Colonic-enteric lumen-apposing metal stents: a promising and safe alternative for endoscopic management of small-bowel obstruction

BACKGROUND AND AIMS

Lumen-apposing metal stents (LAMSs) have revolutionized the treatment of various gastroenterologic conditions that previously required surgery. The use of LAMSs for the management of small-bowel obstruction (SBO) involves EUS-guided coloenterostomy (EUS-CE) between the colon and a dilated loop of the small intestine proximal to the point of obstruction. This procedure is potentially beneficial for patients with malignant SBO who are poor surgical candidates.

METHODS

A retrospective cohort study was conducted at 2 tertiary care hospitals. Patients who underwent EUS-CE for SBO were identified, and data regarding patient demographics, indication for the procedure, location of the obstruction, procedural details, and adverse events were collected. The primary outcome was technical success of the procedure. Secondary outcomes were clinical success, resolution of symptoms, ability to tolerate enteral nutrition, and adverse events.

RESULTS

Twenty-six patients who underwent the EUS-CE procedure were included. Technical success was achieved in all 26 patients, clinical success (resolution of obstructive symptoms) was achieved in 92.3% of patients (24/26), and the ability to resume enteral nutrition in 84.6% (22/26). Adverse events occurred in 4 patients (15.4%) and included bleeding (1/26), diarrhea (2/26), and postprocedure sepsis (1/26). Patients were followed for a mean of 54.8 days (range, 2-190).

CONCLUSIONS

This study highlights that EUS-CE with LAMSs can be performed with high technical and clinical success for the management of SBO, particularly in patients with malignant obstructions who are not suitable candidates for surgical interventions. Further research with larger sample sizes will be essential to substantiate its efficacy and safety.

Extrapancreatic Advanced Endoscopic Interventions

As the field of interventional endoscopy advances, conditions that were once treated with surgery are increasingly being treated with advanced endoscopy. Endoscopy is now used for treatment of achalasia, bariatric procedures for obesity; resection of early-stage malignancies in the gastrointestinal tract; and placement of lumen-apposing metal stents in the treatment of biliary obstruction, gastric outlet obstruction, cholecystitis, and drainage of nonpancreatic-related fluid collections or abscesses. Knowledge of the novel terminology, procedural details, expected postintervention imaging findings, and potential complications is vital for radiologists because these procedures are rapidly becoming more mainstream in daily practice. These procedures include peroral endoscopic myotomy for the treatment of achalasia and other esophageal motility disorders; endoscopic sleeve gastroplasty and placement of an intragastric balloon for weight loss; endoscopic submucosal dissection in the resection of tumors of the gastrointestinal tract; and therapeutic endoscopic-guided procedures for the treatment of biliary obstruction, gastric outlet obstruction, acute cholecystitis, and drainage of nonpancreatically related fluid collections. Patients benefit from these minimally invasive procedures, with potential improvement in morbidity and mortality rates, decreased length of hospital stay, and decreased health care costs when compared with the surgical alternative. Complications of these procedures include leaks or perforations, infections or abscesses, fistulas, and occlusion and migration of stents. An invited commentary by Pisipati and Pannala is available online. ^©RSNA, 2022.

Endoscopic ultrasound-directed transgastric ERCP (EDGE): a retrospective multicenter study

BACKGROUND

Endoscopic ultrasound-directed transgastric endoscopic retrograde cholangiopancreatography (ERCP; EDGE) is an alternative to enteroscopy- and laparoscopy-assisted ERCP in patients with Roux-en-Y gastric bypass anatomy. Although short-term results are promising, the long-term outcomes are not known. The aims of this study were: (1) to determine the rates of long-term adverse events after EDGE, with a focus on rates of persistent gastrogastric or jejunogastric fistula; (2) to identify predictors of persistent fistula; (3) to assess the outcomes of endoscopic closure when persistent fistula is encountered.

METHODS

This was a multicenter retrospective study involving 13 centers between February 2015 and March 2019. Adverse events were defined according to the ASGE lexicon. Persistent fistula was defined as an upper gastrointestinal series or esophagogastroduodenoscopy showing evidence of fistula.

RESULTS

178 patients (mean age 58 years, 79 % women) underwent EDGE. Technical success was achieved in 98 % of cases (175/178), with a mean procedure time of 92 minutes. Periprocedural adverse events occurred in 28 patients (15.7 %; mild 10.1 %, moderate 3.4 %, severe 2.2 %). The four severe adverse events were managed laparoscopically. Persistent fistula was diagnosed in 10 % of those sent for objective testing (9/90). Following identification of a fistula, 5 /9 patients underwent endoscopic closure procedures, which were successful in all cases.

CONCLUSIONS

The EDGE procedure is associated with high clinical success rates and an acceptable risk profile. Persistent fistulas after lumen-apposing stent removal are uncommon, but objective testing is recommended to identify their presence. When persistent fistulas are identified, endoscopic treatment is warranted, and should be successful in closing the fistula.

