Investigating the causal relationship between inflammatory bowel disease and simple appendicitis using Mendelian randomization.

The relationship between simple appendicitis and inflammatory bowel disease (IBD) is not clear. In this study, we approach the issue from a genetic perspective, using Mendelian randomization (MR) tools to explore the potential causal connection between the two. We used GWAS data from 12,882 IBD patients (21,770 controls), 5956 crohn's disease (CD) patients (14,927 controls), 6968 ulcerative colitis (UC) patients (20,464 controls), and 4604 simple appendicitis patients (481,880 controls). These statistical data were derived from a large-scale whole-genome association study of individuals with European ancestry. The primary analytical method for inferring the causal relationship between the conditions involved the use of the Inverse Variance Weighting (IVW) method as the main approach for bidirectional MR analysis. The MR analysis results predicted IBD was associated with a lower risk of simple appendicitis (OR: 0.947 (0.911, 0.984), p = 0.005). The results for CD (OR: 0.948 (0.916, 0.981), p = 0.002) and UC (OR: 0.954 (0.917, 0.992), p = 0.020) are consistent with this finding. In the reverse MR analysis, there is no significant association between simple appendicitis and the occurrence of IBD (p > 0.05), and the same holds true for CD and UC (p > 0.05). Our MR study results suggest a potential negative causal effect of IBD on the occurrence of simple appendicitis. Conversely, there does not appear to be a significant causal relationship between simple appendicitis and the risk of developing IBD.

Evaluation of diagnostic value and Mendelian randomization study of appendicitis hub genes obtained by WGCNA analysis.

The timely and precise diagnosis of appendicitis was deemed essential. This study sought to examine the diagnostic significance of hub genes linked to appendicitis and to delve deeper into the pathophysiology of the condition. Differential gene expression analysis revealed distinct genes in the appendicitis group compared to other abdominal pain group, while weighted gene co-expression network analysis identified appendicitis-associated modules. Further analysis of common genes was conducted using Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analysis. The diagnostic efficiency of hub genes was explored through the use of nomograms and receiver operator characteristic curves. Additionally, immunoinfiltration analysis was performed to investigate the immune cell infiltration in both groups. The causal relationship between hub genes and appendicitis, as well as gut microbiota and appendicitis, was ultimately examined through Mendelian randomization. By conducting differential expression analysis and weighted gene co-expression network analysis, a total of 757 common genes were identified. Subsequent Kyoto Encyclopedia of Genes and Genomes and Gene Ontology enrichment analyses revealed that these common genes were primarily associated with positive regulation of cell adhesion, focal adhesion, protein serine kinase activity, and amyotrophic lateral sclerosis. Utilizing Cytoscape software, the top 10 genes with the highest degree of interaction were identified as RPS3A, RPSA, RPL5, RPL37A, RPS27L, FLT3LG, ARL6IP1, RPL32, MRPL3, and GSPT1. Evaluation using nomograms and receiver operator characteristic curves demonstrated the diagnostic value of these hub genes. Ultimately, a causal relationship between hub genes and appendicitis was not identified in our study. Nevertheless, our findings indicate that appendicitis is correlated with 9 gut microbiota. This study identified 5 hub genes, specifically HSP90AA1, RPL5, MYC, CD44, and RPS3A, which exhibit diagnostic significance of appendicitis. Furthermore, the elucidation of these hub genes aids in enhancing our comprehension of the molecular pathways implicated in the development of appendicitis.

Single-cell sequencing of the vermiform appendix during development identifies transcriptional relationships with appendicitis in preschool children.

BACKGROUND: The development of the human vermiform appendix at the cellular level, as well as its function, is not well understood. Appendicitis in preschool children, although uncommon, is associated with a high perforation rate and increased morbidity. METHODS: We performed single-cell RNA sequencing (scRNA-seq) on the human appendix during fetal and pediatric stages as well as preschool-age inflammatory appendices. Transcriptional features of each cell compartment were discussed in the developing appendix. Cellular interactions and differentiation trajectories were also investigated. We compared scRNA-seq profiles from preschool appendicitis to those of matched healthy controls to reveal disease-associated changes. Bulk transcriptomic data, immunohistochemistry, and real-time quantitative PCR were used to validate the findings. RESULTS: Our analysis identified 76 cell types in total and described the cellular atlas of the developing appendix. We discovered the potential role of the BMP signaling pathway in appendiceal epithelium development and identified HOXC8 and PITX2 as the specific regulons of appendix goblet cells. Higher pericyte coverage, endothelial angiogenesis, and goblet mucus scores together with lower epithelial and endothelial tight junction scores were found in the preschool appendix, which possibly contribute to the clinical features of preschool appendicitis. Preschool appendicitis scRNA-seq profiles revealed that the interleukin-17 signaling pathway may participate in the inflammation process. CONCLUSIONS: Our study provides new insights into the development of the appendix and deepens the understanding of appendicitis in preschool children.

