The vermiform appendix: an immunological organ sustaining a microbiome inoculum

The association of appendectomy with prognosis and tumor-associated macrophages in patients with colorectal cancer

The vermiform appendix plays an important role in colorectal immunity and the homeostasis of the gut microbiome. We aimed to evaluate the prognostic value of prior appendectomy for patients with colorectal cancer (CRC). This study revealed that prior appendectomy is an independent risk factor for the prognosis of patients with CRC, based on a multicentral CRC cohort. We further demonstrated that appendectomy induced a poor prognosis of CRC through the depletion of M1 macrophage cells in AOM-induced mice, which was confirmed in age-, sex-, and location-matched patients' cohorts and orthotopic model models with the CT26 cell line. Poor responses to anti-PD-1 immunotherapy were detected in patients with CRC with appendectomy, and cetuximab is an effective treatment for patients with appendectomy-associated colorectal cancer (APD-CRC) to improve their prognosis. Our study will provide a reference for developing treatment plans for a considerable number of patients with APD-CRC, which is of great clinical significance.

Exploring the causality of appendectomy and ischaemic heart disease: a Mendelian randomization study and meta-analysis

Background

The risk of ischaemic heart disease (IHD) is increased in appendectomy patients, but it is not clear whether there is a causal relationship. We aimed to systematically estimate the causal relationship between appendectomy and IHD and its subtypes, acute myocardial infarction (AMI) and angina pectoris (AP), using Mendelian randomization (MR) study methods and meta-analysis.

Methods

As the discovery cohort analysis, we extracted independent genetic variants strongly associated with appendectomy from the FinnGen study (28,601 cases) as instrumental variables (IVs). Genome-wide association study (GWAS) from UK Biobank were selected for outcome data. A first two-sample MR analysis was then conducted. As the replication cohort, IVs associated with appendectomy were extracted in the UK Biobank (50,105 cases). GWAS from the FinnGen study were selected for outcome data. A second MR analysis was then performed. Finally, meta-analyses were applied to assess the combined causal effects of the MR results.

Results

In the discovery cohort, there was a significant positive causal relationship between appendectomy and IHD and its subtypes AMI and AP. The replication cohort only found a positive causal relationship between appendectomy and AMI. Meta-analysis showed a positive causal relationship between appendectomy and IHD (OR: 1.128, 95% CI: 1.067-1.193, P = 2.459e-05), AMI (OR: 1.195, 95% CI: 1.095-1.305, P = 6.898e-05), and AP (OR: 1.087, 95% CI: 1.016-1.164, P = 1.598e-02).

Conclusions

This comprehensive MR analysis suggests that genetically predicted appendectomy may be a risk factor for the development of IHD and its subtypes AMI and AP. We need to continue to pay attention to these links.

Risk of colorectal cancer and adenoma after an appendectomy: results from three large prospective cohort studies and meta-analysis

PURPOSE

The relationship between appendectomy and subsequent colorectal cancer risk remains unclear, and no study has examined its association with colorectal adenoma.

METHODS

We used data from three prospective cohorts: Health Professionals Follow-up Study, Nurses' Health Study (NHS), and NHSII. Appendectomy history was self-reported at baseline. Colorectal cancer risk was analyzed with Cox proportional hazard models among 224,109 participants followed up to 32 years. Colorectal adenoma risk was evaluated among 157,490 participants with at least one lower gastrointestinal endoscopy during follow-up with logistic regression models accounting for repeated observations. We also performed a meta-analysis of cohort studies that examined association between appendectomy and colorectal cancer risk.

RESULTS

We documented 3,384 colorectal cancers, 13,006 conventional adenomas, and 11,519 serrated polyps during the follow-up period. Compared to participants without appendectomy, those who reported appendectomy history were not at higher risk of colorectal (HR [95% CI], 0.92 [0.84-1.00]), colon (0.92 [0.83-1.01]), or rectal (0.85 [0.70-1.03]) cancer. Similarly, appendectomy history was not associated with higher risk of conventional adenoma (OR [95% CI], 1.00 [0.97-1.02]), serrated polyp (0.97 [0.94-1.00]), or high-risk adenoma (0.96 [0.92-1.01]). The meta-analysis showed appendectomy was associated with a higher risk of colorectal cancer within a short time after the procedure (1.68 [1.01-2.81]), while the long-term risk was slightly inverse (0.94 [0.90-0.97]).

CONCLUSION

We found no evidence of an association between appendectomy history and long-term risk of colorectal cancer or its precursors. The observed higher risk of colorectal cancer right after appendectomy in the first few years is likely due to reverse causation.

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.

Laparoscopic ileocecal-sparing vs traditional right hemicolectomy for cancer of the hepatic flexure or proximal transverse colon: a dual-center propensity score-matched study

Background

Traditional right hemicolectomy (TRH) is the standard treatment for patients with nonmetastatic right colon cancer. However, the ileocecum, a vital organ with mechanical and immune functions, is removed in these patients regardless of the tumor location. This study aimed to evaluate the technical and oncological safety of laparoscopic ileocecal-sparing right hemicolectomy (LISH).

Method

Patients who underwent LISH at two tertiary medical centers were matched 1:2 with patients who underwent TRH by propensity score matching based on sex, age, body mass index, tumor location, and disease stage. Data on surgical and perioperative outcomes were collected. Oncological safety was evaluated in a specimen-oriented manner. Lymph nodes (LNs) near the ileocolic artery (ICA) were examined independently in the LISH group. Disease outcomes were recorded for patients who completed one year of follow-up.

