Molecular and Microbial Detections of Streptococcus mutans and Lactobacilli in Dental Caries: An Experimental Study on Iranian Children Aged 5-9

OBJECTIVES

Lactobacilli and Streptococcus mutans are stigmatized as cariogenic bacteria, but few studies have simultaneously examined the quantitative and qualitative aspects of lactobacilli and S. mutans in childhood dental caries. Therefore, this study aimed to detect the presence of S. mutans and lactobacilli in dental caries using Snyder's test, colony counting, and PCR in the primary teeth of Iranian children with dental caries.

MATERIAL AND METHODS

A cross-sectional study was conducted in Kerman, Iran, from March to Jun 2024. After dental examinations, 120 eligible children aged 5-9 were chosen using simple random sampling and classified into four groups based on their decayed, missing, and filled (primary) teeth (dmft) index: Group 1 (dmft = 0), Group 2 (dmft = 4-6), Group 3 (dmft = 7-9), and Group 4 (dmft = 10-13). The salivary levels of lactobacilli and S. mutans were calculated using colony counting (CFU/ml). Moreover, Snyder's test was applied to evaluate caries activity. PCR was also performed for molecular detection of lactobacilli (16S rRNA gene) and S. mutans (gftB gene). Lastly, the association between bacterial counting, molecular findings, and Snyder's test was estimated through statistical methods using SPSS 27.

RESULTS

Significant differences were found between the age and the PCR results of lactobacilli and S. mutans among all dmft Groups (p < 0.05). Moreover, positive significant correlations were observed between the counts of lactobacilli and S. mutans in dmft Group 1 compared to other dmft Groups (p < 0.05). Furthermore, the counts of these two bacteria differed significantly in Snyder's test (p < 0.05). However, Snyder's test differed significantly from the S. mutans PCR (p < 0.05), but not from the lactobacilli PCR (p > 0.05).

CONCLUSIONS

The results of the study could potentially be considered a promising and cost-effective screening program to identify children who are susceptible to dental caries.

Association of HLA-DQ4/5 genotype polymorphisms with celiac disease in a group of children in Southwest Iran: A case-control study

Background and Aim

Celiac disease (CD) has proinflammatory and pathogenic immune responses to gluten in intestinal tissue, leading to structural changes in the mucosa of the small intestine. The association of human leukocyte antigen (HLA)-DQ2 and DQ8 genotypes with CD has been previously reported. This test has a negative predictive value close to 100%, so its main purpose is to rule out the detection of CD completely or almost completely. There is limited information regarding HLA-DQ4/5 in CD. This study was conducted to determine the HLA-DQ4/5 genotypes in a group of Southwestern Iranian children with CD.

Methods

We conducted a case-control study in Southwest Iran involving 100 participants, employing a nonprobabilistic sampling method. Samples were taken from participants' oral buccal mucosa at Imam Sajjad Hospital of Yasuj, Iran. Then DNA was extracted from these samples and used to determine the frequency of HLA-DQ4/5 genotypes through Sequence-Specific Primer-Polymerase Chain Reaction assay. SPSS 20 was utilized for statistical analyses.

Results

Fifty diagnosed patients with CD (high anti-tissue transglutaminase [tTG]-IgA level [upper limit of normal] with pathological findings of Marsh III) and 50 non-CD individuals (normal anti-tTG-IgA level and normal total IgA level) were enrolled in the study from August 5, 2022 to October 15, 2023. Findings showed that the DQ4a*4b allele has the highest frequency in the CD samples (78%, p < 0.01) followed by the DQ5a*5b allele (12%, p < 0.01). Additionally, there was a higher prevalence of DQ4/DQ5 in patients with CD compared to controls (odds ratio = 6.5, confidence interval = 0.84 to 69.46, p < 0.01). Furthermore, a significant association was found among HLA DQ4/5 genotype, age (>9.5) (p < 0.01), and gender (female) (p < 0.05).

Conclusion

The observed significant differences among HLA-DQ4 and HLA-DQ5 in Iranian CD samples against controls and the high value of the relative risks showed the significant function of the studied alleles in the prevalence of CD in Iranian patients.

Correlation between JAK2, STAT3, and CTLA4 Relative Gene Expressions and Oral Squamous Cell Carcinoma

Statement of the Problem

Oral squamous cell carcinoma (OSCC) is the eighth leading cause of cancer-related death worldwide. JAK2 and STAT3 primarily influence intrinsic tumor cell behavior, and CTLA4 impacts the interplay between the tumor and the host immune system in the context of cancers. There is scarce information regarding the involvement and roles of JAK2, STAT3, and CTLA4 genes in OSCC; however, the molecular mechanisms are still unclear.

Purpose

This study examined the relationship between JAK2, STAT3, and CTLA4 gene expression levels and OSCC in a group of patients in the southeast of Iran.

Materials and Method

This cross-sectional study was conducted in which the relative gene expression levels of JAK2, STAT3, and CTLA4 were compared between 23 oral paraffin tissue blocks collected from OSCC patients and 20 fresh gingival tissues collected from healthy individuals. The Real-Time quantitative PCR (RT-qPCR) assay was employed to assess relative gene expression levels. SPSS 27 was employed to perform statistical analyses.

Results

Significant differences were found between OSCC patients and healthy individuals concerning gene expression levels of JAK2 (2.4-fold, p< 0.0001), STAT3 (2.32-fold, p< 0.0001), and CTLA4 (4.09-fold, p< 0.0001). Additionally, there were significant positive correlations among JAK2-STAT3 (ρ= 0.667, p< 0.001), JAK2-CTLA4 (ρ= 0.771, p< 0.001), and STAT3-CTLA4 (ρ= 0.635, p= 0.001) co-expressions. Moreover, gender, age groups, and tumor locations did not significantly correlate with the expression levels of these genes (p> 0.05). Nevertheless, significant differences occurred between histopathological grades and the gene expression levels of JAK2 (p< 0.001), STAT3 (p= 0.001), and CTLA4 (p< 0.001).

Conclusion

The overexpression of JAK2, STAT3, and CTLA4 can be considered triggers for OSCC development. It may be beneficial to conduct future research on OSCC by considering downstream genes involved in the JAK2/STAT3/CTLA4 axis.