for humanity today. Additional preventive or therapeutic modalities are needed to help people to achieve the best possible health outcomes in the context of the evolving COVID-19 threat. Intermittent fasting is a potential complementary therapy that not only impacts chronic disease risk but also has good evidence of an impact on infectious diseases. While the data regarding fasting and COVID-19 outcomes are very limited, the conceptual connection of fasting to better outcomes includes a variety of mechanisms in human biology. This paper reviews the known mechanisms of disease impacted by SARS-CoV-2 infection and the potential or likely direct or indirect counteractions that fasting may provide that may reduce the severity of COVID-19 and help to realize the best possible health outcomes. Furthermore, fasting adds no financial cost to a care plan and, when practiced safely, is available to most adults without limitation. Further research is needed on the impact of intermittent fasting on human health in the fight against infectious diseases including COVID-19.

The vermiform cecal appendix, expendable or essential? A narrative review

PURPOSE OF REVIEW

The vermiform cecal appendix is a small thin pouch-like tube of intestinal tissue situated in the lower right abdomen. It is attached at the junction of the large intestine between the ascending colon and small intestine. Historically, the appendix has been labeled redundant with no significant function, a remnant of evolution. This idea was thought to represent a function that may have been critical for survival that became nonsignificant over time. Evolutionary biologists deemed it to be a vestigial organ that early in human evolution was a dedicated organ that was useful and exploited by herbivorous ancestors.

RECENT FINDINGS

Currently, the vermiform cecal appendix has generated significant renewed research interest. As such it has been reported to present a site with a high concentration of lymphoid tissue and a biofilm microbiome that approximately mirrors that which is found in the large bowel.

SUMMARY

Research suggests that the vermiform cecal appendix may be the site of a safe-house biofilm that could re-inoculate the large bowel. Given that the appendix has no known role in digestion, the network of lymphoid tissue and microbiome could constitute an initial site of bacterial translocations that can influence early life ontology and immunological tolerance. A dysbiotic microbiome in the appendix is posited to trigger inflammatory sequelae.

Mucosal Immunity and the Gut-Microbiota-Brain-Axis in Neuroimmune Disease

Recent advances in next-generation sequencing (NGS) technologies have opened the door to a wellspring of information regarding the composition of the gut microbiota. Leveraging NGS technology, early metagenomic studies revealed that several diseases, such as Alzheimer's disease, Parkinson's disease, autism, and myalgic encephalomyelitis, are characterized by alterations in the diversity of gut-associated microbes. More recently, interest has shifted toward understanding how these microbes impact their host, with a special emphasis on their interactions with the brain. Such interactions typically occur either systemically, through the production of small molecules in the gut that are released into circulation, or through signaling via the vagus nerves which directly connect the enteric nervous system to the central nervous system. Collectively, this system of communication is now commonly referred to as the gut-microbiota-brain axis. While equally important, little attention has focused on the causes of the alterations in the composition of gut microbiota. Although several factors can contribute, mucosal immunity plays a significant role in shaping the microbiota in both healthy individuals and in association with several diseases. The purpose of this review is to provide a brief overview of the components of mucosal immunity that impact the gut microbiota and then discuss how altered immunological conditions may shape the gut microbiota and consequently affect neuroimmune diseases, using a select group of common neuroimmune diseases as examples.

Endoscopic retrograde appendicitis therapy (ERAT) vs appendectomy for acute uncomplicated appendicitis: A prospective multicenter randomized clinical trial

OBJECTIVE

To compare the efficacy and feasibility of endoscopic retrograde appendicitis therapy (ERAT) with appendectomy for treating acute uncomplicated appendicitis.

METHODS

This was a prospective multicenter randomized trial in which consecutive patients were randomized at a ratio of 1:1 to receive either ERAT or appendectomy. The outcomes included technical success rate, procedure time, postoperative pain relief, postoperative analgesic use, time to soft diet intake, length of postoperative hospital stay, postoperative complications, and recurrence rate.