Results

In all, 34 patients in the LISH group and 68 patients in the TRH group were matched. LISH added 8 minutes to the dissection of LNs around the ileocolic vessels (groups 201/201d, 202, and 203 LNs), without affecting the total operation time, blood loss, or perioperative adverse event rate. Compared with TRH, LISH had a comparable lymphadenectomy quality, specimen quality, and safety margin while preserving a more functional bowel. The LISH group had no cases of LN metastasis near the ICA. No difference was detected in the recurrence rate at the 1-year follow-up time point between the two groups.

Conclusion

In this dual-center study, LISH presented comparable surgical and oncological safety for patients with hepatic flexure or proximal transverse colon cancer.

Environmental and Microbial Factors in Inflammatory Bowel Disease Model Establishment: A Review Partly through Mendelian Randomization

Inflammatory bowel disease (IBD) is a complex condition resulting from environmental, microbial, immunologic, and genetic factors. With the advancement of Mendelian randomization research in IBD, we have gained new insights into the relationship between these factors and IBD. Many animal models of IBD have been developed using different methods, but few studies have attempted to model IBD by combining environmental factors and microbial factors. In this review, we examine how environmental factors and microbial factors affect the development and progression of IBD, and how they interact with each other and with the intestinal microbiota. We also summarize the current methods for creating animal models of IBD and compare their advantages and disadvantages. Based on the latest findings from Mendelian randomization studies on the role of environmental factors in IBD, we discuss which environmental and microbial factors could be used to construct a more realistic and reliable IBD experimental model. We propose that animal models of IBD should consider both environmental and microbial factors to better mimic human IBD pathogenesis and to reveal the underlying mechanisms of IBD at the immune and genetic levels. We highlight the importance of environmental and microbial factors in IBD pathogenesis and offer new perspectives and suggestions for improving experimental animal modeling. Our goal is to create a model that closely resembles the clinical picture of IBD.

Elevated Colon Cancer Rates Linked to Prior Appendicitis: A Retrospective Cohort Study Based on Data from German General Practices

Background/Objective: The association between appendicitis and colon cancer is not yet fully understood. Previous studies have shown contradictory results. Currently, no population-based data from Germany are available with regard to the incidence of colon cancer following appendicitis. This study investigated the association between appendicitis and the incidence of colon cancer in Germany. Methods: In this retrospective cohort study, the incidence of colon cancer was compared for patients with appendicitis and patients without appendicitis, matched for age, sex, index year, average annual consultation frequency, and comorbidity. The aim of the study was to explore the relationship between appendicitis and the incidence of colon cancer. The evaluation was carried out using logistic regression analyses. Results: The study included 49,790 people with and without appendicitis, with a median age of 41 years. During a follow-up period of up to 15 years, 1.04% of cases with appendicitis and 0.60% of cases without appendicitis were newly diagnosed with colon cancer, with some 36.4% of colon cancer cases diagnosed within the first six months after appendicitis. Regression analyses revealed a significant association between appendicitis and colon cancer, particularly in men and in the age groups 41-50 (HR: 10.30; 95% CI: 1.03-43.82) and 18-30 years (HR: 8.17; 95% CI: 1.03-64.58). Conclusions: The present retrospective cohort study suggests an association between appendicitis and the incidence of colon cancer in Germany. Based on our results, we recommend offering a colonoscopy or at least a stool test within 12 months after appendicitis, especially for 18-50-year-olds and >60-year-olds in good general health.

Roles for Bile Acid Signaling and Nonsense-Mediated Ribonucleic Acid Decay in Small Bowel Resection-Associated Liver Injury

INTRODUCTION

Massive intestinal loss resulting in short bowel syndrome has been linked to intestinal failure associated liver disease. Efforts to elucidate the driving force behind the observed hepatic injury have identified inflammatory mediators, alterations in the microbiome, extent of structural and functional intestinal adaptation, and toxic shifts in the bile acid pool. In the present study, we posit that ileocecal resection interrupts the delivery of these hepatotoxic substances to the liver by physically disrupting the enterohepatic circulation, thereby shielding the liver from exposure to the aforementioned noxious stimuli.

METHODS

Mice underwent sham, 50% proximal, or 50% distal small bowel resection (SBR), with or without tauroursodeoxycolic acid supplementation. Enterohepatic signaling and nonsense-mediated ribonucleic acid (RNA) decay were evaluated and correlated with hepatic injury.

RESULTS

When compared to 50% proximal SBR, mice that underwent ileocecal resection exhibited reduced hepatic oxidative stress and exhibited a more physiological bile acid profile with increased de novo bile acid synthesis, enhanced colonic bile acid signaling, and reduced hepatic proliferation. Distal intestinal resection promoted an adaptive response including via the nonsense-mediated RNA decay pathway to satisfactorily process injurious messenger RNA and successfully maintain homeostasis. By contrast, this adaptive response was not observed in the proximal SBR group and hepatic injury persisted.

CONCLUSIONS

In summary, interruption of enterohepatic circulation via ileocecal resection abrogates the liver's exposure to toxic and inflammatory mediators while promoting physiological adaptations in bile acid metabolism and maintaining existing homeostatic pathways.

[Association between previous appendectomy and cognitive impairment in adults: a case-control study]

OBJECTIVE

To determine the relationship between appendectomy and cognitive impairment in adults aged 50-70 years.

MATERIAL AND METHODS

A case-control study was carried out with 270 patients between May and July 2023. Ninety cases (with cognitive impairment) and 180 controls (without impairment), diagnosed by the Montreal Cognitive Assessment (MoCA), were assessed.

