|Year : 2023 | Volume
| Issue : 2 | Page : 116-121
Variation in the expression of interstitial cell of cajal-like cell (CD117) across congenital pelvic-ureteric junction obstruction and its renal sonological and functional correlation: A prospective observational study
Kumar Ashish1, Simmi K Ratan2, Yogesh Kumar Sarin3, Nita Khurana4, Jyoti Kumar5
1 Department of General Surgery, Narayan Medical College and Hospital, Sasaram, Bihar; Department of Pediatric Surgery, Maulana Azad Medical College, New Delhi, India
2 Department of Pediatric Surgery, Maulana Azad Medical College, New Delhi, India
3 Department of Pediatric Surgery, Lady Hardinge Medical College, New Delhi, India
4 Department of Pathology, Maulana Azad Medical College, New Delhi, India
5 Department of Radiodiagnosis, Maulana Azad Medical College, New Delhi, India
|Date of Submission||15-Aug-2022|
|Date of Decision||06-Oct-2022|
|Date of Acceptance||09-Oct-2022|
|Date of Web Publication||30-Nov-2022|
Simmi K Ratan
G-8/6, 2nd Floor, Malviya Nagar, New Delhi - 110 017
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aims and Objectives: This study aims to study the variation in the expression of CD117-positive interstitial cells of Cajal-like cells (ICC-LC) across the upper urinary tract region in children presenting with pelvic-ureteric junction obstruction (PUJO) and its association with renal functional and sonological parameters of patients.
Materials and Methods: A prospective observational study was done on 20 children with congenital PUJO who underwent dismembered pyeloplasty. All children underwent renal sonography (anteroposterior pelvic diameter [APPD], pelvicalyceal ratio [P/C ratio], Mid polar renal parenchymal diameter [MPPD]) and functional imaging scan (LLEC scan or DTPA scan). Three specimens were taken intraoperatively from above PUJ, at the level of PUJ, and below PUJ. Those were examined immunohistochemically using CD117 to count ICC-LC using standard criteria. Variation in the expression of CD117-positive ICC-LC was correlated with the abovestated parameters.
Results: The number of CD117-positive ICC-LC showed a continuous decreasing trend above downward. P/C ratio and APPD showed a parallel trend with ICC-LC distribution, whereas split renal function (SRF) showed an inverse relationship with the expression of ICC-LC. Children with lesser severity of obstruction (APPD <30 mm and SRF >40%) showed a uniform decreasing trend in the number of CD117-positive ICC-LC across PUJ. Children with more severe obstruction (APPD >30 mm and SRF <40%) showed a decrease in the expression of ICC-LC up to the level of PUJO followed by a sudden relatively increased expression of ICC-LC below the obstruction.
Conclusion: The expression of ICC-LC shows a uniformly decreasing trend across obstruction when the severity of obstruction is less. Resurgence in the number of ICC-LC below PUJ in subjects with severe obstruction hints at the emergence of a new pacemaker area below severely blocked PUJ akin to that seen in complete heart block patients and deserves early attention.
Keywords: Children, interstitial cells of Cajal, pelviureteric obstruction
|How to cite this article:|
Ashish K, Ratan SK, Sarin YK, Khurana N, Kumar J. Variation in the expression of interstitial cell of cajal-like cell (CD117) across congenital pelvic-ureteric junction obstruction and its renal sonological and functional correlation: A prospective observational study. J Indian Assoc Pediatr Surg 2023;28:116-21
|How to cite this URL:|
Ashish K, Ratan SK, Sarin YK, Khurana N, Kumar J. Variation in the expression of interstitial cell of cajal-like cell (CD117) across congenital pelvic-ureteric junction obstruction and its renal sonological and functional correlation: A prospective observational study. J Indian Assoc Pediatr Surg [serial online] 2023 [cited 2023 Mar 24];28:116-21. Available from: https://www.jiaps.com/text.asp?2023/28/2/116/362392
| Introduction|| |
Pelvic-ureteric junction obstruction (PUJO) is the most common cause of congenital obstruction of the urinary system with a prevalence of 1 in 1000–2000 neonates. The cause of this obstruction of propulsion of urine across the pelvic-ureteric junction (PUJ) is not yet known well, although it is considered to be multifactorial. It is accepted that the mechanism by which urine gets propelled toward the bladder is myogenic in nature (that is without being influenced by nerves),, most likely due to the presence of pacemaker cells in the urinary tract. The latter was considered to be “atypical” smooth muscle cells (SMCs), bearing several morphological and electrical characteristics similar to cardiac sinoatrial node cells. These were found to be more numerous in the proximal regions of the pelvis, with their number decreasing with the distance from the renal fornix. As per considerable evidence, these are present even in the ureter as depicted by spontaneous peristaltic wave generation in the ureter after disconnection.
