Rectal Indomethacin and Spraying of Duodenal Papilla With Epinephrine Increases Risk of Pancreatitis Following Endoscopic Retrograde Cholangiopancreatography

Pharmacological and Endoscopic Interventions for Prophylaxis of Post-Endoscopic Retrograde Cholangiopancreatography Pancreatitis

Background

Post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP) represents the most common serious complication after endoscopic retrograde cholangiopancreatography (ERCP). Rectal non-steroidal anti-inflammatory drugs (NSAIDs) and pancreatic duct stenting (PDS) are the prophylactic interventions with more evidence and efficacy; however, PEP still represents a significant source of morbidity, mortality, and economic burden. Chronic statin use has been proposed as a prophylactic method that could be cheap and relatively safe. However, the evidence is conflicting. We aimed to evaluate the impact of endoscopic and pharmacological interventions including chronic statin and aspirin use, on the development of PEP.

Methods

A retrospective cohort study evaluated consecutive patients undergoing ERCP at John H. Stroger, Jr. Hospital of Cook County in Chicago from January 2015 to March 2018. Univariate and multivariate analyses were performed using logistic regression.

Results

A total of 681 ERCPs were included in the study. Twelve (1.76%) developed PEP. Univariate, multivariate, and subgroup analyses did not show any association between chronic statin or aspirin use and PEP. PDS and rectal indomethacin were protective in patients undergoing pancreatic duct injection. Pancreatic duct injection, female sex, and younger age were associated with a higher risk. History of papillotomy was associated with lower risk only in the univariate analysis (all P values < 0.05).

Conclusion

Chronic use of statins and aspirin appears to add no additional benefit to prevent ERCP pancreatitis. Rectal NSAIDs, and PDS after appropriate patient selection continue to be the main prophylactic measures. The lower incidence at our center compared with the reported data can be explained by the high rates of rectal indomethacin and PDS, the use of noninvasive diagnostic modalities for patient selection, and the expertise of the endoscopists.

Combination Topical Epinephrine and Non-steroidal Inflammatory Drugs in the Prevention of Post-ERCP Pancreatitis: A Systematic Review

BACKGROUND

The utility of combination rectal NSAID and topical epinephrine (EI) or rectal NSAID and normal saline (SI) sprayed on duodenal papilla in the prevention of post-ERCP pancreatitis (PEP) has been studied but results have been conflicting.

AIMS

To evaluate the benefit of using combination prophylaxis in preventing PEP.

METHODS

A literature search was performed using Scopus, PubMed/MEDLINE, and Cochrane databases in May 2021. Randomized controlled trials (RCTs) involving adults patients who underwent ERCP and received EI versus SI were eligible for inclusion. The pooled effect was expressed as odds ratio (OR) to assess the rate of PEP, severity of PEP, and specific adverse events. The results were pooled using Reviewer Manager 5.4 software.

RESULTS

Six RCTs involving 4016 patients were included in the final analysis. The EI group did not demonstrate any significant benefit over SI group in preventing PEP (OR = 1.00, 95% CI [0.68, 1.45], P = 0.98), irrespective of gender or the epinephrine concentration used. The tests for subgroup differences were not statistically significant with P-values of 0.66 and 0.28, respectively. The addition of topical epinephrine to rectal NSAID did not improve the rate of moderate to severe PEP (OR = 0.94, P = 0.86) or PEP in high-risk patients (OR = 1.14, 95%, P = 0.73). The rates of infection, including cholangitis and sepsis (OR = 0.63, P = 0.07), gastrointestinal bleeding (OR = 1.25, P = 0.56) and procedure-related death (OR = 0.71, P = 0.59) were similar between both groups.

CONCLUSION

The addition of topical epinephrine did not demonstrate any benefit over rectal NSAID alone in preventing PEP or reducing other procedure-related adverse events.

Efficacy of Combined Management with Nonsteroidal Anti-inflammatory Drugs for Prevention of Pancreatitis After Endoscopic Retrograde Cholangiography: a Bayesian Network Meta-analysis

OBJECTIVES

To systematically evaluate the clinical efficacy of rectal nonsteroidal anti-inflammatory drugs (NSAIDs) alone or in combination with other agents for preventing pancreatitis after endoscopic retrograde cholangiopanography.