RESULTS

From August 2013 to December 2015, 110 patients with acute uncomplicated appendicitis were randomized to ERAT or appendectomy. The technical success rate was 94.55% for ERAT compared with 100% for appendectomy. Recurrence of appendicitis within 3-year follow-up occurred in 8 patients following ERAT. Postoperative abdominal pain was less frequent with ERAT than with appendectomy (21.15% [11/52] vs 87.27% [48/55], P < 0.001). Soft diet intake begun earlier after ERAT than appendectomy (6 h vs 48 h, P < 0.001), and post-procedure hospital stay was shorter (3 days vs 5 days, P < 0.001), as was the use of analgesics postoperatively (9.09% vs 49.09%, P < 0.001).

CONCLUSIONS

ERAT is a feasible, safe, and effective alternative approach for the management of acute uncomplicated appendicitis. Compared with appendectomy, advantages of ERAT include no skin wound, organ preservation, reduced postoperative pain, early food intake, quick recovery, fewer postoperative complications, and shorter post-procedure hospitalization. The unsolved problem related to ERAT is the recurrence of appendicitis.

A concise pathophysiological model of acute appendicitis against the background of the COVID-19 pandemic

One of the most common clinical pictures has become the focus of attention during the COVID-19 pandemic: acute appendicitis with the associated diagnostics and therapy. The aim of the work is to show inconsistencies with regard to epidemiology, pathophysiology and therapy against the background of the pandemic with special attention to the conditions for children and to explain the pathophysiological processes that are likely to underlie the disease based on scientifically plausible models.

Endoscopic retrograde appendicitis therapy versus laparoscopic appendectomy for uncomplicated acute appendicitis

BACKGROUND

Endoscopic retrograde appendicitis therapy (ERAT) is a new and minimally invasive technique for the treatment of acute appendicitis. This study aimed to assess the efficacy and clinical outcomes of ERAT versus laparoscopic appendectomy for patients with uncomplicated acute appendicitis.

METHODS

We adopted propensity score matching (1:1) to compare ERAT and laparoscopic appendectomy in patients with uncomplicated acute appendicitis between April 2017 and March 2020. We reviewed 2880 patients with suspected acute appendicitis, of whom 422 patients with uncomplicated acute appendicitis met the matching criteria (ERAT 79; laparoscopic appendectomy 343), yielding 78 pairs of patients.

RESULTS

The rate of curative treatment within 1 year after ERAT was 92.1 % (95 % confidence interval [CI] 83.8 % to 96.3 %). The percentage of patients recording visual analog scale values of  ≤ 3 for pain at 6 hours after treatment was 94.7 % (95 %CI 87.2 % to 97.9 %) in the ERAT group, which was significantly higher than that in the laparoscopic appendectomy group (83.3 %; 95 %CI 73.5 % to 90.0 %). Median procedure time and median hospital length of stay were significantly lower in the ERAT group compared with the laparoscopic appendectomy group. At 1 year, the median recurrence time was 50 days (interquartile range 25-127) in the ERAT group. The overall adverse event rate was 24.4 % (95 %CI 14.8 % to 33.9 %) in the laparoscopic appendectomy group and 18.4 % (95 %CI 9.7 % to 27.1 %) in the ERAT group, with no significant difference between the two groups.

CONCLUSION

ERAT was a technically feasible method of treating uncomplicated acute appendicitis compared with laparoscopic appendectomy.

Childhood appendicitis and future risk of inflammatory bowel disease - A nationwide cohort study in Sweden 1973-2017

AIM

The aim of this study was to investigate the association between juvenile appendicitis, treated conservatively or with appendectomy, and adult risk of inflammatory bowel disease (IBD), either ulcerative colitis (UC) or Crohn's disease (CD). We used nationwide population data from more than 100,000 individuals followed for over four decades.

METHOD

All Swedish patients discharged with a diagnosis of appendicitis before the age of 16 years between 1973 to 1996 were identified. Everyone diagnosed with appendicitis was matched to an individual in the general population without a history of juvenile appendicitis (unexposed) of similar age, sex and region of residence. The study population was retrospectively followed until 2017 for any development of UC or CD. Cox proportional-hazards models compared disease-free survival time between exposed and unexposed individuals, also analysing the impact of treatment (conservative treatment versus appendectomy).

