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Objectives: Autoimmune pancreatitis (AIP) is an increasingly recognized disease entity, but data in children are limited. AIP presentation and outcome in children might differ from the adult experience. We aim to determine the characteristic features of AIP in children., Methods: Data about clinical symptoms, imaging, histology, and treatment were collected using two sources: (i) a systematic literature search and (ii) the INSPPIRE database, the largest international multicenter study of pancreatitis in children and the Cliniques Universitaires St-Luc (CUSL) registry., Results: We identified 48 AIP cases: 30 from literature review, 14 from INSPPIRE, and 4 from CUSL. The median age at diagnosis was 13 years (range 2-17 years). Abdominal pain (43/47, 91%) and/or obstructive jaundice (20/47, 42%) were the most common symptoms at diagnosis. Elevated serum IgG4 levels were only observed in 9/40 (22%) children. Cross-sectional imaging studies were abnormal in all children including hypointense global or focal gland enlargement (39/47, 83%), main pancreatic duct irregularity (30/47, 64%), and common bile duct stricture (26/47, 55%). A combination of lymphoplasmacytic inflammation, pancreatic fibrosis, and ductal granulocyte infiltration were the main histological findings (18/25, 72%). Children with AIP had a prompt clinical response to steroids. Complications of AIP included failure of exocrine (4/25, 16%) and endocrine (3/27, 11%) pancreas function., Conclusions: Pediatric AIP has a distinct presentation with features similar to type 2 AIP in adults. This comprehensive report on the largest group of children with AIP to date is expected to help with the diagnosis and management of this disease and pave the way for future research studies.

To define developmental patterns, we determined the rate of protein and DNA synthesis in rat pancreas at birth, 1, 2, 3, 7, 10, 14, 21, 28 days, 2 months, 3 months, and in adults. Fragments of freshly minced pancreas were incubated with [3H]-thymidine and [14C]-leucine and the DNA and protein synthesis rates were measured. We found that DNA content was lowest at birth, rose through day 3, plateaued at about 8 mg/g wet weight through day 14, then slowly decreased to the adult value of about 5 mg/g at 2 months; protein content, although high at birth, decreased rapidly to a value of 80 mg/g at day 3 and slowly rose to the adult value of 160 mg/g; protein synthesis, low at birth, rapidly increased to about five times the adult value by day 3, and remained elevated for the 1st month; DNA synthesis was 15 times the adult rate at birth, increased to 30 times at 3 days of age, then declined slowly in an exponential fashion to the adult value. We conclude that the pancreas at birth is poised biosynthetically to undergo a rapid hyperplastic and hypertrophic response, and this process reaches a maximal rate at about 3 days of age.

Mechanisms and development of pancreas and pancreatic secretory function were studied in the rat. Injections of cholecystokinin octapeptide and hydrocortisone into pregnant rats altered pancreatic size, zymogen enzyme, and DNA content in the fetal newborn pancreas. These studies suggest that the developmental signals for pancreatic function may be related to endogenous release of cholecystokinin or hydrocortisone in the perinatal period.

Hydrocortisone and cholecystokinin-octapeptide (CCK-8) were injected into newborn rats on days 1-5 of life. Both agents induced significant increases in pancreatic weight, protein, DNA, and specific activities of amylase, chymotrypsinogen, and lipase. The ability of the pancreas to secrete amylase in response to carbachol was decreased by the administration of hydrocorticosterone at age 7 days. CCK-8 increased basal secretion at 7 days. We conclude that growth and secretory capacity of the newborn rat pancreas are under the control of both glucocorticoids and cholecystokinin.

Isolated acini were prepared from the pancreas of immature rats (age less than 1 hr. - 48 hrs) in order to study the development of the secretory process. The ultrastructural integrity of the acinar cells was maintained after digestion and stimulation with secretagogues. Acini prepared from rats aged 24 - 48 hours responded to both CCK-8 and carbachol with significant increases in amylase release. Although typical biphasic dose response curves were obtained, the curves were shifted to the right by 1 - 2 log units, compared to the responses of adult acini. At ages younger than 24 hours, acini were insensitive to secretagogues but were sensitive to the calcium ionophore A23187. CCK receptors were virtually absent from membranes prepared from newborn pancreases, but binding of CCK, although small, was measurable at 12 hours and slowly increased up to 48 hours. A greater amount of binding was seen at 72 hours, which appeared constant up to 14 days. At 21 days, adult levels of binding were found. These results confirm previous studies that the rat pancreas is insensitive to secretagogues in the first 24 hours of life. After age 24 hours the secretory process is intact but less sensitive to secretory agents than the more mature pancreas. In the case of CCK, this may be due to lesser numbers of CCK receptors and/or affinity of CCK for its receptor.