RESULTS

31.11% of the total cases with cognitive impairment were submitted to an appendectomy, with an average of 25 years since surgery. Regarding other surgeries: 40% with impairment underwent cholecystectomy and 23.33% reported other operations. The analysis revealed significant differences in age, body mass index, hypertension, diabetes and smoking between the groups. However, there was no significant difference by gender. Logistic regression analysis highlighted that age and past appendectomy were strongly associated with cognitive impairment, with an Odds Ratio (OR) of 1.20 and 12.91, respectively. Associations were also found with cholecystectomy (OR 7.33), other surgeries (OR 13.39) and smoking (OR 6.91).

CONCLUSION

Appendectomy might be a significant risk factor for cognitive impairment in adults aged 50-70 years.

Endoscopic retrograde appendicitis therapy versus appendectomy or antibiotics in the modern approach to uncomplicated acute appendicitis: A systematic review and meta-analysis

INTRODUCTION

Endoscopic retrograde appendicitis therapy has been proposed as an alternative strategy for treating appendicitis, but debate exists on its role compared with conventional treatment.

METHODS

This systematic review was performed on MEDLINE, Cochrane Central Register of Controlled Trials, and EMBASE. The last search was in April of 2023. The risk ratio with a 95% confidence interval was calculated for dichotomous variables, and the mean difference with a 95% confidence interval for continuous variables. The risk of bias was assessed using the Cochrane Risk of Bias 2.0 tool (randomized controlled trials) and the Risk of Bias in Non-Randomized Studies of Intervention tool (non-randomized controlled trials).

RESULTS

Six studies met the eligibility criteria. Four studies compared endoscopic retrograde appendicitis therapy (n = 236 patients) and appendectomy (n = 339) and found no differences in technical success during index admission (risk ratio 0.97, 95% confidence interval [0.92,1.02]). Appendectomy showed superior outcomes for recurrence at 1-year follow-up (risk ratio 11.28, 95% confidence interval [2.61,48.73]). Endoscopic retrograde appendicitis therapy required shorter procedural time (mean difference -14.38, 95% confidence interval [-20.17, -8.59]) and length of hospital stay (mean difference -1.19, 95% confidence interval [-2.37, -0.01]), with lower post-intervention abdominal pain (risk ratio 0.21, 95% confidence interval [0.14,0.32]). Two studies compared endoscopic retrograde appendicitis therapy (n = 269) and antibiotic treatment (n = 280). Technical success during admission (risk ratio 1.11, 95% confidence interval [0.91,1.35]) and appendicitis recurrence (risk ratio 1.07, 95% confidence interval [0.08,14.87]) did not differ, but endoscopic retrograde appendicitis therapy decreased the length of hospitalization (mean difference -1.91, 95% confidence interval [-3.18, -0.64]).

CONCLUSION

This meta-analysis did not identify significant differences between endoscopic retrograde appendicitis therapy and appendectomy or antibiotics regarding technical success during index admission and treatment efficacy at 1-year follow-up. However, a high risk of imprecision limits these results. The advantages of endoscopic retrograde appendicitis therapy in terms of reduced procedural times and shorter lengths of stay must be balanced against the increased risk of having an appendicitis recurrence at one year.

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.

Appendectomy Mitigates Coxsackievirus B3-Induced Viral Myocarditis

Appendix has a distinct abundance of lymphatic cells and serves as a reservoir of microbiota which helps to replenish the large intestine with healthy flora. And it is the primary site of IgA induction, which shapes the composition of the intestinal microbiota. Recent population-based cohort studies report that appendectomy is associated with an increased risk of acute myocardial infarction and ischemic heart disease. Here, whether appendectomy has an effect on the occurrence and development of coxsackievirus B3 (CVB3)-induced viral myocarditis is studied. 103 TCID50 CVB3 was inoculated i.p. into appendectomized and sham-operated mice. RNA levels of viral load and pro-inflammatory cytokines in the hearts and the intestine were detected by RT-PCR. Compared to sham-operated mice, appendectomized mice exhibited attenuated cardiac inflammation and improved cardiac function, which is associated with a systemic reduced viral load. Appendectomized mice also displayed a reduction in cardiac neutrophil and macrophage infiltration and pro-inflammatory cytokine production. Mechanistically, we found that CVB3 induced an early and potent IL-10 production in the cecal patch at 2 days post infection. Appendectomy significantly decreased intestinal IL-10 and IL-10+ CD4+ Treg frequency which led to a marked increase in intestinal (primary entry site for CVB3) anti-viral IFN-γ+ CD4+ T and IFN-γ+ CD8+ T response and viral restriction, eventually resulting in improved myocarditis. Our results suggest that appendix modulates cardiac infection and inflammation through regulating intestinal IL-10+ Treg response.

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.

