Low-grade intestinal inflammation two decades after pelvic radiotherapy

BACKGROUND

Radiotherapy is effective in the treatment of cancer but also causes damage to non-cancerous tissue. Pelvic radiotherapy may produce chronic and debilitating bowel symptoms, yet the underlying pathophysiology is still undefined. Most notably, although pelvic radiotherapy causes an acute intestinal inflammation there is no consensus on whether the late-phase pathophysiology contains an inflammatory component or not. To address this knowledge gap, we examined the potential presence of a chronic inflammation in mucosal biopsies from irradiated pelvic cancer survivors.

METHODS

We biopsied 24 cancer survivors two to 20 years after pelvic radiotherapy, and four non-irradiated controls. Using tandem mass tag (TMT) mass spectrometry and mRNA sequencing (mRNA-seq), we charted proteomic and transcriptomic profiles of the mucosal tissue previously exposed to a high or a low/no dose of radiation. Changes in the immune cell populations were determined with flow cytometry. The integrity of the protective mucus layers were determined by permeability analysis and 16S rRNA bacterial detection.

FINDINGS

942 proteins were differentially expressed in mucosa previously exposed to a high radiation dose compared to a low radiation dose. The data suggested a chronic low-grade inflammation with neutrophil activity, which was confirmed by mRNA-seq and flow cytometry and further supported by findings of a weakened mucus barrier with bacterial infiltration.

INTERPRETATION

Our results challenge the idea that pelvic radiotherapy causes an acute intestinal inflammation that either heals or turns fibrotic without progression to chronic inflammation. This provides a rationale for exploring novel strategies to mitigate chronic bowel symptoms in pelvic cancer survivors.

FUNDING

This study was supported by the King Gustav V Jubilee Clinic Cancer Foundation (CB), The Adlerbertska Research Foundation (CB), The Swedish Cancer Society (GS), The Swedish State under the ALF agreement (GS and CB), Mary von Sydow's foundation (MA and VP).

Local and systemic expressions of MMP-9, TIMP-1 and PAI-1 in patients undergoing surgery for clinically suspected appendicitis

BACKGROUND/AIMS

To examine, compare and correlate the expressions of matrix metalloproteinase 9 (MMP-9), tissue inhibitor of metalloproteinase 1 (TIMP-1) and plasminogen activator inhibitor type 1 (PAI-1) in appendiceal tissue and pre- and postoperative blood samples in patients undergoing surgery for clinically suspected appendicitis.

METHODS

Fifty-seven patients with complete tissue and blood samples were included and divided into groups of noninflamed appendix/lymphadenitis (n = 7), phlegmonous appendicitis (n = 30), gangrenous appendicitis (n = 11) and perforated appendicitis (n = 9). The protein expressions were assessed with ELISAs. The local expressions of MMP-9, TIMP-1 and PAI-1 were correlated with the systemic expressions at the time of surgery while the systemic individual differences between surgery and recovery were compared.

RESULTS

There was a positive correlation between tissue and plasma PAI-1 (p < 0.05). The individual differences for plasma MMP-9 and PAI-1 were statistically nonsignificant, while they were higher for TIMP-1 in patients with perforated appendicitis compared with phlegmonous (p < 0.0001) and gangrenous appendicitis (p < 0.01).

CONCLUSIONS

Plasma PAI-1 reflected the levels in appendiceal tissue at the time of surgery. Systemic TIMP-1 could have the potential of distinguishing perforated from nonperforated appendicitis.

Endoscopic biopsies in Ussing chambers evaluated for studies of macromolecular permeability in the human colon

OBJECTIVE

Studies of mucosal permeability to protein antigens in humans are limited to in vitro techniques. The use of surgical specimens for such studies has major shortcomings. Endoscopic biopsies in Ussing chambers have been introduced as a means of studying secretion and transepithelial permeability, but have not been evaluated for studies of protein antigen uptake in human intestine.

MATERIAL AND METHODS

Standard forceps biopsies from the sigmoid colon of 24 healthy volunteers were mounted in Ussing chambers with an exposed tissue area of 1.76 mm2. 51Cr-EDTA (paracellular probe) and horseradish peroxidase (HRP; 45 kDa protein antigen) were used as permeability markers. Mucosal permeability, electrophysiology, histology and energy contents of the biopsies were studied over time. To evaluate the ability of the technique to detect permeability changes, the mucosa was modulated with capric acid, a medium-chain fatty acid, known to affect tight junctions.

RESULTS

In the Ussing chamber the mucosal biopsies were viable for 160 min with stable levels of ATP and lactate, and only minor changes in morphology. Steady-state permeability with low variability was seen for both markers during the 30-90 min period. Exposure to capric acid induced a rapid decrease in short-circuit current (Isc) and a slower reversible decrease in transepithelial resistance (TER), as well as an increased permeability to 51Cr-EDTA and HRP.

CONCLUSIONS

Endoscopic biopsies of human colon are viable in Ussing chambers and are reliable tools for studies of mucosal permeability to protein antigens. The technique offers a broad potential for studies of mucosal function in the pathophysiology of human gastrointestinal diseases.

Even small amounts of gluten cause relapse in children with celiac disease

BACKGROUND

Previously, a gluten challenge was customary to establish the diagnosis of celiac disease in children. There are no clear recommendations on how to perform this challenge or what markers to rely on for timing the biopsy after the challenge. The authors' aim was to monitor gluten intake, clinical symptoms, and antibody kinetics to evaluate the influence of gluten exposure during the challenge.

METHODS

Twenty-five children under investigation for suspected celiac disease were challenged. One child was excluded because blood samples, food records, or biopsy was lacking. Median age at the postchallenge biopsy was 3.8 (2.7-8.8) years. The families kept daily records of the children's gluten intake and of symptoms that occurred. Blood samples were taken monthly for analysis of antigliadin and endomysium antibodies and total immunoglobulin A (IgA). A third biopsy was performed when clinical symptoms suggested a relapse.

RESULTS

All 24 children showed deterioration of the mucosa or elevated antibodies during gluten challenge. Median duration of the challenge was 13 (5-51) weeks, and mean gluten intake was 1.7 (0.2-4.3) g/d and 0.1 (0.02-0.26) g/kg daily.

CONCLUSIONS

Gluten intake during the challenge varied widely, and the parents were unable to give their children the recommended amount. Despite the small amounts given, all children showed signs of relapse at a clinical, laboratory, or histologic level. Much smaller amounts of gluten than previously suggested seem sufficient to cause relapse during gluten challenge in children.