Mining and exploration of appendicitis nursing targets: An observational study.

Appendicitis is an inflammation caused by obstruction of the appendiceal lumen or termination of blood supply leading to appendiceal necrosis followed by secondary bacterial infection. The relationship between TYROBP gene and the nursing of appendicitis remains unclear. The appendicitis dataset GSE9579 profile was downloaded from the gene expression omnibus database generated from GPL571. Differentially expressed genes were screened, followed by weighted gene co-expression network analysis, functional enrichment analysis, gene set enrichment analysis, construction and analysis of protein-protein interaction network, Comparative Toxicogenomics Database analysis, and immune infiltration analysis. Heatmaps of gene expression levels were plotted. A total of 1570 differentially expressed genes were identified. According to gene ontology analysis, they were mainly enriched in organic acid metabolic process, condensed chromosome kinetochore, oxidoreductase activity. In Kyoto Encyclopedia of Gene and Genome analysis, they mainly concentrated in metabolic pathways, P53 signaling pathway, PPAR signaling pathway. The soft threshold power in weighted gene co-expression network analysis was set to 12. Through the construction and analysis of protein-protein interaction network, 5 core genes (FCGR2A, IL1B, ITGAM, TLR2, TYROBP) were obtained. Heatmap of core gene expression levels revealed high expression of TYROBP in appendicitis samples. Comparative Toxicogenomics Database analysis found that core genes (FCGR2A, IL1B, ITGAM, TLR2, TYROBP) were closely related to abdominal pain, gastrointestinal dysfunction, fever, and inflammation occurrence. TYROBP gene is highly expressed in appendicitis, and higher expression of TYROBP gene indicates worse prognosis. TYROBP may serve as a molecular target for appendicitis and its nursing.

Expression of Calretinin in the Cecal Muscularis Interna: Observation and Hypothetical Relevance to Appendicitis.

BACKGROUND: The unexpected observation of calretinin immunoreactivity in smooth muscle cells in the muscularis propria of the cecum led to a more detailed examination of calretinin expression and its possible relationship to propulsive contractile activity around the vermiform appendix. METHODS: Immunohistochemistry and RNA in situ hybridization were performed to analyze calretinin expression in intestinal samples from 33 patients at ages ranging from mid-gestation fetuses to adults, as well as in some potentially relevant animal models. Dual immunolabeling was done to compare calretinin localization with markers of smooth muscle and interstitial cells of Cajal. RESULTS: Calretinin expression was observed consistently in the innermost smooth muscle layers of the muscularis interna in the human cecum, appendiceal base, and proximal ascending colon, but not elsewhere in the intestinal tract. Calretinin-positive smooth muscle cells did not co-express markers located in adjacent interstitial cells of Cajal. Muscular calretinin immunoreactivity was not detected in the ceca of mice or macaques, species which lack appendices, nor in the rabbit cecum or appendix. CONCLUSIONS: Localized expression of calretinin in cecal smooth muscle cells may reduce the likelihood of retrograde, calcium-mediated propulsive contractions from the proximal colon and suppress pro-inflammatory fecal stasis in the appendix.

Gene Expression Profiling in Pediatric Appendicitis.