The Vermiform Appendix and Its Pathologies

The vermiform appendix is a muscular cylindrical structure originating near the junction of the cecum and ileum, averaging 9 cm (5-35 cm) in size. As the most mobile viscera, it can adopt several positions, the most common being the retrocecal position. Perceived as an atavistic organ lacking physiological relevance, the vermiform appendix appears to be involved in immune function, serving in the maturation of B lymphocytes and the production of immunoglobulin A, in endocrine function, excreting amines and hormones in the 2-3 mL of mucus secreted daily, and in digestive function, by storing beneficial bacteria from where they can recolonize the colon. With a lumen of about 6 mm, the vermiform appendix has a reduced storage capacity, so any blockage of the appendix with fecoliths (fecaliths), seeds derailed from the colon, or enlarged lymph nodes prevents drainage and intraluminal accumulation of secreted mucus. Unable to relax, the appendix wall severely limits its intraluminal volume, so mucus accumulation leads to inflammation of the appendix, known generically as appendicitis. In addition, the vermiform appendix may be the site of the development of neoplastic processes, which may or may not involve mucus production, some of which can significantly affect the standard of living and ultimately lead to death. In general, mucinous tumors may have a better prognosis than non-mucinous tumors. This review takes a comprehensive path, starting by describing the anatomy and embryology of the vermiform appendix and further detailing its inflammatory pathologies, pathologies related to congenital anomalies, and appendix tumors, thus creating an up-to-date framework for better understanding, diagnosis, and treatment of these health problems.

Neurodegenerative and Neurodevelopmental Diseases and the Gut-Brain Axis: The Potential of Therapeutic Targeting of the Microbiome

The human gut microbiome contains the largest number of bacteria in the body and has the potential to greatly influence metabolism, not only locally but also systemically. There is an established link between a healthy, balanced, and diverse microbiome and overall health. When the gut microbiome becomes unbalanced (dysbiosis) through dietary changes, medication use, lifestyle choices, environmental factors, and ageing, this has a profound effect on our health and is linked to many diseases, including lifestyle diseases, metabolic diseases, inflammatory diseases, and neurological diseases. While this link in humans is largely an association of dysbiosis with disease, in animal models, a causative link can be demonstrated. The link between the gut and the brain is particularly important in maintaining brain health, with a strong association between dysbiosis in the gut and neurodegenerative and neurodevelopmental diseases. This link suggests not only that the gut microbiota composition can be used to make an early diagnosis of neurodegenerative and neurodevelopmental diseases but also that modifying the gut microbiome to influence the microbiome-gut-brain axis might present a therapeutic target for diseases that have proved intractable, with the aim of altering the trajectory of neurodegenerative and neurodevelopmental diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, autism spectrum disorder, and attention-deficit hyperactivity disorder, among others. There is also a microbiome-gut-brain link to other potentially reversible neurological diseases, such as migraine, post-operative cognitive dysfunction, and long COVID, which might be considered models of therapy for neurodegenerative disease. The role of traditional methods in altering the microbiome, as well as newer, more novel treatments such as faecal microbiome transplants and photobiomodulation, are discussed.

Association of the Bacteria of the Vermiform Appendix and the Peritoneal Cavity with Complicated Acute Appendicitis in Children

BACKGROUND

Primary infection has been questioned as the pathogenetic cause of acute appendicitis. We attempted to identify the bacteria involved and to investigate if their species, types, or combinations affected the severity of acute appendicitis in children.

METHODS

Samples from both the appendiceal lumen and the peritoneal cavity of 72 children who underwent appendectomy were collected to perform bacterial culture analysis. The outcomes were studied to identify if and how they were associated with the severity of the disease. Regression analysis was performed to identify any risk factors associated with complicated appendicitis.

RESULTS

Escherichia coli, Pseudomonas aeruginosa, and Streptococcus species were the most common pathogens found in the study population. The same microorganisms, either combined or separate, were the most common in the appendiceal lumen and the peritoneal cavity of patients with complicated appendicitis. Gram-negative bacteria and polymicrobial cultures in the peritoneal fluid and in the appendiceal lumen were associated with complicated appendicitis. Polymicrobial cultures in the peritoneal cavity presented a four times higher risk of complicated appendicitis.

CONCLUSIONS

Polymicrobial presentation and Gram-negative bacteria are associated with complicated appendicitis. Antibiotic regimens should target the combinations of the most frequently identified pathogens, speculating the value of early antipseudomonal intervention.

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.

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.

Disturbed Pediatric Gut Microbiome Maturation in the Developmental Origins of Subsequent Chronic Disease

The microbiome is known to play an important role in the development and maintenance of human health. During early childhood the gut microbiome undergoes a rapid evolution, making this developmental window most susceptible to microbial manipulation and, therefore, most vulnerable to environmental stimuli. Such stimuli may induce persistent alterations (or dysbiosis) in microbiome and/or host physiology, thereby resulting in susceptibility to subsequent disease development. This phenomenon is frequently described as "the microbial developmental origins of disease." In this topic of the month, we call attention to the microbial developmental origins of disease by examining the potential for childhood antibiotic exposures and appendectomy (ie, inducers of dysbiosis) to influence the pathogenesis of certain multifactorial, common diseases (eg, celiac disease, inflammatory bowel disease, obesity), especially those with increasing incidence worldwide. We conclude that fully appreciating the critical components in the microbial developmental origins of common chronic disorders is a major task ahead of pediatric gastroenterologists in the 21st century. Such information will be key in working to prevent numerous common and emerging disorders.

Colonic drug delivery: Formulating the next generation of colon-targeted therapeutics

Colonic drug delivery can facilitate access to unique therapeutic targets and has the potential to enhance drug bioavailability whilst reducing off-target effects. Delivering drugs to the colon requires considered formulation development, as both oral and rectal dosage forms can encounter challenges if the colon's distinct physiological environment is not appreciated. As the therapeutic opportunities surrounding colonic drug delivery multiply, the success of novel pharmaceuticals lies in their design. This review provides a modern insight into the key parameters determining the effective design and development of colon-targeted medicines. Influential physiological features governing the release, dissolution, stability, and absorption of drugs in the colon are first discussed, followed by an overview of the most reliable colon-targeted formulation strategies. Finally, the most appropriate in vitro, in vivo, and in silico preclinical investigations are presented, with the goal of inspiring strategic development of new colon-targeted therapeutics.

