Rune Horneland

Antibody-secreting plasma cells persist for decades in human intestine

Plasma cells (PCs) produce antibodies that mediate immunity after infection or vaccination. In contrast to PCs in the bone marrow, PCs in the gut have been considered short lived. In this study, we studied PC dynamics in the human small intestine by cell-turnover analysis in organ transplants and by retrospective cell birth dating measuring carbon-14 in genomic DNA. We identified three distinct PC subsets: a CD19+ PC subset was dynamically exchanged, whereas of two CD19− PC subsets, CD45+ PCs exhibited little and CD45− PCs no replacement and had a median age of 11 and 22 yr, respectively. Accumulation of CD45− PCs during ageing and the presence of rotavirus-specific clones entirely within the CD19− PC subsets support selection and maintenance of protective PCs for life in human intestine.

Pancreas Transplantation With Enteroanastomosis to Native Duodenum Poses Technical Challenges—But Offers Improved Endoscopic Access for Scheduled Biopsies and Therapeutic Interventions

To facilitate endoscopic access for rejection surveillance and stenting of the pancreas, we have abandoned the duodenojejunostomy (DJ) in favor of duodenoduodenostomy (DD) in pancreas transplantation (PTx). From September 2012 to September 2013 we performed 40 PTx with DD; 20 solitary‐PTx (S‐PTx) and 20 simultaneous pancreas and kidney transplantation (SPK). We compared the outcomes with results from 40 PTx‐DJ (10 S‐PTx and 30 SPK) from the preceding era. The DD‐enteroanastomoses were performed successfully. Endoscopic pancreas biopsies (endoscopic ultrasound examination [EUS]) yielded representative material in half of the cases. One exocrine fistula was treated by endoscopic stenting. PTxs‐DD were associated with a higher rate of thrombosis compared to PTx‐DJ (23% vs. 5%) and reoperations (48% vs. 30%), as well as inferior graft survival (80% vs. 88%). Time on waiting list, HLA A + B mismatches and reoperations were associated with graft loss. Only recipient age remained an independent predictor of patient death in multivariate analysis. PTx‐DD showed a higher rate of thrombosis and inferior results, but facilitated a protocol biopsy program by EUS that was feasible and safe. Given that technical difficulties can be solved, the improved endoscopic access might confer long‐term benefits, yet this remains to be proven.

Transcriptional and functional profiling defines human small intestinal macrophage subsets

Macrophages (Mfs) are instrumental in maintaining immune homeostasis in the intestine, yet studies on the origin and heterogeneity of human intestinal Mfs are scarce. Here, we identified four distinct Mf subpopulations in human small intestine (SI). Assessment of their turnover in duodenal transplants revealed that all Mf subsets were completely replaced over time; Mf1 and Mf2, phenotypically similar to peripheral blood monocytes (PBMos), were largely replaced within 3 wk, whereas two subsets with features of mature Mfs, Mf3 and Mf4, exhibited significantly slower replacement. Mf3 and Mf4 localized differently in SI; Mf3 formed a dense network in mucosal lamina propria, whereas Mf4 was enriched in submucosa. Transcriptional analysis showed that all Mf subsets were markedly distinct from PBMos and dendritic cells. Compared with PBMos, Mf subpopulations showed reduced responsiveness to proinflammatory stimuli but were proficient at endocytosis of particulate and soluble material. These data provide a comprehensive analysis of human SI Mf population and suggest a precursor-progeny relationship with PBMos.

Giardia lamblia infection after pancreas-kidney transplantation

Infection is a common complication of solid organ transplantation. It is associated with an increased risk of acute cellular rejection and loss of graft function. The most common infections are due to bacteria and viruses, including transmission of cytomegalovirus from donor to recipient. In the past years, an increasing number of parasitic infections have been documented in transplant recipients. We describe the first reported case of intestinal Giardia lamblia transmission following simultaneous pancreas and kidney transplantation.