Importance: Appendicitis is the most common indication for urgent surgery in the pediatric population, presenting across a range of severity and with variable complications. Differentiating simple appendicitis (SA) and perforated appendicitis (PA) on presentation may help direct further diagnostic workup and appropriate therapy selection, including antibiotic choice and timing of surgery. Objective: To provide a mechanistic understanding of the differences in disease severity of appendicitis with the objective of developing improved diagnostics and treatments, specifically for the pediatric population. Design, Setting, and Participants: The Gene Expression Profiling of Pediatric Appendicitis (GEPPA) study was a single-center prospective exploratory diagnostic study with transcriptomic profiling of peripheral blood collected from a cohort of children aged 5 to 17 years with abdominal pain and suspected appendicitis between November 2016 and April 2017 at the Alberta Children's Hospital in Calgary, Alberta, Canada, with data analysis reported in August 2023. There was no patient follow-up in this study. Exposure: SA, PA, or nonappendicitis abdominal pain. Main Outcomes and Measures: Blood transcriptomics was used to develop a hypothesis of underlying mechanistic differences between SA and PA to build mechanistic hypotheses and blood-based diagnostics. Results: Seventy-one children (mean [SD] age, 11.8 [3.0] years; 48 [67.6%] male) presenting to the emergency department with abdominal pain and suspected appendicitis were investigated using whole-blood transcriptomics. A central role for immune system pathways was revealed in PA, including a dampening of major innate interferon responses. Gene expression changes in patients with PA were consistent with downregulation of immune response and inflammation pathways and shared similarities with gene expression signatures derived from patients with sepsis, including the most severe sepsis endotypes. Despite the challenges in identifying early biomarkers of severe appendicitis, a 4-gene signature that was predictive of PA compared to SA, with an accuracy of 85.7% (95% CI, 72.8-94.1) was identified. Conclusions: This study found that PA was complicated by a dysregulated immune response. This finding should inform improved diagnostics of severity, early management strategies, and prevention of further postsurgical complications.

[Detection of SARS-CoV-2 RNA in the mucosa of the appendices of children with COVID-19]. / Vyyavlenie RNK SARS-CoV-2 v slizistoi obolochke cherveobraznogo otrostka u detei s COVID-19.

Background. The novel coronavirus infection (COVID-19) often manifests in children as diarrhea, vomiting, abdominal pain, and some children develop acute appendicitis. To elucidate the role of SARS-CoV-2 in the development of acute appendicitis, a more detailed study of the presence of its genetic material in the tissue of the appendix. OBJECTIVE: Determination of SARS-CoV-2 RNA in appendices of children with COVID-19 by fluorescence in situ hybridization (FISH). MATERIAL AND METHODS: A retrospective analysis of case histories and morphological analysis using FISH of appendices of pediatric patients with established clinical diagnosis of acute appendicitis and confirmed infection with SARS-CoV-2 was performed. The material was divided into 3 groups: 1st -appendices obtained during appendectomy in children with established clinical diagnosis of «coronavirus infection¼ (COVID-19, PCR+) (n=42; mean age 10.8 years); 2nd - appendices of children (n=55; mean age 9.7 years) with acute appendicitis obtained before the onset of the COVID-19 pandemic; 3rd (control) group (n=38; mean age 10.3 years) - autopsy material of the appendices (intact). RESULTS: In all samples of the appendices of the 1st group, a positive SARS-CoV-2 viral RNA signal was noted in the cytoplasm of most epithelial cells and single immunocompetent cells. The signal intensity remained the same in all slides, regardless of age. In all samples obtained from patients without COVID-19 (groups 2 and 3), confocal microscopy did not reveal a signal, which indicates successful adaptation of the FISH method in this study and excludes the false positive results. CONCLUSION: In the epithelium of the appendices of children of different age with COVID-19, the FISH method revealed SARS-CoV-2 RNA, which does not exclude the association between viral invasion and the development of acute appendicitis.

Investigation of VGLL3 and sub-target genes in the aetiology of paediatric acute appendicitis: a prospective case-control study.

PURPOSE: Vestigial like family member 3 (VGLL3) and its sub-target genes show considerable transcriptomic overlap in terms of several autoimmune and inflammatory diseases. Herein, we investigated the role of VGLL3 rs13074432 polymorphism and its sub-target genes in the aetiology of acute appendicitis (AA). METHODS: In this prospective case-control study, we included 250 patients (age, 0-18 years) who underwent appendectomy with the diagnosis of AA (patient group; blood and appendix tissue samples) and 200 healthy children (control group; only blood samples) without appendectomy. ELISA method was used for protein-level detection of VGLL3 and sub-target genes expression change in obtained tissue samples, and real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used for mRNA level detection. Genotyping analyses were performed on DNA samples isolated from blood using TaqMan SNP genotyping test. RESULTS: The frequency of TT variant genotype (p < 0.001) and T allele (p = 0.002) showed a significant decrease in the patient group compared with the control group. No significant correlation was observed between the expression of VGLL3 in the appendiceal tissue and patient clinical and demographic data (p > 0.050). CONCLUSION: This study revealed that the VGLL3 gene and its sub-target genes are associated with AA aetiology.