RESULTS

The final cohort consisted of 52,391 individuals exposed to appendicitis (1,674,629 person years) and 51,415 unexposed individuals (1,638,888 person years). Childhood appendicitis with appendectomy was associated with a significantly lower risk of adult IBD [adjusted hazard ratio (aHR) 0.48 (0.42-0.55)], UC [aHR 0.30 (0.25-0.36)] and CD [aHR 0.82 (0.68-0.97)]. Those treated conservatively had a lower risk of adult UC [aHR 0.29 (0.12-0.69)] but not CD [aHR 1.12 (0.61-2.06)] compared with unexposed individuals.

CONCLUSION

Juvenile appendicitis treated with appendectomy was associated with a decreased risk of adult IBD, both UC and CD. Those treated conservatively instead of with surgery had a lower risk of UC only. Our findings warrant more research on the role of the appendix and gut microbiota in the pathogenesis of IBD.

Early Introduction of Plant Polysaccharides Drives the Establishment of Rabbit Gut Bacterial Ecosystems and the Acquisition of Microbial Functions

In mammals, the introduction of solid food is pivotal for the establishment of the gut microbiota. However, the effects of the first food consumed on long-term microbiota trajectory and host response are still largely unknown. This study aimed to investigate the influences of (i) the timing of first solid food ingestion and (ii) the consumption of plant polysaccharides on bacterial community dynamics and host physiology using a rabbit model. To modulate the first exposure to solid nutrients, solid food was provided to suckling rabbits from two different time points (3 or 15 days of age). In parallel, food type was modulated with the provision of diets differing in carbohydrate content throughout life: the food either was formulated with a high proportion of rapidly fermentable fibers (RFF) or was starch-enriched. We found that access to solid food as of 3 days of age accelerated the gut microbiota maturation. Our data revealed differential effects according to the digestive segment: precocious solid food ingestion influenced to a greater extent the development of bacterial communities of the appendix vermiformis, whereas life course polysaccharides ingestion had marked effects on the cecal microbiota. Greater ingestion of RFF was assumed to promote pectin degradation as revealed by metabolomics analysis. However, transcriptomic and phenotypic host responses remained moderately affected by experimental treatments, suggesting little outcomes of the observed microbiome modulations on healthy subjects. In conclusion, our work highlighted the timing of solid food introduction and plant polysaccharides ingestion as two different tools to modulate microbiota implantation and functionality.

IMPORTANCE Our study was designed to gain a better understanding of how different feeding patterns affect the dynamics of gut microbiomes and microbe–host interactions. This research showed that the timing of solid food introduction is a key component of the gut microbiota shaping in early developmental stages, though with lower impact on settled gut microbiota profiles in older individuals. This study also provided in-depth analysis of dietary polysaccharide effects on intestinal microbiota. The type of plant polysaccharides reaching the gut through the lifetime was described as an important modulator of the cecal microbiome and its activity. These findings will contribute to better define the interventions that can be employed for modulating the ecological succession of young mammal gut microbiota.

Appendix and Ulcerative Colitis: a Key to Explaining the Pathogenesis and Directing Novel Therapies?

The vermiform appendix is generally considered a redundant organ, but recent evidence suggests that the appendix could contribute to the pathogenesis of inflammatory bowel diseases, in particular ulcerative colitis (UC), and may even have a therapeutic role; however, mechanisms of the appendix involvement remain unclear. Here, we highlight current evidence on the link between the appendix and UC and consider plausible therapeutic implications. A literature search was conducted using PubMed and PubMed Central from inception to Nov 2021 using the terms "Appendix", "UC", "Appendix & UC," "Appendectomy", and "Peri-appendicular patch," including only articles published in English. Reference lists from the selected studies were manually searched and reviewed to gather additional related reports. Inflammation around the appendix ("peri-appendicular patch") has been frequently observed in UC patients without other cecal involvement, and this inflammation can even precede the onset of UC. Epidemiologic studies propose that appendectomy reduces the risk of developing UC or even the risk of flare after UC is diagnosed, although this remains controversial. We reviewed studies showing altered host-microbe interactions in the appendix in UC, which suggest that the appendix could act as a priming site for disease via alterations in the immune response and changes in microbiota carried distally to the colon. In summary, recent literature suggests a possible role for microbes and immune cells within the appendix; however, the role of the appendix in the pathogenesis of UC remains unclear. Further research could clarify the therapeutic potential related to this organ.