METHODS

We carried out a literature search of random controlled trials (RCTs) on preventing post-operative pancreatitis by administration of the anti-inflammatory drugs, indomethacin and diclofenac, following endoscopic retrograde cholangiopancreatography (ERCP). The databases searched for relevant publications up to July 7, 2021, included PubMed, Cochrane Library, and Embase. We screened the literature according to inclusion criteria and analyzed the extracted data. The overall population and high-risk patient groups were analyzed, with the main outcome being the incidence of PEP.

RESULTS

The search identified 32 RCTs that included 15019 patients with post-ERCP pancreatitis and 9 different interventions. The results of the overall population network meta-analysis showed that NSAIDs alone, high-dose NSAIDs, and a combination of NSAIDs significantly reduced the incidence of PEP compared with placebo. However, compared with placebo, there was no statistically significant difference between the two interventions (NSAIDs + standard hydration and high-dose NSAIDs). In addition, NSAIDs + sublingual nitrates were associated with a lower incidence of PEP compared to that observed with NSAIDs alone. Probability ranking results showed that NSAIDs + sublingual nitrate had the best effect, followed by NSAIDs + standard hydration, NSAIDs + melatonin, NSAIDs + aggressive hydration, NSAIDs + somatostatin, NSAIDs alone, NSAIDs + epinephrine, high-dose NSAIDs, and placebo. In the high-risk subgroup, the results of the network meta-analysis showed that NSAIDs alone, high-dose NSAIDs, and a combination of NSAIDs showed no statistically significant difference in their ability to reduce the incidence of PEP compared with placebo. Probability ranking results showed that NSAIDs + hydration had the best effect, followed by NSAIDs + sublingual nitroglycerin and NSAIDs + aggressive hydration.

CONCLUSION

Of the nine interventions, NSAIDs + sublingual nitrates had considerably better efficacy than the other drugs for reducing the incidence of PEP in the overall population. In high-risk patients, NSAIDs + standard hydration may be the best preventive treatment; however, more randomized, controlled trials are needed to validate our results.

TRIAL REGISTRATION

Name of the registry: PROSPERO-International prospective register of systematic reviews. Unique identifying number or registration ID: CRD42021282205.

Rectal NSAIDs-based combination modalities are superior to single modalities for prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis: a network meta-analysis

BACKGROUND/AIMS

Different modalities have been employed to reduce the risk and severity of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP). However, there has been a paucity of studies comparing the efficacy of various prophylactic modalities for preventing PEP. This network meta-analysis (NMA) aimed to determine the relative efficacy of pancreatic duct stents and pharmacological modalities for preventing PEP.

METHODS

We performed a systematic and comprehensive search to identify and analyze all randomized controlled studies published until June 2020 that examined the effectiveness of pancreatic duct stents, rectal non-steroidal anti-inflammatory drugs (NSAIDs) based regimens, hydration, and their combinations for the prevention of PEP. The primary outcome was the frequency of PEP. An NMA was performed to combine direct and indirect comparisons of different prophylactic modalities.

RESULTS

The NMA included 46 studies evaluating 18 regimens in 16,241 patients. Based on integral analysis of predictive interval plots, and expected mean ranking and surface under the cumulative ranking curve values, combination prophylaxis with indomethacin + lactated Ringer's solution (LR), followed by diclofenac + nitrate and indomethacin + normal saline, was found to be the most efficacious modality for the overall prevention of PEP. Indomethacin + LR, followed by diclofenac and pancreatic duct stents, was the most efficacious modality for high-risk groups.

CONCLUSION

Rectal NSAIDs-based combination regimens with aggressive hydration or nitrate are superior to single modalities for the prevention of PEP.

Application of non-steroidal anti-inflammatory drugs in prevention of pancreatitis after endoscopic retrograde cholangiopancreatography

Endoscopic retrograde cholangiopancreatography (ERCP) is one of the most important methods for the clinical diagnosis and treatment of biliary and pancreatic diseases. Post-ERCP pancreatitis (PEP) is the most common complication. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used in clinical prevention of PEP, but the application standards are not unified. This article reviews the progress in the research of the preventive effect of different types of NSAIDs on PEP, their administration routes, timing, and dosage, and combination with other drugs, as well as the preventive effect of NSAIDs in different risk stratification populations, and points out that indomethacin and diclofenac are the most commonly used types of NSAIDs, which should be given at 100 mg via rectal administration before ERCP in all non-selected patients with no contraindications.