Recently, similarities were also found between these “atypical” SMCs present in the urinary tract and the intestinal pacemaker cells, recognized as interstitial cells of Cajal (ICC). Hence, these were also called ICC-like cells (ICC-LC). Akin to gut motility, the distribution and expression of ICC-LC have also been linked to pyeloureteral peristalsis. ICC-LC are known to possess a c-kit receptor, similar to the mast cell having a similar receptor. However, mast cells can be differentiated from ICC-LC based on their morphology and distribution within the tissues.
Although few workers had found a significant decrease in the number of ICC-LC in the upper urinary tract in the ureteropelvic junction region in subjects with PUJO, other reports have contradictorily shown either increase in density or no change in density of these cells in this region. Furthermore, there is experimental evidence to suggest that the number of ICC-LC could be related to the severity of PUJO; but none of the available studies have touched on this aspect.
In view of what has been stated above a need for a study was felt wherein the distribution of ICC-LC across the upper urinary tract could be studied in subjects with PUJO in relation to sonological findings to fill in the lacuna of knowledge in this aspect.
| Materials and Methods|| |
It was a prospective analytical study done in the department of pediatric surgery at a tertiary referral center over 21 months (November 2016 to July 2018) including 20 consecutive children of PUJO (up to 12 years of age) undergoing dismembered (Anderson–Hynes) pyeloplasty based on standard indications. Neonates, syndromic patients, patients having secondary PUJO, vesicoureteric reflux, previous surgery on kidneys, and extrinsic causes of PUJO were excluded from the study. All subjects underwent renal sonological scan for the anteroposterior pelvic diameter (APPD), SFU grading, and renal parenchymal thickness in millimeters at Mid polar renal parenchymal diameter (MPPD). Functional imaging using DTPA/LLEC was done for all subjects as a renal dynamic scan for the pattern of execration curve and split renal function (SRF).
Three specimens of 5 mm each were taken from the redundant excised pelvis above PUJO (sample 1), at the site of PUJ obstruction (sample 2), and just below PUJ (sample 3). Layers of lamina propria and muscularis mucosa were examined immune-histologically using CD117. In each specimen, 10 neighboring well-stained, oriented high-power ﬁelds (HPF) of 0.136 mm2 were evaluated, and the number of c-kit-positive ICC-LCs/HPF was counted.
The distribution of ICC-LCs/10 HPF was computed for each subject at, above, and below PUJO subjects. Further, the number of ICC-LC at three locations was correlated with APPD, SFU grading, MPPT, SRF, and APPD/MPPT ratio (pelvicalyceal ratio [P/C ratio]) following classifying subjects based on the severity of obstruction.
| Results|| |
The striking observation was that in a composite group of subjects, the number of ICC-LC showed a continuous decreasing trend across PUJ from above downward. The mean number of ICC in samples 1, 2, and 3 were 22.9 ± 10, 17.4 ± 7, and 15 ± 3.1, respectively [Figure 1]. Overall, there was a fall in the number of ICC by 15% between samples 1 and 2 and 10% between samples 2 and 3, although neither of these differences was statistically significant.
|Figure 1: Median number of ICC-LC across PUJO. ICC-LC: Interstitial cells of Cajal-like cells, PUJO: Pelvic-ureteric junction obstruction|
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Another interesting observation was that each of the parameters P/C ratio and APPD showed variable relation with ICC-LC distribution across PUJO. Both these parameters had a positive correlation with ICC-LC number both above and below PUJO, but a negative correlation at the level of PUJO [Figure 2]. Another noteworthy fact was a reverse relation between ICC density and SRF.
|Figure 2: Association of SRF, APPD, and P/C ratio at three levels. SRF: Split renal function, P/C ratio: Pelvicalyceal ratio|
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These observations led us to delve further to analyze how the distribution of ICC-LC could differ between those with a lesser and severe degree of obstruction. This was performed by dividing the data into two subgroups using the median values of the group, i.e., APPD (30 mm), SRF (40%), MPPT (5 mm), and P/C ratio (5.1). Those with less favorable parameters were grouped as comparatively more obstructed. The distribution of ICC-LC was studied in relation to each of these parameters.