Detection of Enterobius vermicularis in archived formalin-fixed paraffin-embedded (FFPE) appendectomy blocks: It's potential to compare genetic variations based on mitochondrial DNA (cox1) gene.

Acute appendicitis represents one of the most common causes of emergency abdominal surgery worldwide. Meanwhile, Enterobius vermicularis has been suggested as one of the probable causes of appendicitis. In this study, the morphological characteristics of the remnant pinworms and pathologic changes were explored in old-archived FFPE tissues of appendectomies. Moreover, we provide the first molecular identification, genetic, and haplotype variation of this nematode from the old-archived FFPE tissue section of appendectomy using the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. Seventeen FFPE appendectomies with E. vermicularis infection, stored over 12-22 years, were collected from two different geographical areas of Iran. In the histopathological examination, tissue changes were observed in thirteen cases (76.4%) and inflammation in four blocks (23.5%). After DNA extraction, the cox1 gene was amplified in twelve (70.6%) cases using the nested polymerase chain reaction (PCR). Phylogenetic analysis and a median-joining network of 78 available cox1 sequences of E. vermicularis revealed 59 haplotypes. We identified five haplotypes that fell into type B. All Haplotypes are novel except for two haplotypes, Hap32 and Hap37, identical to E. vermicularis sequences from Iran, Greece, and Germany. The ranges of diversity distance and haplotype diversity within the isolates were 0-1.9% and HD:0.643-0.667, subsequently. Overall, the absence of inflammation or even tissue changes in some sections can suggest the possible non-inflammatory role of E. vermicularis in appendicitis. Although FFPE material suffers from PCR inhibition, we could successfully use nested PCR to characterize E. vermicularis in old-archived appendectomy blocks and suggest this method as a complementary diagnosis technique in pathology. While the predominant type was B in the Middle East and Europe, further studies on a larger sample size from different geographical regions could probably confirm the results obtained in the present study.

Molecular and phylogenetic analysis of E. vermicularis in appendectomy specimens from Iran.

Human infection with Enterobius vermicularis occurs worldwide, particularly in children. The role of E. vermicularis in appendicitis is neglected. This study was designed to investigate genotypes of E. vermicularis detected from appendectomy specimens in the human population from Iran and clarify the intra-species variation of the parasite. Seventy appendectomies for acute clinical appendicitis isolates from Azerbaijan and North Khorasan of Iran were used in the present study. The genetic information of Tehran and Hamedan regions was also obtained from GenBank for comparison and analysis. The nucleotide sequence of cytochrome c oxidase subunit 1 (cox1) gene was analyzed to perform genetic differentiation, haplotype network analysis, and population structure. Phylogenetic analysis of all the isolates were included in type B haplogroup. The number of haplotypes in all geographical locations of Iran is not much. Network analysis of sequences for regions such as Thailand, Iran, Denmark, and Poland show three classified subtypes B1, B2, and B3 in the B haplogroup. It seems that the haplotypes of E. vermicularis detected from appendectomy are B type, and divided into three subtypes. Further research using another genetic marker is required to elucidate the genetic variation of the parasites in detail.

Causal effects of gut microbiota on appendicitis: a two-sample Mendelian randomization study.

Background: Previous research has posited a potential correlation between the gut microbiota and the onset of appendicitis; however, the precise causal connection between appendicitis and the gut microbiota remains an unresolved and contentious issue. Methods: In this investigation, we performed a Mendelian randomization (MR) analysis employing publicly accessible summary data extracted from genome-wide association studies (GWAS) to elucidate the potential causal nexus between the gut microbiota and the development of appendicitis. We initially identified instrumental variables (IVs) through a comprehensive array of screening methodologies, subsequently executing MR analyses using the Inverse Variance Weighted (IVW) technique as our primary approach, supplemented by several alternative methods such as MR Egger, weighted median, simple mode, and weighted mode. Additionally, we implemented a series of sensitivity analysis procedures, encompassing Cochran's Q test, MR-Egger intercept test, Mendelian Randomized Polymorphism Residual and Outlier (MR-PRESSO) test, and a leave-one-out test, to affirm the robustness and validity of our findings. Results: Our investigation indicates that an elevated prevalence of Deltaproteobacteria, Christensenellaceae, Desulfovibrionaceae, Eubacterium ruminantium group, Lachnospiraceae NK4A136 group, Methanobrevibacter, Desulfovibrionales, and Euryarchaeota is inversely associated with the risk of appendicitis. Conversely, we observed a positive correlation between an increased abundance of Family XIII, Howardella, and Veillonella and the susceptibility to appendicitis. Sensitivity analyses have corroborated the robustness of these findings, and Mendelian randomization analyses provided no indications of reverse causality. Conclusion: Our Mendelian randomization (MR) analysis has unveiled potential advantageous or detrimental causal associations between the gut microbiota and the occurrence of appendicitis. This study offers novel theoretical and empirical insights into the understanding of appendicitis pathogenesis, along with its implications for preventive and therapeutic strategies.