Spatial dynamics of inflammation-causing and commensal bacteria in the gastrointestinal tract

In recent years, new research programmes have been initiated to understand the role of gut bacteria in health and disease, enabled in large part by the emergence of high-throughput sequencing. As new genomic and other data emerge it will become important to explain observations in terms of underlying population mechanisms; for instance, it is of interest to understand how resident bacteria interact with their hosts and pathogens, and how they play a protective role. Connecting underlying processes with observed patterns is aided by the development of mathematical models. Here, we develop a spatial model of microbial populations in the gastrointestinal tract to explore conditions under which inflammation-causing bacteria can invade the gut and under which such pathogens become persistent. We find that pathogens invade both small and large intestine from even a relatively small inoculum size but are usually eliminated by the host response. When the immune response is weak, the pathogen is able to persist for a long period. Spatial structure affects these dynamics by creating moving refugia which facilitate bouts of pathogen resurgence and inflammation in persistent infections. Space also plays a role in repopulation by commensals after infection. We further find that the rate of decay of inflammation has a stronger effect on outcomes than the initiation of inflammation or other parameters. Finally, we explore the impact of partially inflammation-resistant commensals on these dynamics.

Clostridioides difficile infection after appendectomy: An analysis of short-term outcomes from the NSQIP database

BACKGROUND

Clostridioides difficile infection can be a significant complication in surgical patients. The purpose of this study was to describe the incidence and impact on outcomes of Clostridioides difficile infection in adult patients after appendectomy.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program data set was used to identify all patients with the primary procedure code of appendectomy between 2016 and 2018. Patient demographics and clinical characteristics were extracted from the database, and descriptive statistics were performed. A multivariate logistic regression was created to identify predictors of Clostridioides difficile infection following appendectomy.

RESULTS

A total of 135,272 patients who underwent appendectomy were identified, and of those, 469(0.35%) developed Clostridioides difficile infection. Patients with Clostridioides difficile infection were more likely to be older (51.23 vs 40.47 years; P < .0001), female (P = .004), American Society of Anesthesiology score >2 (P < .0001), present with septic shock (P < .0001), or lack functional independence (P < .0001). Patients with Clostridioides difficile infection were more likely to have increased operative time (62.9 vs 50.4 minutes; P < .0001), have perforated appendicitis (48.9% vs 23.5%; P < .0001), and underwent open surgery (7.0% vs 4.0%; P = .0006). Postoperatively, patients with Clostridioides difficile infection required a longer length of stay (4.8 vs 1.8 days; P < .0001), had increased mortality (2.1% vs 0.1%; P < .0001), higher incidences of postoperative abscess (14.9% vs 2.9%; P < .0001), postoperative sepsis (15.1% vs 4.0%; P < .0001), and readmission (30.7% vs 3.4%; all P < .0001). On multivariate analysis, older age (P < .0001), female sex (P = .0043), septic shock (P = .0002), open surgery (P = .037), and dirty wound class (P = .0147) were all independently predictive factors of Clostridioides difficile infection after appendectomy.

CONCLUSION

Clostridioides difficile infection is an uncommon postoperative complication of appendectomy and is associated with worse outcomes and higher mortality. Older patients, female sex, those with sepsis, and those undergoing open surgery are at higher risk for developing Clostridioides difficile infection.

Alpha-synuclein and tau are abundantly expressed in the ENS of the human appendix and monkey cecum