Altered gut microbiome composition by appendectomy contributes to colorectal cancer

Appendectomy impacts the homeostasis of gut microbiome in patients. We aimed to study the role of appendectomy in colorectal cancer (CRC) risk through causing gut microbial dysbiosis. Population-based longitudinal study (cohort 1, n = 129,155) showed a 73.0% increase in CRC risk among appendectomy cases throughout 20 years follow-up (Adjusted sub-distribution hazard ratio (SHR) 1.73, 95% CI 1.49-2.01, P < 0.001). Shotgun metagenomic sequencing was performed on fecal samples from cohort 2 (n = 314). Gut microbial dysbiosis in appendectomy subjects was observed with significant enrichment of 7 CRC-promoting bacteria (Bacteroides vulgatus, Bacteroides fragilis, Veillonella dispar, Prevotella ruminicola, Prevotella fucsa, Prevotella dentalis, Prevotella denticola) and depletion of 5 beneficial commensals (Blautia sp YL58, Enterococcus hirae, Lachnospiraceae bacterium Choco86, Collinsella aerofaciens, Blautia sp SC05B48). Microbial network analysis showed increased correlation strengths among enriched bacteria and their enriched oncogenic pathways in appendectomy subjects compared to controls. Of which, B. fragilis was the centrality in the network of the enriched bacteria. We further confirmed that appendectomy promoted colorectal tumorigenesis in mice by causing gut microbial dysbiosis and impaired intestinal barrier function. Collectively, this study revealed appendectomy-induced microbial dysbiosis characterized by enriched CRC-promoting bacteria and depleted beneficial commensals, signifying that the gut microbiome may play a crucial role in CRC development induced by appendectomy.

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.

Non-operative management of acute appendicitis in children

Appendicitis is one of the most common surgical emergencies in children and adults. Appendectomy as the standard care has been challenged in the recent years with growing evidence about non-operative treatment as a potential primary treatment in patients presenting with signs and symptoms suggestive of acute appendicitis. This review aims to establish where the recent research stands regarding conservative treatment of acute appendicitis, especially in children. There are several studies that report the potential safety and efficacy of treating acute appendicitis non-operatively. Several studies have challenged the concept of acute appendicitis being a progressive disease that always ends in perforation, rather than a disease that can present as different forms with only a defined number of cases progressing to perforation. The lack of randomized controlled studies is a limitation and well-designed randomized controlled trials are needed to determine the role of non-operative management of acute appendicitis in children.

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.

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.

The appendix‐mucosal immunity and tolerance in the gut: consequences for the syndromes of appendicitis and its epidemiology

The cause of appendicitis is unknown. A review is presented across diverse sources relating to the biology of the appendix and its perturbations. A mechanistic model of the function of the appendix is presented, and its application to the syndromes and consequences of appendicitis is described.

Digesting recent findings: gut alpha-synuclein, microbiome changes in Parkinson's disease

Two hallmarks of Parkinson's disease (PD) are the widespread deposition of misfolded alpha-synuclein (αSyn) protein in the nervous system and loss of substantia nigra dopamine neurons. Recent research has suggested that αSyn aggregates in the enteric nervous system (ENS) lead to prodromal gastrointestinal (GI) symptoms such as constipation in PD, then propagating to the brain stem and eventually triggering neurodegeneration and motor symptoms. Additionally, whether the microbiome changes in PD contribute to the primary pathogenesis or, alternatively, are consequential to either the disease process or medication is still unclear. In this review, we discuss the possible roles of αSyn and microbiome changes in the GI system in PD and consider if and how the changes interact and contribute to the disease process and symptoms.

Appendicitis in Far North Queensland: a new take on an old story

BACKGROUND

Appendicitis is a leading cause of surgical hospital admission. To date, there have been no published epidemiological studies describing appendicitis in tropical and remote Australia and none specifically documenting appendicitis in Indigenous Australians. This descriptive study used available state data to investigate appendicitis across Far North Queensland (FNQ).

METHODS

Queensland Health hospital admission data for FNQ was analysed to explore appendicitis epidemiology and outcomes in FNQ, 2012-2018. Population data for the same time period provided rates.

RESULTS

Over the study period, 3458 hospital presentations for appendicitis were available for analysis. Mean incidence was 178 per 100 000/yr. Median age was 27 years with 50.1% female patients. The annual rate of appendicitis was higher in the Indigenous population. Most patients had a laparoscopic procedure with a low rate of conversion to open surgery (2.6%). More than 80% of patients were discharged from hospital in less than 3 days. Intensive care (ICU) admission rate was low overall (1.1%) although higher for Indigenous people (2.4%). Following discharge, the hospital re-admission rate was 3.8% and all-cause mortality was 0.03%.

CONCLUSION

The incidence of appendicitis in FNQ is higher than that reported in the rest of Australia in both Indigenous and non-Indigenous populations. Despite logistical challenges of health care, clinical outcomes are in line with best practice across the country. Clinicians in FNQ should maintain a high index of suspicion for diagnosing appendicitis in rural and remote settings.

The use of the ratio of C-reactive protein to albumin for the diagnosis of complicated appendicitis in children

PURPOSE

No reliably specific marker for complicated appendicitis has been identified. The ratio of serum C-reactive protein (CRP) to albumin (ALB) (CRP/ALB ratio) is a new inflammation-based prognostic score that is associated with the severity of inflammation. The aim of this study was to evaluate the predictive value of CRP/ALB ratio for the diagnosis of complicated appendicitis in children.