Outcomes in pancreas transplantation with exocrine drainage through a duodenoduodenostomy versus duodenojejunostomy

Until recently, pancreas transplantation has mostly been performed with exocrine drainage via duodenojejunostomy (DJ). Since 2012, DJ was substituted with duodenoduodenostomy (DD) in our hospital, allowing endoscopic access for biopsies. This study assessed safety profiles with DD versus DJ procedures and clinical outcomes with the DD technique in pancreas transplantation. DD patients (n = 117; 62 simultaneous pancreas–kidney [SPKDD] and 55 pancreas transplantation alone [PTADD] with median follow‐up 2.2 years) were compared with DJ patients (n = 179; 167 SPKDJ and 12 PTADJ) transplanted in the period 1998–2012 (pre‐DD era). Postoperative bleeding and pancreas graft vein thrombosis requiring relaparotomy occurred in 17% and 9% of DD patients versus 10% (p = 0.077) and 6% (p = 0.21) in DJ patients, respectively. Pancreas graft rejection rates were still higher in PTADD patients versus SPKDD patients (p = 0.003). Hazard ratio (HR) for graft loss was 2.25 (95% CI 1.00, 5.05; p = 0.049) in PTADD versus SPKDD recipients. In conclusion, compared with the DJ procedure, the DD procedure did not reduce postoperative surgical complications requiring relaparatomy or improve clinical outcomes after pancreas transplantation despite serial pancreatic biopsies for rejection surveillance. It remains to be seen whether better rejection monitoring in DD patients translates into improved long‐term pancreas graft survival.

Pancreas transplant rejection episodes are not revealed by biopsies of the donor duodenum in a prospective study with paired biopsies

The surgical technique with duodeno‐duodenal enteroanastomosis of pancreas transplants allows for representative endoscopic ultrasound‐guided needle biopsies of the donor duodenum and the pancreas graft. We assessed whether histological findings in transplanted donor duodenal biopsies can indicate rejection in the transplanted pancreas. Since September 2012, a duodeno‐duodenal enteroanastomosis has been the default technique for pancreas transplantations at our center. In 67 recipients we prospectively examined 113 endoscopic ultrasound‐guided procedures with representative biopsies from the duodenum grafts and the pancreas grafts (97 per protocol and 16 on indication). All graft biopsies were evaluated according to established rejection criteria. A total of 22 biopsy‐proven pancreas rejections were detected, with 2 matching duodenal biopsies showing rejection. This gives a sensitivity of 9% for detection of a pancreas rejection by duodenal biopsies. The other matching duodenal biopsies were either normal (n = 13) or indeterminate (n = 7). Rejection of the donor duodenum was found in only 6/113 biopsies, with 2 concurrent pancreas rejections. In conclusion, the donor duodenum is not a useful reporter organ for rejection in the pancreas graft.

Transcriptional profiling reveals monocyte-related macrophages phenotypically resembling DC in human intestine

The tissue dendritic cell (DC) compartment is heterogeneous, and the ontogeny and functional specialization of human tissue conventional DC (cDC) subsets and their relationship with monocytes is unresolved. Here we identify monocyte-related CSF1R+Flt3- antigen presenting cells (APCs) that constitute about half of the cells classically defined as SIRPα+ DCs in the steady-state human small intestine. CSF1R+Flt3- APCs express calprotectin and very low levels of CD14, are transcriptionally related to monocyte-derived cells, and accumulate during inflammation. CSF1R+Flt3- APCs show typical macrophage characteristics functionally distinct from their Flt3+ cDC counterparts: under steady-state conditions they excel at antigen uptake, have a lower migratory potential, and are inefficient activators of naïve T cells. These results have important implications for the understanding of the ontogenetic and functional heterogeneity within human tissue DCs and their relation to the monocyte lineage.

Calcium: A Crucial Potentiator for Efficient Enzyme Digestion of the Human Pancreas

