MORPHOLOGIC EVIDENCE OF THE INFLAMMATION AS A CAUSE OF
PROSTATIC BENIGN HIPERPLASY

César  T.  Vela-Velasquez, Ignacio Gutierrez, Kelma Malpartida, Mauro Ruiz

Instituto de Investigación de Citopatología-CITOPAT

Servicio de Patología Hospital “Alberto Sabogal Sologuren”-Callao-PERU

2005 

Prostatic Benign Hiperplasy (PBH) is the most common urologic pathology in males since 40 years old, it carries clinical symptoms and signs that disturb the function of prostate and other organs.

Adult prostate weights around 20 grams at 30 years old, having a growth to 35 grams at the age of 90, being the age a factor for the development of PBH.

The genesis of PBH has been associated too, with molecular elements like epidermal growth factor, fibroblasts growth factor, alpha and beta transforming growth factor, like – insuline growth factors and cycle cell inhibitors like kinase p27 and some proteins and polyunsaturated and unsaturateds fatty acids that play a role in the cells oxidative process (4,6,17,18,22). Also, other causes like infections (20), embryology factors (12) and even, a hormonal theory, because some hormones like androgens can produce fibroblast stimulation, creating collagen fibers that form part of the extracellular component and increasing the epithelial growth because of an interaction between epithelium and stroma (10,16).

In our experience and the experience of others investigators (13,14), the prostates that come to the Service of Pathologic Anatomy with PBH have a common factor: chronic and acute inflammation.

We believe that infections cause inflammation and this, tissue hypoxia, conditionating cellular necrosis, then, the homeostatic mechanism makes that the necrotic tissue will be eliminated and finally, replaced by collagen fibers. The proliferation of collagen fibers causes the increase of stromal volume and this fact, produces glandular ectasy. This process will repeat cyclically  and it will conditionate, finally, the increase of prostatic volume, it means PBH.

Our objective is to investigate if the inflammation produces structural changes in the prostate that will conditionate the PBH.

MATERIAL AND METHODS

In “Alberto Sabogal Sologuren Hospital” – EsSALUD (Callao – Peru), we studied the prostates that arrived to the Service of Pathologic Anatomy during the period of February to April 2005. They came from the Surgery Room of the Hospital and were obtained by suprapubic prostatectomy. As a control group we used prostates from autopsies.

   In the group of PBH, we used the following inclusion criteria:
- Age of the patients between 50 to 70 years old.
- Weight of the prostate: over 40 grams.
- Integrity of the prostate: complete (not in pieces).
- Absence of neoplasic pathology.

   In the control group, we used the following inclusion criteria:
- Age of the patients between 50 to 70 years old.
- Weight of the prostate: less than 30 grams.
- Integrity of the prostate: complete (not in pieces).
- Absence of neoplasic pathology.

            In total, we worked with 8 prostates obtained surgically and 6 prostates obtained by autopsy.

            Prostates previously fixed in formaline were identified, measured and weighted; we obtained 6 cuts by chance for each one; they were processed with the ussual tecnique of paraffin inclusion and cut in 5 micras sections. For each cut we obtained 2 slides, one for Hematoxilin – Eosin stain and another for Masson´s Trichrome stain, because of that we obtained a total of 96 slides in the group of PBH (48 with Hematoxilin – Eosin stain and 48 with Masson´s Trichrome stain) and 72 slides in the control group (36 with Hematoxilin – Eosin stain and 36 with Masson´s Trichrome stain).

            One of the investigators put all the slides together, mixed and gave all of them a new code by chance, saving the new codes in a sealed envelope that wasn´t opened until the end of the measurements.

            With the new codes, another investigator that didn´t know these codes, took 2 microphotographs for each slide (with a three - ocular microscope and a Labor Tech digital camera, connected to a Pentium IV computer) without looking throw the ocular of the microscope and focusing with the monitor of the computer. For studying the morphologic components with Masson´s Trichrome stain, the microphotographs were taken in the 2 first fields focussed. The evaluation of the inflammation was made in the prostatic stroma in the slides stained with Hematoxilin – Eosin.

            In both cases, the fields for the microphotographs were located by chance with movements of the slide.

           The microphotographs were revealed in jumbo paper (13.7 x 10 cm.) in a photostudy Fujifilm certified and were labeled with the new codes in the reverse of the paper automatically during the revealed process.

            The microphotographs with Hematoxilin – Eosin stain, were all of them mixed again; then, the investigators proceed to identify and count the inflammatory cells.

            Also, the microphotographs with Masson´s Trichrome stain, were mixed and we proceed to cut each one of the components (the investigator who took the microphotographs did´nt participate in this stage), difference them in: collagen fibers, smooth muscle, intersticial space, blood vessel component, glandular epithelium and intraglandular space.