α-Synuclein (α-syn) proteinopathy in the neurons of the Enteric Nervous System (ENS) is proposed to have a critical role in Parkinson's disease (PD) onset and progression. Interestingly, the ENS of the human appendix harbors abundant α-syn and appendectomy has been linked to a decreased risk and delayed onset of PD, suggesting that the appendix may influence PD pathology. Common marmosets and rhesus macaques lack a distinct appendix (a narrow closed-end appendage with a distinct change in diameter at the junction with the cecum), yet the cecal microanatomy of these monkeys is similar to the human appendix. Sections of human appendix (n = 3) and ceca from common marmosets (n = 4) and rhesus macaques (n = 3) were evaluated to shed light on the microanatomy and the expression of PD-related proteins. Analysis confirmed that the human appendix and marmoset and rhesus ceca present thick walls comprised of serosa, muscularis externa, submucosa, and mucosa plus abundant lymphoid tissue. Across all three species, the myenteric plexus of the ENS was located within the muscularis externa with nerve fibers innervating all layers of the appendix/ceca. Expression of α-syn and tau in the appendix/cecum was present within myenteric ganglia and along nerve fibers of the muscularis externa and mucosa in all species. In the myenteric ganglia α-syn, p-α-syn, tau and p-tau immunoreactivities (ir) were not significantly different across species. The percent area above threshold of α-syn-ir and tau-ir in the nerve fibers of the muscularis externa and mucosa were greater in the human appendix than in the NHP ceca (α-syn-ir p<0.05; tau-ir p<0.05). Overall, this study provides critical translational evidence that the common marmoset and rhesus macaque ceca are remarkably similar to the human appendix and, thus, that these NHP species are suitable for studying the development of PD linked to α-syn and tau pathological changes in the ENS.

Incidence of Early and Late-Onset Clostridioides difficile Infection following Appendectomy Compared to Other Common Abdominal Surgical Procedures

Introduction. Clostridioides difficile associated diarrhea (CDAD) is a major public health issue. The appendix may function as a reservoir for the intestinal microbiome, which may repopulate the intestine following enteric infections including CDAD. Patients/Methods. This retrospective cohort study includes a total of 12,039 patients undergoing appendectomy, hemicolectomy, and cholecystectomy at a single center between 1992 and 2011 who were diagnosed with early and late-onset CDAD and were followed for a minimum of two years. Results. Cumulative CDAD rates were 2.3% after appendectomy, 6.4% after left and 6.8% after right hemicolectomy, and 4% after cholecystectomy with a median onset of 76 (range 1–6011) days after the procedure. Median time to CDAD onset was 76 days after appendectomy, 23 days after left, 54 days after right hemicolectomy, and 122 days after cholecystectomy ( $p<0.05$ ). Late-onset CDAD (>1 year) was significantly more common following appendectomy (37%) and cholecystectomy (39%) than after left (17%) and right (21%) hemicolectomy. Significant differences in age, gender, complication rate, and length of hospitalization between the four groups need to be considered when interpreting the results. Conclusion. The incidence of CDAD after various abdominal surgeries ranged between 2% and 7% in this study. Whereas, hemicolectomy patients had predominantly early onset CDAD, and appendectomy and cholecystectomy may increase the risk for late-onset CDAD. Appendectomy per se does not seem to increase the risk for late-onset CDAD.

Vermiform Appendix and the Potential for Missed Pathologies

Introduction

The appendix is considered an appendage of little value and is often treated disdainfully, be it as part of evolutionary process, on a grossing table, under a microscope or while archiving specimens and slides. It is only recently, with data indicating its importance in gut immunity and as the origin of pseudomyxoma, that its space in a human body appears vindicated.

Aim

Our aim was to screen the histopathologic spectrum of appendix lesions observed in our hospital for rare, incidental or clinico-radiologically uncertain lesions that would help emphasize a necessary seriousness in its sampling.

Method

All appendectomy specimens over ten years were screened for diagnosis other than acute/chronic/resolving appendicitis and pseudomyxoma peritonei. Among the recorded rare diagnoses, one representative case each, based on interesting history or pathology, was selected for discussion.

Observation

Forty-three lesions were found to meet inclusion criteria comprising 12 varied etiologies. Among these, 25 had a normal-appearing appendix and 27 were not suspected on radiology or on clinical/surgical assessment. Histopathology comprised, among others, neoplastic entities such as (Diffuse large B-cell) lymphoma, metastasis, carcinoid as well as interesting non-neoplastic diagnoses such as pinworm infestation (in the elderly) and (post-menopausal) endometriosis.

Conclusion

Sampling and histopathologic assessment of the appendix should be compulsory, careful and representative. Each specimen must be treated as harboring a potential pathology, until microscopically proven otherwise because missed “rare” diagnoses could delay therapy or alter key management decisions as cancer staging.