Evaluation of the Rho-kinase gene expression and polymorphisms in adult patients with acute appendicitis: a differential impact of gender.

OBJECTIVE: Acute appendicitis represents one of the most common causes of acute intra-abdominal emergencies worldwide. In this case-control study, we aimed to investigate associations of Rho-kinase gene expression and polymorphisms with acute appendicitis in a Turkish population. We also aimed to study the effects of gender on these parameters. METHODS: A total of 93 unrelated patients with acute appendicitis and 93 healthy controls in the Department of Emergency Medicine, Erciyes University, between June 2019 and June 2021 were included in this study. Genomic DNA was isolated from peripheral leukocytes, and the LightCycler 480 II real-time polymerase chain reaction was utilized to detect Rho-kinase1 gene rs35996865 and Rho-kinase2 gene rs2230774 (Thr431Asn) polymorphisms. Quantitative real-time polymerase chain reaction was applied to determine Rho-kinase1 and Rho-kinase2 gene expressions. RESULTS: There was a marked increase in Rho-kinase1, but not in Rho-kinase2, mRNA expression, and this increase was evident only in male patients (p=0.0008). No significant differences were found in allele and genotype frequencies for Rho-kinase1 gene rs35996865 and Rho-kinase2 gene rs2230774 polymorphisms between the patients with acute appendicitis and the control group. CONCLUSIONS: Our data imply that Rho-kinase1 (rs35996865) and Rho-kinase2 (rs2230774) gene variants are not risk factors for the development of acute appendicitis in the Turkish population. However, increased mRNA expression of the Rho-kinase1 gene in males indicated that Rho-kinase1 is involved in the pathogenesis of acute appendicitis in a gender-specific way.

Differential expression of Chitinase 3-Like 1 protein in appendicitis and appendix carcinomas.

BACKGROUND: Chitinase 3-Like 1 (CHI3L1) has been used as an inflammatory biomarker for a variety of diseases, but its expression in acute appendicitis and appendix carcinomas remains unclear. METHODS: Sixty cases of patients were studied, including 46 acute appendicitis and 14 appendix carcinomas. We divided the acute appendicitis group into acute uncomplicated appendicitis (AUA), suppurative appendicitis (SA), and gangrenous appendicitis (GA). The appendix carcinoma group was divided into appendiceal neuroendocrine neoplasms (ANENs) and appendiceal mucinous neoplasms (AMN). Controls were 32 healthy donors. Blood neutrophil to lymphocyte ratio (NLR), CHI3L1, C-reactive protein (CRP), interleukin-6 (IL-6), and serum amyloid A (SAA) were measured in the patients. Meanwhile, immunohistochemistry and immunofluorescence were used to identify the expression level and location of CHI3L1 in different cell types in appendix tissues. RESULTS: Compared with the controls, CHI3L1 serum levels were up-regulated in SA, GA, and AMN groups, while no significant difference was observed in the AUA and ANEN groups. Immunofluorescence revealed that CHI3L1 expression was high in macrophages and adenocarcinoma cells of appendix tissues but not in the neuroendocrine carcinoma tissues. Moreover, levels of NLR and CRP in the SA and GA groups were considerably higher than in the control group. IL-6 and SAA in SA, GA, ANENs, and AMN groups were also increased compared with the control group. In addition, CHI3L1 displayed good performance in predicting appendicitis, with an AUC of 0.862. CONCLUSION: CHI3L1 was highly expressed in acute appendicitis and appendiceal mucinous neoplasms, which can be used as a novel biomarker predicting appendicitis.

Impact of Human Genetic Variation on C-Reactive Protein Concentrations and Acute Appendicitis.