Transpapillary drainage has no added benefit on treatment outcomes in patients undergoing EUS-guided transmural drainage of pancreatic pseudocysts: a large multicenter study

BACKGROUND AND AIMS

The need for transpapillary drainage (TPD) in patients undergoing transmural drainage (TMD) of pancreatic fluid collections (PFCs) remains unclear. The aims of this study were to compare treatment outcomes between patients with pancreatic pseudocysts undergoing TMD versus combined (TMD and TPD) drainage (CD) and to identify predictors of symptomatic and radiologic resolution.

METHODS

This is a retrospective review of 375 consecutive patients with PFCs who underwent EUS-guided TMD from 2008 to 2014 at 15 academic centers in the United States. Main outcome measures included TMD and CD technical success, treatment outcomes (symptomatic and radiologic resolution) at follow-up, and predictors of treatment outcomes on logistic regression.

RESULTS

A total of 375 patients underwent EUS-guided TMD of PFCs, of which 174 were pseudocysts. TMD alone was performed in 95 (55%) and CD in 79 (45%) pseudocysts. Technical success was as follows: TMD, 92 (97%) versus CD, 35 (44%) (P = .0001). There was no difference in adverse events between the TMD (15%) and CD (14%) cohorts (P = .23). Median long-term (LT) follow-up after transmural stent removal was 324 days (interquartile range, 72-493 days) for TMD and 201 days (interquartile range, 150-493 days) (P = .37). There was no difference in LT symptomatic resolution (TMD, 69% vs CD, 62%; P = .61) or LT radiologic resolution (TMD, 71% vs CD, 67%; P = .79). TPD attempt was negatively associated with LT radiologic resolution of pseudocyst (odds ratio, 0.11; 95% confidence interval, 0.02-0.8; P = .03).

CONCLUSIONS

TPD has no benefit on treatment outcomes in patients undergoing EUS-guided TMD of pancreatic pseudocysts and negatively affects LT resolution of PFCs.

Hepatitis C: Treatment of difficult to treat patients

Over the past several years, more so recently, treatment options for hepatitis C virus (HCV) have seemed to exponentially grow. Up until recently, the regimen of pegylated interferon (peg-IFN) and ribavirin (RBV) stood as the standard of care. Direct acting antivirals, which target nonstructural proteins involved in replication and infection of HCV were first approved in 2011 as an addition to the peg-IFN and RBV regimen and with them have come increased sustained virological response rates (SVR). The previously reported 50%-70% SVR rates using the combination of peg-IFN and RBV are no longer the standard of care with direct acting antiviral (DAA) based regimens now achieving SVR of 70%-90%. Peg-IFN free as well as "all oral" regimens are also available. The current randomized controlled trials available show favorable SVRs in patients who are naive to treatment, non-cirrhotic, and not human immunodeficiency virus (HIV)-co-infected. What about patients who do not fit into these categories? In this review, we aim to discuss the currently approved and soon to be approved DAAs while focusing on their roles in patients that are treatment experienced, cirrhotic, or co-infected with HIV. In this discussion, review of the clinical trials leading to recent consensus guidelines as well as discussion of barriers to treatment will occur. A case will attempt will be made that social services, including financial support and drug/alcohol treatment, should be provided to all HCV infected patients to improve chances of cure and thus prevention of late stage sequela.

Factor V Leiden improves in vivo hemostasis in murine hemophilia models

The role of factor V Leiden (FVL) as a modifier of the severe hemophilia phenotype is still unclear. We used mice with hemophilia A or B crossed with FVL to elucidate in vivo parameters of hemostasis. Real-time thrombus formation in the microcirculation was monitored by deposition of labeled platelets upon laser-induced endothelial injury using widefield microscopy in living animals. No thrombi formed in hemophilic A or B mice following vascular injuries. However, hemophilic mice, either heterozygous or homozygous for FVL, formed clots at all injured sites. Injection of purified activated FV into hemophilic A or B mice could mimic the in vivo effect of FVL. In contrast to these responses to a laser injury in a microvascular bed, FVL did not provide sustained hemostasis following damage of large vessels in a ferric chloride carotid artery injury model, despite of the improvement of clotting times and high circulating thrombin levels. Together these data provide evidence that FVL has the ability to improve the hemophilia A or B phenotype, but this effect is principally evident at the microcirculation level following a particular vascular injury. Our observations may partly explain the heterogeneous clinical evidence of the beneficial role of FVL in hemophilia.

