Mast-Cell Tryptase Release Contributes to Disease Progression in Lymphangioleiomyomatosis.

Rationale: Lymphangioleiomyomatosis (LAM) is a multisystem disease that causes lung cysts and respiratory failure. Loss of TSC (tuberous sclerosis complex) gene function results in a clone of "LAM cells" with dysregulated mTOR (mechanistic target of rapamycin) activity. LAM cells and fibroblasts form lung nodules that also contain mast cells, although their significance is unknown. Objectives: To understand the mechanism of mast-cell accumulation and the role of mast cells in the pathogenesis of LAM. Methods: Gene expression was examined using transcriptional profiling and qRT-PCR. Mast cell/LAM nodule interactions were examined in vitro using spheroid TSC2-null cell/fibroblast cocultures and in vivo using an immunocompetent Tsc2-null murine homograft model. Measurements and Main Results: LAM-derived cell/fibroblast cocultures induced multiple CXC chemokines in fibroblasts. LAM lungs had increased tryptase-positive mast cells expressing CXCRs (CXC chemokine receptors) (P < 0.05). Mast cells located around the periphery of LAM nodules were positively associated with the rate of lung function loss (P = 0.016). LAM spheroids attracted mast cells, and this process was inhibited by pharmacologic and CRISPR/cas9 inhibition of CXCR1 and CXCR2. LAM spheroids caused mast-cell tryptase release, which induced fibroblast proliferation and increased LAM-spheroid size (1.36 ± 0.24-fold; P = 0.0019). The tryptase inhibitor APC366 and sodium cromoglycate (SCG) inhibited mast cell-induced spheroid growth. In vivo, SCG reduced mast-cell activation and Tsc2-null lung tumor burden (vehicle: 32.5.3% ± 23.6%; SCG: 5.5% ± 4.3%; P = 0.0035). Conclusions: LAM-cell/fibroblast interactions attract mast cells where tryptase release contributes to disease progression. Repurposing SCG for use in LAM should be studied as an alternative or adjunct to mTOR inhibitor therapy.

Histopathology and mismatch repair status of 458 consecutive colorectal carcinomas.

Defects in the mismatch repair (MMR) genes hMLH1 and hMSH2 have been found in 10% to 20% of sporadic colorectal carcinomas and also many cases of hereditary nonpolyposis colorectal cancer syndrome. Patients with these tumors have an improved prognosis and may show greater sensitivity to chemotherapy. We examined 458 resected colorectal carcinomas from 430 consecutive patients and used immunohistochemistry to determine which tumors lacked expression of these genes (MMR-d). We correlated the status of MMR-d or "intact" expression with stage, site, and histology. Eighty-nine of 458 tumors (19.4%) were MMR-d, including 80 hMLH1 and 9 hMSH2 tumors. A total of 6% of patients had synchronous tumors, and 37.7% of these were MMR-d (P=0.0008). A high proportion of patients with previous breast cancer (4 of 6 patients) had hMLH1-defective colorectal carcinomas. MMR-d tumors presented at an earlier stage than intact tumors, and the node-positive MMR-d tumors were less likely than intact tumors to have pericolonic extranodal tumor deposits (18.2% vs. 44%). The proportion of tumors at each site that were MMR-d increased progressively from cecum (32%) to ascending (35%) to transverse colon, where 41% of all tumors were defective. The proportions then rapidly decreased, reaching the lowest rate (4.7%) in the rectum. Both types of MMR-d tumors more often had expansive borders, intraepithelial lymphocytosis, peritumoral lymphoid, and Crohn's-like lymphoid responses than the intact tumors; the frequencies of these features diminished with advancing stage. Tumor budding was less common in stage II and III MMR-d tumors than in intact tumors. Keloid and myxoid type stromas correlated with stage and vascular invasion and were not related to mismatch repair status. Significant differences existed between the hMLH1 and hMSH2 tumors. The reported right-sided preponderance of MMR-d tumors is due to most hMLH1, but not hMSH2, tumors being found there (87.5% vs. 44.4%). hMSH2 tumors were most common in the rectum (55.6%). Mucinous tumors were common in hMLH1 tumors (36.3%) but not in hMSH2 tumors (11.1%). hMLH1 tumors were most likely to be poorly differentiated (70%), which was uncommon with hMSH2 tumors (22.2%). hMSH2 tumors were more likely to be confined to the wall (66.7%) than hMLH1 (20%) or intact tumors (23%). We conclude that hMLH1 and hMSH2-defective tumors have distinctly differing histologic features from each other.

Selective use of preoperative endoscopic retrograde cholangiopancreatography in the era of laparoscopic cholecystectomy.

BACKGROUND: The use of endoscopic retrograde cholangiopancreatography (ERCP) in the management of suspected common bile duct (CBD) stones prior to laparoscopic cholecystectomy is common. The associated morbidity can be significant. The present study determines significant predictors of CBD stones and improves the selection of patients for preoperative ERCP. METHODS: All preoperative ERCP for suspected CBD stones in the year 1998 were studied retrospectively. Univariate and multivariate analyses of a number of clinical, biochemical and radiological variables were carried out to determine the best predictors of CBD stones. RESULTS: A total of 112 patients had successful preoperative ERCP. Sixty-one per cent of these were negative for stones and the morbidity was 9%. Univariate analysis revealed the following variables as predictors: cholangitis (P = 0.006), abnormal serum bilirubin > or = 3 days (P = 0.002), serum alkaline phosphatase > or = 130 U/L (P = 0.002), deranged liver function tests (P = < 0.001) and CBD diameter > or = 8 mm (P = 0.009) with positive predictive values of 80%, 68%, 49%, 38% and 52%, respectively. Multivariate analysis revealed the model with the best ability to discriminate for CBD stones (P = 0.0005) was cholangitis, abnormal serum bilirubin for > or = 3 days and CBD diameter > or = 8 mm. The best predictors from this study had a sensitivity of 80% and a specificity of 27%. CONCLUSIONS: The predictors of CBD stones are imprecise. Until laparoscopic exploration of CBD becomes widely available, ERCP prior to cholecystectomy will remain popular. The use of stricter selection criteria can reduce the number of negative preoperative ERCP.