METHODS

A retrospective study of 296 children with acute appendicitis was conducted with assessments of demographic data, clinical symptoms, pre-operative laboratory results, abdominal ultrasound examinations and clinical outcomes. According to the postoperative pathological results, patients were divided into a simple appendicitis group (169 patients) and a complicated appendicitis group (127 patients). SPSS version 22.0 was used to analyse the data.

RESULTS

Of the 296 patients, CRP/ALB ratio was higher in complicated appendicitis than in simple appendicitis (P < 0.05). Logistic regression analysis showed that higher levels of white blood cell count (WBC), CRP, CRP/ALB ratio, and increased incidence in submucosal layer loss and appendicolith were independent risk factors for complicated appendicitis in children. Receiver operating characteristic curve analysis showed that the area under the curve of the CRP/ALB ratio (0.883) was larger than that of WBC (0.702), CRP (0.802), ALB (0.835), submucosal layer loss (0.633) and appendicolith (0.673). A CRP/ALB ratio ≥ 1.39 was found to be a significant marker in the prediction of complicated appendicitis, with 86.61% sensitivity and 84.62% specificity. Patients with a CRP/ALB ratio ≥ 1.39 had a 31.263 times higher chance of having complicated appendicitis (95% CI: 16.449-59.418) than those with a CRP/ALB ratio < 1.39.

CONCLUSION

The admission CRP/ALB ratio was significantly higher in children with complicated appendicitis. The CRP/ALB ratio is a novel but promising haematological marker that aids in the differentiation of acute complicated and simple appendicitis.

Appendectomy Is Associated With Alteration of Human Gut Bacterial and Fungal Communities

Recent research has revealed the importance of the appendix in regulating the intestinal microbiota and mucosal immunity. However, the changes that occur in human gut microbial communities after appendectomy have never been analyzed. We assessed the alterations in gut bacterial and fungal populations associated with a history of appendectomy. In this cross-sectional study, we investigated the association between appendectomy and the gut microbiome using 16S and ITS2 sequencing on fecal samples from 30 healthy individuals with prior appendectomy (HwA) and 30 healthy individuals without appendectomy (HwoA). Analysis showed that the gut bacterial composition of samples from HwA was less diverse than that of samples from HwoA and had a lower abundance of Roseburia, Barnesiella, Butyricicoccus, Odoribacter, and Butyricimonas species, most of which were short-chain fatty acids-producing microbes. The HwA subgroup analysis indicated a trend toward restoration of the HwoA bacterial microbiome over time after appendectomy. HwA had higher gut fungi composition and diversity than HwoA, even 5 years after appendectomy. Compared with those in samples from HwoA, the abundance correlation networks in samples from HwA displayed more complex fungal–fungal and fungal–bacterial community interactions. This study revealed a marked impact of appendectomy on gut bacteria and fungi, which was particularly durable for fungi.

Predicting the postmortem interval using human intestinal microbiome data and random forest algorithm

Gradual changes in microbial communities in a human body after death can be used to determine postmortem interval (PMI). In this study, gut microflora samples were collected from the vermiform appendix and the transverse colon of human cadavers with PMIs between 5 and 192 h. The results revealed that the appendix might be an excellent intestinal sampling site and the appendix flora had an inferred succession rule during human body decomposition. Firmicutes, Bacteroidetes, and their respective subclasses showed a predictable successionrule in relative abundance over time. A Random Forest regression model was developed to correlate human gut microbiota with PMI. We believe that our findings have increased the knowledge of the composition and abundance of the gut microbiota in human corpses, and suggest that the use of the human appendix microbial succession may be a potential method for forensic estimation of the time of death.

Risk of Inflammatory Bowel Disease Following Appendectomy in Adulthood

Background: The appendix has a complicated immune function, and appendectomy may derange the immune system. Studies on the relationship between appendectomy and subsequent inflammatory bowel disease (IBD) have been inconsistent. We conducted a nationwide cohort study consisting of individuals who underwent appendectomy to evaluate the incidence and risk of ulcerative colitis (UC) and Crohn's disease (CD).

Methods: We identified patients aged >20 years who underwent appendectomy between 2000 and 2012 from inpatient claims of the National Health Insurance Research Database (NHIRD) and assigned them to the appendectomy cohort. Then, we randomly selected patients without appendectomy in the NHIRD and assigned them to the comparison cohort in a frequency-matched 1:1 ratio based on sex, age, and index year. We tracked down all participants until IBD diagnosis, death, or the end of 2013. Cox models were used to estimate the hazard ratio (HR), and 95% confidence intervals (CIs) were used to compare the IBD risk between the appendectomy and comparison cohorts.

Results: The appendectomy and comparison cohorts in the study consisted of 246 562 patients each. The appendectomy cohort exhibited a 2.23- and 3.48-fold higher risk of UC (adjusted HR = 2.23, 95% CI = 1.59-3.12) and CD (adjusted HR = 3.48, 95% CI = 2.42-4.99), respectively, than did the comparison cohort. UC and CD risks significantly increased in the appendectomy cohort regardless of whether appendicitis was present.

Conclusions: Our study suggests that appendectomy increases UC and CD risks irrespective of appendicitis.

Long-term effects of appendectomy in humans: is it the optimal management of appendicitis?