Background: Acute appendicitis is one of the most common abdominal emergencies worldwide. Both environmental and genetic factors contribute to the disease. C-reactive protein (CRP) is an important biomarker in the diagnosis of acute appendicitis. CRP concentrations are significantly affected by genetic variation. However, whether such genetic variation is causally related to appendicitis risk remains unclear. In this study, the causal relationship between single-nucleotide polymorphisms (SNPs) associated with circulating CRP concentrations and the risk and severity of acute appendicitis was investigated. Methods: CRP concentrations in serum of appendicitis patients (n = 325) were measured. Appendicitis was categorized as complicated/uncomplicated and gangrenous/non-gangrenous. Imputed SNP data (n = 287) were generated. A genome-wide association study (GWAS) on CRP concentrations and appendicitis severity was performed. Intersection and colocalization of the GWAS results were performed with appendicitis and CRP-associated loci from the Pan-UKBB cohort. A functional-genomics approach to prioritize genes was employed. Results: Thirteen percent of significant CRP quantitative trait loci (QTLs) that were previously identified in a large cohort of healthy individuals were replicated in our small patient cohort. Significant enrichment of CRP-QTLs in association with appendicitis was observed. Among these shared loci, the two top loci at chromosomes 1q41 and 8p23.1 were characterized. The top SNP at chromosome 1q41 is located within the promoter of H2.0 Like Homeobox (HLX) gene, which is involved in blood cell differentiation, and liver and gut organogeneses. The expression of HLX is increased in the appendix of appendicitis patients compared to controls. The locus at 8p23.1 contains multiple genes, including cathepsin B (CTSB), which is overexpressed in appendix tissue from appendicitis patients. The risk allele of the top SNP in this locus also increases CTSB expression in the sigmoid colon of healthy individuals. CTSB is involved in collagen degradation, MHC class II antigen presentation, and neutrophil degranulation. Conclusions: The results of this study prioritize HLX and CTSB as potential causal genes for appendicitis and suggest a shared genetic mechanism between appendicitis and CRP concentrations.

Distribution of RET proto-oncogene variants in children with appendicitis.

BACKGROUND: In addition to patient-related systemic factors directing the immune response, the pathomechanisms of appendicitis (AP) might also include insufficient drainage leading to inflammation caused by decreased peristalsis. Genetic predisposition accounts for 30%-50% of AP. M. Hirschsprung (HSCR), also characterized by disturbed peristalsis, is associated with variants in the RET proto-oncogene. We thus hypothesized that RET variants contribute to the etiology of AP. METHODS: DNA from paraffin-embedded appendices and clinical data of 264 children were analyzed for the RET c.135A>G variant (rs1800858, NC_000010.11:g.43100520A>G). In 46 patients with gangrenous or perforated AP (GAP), peripheral blood DNA was used for RET sequencing. RESULTS: Germline mutations were found in 13% of GAP, whereas no RET mutations were found in controls besides the benign variant p.Tyr791Phe (NC_000010.11:g.43118460A>T). In GAP, the polymorphic G-allele in rs2435352 (NC_000010.11:g.43105241A>G) in intron 4 was underrepresented (p = 0.0317). CONCLUSION: Our results suggest an impact of the RET proto-oncogene in the etiology of AP. Mutations were similar to patients with HSCR but no clinical features of HSCR were observed. The pathological phenotypes in both populations might thus represent a multigenic etiology including RET germline mutations with phenotypic heterogeneity and incomplete penetrance.

Novel molecular biomarkers and diagnosis of acute appendicitis in children.

Reliable and efficient diagnosis of pediatric appendicitis is essential for the establishment of a clinical management plan and improvement of patient outcomes. Current strategies used to diagnose a child presenting with a suspected appendicitis include laboratory studies, clinical scores and diagnostic imaging. Although these modalities work in conjunction with each other, one optimal diagnostic strategy has yet to be agreed upon. The recent introduction of precision medicine techniques such as genomics, transcriptomics, proteomics and metabolomics has increased both the diagnostic sensitivity and specificity of appendicitis. Using these novel strategies, the integration of precision medicine into clinical practice via point-of-care technologies is a plausible future. These technologies would assist in the screening, diagnosis and prognosis of pediatric appendicitis.

Association Between NEDD4L Variation and the Genetic Risk of Acute Appendicitis: A Multi-institutional Genome-Wide Association Study.