Genetic analysis of the antibody response to AAV2 and factor IX

We have analyzed the antibody response against either AAV2 or canine F.IX (cF.IX) in parental C57BL/6 (B6) and DBA/2 (D2) and 18 strains of B6 x D2 (BXD) recombinant inbred (RI) strains of mice after iv administration of AAV2-(ApoE)4/hAAT-cF.IX. There was a higher anti-AAV2 capsid response in B6 compared to D2 mice, with IgG2b being the major isotype separating the high and low responders in these two strains. In contrast, the antibody response to cF.IX was lower than the response to the AAV2 capsid and was limited to the IgG1 isotype in both strains. Genetic linkage analysis of the IgG2b anti-AAV2 antibody response in BXD RI strains revealed a significant locus at D4Mit164 (29 cM, LRS=15.3) and two suggestive loci at D6Mit16 (30.5 cM, LRS=11.2) and D17Mit187 (47.4 cM, LRS=13.1). Genetic linkage analysis of the IgG1 anti-cF.IX antibody response revealed a suggestive locus at D1Mit218 (67 cM, LRS=14.1). Significant epistatic interaction was found between two loci (D8Mit45 and D16Mit47; LOD=6.54) for anti-AAV2 and two other loci (D5Mit348 and D15Mit161; LOD=7.66) for anti-cF.IX. These results indicate that multiple genetic loci independently regulate the isotype-specific antibody response to the AAV2 capsid and the cF.IX transgene.

Impaired activation of islet-reactive CD4 T cells in pancreatic lymph nodes of B cell-deficient nonobese diabetic mice

Despite the impressive protection of B cell-deficient (muMT(-/-)) nonobese diabetic (NOD) mice from spontaneous diabetes, existence of mild pancreatic islet inflammation in these mice indicates that initial autoimmune targeting of beta cells has occurred. Furthermore, muMT(-/-) NOD mice are shown to harbor a latent repertoire of diabetogenic T cells, as evidenced by their susceptibility to cyclophosphamide-induced diabetes. The quiescence of this pool of islet-reactive T cells may be a consequence of impaired activation of T lymphocytes in B cell-deficient NOD mice. In this regard, in vitro anti-CD3-mediated stimulation demonstrates impaired activation of lymph node CD4 T cells in muMT(-/-) NOD mice as compared with that of wild-type counterparts, a deficiency that is correlated with an exaggerated CD4 T cell:APC ratio in lymph nodes of muMT(-/-) NOD mice. This feature points to an insufficient availability of APC costimulation on a per T cell basis, resulting in impaired CD4 T cell activation in lymph nodes of muMT(-/-) NOD mice. In accordance with these findings, an islet-reactive CD4 T cell clonotype undergoes suboptimal activation in pancreatic lymph nodes of muMT(-/-) NOD recipients. Overall, the present study indicates that B cells in the pancreatic lymph node microenvironment are critical in overcoming a checkpoint involving the provision of optimal costimulation to islet-reactive NOD CD4 T cells.

I-Ag7-mediated antigen presentation by B lymphocytes is critical in overcoming a checkpoint in T cell tolerance to islet beta cells of nonobese diabetic mice

B cell-deficient nonobese diabetic (NOD) mice are protected from the development of spontaneous autoimmune diabetes, suggesting a requisite role for Ag presentation by B lymphocytes for the activation of a diabetogenic T cell repertoire. This study specifically examines the importance of B cell-mediated MHC class II Ag presentation as a regulator of peripheral T cell tolerance to islet beta cells. We describe the construction of NOD mice with an I-Ag7 deficiency confined to the B cell compartment. Analysis of these mice, termed NOD BCIID, revealed the presence of functionally competent non-B cell APCs (macrophages/dendritic cells) with normal I-Ag7 expression and capable of activating Ag-reactive T cells. In addition, the secondary lymphoid organs of these mice harbored phenotypically normal CD4+ and CD8+ T cell compartments. Interestingly, whereas control NOD mice harboring I-Ag7-sufficient B cells developed diabetes spontaneously, NOD BCIID mice were resistant to the development of autoimmune diabetes. Despite their diabetes resistance, histologic examination of pancreata from NOD BCIID mice revealed foci of noninvasive peri-insulitis that could be intentionally converted into a destructive process upon treatment with cyclophosphamide. We conclude that I-Ag7-mediated Ag presentation by B cells serves to overcome a checkpoint in T cell tolerance to islet beta cells after their initial targeting has occurred. Overall, this work indicates that the full expression of the autoimmune potential of anti-islet T cells in NOD mice is intimately regulated by B cell-mediated MHC class II Ag presentation.

Contribution of the innate immune system to autoimmune diabetes: a role for the CR1/CR2 complement receptors

B lymphocytes are required for diabetogenesis in nonobese diabetic (NOD) mice. The complement component of the innate immune system regulates B cell activation and tolerance through complement receptors CR1/CR2. Thus, it is important to assess the contribution of complement receptors to autoimmune diabetes in NOD mice. Examination of the lymphoid compartments of NOD mice revealed striking expansion of a splenic B cell subset with high cell surface expression of CR1/CR2. This subset of B cells exhibited an enhanced C3 binding ability. Importantly, long-term in vivo blockade of C3 binding to CR1/CR2 prevented the emergence of the CR1/CR2(hi) B cells and afforded resistance to autoimmune diabetes in NOD mice. These findings implicate complement as an important regulatory element in controlling the T cell-mediated attack on islet beta cells of NOD mice.