Subjects with APPD <30 mm showed a uniform craniocaudal decreasing trend of the median value of ICC-LC count from above downward. On the other hand, children with APPD >31.5 mm initially showed a more severe degree of fall [Figure 3]. This was followed by an unexpected 16% increase in their number from the level of PUJ to below it. Hence, subjects with higher APPD (>30 mm) not only showed a different trend of distribution of ICC-LC from those with a lesser severe degree of obstruction but in them, there was a significant correlation between the percent fall of ICC-LC between samples 1 and 2 with APPD [Table 1].
|Table 1: Percentage median fall in the number of interstitial cells of Cajal-like cells in relation to the anteroposterior pelvic diameter|
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|Figure 3: Median number of ICC-LC across PUJ in association with APPD. ICC-LC: Interstitial cells of Cajal-like cells, PUJ: Pelvic-ureteric junction|
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In renal units with SRF <40% (poorer function), there was a 33.3% decrease in the expression of ICC-LC from above PUJ (sample 1) to the level of PUJ (sample 2), which was statistically not significant [Figure 4].
|Figure 4: Median number of ICC-LC across PUJ in association with SRF. ICC-LC: Interstitial cells of Cajal-like cells, PUJ: Pelvic-ureteric junction, SRF: Split renal function|
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Thereafter, there was a 16.6% median increase in the expression of ICC-LC from sample 2 to sample 3 (PUJ downward). The patients with SRF >40% (better functioning) paralleled the trend of lesser APPD <30 mm, i.e.,14% fall between samples 1 and 2 and 12% fall between samples 2 and 3 in [Table 2], none of these being significant.
|Table 2: Percentage median fall in the number of interstitial cells of Cajal-like cells in relation to split renal function|
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A similar trend of difference in ICC-LC distribution was noted for better and worse functioning renal units using MPPT <5 mm or P/C ratio >5.1 also, but no difference between the drop in the number of ICC-LC between samples 1 and 2 was significant.
| Discussion|| |
Although ICC was first described in 1982 by Cajal in GIT, it was Lang et al. who in the year 1999 first described a population of electrically active ICC-LC in the upper urinary tract of the guinea pig. However, work on the human urinary system in this context was very sparse. The earliest study in this regard on the human being was first done by Solari et al. in 2003. They concluded that the density of ICCs was markedly decreased in the obstructed PUJ specimens at the level of obstruction [Table 3].
|Table 3: Comparison of different studies of interstitial cells of Cajal-like cells distribution in pelvic-ureteric junction obstruction|
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However, some contradictory observations were made by Koleda et al. in 2012. They described an increase in ICC-LC at the level of PUJ in pyeloureteral junction obstructive disease and explained the phenomenon as a compensatory mechanism for the loss of the ability to conduct urine from the pelvis toward the ureter due to increased fibrosis and loss of SMCs, which are primary pacemaker cells. Compensatory hyperplasia of the ICC-LC (responsible for the secondary peristalsis) occurred to overcome this obstruction.
In our study, the number of ICC-LC was higher above PUJ in comparison to the number of ICC-LC at the level of PUJ and below PUJ. Furthermore, there was a less steep decline in the expression of ICC-LC from the level of PUJO to below it than what was noted between above the level of PUJ to PUJ. The mean number of ICC-LC above PUJ, at PUJ, and below PUJ is 22.9 ± 10.9, 17.4 ± 7, and 15 ± 3.1), respectively. Furthermore, the number of ICC-LC decreased from cranially to caudally across PUJ.
Similar to Solari et al., Yang et al., and Inugala et al., the main fact that emerges in our study is that the number of ICC-LC decreases at the level of PUJ in a patient with PUJO. It may be due to fibrosis and replacement of ICC-LC at the level of obstruction.