Controversies in ERCP: Indications and preparation

The aim of the series of papers on controversies of biliopancreatic drainage procedures is to discuss the pros and cons of the varying clinical practices and techniques in ERCP and EUS for drainage of biliary and pancreatic ducts. The first part focuses on indications, clinical and imaging prerequisites before ERCP, sedation options, post-ERCP pancreatitis (PEP) prophylaxis, and other related technical topics. In the second part, specific procedural ERCP-techniques including precut techniques and its timing as well as management algorithms are discussed. In addition, controversies in EUS-guided bile duct and pancreatic drainage procedures are under preparation.

Is the Combination of Rectal Diclofenac and Intravenous Ringer Lactate Superior to Individual Therapy for Prophylaxis of Post-Endoscopic Retrograde Cholangiopancreatography Pancreatitis: A Prospective, Open-Label, Single-Center Randomized Trial

METHODS

This was single-center, open-label, randomized trial. Patients who were undergoing ERCP and who were at high risk for the development of PEP were selected for the study. Patients were randomized into 3 treatment groups: diclofenac suppository group, RL group, and a combination group.

RESULTS

Eight of 57 patients (14.03%) in the diclofenac group, 9 of 57 patients (15.78%) in the RL group, and 6 of 57 patients (10.52%) in the combination group developed PEP. The incidence of PEP between the three groups was not statistically significant (P = 0.70). Serum amylase level of >252 U/L had 91.3% sensitivity and 92.6% specificity for the diagnosis of PEP.

CONCLUSIONS

Post-ERCP pancreatitis is usually mild to moderate 95% times. Female sex, age younger than 50 years, a benign indication of ERCP, and low bilirubin levels have higher chances of PEP. A combination of rectal diclofenac and hydration with RL does not offer better protection for PEP, as compared with individual prophylaxis.

Prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis with a combination of pharmacological agents based on rectal non-steroidal anti-inflammatory drugs: A systematic review and network meta-analysis

BACKGROUND AND AIMS

Rectally administered non-steroidal anti-inflammatory drugs (NSAIDs) are effective but suboptimal in the prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis or PEP. New trials with the combination of rectal NSAIDs and other pharmacological agents have been conducted. This network meta-analysis (NMA) aimed to determine the relative efficacy of combination regimens and identify an optimal regimen for preventing PEP.

METHODS

We performed a systematic and comprehensive search to identify and analyze all the randomized controlled studies published until October 15, 2019, examining rectal NSAIDs and their combination with other pharmacological agents for the prevention of PEP. The primary outcome was the frequency of PEP. We conducted an NMA to combine the direct and indirect comparisons of rectal NSAIDs and their combination with other pharmacological agents.

RESULTS

The NMA included 24 studies evaluating 14 regimens in 11 321 patients. According to predictive interval plot and surface under the cumulative ranking curve values, indomethacin + lactated Ringer's solution, followed by diclofenac + nitrate and indomethacin + normal saline, is the most efficacious combination of pharmacological agents for the overall prevention of PEP. Rectal indomethacin alone is the most efficacious agent for prevention of moderate to severe PEP, and rectal diclofenac is the most useful agent for prevention of PEP among the high-risk group.

CONCLUSIONS

Rectal indomethacin with intravenous hydration and rectal diclofenac with sublingual nitrate are the most efficacious combination regimens for the overall prevention of PEP.

Network meta-analysis of prophylactic pancreatic stents and non-steroidal anti-inflammatory drugs in the prevention of moderate-to-severe post-ERCP pancreatitis

BACKGROUND

There is an ongoing debate that non-steroidal anti-inflammatory drugs (NSAID) or prophylactic pancreatic stents (PPS) are more beneficial in preventing post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP). In our present network meta-analysis, we aimed to compare PPSs to rectal NSAIDs in the prevention of moderate and severe PEP in average- and high-risk patients.