INTRODUCTION

Appendectomy remains the gold standard for treating uncomplicated and complicated appendicitis. However, the vermiform appendix may play a significant role in the immune system (secondary immune function) and maintain a reservoir of the normal microbiome for the human body. The aim of this study was to summarize the long-term effects after appendectomy and discuss whether appendectomy is suitable for all appendicitis patients.

AREAS COVERED

A comprehensive and unbiased literature search was performed in PubMed. The terms 'appendix,' 'appendicitis,' 'appendectomy,' and 'endoscopic retrograde appendicitis therapy' were searched in the title and/or abstract. This review summarizes the long-term effects of appendectomy on some diseases in humans and describes three methods including appendectomy, medical treatment, and an 'organ-sparing' technique, named endoscopic retrograde appendicitis therapy (ERAT) to treat appendicitis.

EXPERT OPINION

Appendectomy remains the first-line therapy for appendicitis. The patient's problem is appendix, not appendicitis. If we treat appendicitis, the problem should be resolved. During COVID-19, an initial antibiotic treatment of mild appendicitis represents a promising strategy. For patients who are worried about the long-term adverse effect after appendectomy and have a strong desire to preserve the appendix and are aware of the risk of appendicitis recurrence, medical treatment, or ERAT could be proposed.

Recent advances and health implications of dietary fasting regimens on the gut microbiome

Calorie restriction is a primary dietary intervention demonstrated over many decades in cellular and animal models to modulate aging pathways, positively affect age-associated diseases and, in clinical studies, to promote beneficial health outcomes. Because long-term compliance with daily calorie restriction has proven problematic in humans several intermittent fasting regimens, including alternate day fasting and time-restricted feeding, have evolved revealing similar clinical benefits as calorie restriction. Despite significant research on the cellular and physiological mechanisms contributing to, and responsible for, these observed benefits, relatively little research has investigated the impact of these various fasting protocols on the gut microbiome (GM). Reduced external nutrient supply to the gut may beneficially alter the composition and function of a "fed" gut microflora. Indeed, the prevalent, obesogenic Western diet can promote deleterious changes in the GM, signaling intermediates involved in lipid and glucose metabolism, and immune responses in the gastrointestinal tract. This review describes recent preclinical and clinical effects of varying fasting regimens on GM composition and associated physiology. Although the number of preclinical and clinical interventions are limited, significant data thus far suggest fasting interventions impact GM composition and physiology. However, there are considerable heterogeneities of study design, methodological considerations, and practical implications. Ongoing research on the health impact of fasting regimens on GM modulation is warranted.

Laparoscopic Management of Primary Omental Torsion

Primary omental torsion is an unusual condition, known for its rarity and for the particularity of being intraoperatively diagnosed, in nearly all cases. At the clinical evaluation, this pathology commonly mimics other etiologies of acute abdomen. Hemoperitoneum and necrosis of the omentum are rarely associated with the omental torsion, but when the association is found, then it means that the vascular injuries are irreversible and the required surgical procedure may be far more complex than simple devolvulus. In search of the treatment of choice, laparoscopy proved its effectiveness as a diagnostic and therapeutic tool, while the open surgery approach can be described in many cases as being too invasive. A 37-year-old female patient presented with the generic symptoms of acute appendicitis. Surgical treatment was initiated. During laparoscopy, the abdomen was attentively explored, highlighting the presence of a twisted omentum with hemoperitoneum and necrosis. Omental excision and peritoneal drainage were performed. The evolution was favorable. Another check-up was done at 6 months postoperatively, displaying no signs or symptoms of relapse.

Impact of Appendectomy on Gut Microbiota

Background: Considered vestigial from the classic point of view, the vermiform appendix has long been the subject of intensive studies. The recent understanding of appendix function in the context of unique architecture and bacterial complexity and density allows considering it as a safehouse for intestinal biodiversity. Methods: This review analyzes and assesses the current state of scientific knowledge regarding the role of the vermiform appendix in normal gut microbiota maintenance as a crucial factor of host homeostasis. It also highlights the difference in microbial composition between the large bowel and the appendix, as well as the association between the surgical excision, appendectomy, and dysbiosis-induced diseases. In addition, the review discusses the results of epidemiologic studies on appendectomy as a risk factor for the initiation of gastrointestinal carcinogenesis. It also highlights the association between appendectomy and a series of chronic inflammatory and neurologic disorders, including inflammatory bowel disease.

A clinical prediction model for complicated appendicitis in children younger than five years of age

Background

No reliably specific method for complicated appendicitis has been identified in children younger than five years of age. This study aimed to analyze the independent factors for complicated appendicitis in children younger than five years of age, develop and validate a prediction model for the differentiation of simple and complicated appendicitis.

Methods

A retrospective study of 382 children younger than five years of age with acute appendicitis from January 2007 to December 2016 was conducted with assessments of demographic data, clinical symptoms and signs, and pre-operative laboratory results. According to intraoperative findings and postoperative pathological results, acute appendicitis was divided into simple and complicated appendicitis. Univariate and multivariate analyses were used to screen out the independent factors of complicated appendicitis, and develop a prediction model for complicated appendicitis. Then 156 such patients from January 2017 to December 2019 were collected as validation sample to validate the prediction model. Test performance of the prediction model was compared with the ALVARADO score and Pediatric Appendicitis Score (PAS).

Results

Of the 382 patients, 244 (63.9%) had complicated appendicitis. Age, white blood cell count, and duration of symptoms were the independent factors for complicated appendicitis in children younger than five years of age. The final predication model for complicated appendicitis included factors above. In validation sample, the prediction model exhibited a high degree of discrimination (area under the curve [AUC]: 0.830; 95% confidence interval [CI]: 0.762–0.885) corresponding to a optimal cutoff value of 0.62, and outperformed the PAS (AUC: 0.735; 95% CI: 0.658–0.802), ALVARADO score (AUC: 0.733; 95% CI: 0.657–0.801).

