Chromogenic In Situ Hybridization for DNA Localization of Papillomavirus in humans Genotypes 16 and 18 in Brain Tissues from a Group of WHO Patients from Iraq classification- Based Astrocytoma Grades 1, 2, 3 and 4: Molecularly- Approached Histopathology

Abstract

BACKGROUND:  Recent researches have documented many neurotropic viral infections in astrocytomatous brain tissues and suggesting roles both in the pathogenesis of various astrocytic proliferation as well as astrocytomas. Given that the most prevalent carcinogenic virus in humans is the human papillomavirus (HPV), it deserves further investigation to evaluate its occurrence in brain tissue samples with different astrocytoma grades, including Low-grade astrocytoma, WHO grades 1 and 2, and up to cancerous astrocytomas that include WHO grade 3 and 4 astrocytomas.

OBJECTIVE: To determine the prevalence of brain tissues infected with HPV genotype 16/18 from Iraqi patients with astrocytomas grades 1, 2, 3, and 4 from three Iraqi governorates (Babylon, Baghdad, and AL-Najaf).

MATERIALS AND METHODS: This retrospective A research was carried out on a total of (109) brain tissue specimens collected from (82) patients aged 3 to 75, among them, 49 patients were 33 female patients and 33 male patients, all of whom were diagnosed with WHO-classified astrocytoma grades 1, 2, 3, and 4 based on histopathological examination. Additional 27 brain tissue samples were sourced from neurosurgical - operated patients aged 27 to 72, among them, 17 patients were male and 10 patients were female,  and have served as the control group in this study, where during their histopathological evaluation shown non-tumorous changes in favors of eosinophilic granuloma and reactive gliosis. The In Situ Hybridization technique was employed to identify the presence of HPV genotypes 16 / 18 DNA sequences in the brain tissues analyzed across the various WHO-classified grades of astrocytomatous tumors.

Results: The overall percentage of positive HPV genotypes 16 / 18 DNA sequences detection in the examined brain tissues from astrocytomas grade 1-4 cases was   41.5 % (34 out of 82 cases). The most HPV 16 / 18 - infected brain tumor tissues (14 / 34 cases) are related to the astrocytoma grade (4) which accounted for  41.2 %, followed by astrocytoma grade (3) (9 / 34 cases;  accounted for  26.5  %), astrocytoma grade (2) (7 / 34 cases;  accounted for  20.5 %), and lastly astrocytoma grade (1) (4 / 34 cases;  accounted for  11.8 %). The most HPV 16 / 18 -infected astrocytoma patients was related to the age stratum (41-60 years) (13 cases;  accounted for  15.9 % out of 41.5%),followed by age strata  of (61-75  years), (21-40 years) and  (41-60 years) (9cases;  accounted for  10.9  % out of 41.5%; 7 cases;   accounted for 8.6% out of 41.5%  %; (5 cases;  accounted for  6.1 % out of 41.5%  ),respectively. Based on the gender of astrocytoma patients, positive HPV 16 / 18 results were revealed in 61.7 % of male patients while in female patients with astrocytoma accounted for 38.3 %.

Regarding the statistical analysis of the percentages of positivity of HPV 16 / 18 detection, the difference between total astrocytoma and control groups was statistically significant (P< 0. 03); between different grades of astrocytomas was statistically significant (P = 0.04); between age strata as well as gender of  astrocytomas patients were also significant (P= 0.03 &  P= 0.02, respectively). 

CONCLUSION:  The significance of HPV 16 and 18 infections in the aetiology, carcinogenesis, and tumorigenesis processes of the examined astrocytoma cases throughout their grades is updated by the current findings, proposing either an initiating role in the induction of these brain tumors (whether in their up-grading) and / or as playing co-factor roles (whether as an early or late events) in any specified grades.