Importance: The familial aspect of acute appendicitis (AA) has been proposed, but its hereditary basis remains undetermined. Objective: To identify genomic variants associated with AA. Design, Setting, and Participants: This genome-wide association study, conducted from June 21, 2019, to February 4, 2020, used a multi-institutional biobank to retrospectively identify patients with AA across 8 single-nucleotide variation (SNV) genotyping batches. The study also examined differential gene expression in appendiceal tissue samples between patients with AA and controls using the GSE9579 data set in the National Institutes of Health's Gene Expression Omnibus repository. Statistical analysis was conducted from October 1, 2019, to February 4, 2020. Main Outcomes and Measures: Single-nucleotide variations with a minor allele frequency of 5% or higher were tested for association with AA using a linear mixed model. The significance threshold was set at P = 5 × 10-8. Results: A total of 29 706 patients (15 088 women [50.8%]; mean [SD] age at enrollment, 60.1 [17.0] years) were included, 1743 of whom had a history of AA. The genomic inflation factor for the cohort was 1.003. A previously unknown SNV at chromosome 18q was found to be associated with AA (rs9953918: odds ratio, 0.99; 95% CI, 0.98-1.00; P = 4.48 × 10-8). This SNV is located in an intron of the NEDD4L gene. The heritability of appendicitis was estimated at 30.1%. Gene expression data from appendiceal tissue donors identified NEDD4L to be among the most differentially expressed genes (14 of 22 216 genes; ß [SE] = -2.71 [0.44]; log fold change = -1.69; adjusted P = .04). Conclusions and Relevance: This study identified SNVs within the NEDD4L gene as being associated with AA. Nedd4l is involved in the ubiquitination of intestinal ion channels and decreased Nedd4l activity may be implicated in the pathogenesis of AA. These findings can improve the understanding of the genetic predisposition to and pathogenesis of AA.

The application of artificial intelligence methods to gene expression data for differentiation of uncomplicated and complicated appendicitis in children and adolescents - a proof of concept study.

BACKGROUND: Genome wide gene expression analysis has revealed hints for independent immunological pathways underlying the pathophysiologies of phlegmonous (PA) and gangrenous appendicitis (GA). Methods of artificial intelligence (AI) have successfully been applied to routine laboratory and sonographic parameters for differentiation of the inflammatory manifestations. In this study we aimed to apply AI methods to gene expression data to provide evidence for feasibility. METHODS: Modern algorithms from AI were applied to 56.666 gene expression data sets from 13 patients with PA and 16 with GA aged 7-17 years by using resampling methods (bootstrap). Performance with respect to sensitivities and specificities where investigated with receiver operating characteristic (ROC) analysis. RESULTS: Within the experimental setting a best performing discriminatory biomarker signature consisting of a set of 4 genes could be defined: ERGIC and golgi 3, regulator of G-protein signaling 2, Rho GTPase activating protein 33, and Golgi Reassembly Stacking Protein 2. ROC analysis showed a mean area under the curve of 84%. CONCLUSIONS: Gene expression based application of AI methods is feasible and represents a promising approach for future discriminatory diagnostics in children with acute appendicitis.

Use of gene expression profiling to identify candidate genes for pretherapeutic patient classification in acute appendicitis.

BACKGROUND: Phlegmonous and gangrenous appendicitis represent independent pathophysiological entities with different clinical courses ranging from spontaneous resolution to septic disease. However, reliable predictive methods for these clinical phenotypes have not yet been established. In an attempt to provide pathophysiological insights into the matter, a genomewide gene expression analysis was undertaken in patients with acute appendicitis. METHODS: Peripheral blood mononuclear cells were isolated and, after histological confirmation of PA or GA, analysed for genomewide gene expression profiling using RNA microarray technology and subsequent pathway analysis. RESULTS: Samples from 29 patients aged 7-17 years were included. Genomewide gene expression analysis was performed on 13 samples of phlegmonous and 16 of gangrenous appendicitis. From a total of 56 666 genes, 3594 were significantly differently expressed. Distinct interaction between T and B cells in the phlegmonous appendicitis group was suggested by overexpression of T cell receptor α and ß subunits, CD2, CD3, MHC II, CD40L, and the B cell markers CD72 and CD79, indicating an antiviral mechanism. In the gangrenous appendicitis group, expression of genes delineating antibacterial mechanisms was found. CONCLUSION: These results provide evidence for different and independent gene expression in phlegmonous and gangrenous appendicitis in general, but also suggest distinct immunological patterns for the respective entities. In particular, the findings are compatible with previous evidence of spontaneous resolution in phlegmonous and progressive disease in gangrenous appendicitis.