METHODS

We performed a systematic search for randomized controlled trials (RCT) from MEDLINE (via PubMed), Embase and Cochrane Central databases. RCTs using prophylactic rectal NSAIDs or PPSs in patients subjected to ERCP at average- and high-risk population were included. The main outcome was moderate and severe PEP defined by the Cotton criteria. Pairwise Bayesian network meta-analysis was performed, and interventions were ranked based on surface under cumulative ranking (SUCRA) values.

RESULTS

Seven NSAID RCTs (2593 patients), and 2 PPS RCTs (265 patients) in the average-risk, while 5 NSAID RCTs (1703 patients), and 8 PPS RCTs (974 patients) in the high-risk group were included in the final analysis. Compared to placebo, only PPS placement reduced the risk of moderate and severe PEP in both patient groups (average-risk: RR = 0.07, 95% CI [0.002-0.58], high-risk: RR = 0.20, 95% CI [0.051-0.56]) significantly. Rectal NSAID also reduced the risk, but this effect was not significant (average-risk: RR = 0.58, 95% CI [0.22-1.3], high-risk: RR = 0.58, 95% CI [0.18-2.3]). Based on SUCRA, PPS placement was ranked as the best preventive method.

CONCLUSION

Prophylactic pancreatic stent placement but not rectal NSAID seems to prevent moderate-to-severe PEP better both, in average- and high-risk patients.

Can topical epinephrine application to the papilla prevent pancreatitis after endoscopic retrograde cholangiopancreatography? Results from a double blind, multicentre, placebo controlled, randomised clinical trial

Background and study aims

Post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) is a complication associated with important morbidity, occasional mortality and high costs. Preventive strategies are suboptimal as PEP continues to affect 4% to 9% of patients. Spraying epinephrine on the papilla may decrease oedema and prevent PEP. This study aimed to compare rectal indomethacin plus epinephrine (EI) versus rectal indomethacin plus sterile water (WI) for the prevention of PEP.

Patients and methods

This multicentre randomised controlled trial included patients aged >18 years with an indication for ERCP and naive major papilla. All patients received 100 mg of rectal indomethacin and 10 mL of sterile water or a 1:10 000 epinephrine dilution. Patients were asked about PEP symptoms via telephone 24 hours and 7 days after the procedure. The trial was stopped half way through after a new publication reported an increased incidence of PEP among patients receiving epinephrine.

Results

Of the 3602 patients deemed eligible, 3054 were excluded after screening. The remaining 548 patients were randomised to EI group (n=275) or WI group (n=273). The EI and WI groups had similar baseline characteristics. Patients in the EI group had a similar incidence of PEP to those in the WI group (3.6% (10/275) vs 5.12% (14/273), p=0.41). Pancreatic duct guidewire insertion was identified as a risk factor for PEP (OR 4.38, 95% CI (1.44 to 13.29), p=0.009).

Conclusion

Spraying epinephrine on the papilla was no more effective than rectal indomethacin alone for the prevention of PEP.

Trial registration number

This study was registered with ClinicalTrials.gov (NCT02959112).

Relationship between papilla-related variables and post endoscopic retrograde cholangiopancreatography pancreatitis: A multicenter, prospective study

BACKGROUND AND AIM

Papilla with hooknose or long protruding shape may increase the difficulty of cannulation during endoscopic retrograde cholangiopancreatography (ERCP). However, the relationship between papilla anatomy and complications of ERCP has not been fully understood. We aimed to investigate the effect of major duodenal papilla morphology on post-ERCP pancreatitis (PEP) and the procedure of cannulation.

METHODS

Patients with native papilla who underwent ERCP were recruited to this multicenter study. Papilla-related variables were collected, including the length of long axis (L), short axis (S) and opening width (OW), transverse fold, periampullary diverticulum (PAD), papilla location, orientation, swelling, and presence of duodenal stenosis. Demographic data and the procedure of cannulation were also prospectively evaluated. The primary outcome was PEP incidence. Multivariate analysis was used to identify high risk factors for PEP.