Conclusion

Age, white blood cell count, and duration of symptoms could be used to predict complicated appendicitis in children younger than five years of age with acute appendicitis. The prediction model is a novel but promising method that aids in the differentiation of acute simple and complicated appendicitis.

The gallbladder and vermiform appendix influence the assemblage of intestinal microorganisms

Surgical procedures for the symptomatic removal of the gallbladder and the vermiform appendix have been posited to adversely shift the assemblage of the intestinal microbiome increasing the risk of disease. The associated mechanisms have been linked with dysbiosis of the gut microbiota. Cholecystectomy causes changes of bile acid compositions and bile secretion patterns as bile acids interact with the intestinal microbiota in a bidirectional capacity. An appendectomy precludes the further recolonization of the proximal colon with a commensal biofilm that could maintain a stable intestinal microbiome. Epidemiological studies indicate that there is an increased risk of disease rather than causality following a cholecystectomy and appendectomy. This narrative review summarizes studies that report on the role that bile salts and the appendix, contribute to the assemblage of the intestinal microbiome in health and disease.

Gut Dysbiosis and the Intestinal Microbiome: Streptococcus thermophilus a Key Probiotic for Reducing Uremia

In the intestines, probiotics can produce antagonistic effects such as antibiotic–like compounds, bactericidal proteins such as bacteriocins, and encourage the production of metabolic end products that may assist in preventing infections from various pathobionts (capable of pathogenic activity) microbes. Metabolites produced by intestinal bacteria and the adoptions of molecular methods to cross-examine and describe the human microbiome have refreshed interest in the discipline of nephology. As such, the adjunctive administration of probiotics for the treatment of chronic kidney disease (CKD) posits that certain probiotic bacteria can reduce the intestinal burden of uremic toxins. Uremic toxins eventuate from the over manifestation of glucotoxicity and lipotoxicity, increased activity of the hexosamine and polyol biochemical and synthetic pathways. The accumulation of advanced glycation end products that have been regularly associated with a dysbiotic colonic microbiome drives the overproduction of uremic toxins in the colon and the consequent local pro-inflammatory processes. Intestinal dysbiosis associated with significant shifts in abundance and diversity of intestinal bacteria with a resultant and maintained uremia promoting an uncontrolled mucosal pro-inflammatory state. In this narrative review we further address the efficacy of probiotics and highlighted in part the probiotic bacterium Streptococcus thermophilus as an important modulator of uremic toxins in the gut of patients diagnosed with chronic kidney disease. In conjunction with prudent nutritional practices it may be possible to prevent the progression of CKD and significantly downregulate mucosal pro-inflammatory activity with the administration of probiotics that contain S. thermophilus.

Mucosa-Environment Interactions in the Pathogenesis of Rheumatoid Arthritis

Mucosal surfaces play a central role in the pathogenesis of rheumatoid arthritis (RA). Several risk factors, such as cigarette smoking, environmental pollution, and periodontitis interact with the host at the mucosal level, triggering immune system activation. Moreover, the alteration of microbiota homeostasis is gaining increased attention for its involvement in the disease pathogenesis, modulating the immune cell response at a local and subsequently at a systemic level. Currently, the onset of the clinical manifest arthritis is thought to be the last step of a series of pathogenic events lasting years. The positivity for anti-citrullinated protein antibodies (ACPAs) and rheumatoid factor (RF), in absence of symptoms, characterizes a preclinical phase of RA-namely systemic autoimmune phase- which is at high risk for disease progression. Several immune abnormalities, such as local ACPA production, increased T cell polarization towards a pro-inflammatory phenotype, and innate immune cell activation can be documented in at-risk subjects. Many of these abnormalities are direct consequences of the interaction between the environment and the host, which takes place at the mucosal level. The purpose of this review is to describe the humoral and cellular immune abnormalities detected in subjects at risk of RA, highlighting their origin from the mucosa-environment interaction.

The Appendix in Parkinson's Disease: From Vestigial Remnant to Vital Organ?

Parkinson's disease (PD) has long been considered a brain disease, but studies now point to the gastrointestinal (GI) tract as a potential starting point for PD. In particular, the human vermiform appendix has been implicated in PD. The appendix is a tissue rich in immune cells, serving as part of the gut-associated lymphoid tissue and as a storehouse for the gut microbiome. The functions of the appendix converge with recent evidence demonstrating that gut inflammation and shifts in the microbiome are linked to PD. Some epidemiological studies have linked removal of the appendix to lowered PD risk, though there is controversy among these associations. What is apparent is that there is an abundance of aggregated forms of α-synuclein in the appendix relevant to PD pathology. α-Synuclein pathology is thought to propagate from gut to brain via the vagus nerve, which innervates GI tract locations, including the appendix. Remarkably, α-synuclein aggregates in the appendix occur not only in PD patients, but are also present in healthy individuals. This has led to the proposal that in the appendix α-synuclein aggregates are not unique to PD. Moreover, the molecular events leading to PD and the mechanisms by which α-synuclein aggregates transfers from gut to brain may be identifiable in the human appendix. The influence of the appendix on GI inflammation, autoimmunity, microbiome storage, and the lymphatic system may be yet unexplored mechanisms by which the appendix contributes to PD. Overall, the appendix represents a promising tissue site to advance our understanding of PD pathobiology.