BACKGROUND Effective digestive enzymes are crucial for successful islet isolation. Supplemental proteases are essential because they synergize with collagenase for effective pancreatic digestion. The activity of these enzymes is critically dependent on the presence of Ca2+ ions at a concentration of 5-10 mM. The present study aimed to determine the Ca2+ concentration during human islet isolation and to ascertain whether the addition of supplementary Ca2+ is required to maintain an optimal Ca2+ concentration during the various phases of the islet isolation process. METHODS Human islets were isolated according to standard methods and isolation parameters. Islet quality control and the number of isolations fulfilling standard transplantation criteria were evaluated. Ca2+ was determined by using standard clinical chemistry routines. Islet isolation was performed with or without addition of supplementary Ca2+ to reach a Ca2+ of 5 mM. RESULTS Ca2+ concentration was markedly reduced in bicarbonate-based buffers, especially if additional bicarbonate was used to adjust the pH as recommended by the Clinical Islet Transplantation Consortium. A major reduction in Ca2+ concentration was also observed during pancreatic enzyme perfusion, digestion, and harvest. Additional Ca2+ supplementation of media used for dissolving the enzymes and during digestion, perfusion, and harvest was necessary in order to obtain the concentration recommended for optimal enzyme activity and efficient liberation of a large number of islets from the human pancreas. CONCLUSIONS Ca2+ is to a large extent consumed during clinical islet isolation, and in the absence of supplementation, the concentration fell below that recommended for optimal enzyme activity. Ca2+ supplementation of the media used during human pancreas digestion is necessary to maintain the concentration recommended for optimal enzyme activity. Addition of Ca2+ to the enzyme blend has been implemented in the standard isolation protocols in the Nordic Network for Clinical Islet Transplantation.Background: Effective digestive enzymes are crucial for successful islet isolation. Supplemental proteases are essential because they synergize with collagenase for effective pancreatic digestion. The activity of these enzymes is critically dependent on the presence of Ca2+ ions at a concentration of 5–10 mM. The present study aimed to determine the Ca2+ concentration during human islet isolation and to ascertain whether the addition of supplementary Ca2+ is required to maintain an optimal Ca2+ concentration during the various phases of the islet isolation process. Methods: Human islets were isolated according to standard methods and isolation parameters. Islet quality control and the number of isolations fulfilling standard transplantation criteria were evaluated. Ca2+ was determined by using standard clinical chemistry routines. Islet isolation was performed with or without addition of supplementary Ca2+ to reach a Ca2+ of 5 mM. Results: Ca2+ concentration was markedly reduced in bicarbonate-based buffers, especially if additional bicarbonate was used to adjust the pH as recommended by the Clinical Islet Transplantation Consortium. A major reduction in Ca2+ concentration was also observed during pancreatic enzyme perfusion, digestion, and harvest. Additional Ca2+ supplementation of media used for dissolving the enzymes and during digestion, perfusion, and harvest was necessary in order to obtain the concentration recommended for optimal enzyme activity and efficient liberation of a large number of islets from the human pancreas. Conclusions: Ca2+ is to a large extent consumed during clinical islet isolation, and in the absence of supplementation, the concentration fell below that recommended for optimal enzyme activity. Ca2+ supplementation of the media used during human pancreas digestion is necessary to maintain the concentration recommended for optimal enzyme activity. Addition of Ca2+ to the enzyme blend has been implemented in the standard isolation protocols in the Nordic Network for Clinical Islet Transplantation.

Cardiac Assessment of Patients With Type 1 Diabetes Median 10 Years After Successful Simultaneous Pancreas and Kidney Transplantation Compared With Living Donor Kidney Transplantation.

Background In recipients with type 1 diabetes, we aimed to determine whether long-term normoglycemia achieved by successful simultaneous pancreas and kidney (SPK) transplantation could beneficially affect progression of coronary artery disease (CAD) when compared with transplantation of a kidney-alone from a living donor (LDK). Methods In 42 kidney transplant recipients with functioning grafts who had received either SPK (n = 25) or LDK (n = 17), we studied angiographic progression of CAD between baseline (pretransplant) and follow-up at 7 years or older. In addition, computed tomography scans for measures of coronary artery calcification and echocardiographic assessment of left ventricular systolic function were addressed at follow-up. Results During a median follow-up time of 10.1 years (interquartile range [IQR], 9.1-11.5) progression of CAD occurred at similar rates (10 of 21 cases in the SPK and 5 of 14 cases in the LDK group; P = 0.49). Median coronary artery calcification scores were high in both groups (1767 [IQR, 321-4035] for SPK and 1045 [IQR, 807-2643] for LDK patients; P = 0.59). Left ventricular systolic function did not differ between the 2 groups. The SPK and LDK recipients were similar in age (41.2 ± 6.9 years vs 40.5 ± 10.3 years; P = 0.80) and diabetes duration at engraftment but with significant different mean HbA1c levels of 5.5 ± 0.4% for SPK and 8.3 ± 1.5% for LDK patients (P < 0.001) during follow-up. Conclusions In patients with both type 1 diabetes and end-stage renal disease, SPK recipients had similar progression of CAD long-term compared with LDK recipients. Calcification of coronary arteries is a prominent feature in both groups long-term posttransplant.