RESULTS

Six hundred and fifty-eight patients were enrolled. Overall PEP incidence was 4.7% (31/658). The papilla of patients complicated with PEP had higher long to short axis (L/S) ratio (odds ratio [OR] 3.84, 95% confidence interval [CI]: 1.37-10.74, P = 0.010), higher long axis to opening width (L/OW) ratio (OR 1.35, 95%CI: 1.06-1.71, P = 0.014), more transverse folds (OR 2.53, 95%CI: 1.02-6.26, P = 0.044), and less periampullary diverticulum (OR 0.21, 95%CI: 0.06-0.70, P = 0.011). Multivariate analysis revealed that the indication of common bile duct stones, normal bilirubin, inadvertent pancreatic duct cannulation > 1, L/S ratio ≥ 1.5, and absence of PAD were independent risk factors for PEP.

CONCLUSION

Besides patient-related and procedure-related factors, papilla-related variables, such as L/S ratio and PAD, can be considered as a third type of factors associated with PEP (Clinicaltrials.gov number: NCT03550768).

Emerging Therapies to Prevent Post-ERCP Pancreatitis

PURPOSE OF REVIEW

The aim of this review is to evaluate emerging, novel therapies for the prevention of post-ERCP pancreatitis.

RECENT FINDINGS

Rectal indomethacin reduces the risk of pancreatitis in low- and average-risk patients, who comprise the majority of patients undergoing ERCP. An 8-h protocol of aggressive lactated Ringer's reduces the risk of pancreatitis in average-risk patients. Sublingual nitrate may provide additional benefit to rectal NSAIDs in preventing PEP. A tacrolimus trough > 2.5 ng/mL was recently shown to be associated with a lower risk of PEP in liver transplant patients undergoing ERCP. Routine usage of rectal indomethacin in all patients undergoing ERCP reduces the risk of PEP. Pancreatic-duct stents reduce the risk of PEP in high-risk patients. There is emerging data that aggressive hydration with lactated Ringer's and nitrates may further reduce PEP. Tacrolimus is a promising potential agent to prevent PEP but needs further clinical study.

Post-endoscopic retrograde cholangiopancreatography pancreatitis prevention using topical epinephrine: systematic review and meta-analysis

Background and study aims  Post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP) is a common complication of endoscopic retrograde cholangiopancreatography (ERCP). Multiple drugs and techniques have been studied for the prevention of PEP. Topical epinephrine has shown mixed results and is still not widely accepted as an alternative for prevention of PEP. We performed a systematic review and meta-analysis to evaluate the efficacy of topical epinephrine in preventing PEP. Methods  A comprehensive literature review was conducted by searching Cochrane library database, Embase and PubMed up to August 2019, to identify all studies that evaluated use of topical epinephrine alone or in conjunction with other agents for prevention of PEP. Outcomes included prevention of PEP with use of topical epinephrine and evaluation of whether addiing epinephrine provides any additional benefit in preventing PEP. All analysis was conducted using Revman 5.3. Results  Eight studies, including six randomized controlled trials and two observational studies with 4123 patients, were included in the meta-analysis. Overall, there was no difference in incidence of PEP in patients who underwent ERCP and were treated with epinephrine spray versus those who were not, RR = 0.63 (CI 0.32-1.24) with heterogeneity (I2 = 72 %). However, on a subgroup analysis, topical epinephrine significantly decreases the risk of PEP when compared to placebo alone (means no intervention was done including no rectal indomethacin)., RR = 0.32 (0.18-0.57). In another subgroup analysis, there was no statistically significant difference in using topical epinephrine along with rectal indomethacin in preventing PEP compared to rectal indomethacin alone RR = 0.87 (0.46-1.64). Conclusion  Topical epinephrine does not provide any additional benefit in preventing PEP when used in conjunction with rectal indomethacin. In subgroup analysis, topical epinephrine appeared to decrease risk of PEP in the absence of rectal indomethacin, and could be considered when rectal indomethacin is unavailable or if there is a contraindication to its use.

Prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis with rectal non-steroidal anti-inflammatory drugs

Acute pancreatitis is the most common and feared adverse event associated with performance of endoscopic retrograde cholangiopancreatography (ERCP). Unremitting effort has been made for over 40 years to minimize the frequency and severity of this complication. Recently, the use of rectal non-steroidal anti-inflammatory drugs (NSAIDs) have opened a new era for its prevention. This review focuses on the role of NSAIDs in pancreatitis, the pharmacokinetics of these agents, and summarizes the results of clinical trials with rectal NSAIDs alone and combination regimens in the prevention of post-ERCP pancreatitis.