The only earlier work in English literature which had studied the c-kit +ve cells above and lower to the PUJ was done by Kuvel et al. In their study, they examined the obstructed segment of 32 cases with intrinsic PUJO, the segment of PUJ with chronic obstruction (15 cases with nephrectomy due to chronic obstruction associated with lithiasis, tumor, and reflux), and the normal PUJ segment (30 patients where nephrectomy was done due to renal tumor or trauma). They observed that the number of ICC-LC was significantly decreased at the level of PUJ in subjects with intrinsic PUJO. However, within 5 mm proximity above and below PUJO, the number of ICC-LC was higher. Furthermore, the number of ICC-LC proximal to obstructed PUJ in children with intrinsic PUJO was higher than what was found in controls.
Studies like Nandan et al. similar to Kuvel et al. concluded that the number of ICC-LC was fewer in pyeloureteric region with loss of motility, muscle hypertrophy, and increased fibrosis. This justifies our observation of the decreased number of ICC-LC at PUJO. Our study also showed that the degree of the severity of obstruction which was based on P/C ratio, APPD, and parenchymal thickness could have affected the distribution of ICC-LC across PUJ.
An interesting observation was that the P/C ratio and APPD showed a direct relationship with ICC-LC distribution across PUJO, whereas SRF of the affected side showed an inverse relationship with ICC-LC distribution across PUJO. While P/C ratio and APPD showed a positive correlation with ICC-LC expression above the PUJO and below the PUJO but it showed a negative correlation with ICC-LC at the level of PUJO; SRF expectedly showed just the opposite trend. This may reflect a higher degree of PUJO obstruction in this set of subjects, which led to an increased workload to overcome the obstruction at PUJO causing an increase in the expression of ICC-LC above PUJO and increased secondary peristalsis below the PUJO, leading to resurgence in their number. We found that while there was a uniformly decreasing trend of ICC numbers craniocaudally across PUJO in children with less severe PUJO; those with severe obstruction had an initial steep decrease in the expression ICC-LC between above PUJ to the level of PUJ followed by a relative increase in the ICC-LC number between PUJ and below it. This relative increase in the number of secondary peristaltic cells below PUJO probably occurred due to the secondary hyperplasia of these cells below obstructed PUJ to propel the urine by secondary peristalsis. There was a statistically significant correlation (P < 0.05) between the percentage fall of ICC-LC between samples 1 and 2 in both groups.
In severe degrees of obstruction, the resurgence in the number of ICC-LC below PUJ is indicative emergence of secondary peristalsis below PUJ. This bears a resemblance to the phenomenon of electrical activity in complete heart block where once the primary pacemaker fails, there is activation and resurgence of secondary lower pacemaker cells to take up its role.
The ICC-LC shows structural and physiological similarities with the pacemaker cell of the heart and nerve cells. The hypothesis of ICC as nerve cells by Cajal was based on the observation that ICC is associated with the myenteric plexus, stained with methylene blue, and silver impregnation according to the Golgi method, similar to neural tissues. Keith saw structural similarities with sinoatrial node cells and hypothesized them to be pacemaker cells. Electrophysiologically intracellular calcium handling plays a key role in the gut pacemaker responsible for spontaneous rhythmicity, as well as in the cardiac pacemaker responsible for spontaneous beating.
| Conclusion|| |
The expression of ICC-LC shows a uniformly decreasing trend across PUJ when the severity of obstruction is less. In severe obstruction, there is a sharp decrease in the number of ICC-LC at the level of PUJ with resurgence in the number of ICC-LC below PUJ. Resurgence in the number of ICC-LC below PUJ in subjects with severe obstruction and in young infants hints at the emergence of a new pacemaker area below severely blocked PUJ akin to that seen in complete heart block patients and deserves early attention. This ICC-LC can be used in future for labeling biopsy and proper functional anastomosis between the pelvis and ureter in case of PUJO similar to Hirschsprung's disease. In future, ICC-LC-guided anastomosis between the pelvis and ureter will be of great help, especially in redo-pyeloplasty.
The limitations of this study were low sample size and limited short study period.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]