Mechanisms and development of secretory function were studied in rat pancreas in vitro. Amylase release from term fetal pancreas was refractory to stimulation by carbamylcholine chloride (carbachol) and cholecystokinin-octapeptide (CCK-OP), but was significantly augmented by calcium ionophore (A23187), DBcAMP, 8-Br-cGMP, and theophylline. The latter agent when combined with either cyclic nucleotide analogue further increased secretory responses. At 1 day and 8 days postnatally, responsiveness to carbachol and CCK-OP had been acquired because amylase secretion stimulated by these agents was brisk and at a level comparable to that found in mature tissue. Increasing extracellular calcium concentrations from 1.23 to 5.28 mM had no effect on basal amylase release in either the fetal or 8-day pancreas. No changes in intracellular cAMP concentrations were found at any age under experimental conditions used. Similarily, in fetal tissue, no changes in cGMP concentrations were found in response to carbachol or A23187. However, at 8 days of age, both agents produced two- to four-fold increases in tissue cGMP levels at 1, 2, and 5 min of incubation. These studies confirm that responsiveness to carbachol and CCK-OP is a maturational process in the pancreas that lags behind the development of intracellular processes involved in stimulus-secretion coupling.

Immature rats were reserpinized to determine whether the model used for adults may be suitable for the study of pancreatic exocrine insufficiency seen in infants with cystic fibrosis. Rats were reserpinized by injections either into pregnant dams or into newborn rats. The dose of reserpine used by others was lethal to immature rats, so lower doses were used. Pancreas from 1-day-old fetal-treated pups was hypoplastic, but concentration of chymotrypsinogen was elevated. At age 7 days hyperplasia was seen. When rats were reserpinized as neonates, hypoplasia and decrease in all parameters measured was observed at age 7 days. Progressive recovery occurred during the following 2 weeks in both groups. Electron microscopic study of the fetal-treated 24-hr-old pancreas revealed evidence of acinar cell degeneration with the presence of abnormal zymogen granules. At age 7 days the pancreas from neonatal-treated rat pups appeared to have a reduced number of granules. At ages 14 and 21 days the pancreas was similar to that seen at age 7 days except that the granules were larger and some acinar lumina were filled with a finely granular, homogeneously dense material. It is concluded that prenatal and neonatal reserpinization of rats induces changes in pancreas similar to those found in cystic fibrosis.

In contrast to morphologic maturity, the newborn rat pancreas is unresponsive to carbachol. At 24 h, carbachol-stimulated secretion of exportable proteins markedly increases. Responsiveness to the calcium ionophore, A23187, is present at term. At age 24 h, pancreas from fasted newborn rats is also unresponsive to carbachol. When cholecystokinin octapeptide or hydrocortisone was administered to fasted newborn rats secretory function developed normally. Thus, responsiveness of newborn rat pancreas to secretagogues matures rapidly and can be induced by hormones.

To define the developmental pattern of the trophic effects of cholecystokinin octapeptide (CCK-8) and hydrocortisone on immature rat pancreas, we injected newborn rats, rats aged 4, 7, 11, 18, and 25 days and 3 months, and adult rats with CCK (5 and 10 micrograms/kg) in gelatin and hydrocortisone (10 mg/kg) for 3 days. Animals were killed, the pancreata were removed, and the concentrations of DNA and protein were measured and DNA and protein synthesis rates determined by incorporation of [3H]thymidine and [14C]leucine, respectively. These values were compared with those of saline-injected controls. DNA concentration was significantly increased over control at ages 2 days to adult by hydrocortisone and by CCK (10 micrograms/kg) in the adult. Protein concentration was increased on days 3-14 by hydrocortisone. DNA synthesis was increased by CCK and decreased by hydrocortisone at 3 months and adult. Protein synthesis was decreased by hydrocortisone at ages 3-14 days. Thus, each agent has its own developmental pattern with age on the rat pancreas.