            Each component was put in an envelope with the code of the microphotograph.

            At the end of the cutting process, we proceed to weight each component in an Ohaus Adventurer AR 3130 Balance, legibillity 0.001 grams.

            With the weights obtained, we calculated the percentages of each component for each microphotograph; for this, we multiplicated the weight of the component for one hundred (100) and divided the result between the total weight of the microphotograph.

            After we finished the 2 before processes, we proceed to open the envelope with the original codes and identified each one of the microphotographs. Then, we tabulate the information of each group (PBH and controls).

            For the statistic analysis, we used the Non Parametric Test “U” of Mann Whitney.

In Table I, we can observe the weights of the prostate, the age and the number of microphotographs took in each group (PBH and controls).

            The number of inflammatory cells in the group of PBH was 6.07 +/- 10.46 and in the control group was 2.64 +/- 3.12.

            The statistic difference of inflammatory cells in both groups using the test U of Mann Whitney had a value of p = 0.043.

            The composition of inflammatory cells in the group of BPH was: lymphocytes 83.02%, polymorphonuclears 13.16%, others 0.53%.

In Table II, we observe the percentage and the statistic difference of the morphologic components of the prostate in both groups.

PBH*: Prostatic benign hiperplasy.
p**: value of p using Non parametric test U of Mann Whitney.

DISCUSSION

The male reproduction system diseases are not restricted to the prostate, however, this is one of the most important organs in the urologic practice. In the last decade an evolution has produced in the therapeutic behavior and in the diagnostic advance of the PBH.

            In this investigation, we raise basically 2 questions: Is the inflammatory factor important in the PBH? and  If the inflammatory factors conditionate some changes in the prostatic structure?

            About the first question, we found significant statistic difference (p<0.05) in the inflammatory component in favor to the group of PBH, for this reason we can deduce that inflammation is a very important factor for the development of PBH, like is suggested in others investigations (1,19), because of being a permanent injury in the prostatic tissue, it produces atrophy of the smooth muscle layer, release of cytokines and expression of growth factors (5,7); all of them produce in the prostatic tissue proliferation of fibroblasts and because of this, production of collagen fibers (11).

            In the evaluation of the composition of the inflammatory cells, in both groups we found a majority of mononuclears (more than 83%), followed in frequency by the polymorphonuclears, who all together are more than 99% of the inflammatory cells.

            For answering, the second question of our investigation, we use an innovative method to quantify the proportion of structural components of the prostate, considerating the computerized methods used for the same reasons by others researchers (2) and then, we compare the alterations in the prostates caused by the inflammatory process.

            Our results show us that there is an structural difference between the prostates with PBH and the controls, so, about the percentage of collagen fibers, we found significant statistic difference (p<0.05) in favor to the group of PBH; in the other hand, about the muscle component, the statistic difference was very significant in favor to the controls (p<0.05), these results coincide with the experimental studies of Janssen and Kessler (8,9).
            The production of collagen fibers will conditionate decreasing of prostatic epithelial component because of the increasing of pressure of hyperplasic stromal tissues against the epithelium; also, the intraluminal pressure press the epithelium against the basal layer, it can modify the function of the epithelial cells like is suggested by Babinski (2).

            We found that the proportion of the glandular epithelium in both study groups is not statistically significant (p=0.059), but the difference between them in favor to the control group needs to be researched.

            In relation to the intersticial space, we found very similar values (p=0.994) in both study groups, this result gives confidentiality to the used method.

            Our results of the blood vessel component show that there is no evidence about the production of hipoxy because of blood vessel insuficience, so, we didn´t find statistic difference in both study groups (p>0.05).

            In relation to the intraglandular space, we didn´t find significant statistic difference between the group of BPH and the controls, there is between them a high statistic correspondence (p=0.879), this can suggest that the dilatations in the intraglandular space that we can see in the microscopy of patients with PBH is not a cause, is a consequence of PBH.

            Our morphologic findings show that inflammation conditionate increasing of collagen fibers and decreasing of the muscle tissue, all of these has as a consequence, the increasing of the prostatic volume. Once installed the inflammatory process, it conditionates tissue hipoxy, this will stimulate the production of collagen fibers (3) and these factors and anothers like hormones that produce the stimulation of growth factors (15, 21), will make that the answer of production of collagen fibers because of the inflammation will be increased, all of these will be repeated ciclically producing at the end, the PBH.

            Because of all the things explained before, we have to start some preventive programs in male population over 39 years old, so, the incidence and the cost that produces PBH will decrease.
            Finally,  it is important to highlight that the method we described for the evaluation of structural components in the prostate is innnovative, easy to reproduce, has a cheap price and can be used in others investigations.

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