Rectal indomethacin with topical epinephrine versus indomethacin alone for preventing Post-ERCP pancreatitis - A systematic review and meta-analysis

BACKGROUND

Recent studies have compared the utility of rectal indomethacin with topical epinephrine (IE) sprayed on duodenal papilla and rectal indomethacin alone (IS) to prevent post-ERCP pancreatitis (PEP) with conflicting results. We performed a systematic review and meta-analysis to evaluate the benefit of using the combination prophylaxis as oppose to rectal indomethacin alone.

METHODS

The following database were searched for our systematic review: PubMed∖Medline, Embase, Cochrane, and Web of Science. We included both randomized controlled trials (RCTs) and cohort studies. Primary outcome was incidence of PEP and secondary outcomes were adverse events and mortality.

RESULTS

A total of 3 studies (all RCTs) with 2244 patients (1132 in IS and 1112 in IE group) were included. The IE group did not demonstrate any significant benefit over IS group in preventing PEP (RR: 1.15, 95% CI 0.62-2.2), mortality (RR: 0.85, 95% CI 0.22-3.24) or overall adverse events (RR: 1.3, 95% CI 0.93-1.7).

CONCLUSION

The combination of rectal indomethacin and topical epinephrine failed to demonstrate any benefit over indomethacin alone in preventing PEP, decreasing mortality and overall adverse events.

Patient-related factors associated with successful cannulation by trainees during hands-on endoscopic retrograde cholangiopancreatography training

BACKGROUND AND AIM

Hands-on endoscopic retrograde cholangiopancreatography (ERCP) training is essential for trainees to grasp the technique. Cannulation success rate (CSR) is considered one of the main indicators of competency of trainees. We aimed to investigate whether patient-related factors had an impact on the CSR of trainees.

METHODS

A post hoc analysis of data from two multicenter studies (NCT02002650 and NCT03057769) was conducted. Patients aged 18-90 years with native papilla undergoing ERCP were eligible for this study. Only procedures involving trainees in centers strictly following "10-min criteria" for initial cannulation were enrolled. Primary outcome was CSR by trainees.

RESULTS

From December 2013 to October 2017, 20 trainees in four centers were involved in initial cannulation in 1044 patients with native papilla. Primary CSR by trainees was 61.0% (436/715), 31.5% (70/222) and 44.9% (48/107) in patients with common bile duct stone (CBDS), biliary stricture (BS) and other indications, respectively (P < 0.001). In multivariate analysis, indication of BS (OR, 0.31; 95% CI, 0.22-0.44; P < 0.001) and presence of type A diverticulum (OR, 1.69; 95% CI, 1.23-2.33; P = 0.001) were both independently associated with cannulation success of trainees. Biliary infection was significantly higher in the BS than in the CBDS group (3.6% vs 0.7%, P = 0.004), whereas other post-ERCP complications were comparable between the two groups.

CONCLUSIONS

Indication of BS and the presence of type A diverticulum were independently associated with the success of cannulation by trainees. These findings indicate that greater effort is needed for trainees to improve the ability of cannulation in BS.

Murine Models of Acute Pancreatitis: A Critical Appraisal of Clinical Relevance

Acute pancreatitis (AP) is a severe disease associated with high morbidity and mortality. Clinical studies can provide some data concerning the etiology, pathophysiology, and outcomes of this disease. However, the study of early events and new targeted therapies cannot be performed on humans due to ethical reasons. Experimental murine models can be used in the understanding of the pancreatic inflammation, because they are able to closely mimic the main features of human AP, namely their histologic glandular changes and distant organ failure. These models continue to be important research tools for the reproduction of the etiological, environmental, and genetic factors associated with the pathogenesis of this inflammatory pathology and the exploration of novel therapeutic options. This review provides an overview of several murine models of AP. Furthermore, special focus is made on the most frequently carried out models, the protocols used, and their advantages and limitations. Finally, examples are provided of the use of these models to improve knowledge of the mechanisms involved in the pathogenesis, identify new biomarkers of severity, and develop new targeted therapies.