Interstitial cells of Cajal network in primary obstructive megaureter

OBJECTIVES

Recent reports showed an altered density of interstitial cells of Cajal (ICCs) and of peripherin immunoreactive nerve fibres in obstructed uretero-pelvic junction. Our aim was to investigate ICCs immunoexpression and ureteral innervation in primary obstructive megaureter (POM).

METHODS

8 specimens of POM were obtained during tailoring. Restricted segments of ureters were divided from the dilated ones. C-kit and peripherin immunohistochemistry were performed.

RESULTS

A normal distribution of ICCs was documented in both circular and longitudinal muscular layers of dilated segments. Marked muscular hypoplasia and a sparse or absent ICCs occurred in longitudinal muscular layer of restricted ureteral segments. A normal distribution of peripherin positive fibres was present in both dilated and restricted segments.

CONCLUSIONS

Our data confirmed a defective muscolarization in restricted, aperistaltic POM. The lacking of ICCs in the longitudinal muscular layer is, probably, due to the absence of c-kit positive muscular embryological precursors. No alteration of peripherin immunoreactive nerve fibres network was observed in both dilated and restricted ureteral segments.

Cajal-like cells in the upper urinary tract: comparative study in various species

The interstitial cells of Cajal (ICC) play an important role in the control of gut motility. The recognition that the ICC cell membrane harbors the c-kit receptor (CD117) sparked rapid advancement in ICC research on the gut and certain pathologies using immunochemical and molecular methods. The question arises whether ICC exist in the upper urinary tract (UUT) and trigger motility. The present study analyzed the distribution of the c-kit receptor in the normal human UUT compared with various species. Immunohistochemistry (alkaline-phosphatase-anti-alkaline-phosphatase technique, immunofluorescence) was applied on serial sections using monoclonal and polyclonal antibodies recognizing the c-kit receptor. C-kit staining was compared with standard endothelial, epithelial, neurogenic, histiocytic, mast cell, and smooth muscle markers, as well as a negative control. Normal proximal, middle, and distal ureter segments were analyzed in rodents, carnivores, porcines, cow, and humans. In all species the c-kit receptor was detected in either round or spindle-shaped cells. Because of their antigenic profile, the round cells were identified as mast cells occurring in all layers of the ureteral wall except the urothelium and were more frequent in humans. In contrast, the population of spindle-shaped cells was marked only by anti-c-kit receptor antibodies, thus resembling ICC. These ICC-like cells were found among the inner and outer smooth muscle layers and in the lamina propria of all species. In humans, spindle-shaped cells were also found vertically oriented within the urothelium. Our morphological data present for the first time the distribution of ICC in the UUT of various species. The ubiquitous distribution in the entire pyeloureteral complex provides strong evidence that ICC generate electrical pacemaker activity within the UUT as an intrinsic system. Animal studies may help to understand the physiological importance of these ICC-like cells. The significance of these findings needs to be evaluated by functional studies and investigations of certain congenital pathologies with disturbance of the urinary outflow.

Autoantibodies against Cajal bodies in systemic lupus erythematosus

BACKGROUND

Cajal bodies (CB) are distinct sub-nuclear domains rich in small nuclear ribonucleoprotein particles (snRNPs); they are involved in pre-mRNA processing. Lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production against different nuclear molecules, including those involved in pre-mRNA processing. The aim of the present investigation is to assess the presence of anti-CB autoantibodies in a cohort of SLE sera.

MATERIAL/METHODS

Antinuclear antibodies (ANA) were screened by indirect immunofluorescence in a batch of 190 sera from patients who met the ACR criteria for SLE classification; fine specificity was determined by Western blot using HEp-2 cells or rat hepatocyte extracts purified by ion exchange chromatography.

RESULTS

Four sera had anti-Cajal body (CB) autoantibodies. Interestingly, all of these patients had intermittent extensive oral and esophageal ulceration. The autoantibodies to CB were of the IgG class, and by Western blot these sera had reactivity against an 80 kDa protein (coilin) associated with Sm proteins.

CONCLUSIONS

Anti-CB autoantibodies constitute an uncommon specificity of SLE; therefore it seems that anti-CB antibody specificity is associated with extensive mucous ulceration.

[Immunohistochemical and ultrastructural heterogeneity of gastrointestinal stromal tumors]

AIMS AND METHODS

Digestive stromal tumors are the most frequent undifferentiated mesenchymal tumors. The prognosis of these tumors is difficult to predict and the histogenesis is still subject to controversy. However, the frequent and specific expression of CD117 (c-kit) by these tumors could suggest an origin from interstitial cells of Cajal. The aim of this study was to analyse the histological and immunohistochemical characteristics of 46 digestive stromal tumors surgically resected, with comparaison of CD34 and CD117 expression in these tumors. Sixteen tumors were analyzed on electron microscopy.

RESULTS

Sixty three and 74% of the stromal tumors were positive for CD117 and CD34 respectively. While CD117 expression was similar in all locations, on the contrary, there was a decreasing gradient of CD34 expression between gastric (87%) and jejunal (33%) tumors. All tumors with skeinoid fibers expressed CD117. Focal expression of smooth muscle actin was noted in 43% of the cases. The ultrastructural study showed no correlation with the immunohistochemical results.

CONCLUSION

Digestive stromal tumors show an immunophenotypic and ultrastructural heterogeneity. CD117 expression is frequent, but not constant.