Presence of Adenovirus-36 DNA in Adipose Tissue of Women: Relationship with Adipocyte Morphology and the Expression of C/EBPβ and HIF-1α

Abstract

Background: Human adenovirus 36 (HAd36) infection has been associated with obesity. Experiments using 3T3-L1 adipocyte cultured cells and human adipose stem cells (hASCc) have shown that HAd36 stimulates the expression of genes implicated in cell differentiation and increased lipid accumulation. The presence of HAd36 in adipose tissue of overweight and obese women has also been confirmed. This study aims to analyze the presence of HAd36 DNA in the adipose tissue of women undergoing surgery for weight reduction and its relationship with obesity through changes in adipocyte morphology as well as the expression of C/EBPβ and HIF-1α.

Methods: Fifty-two subcutaneous adipose tissue biopsies were collected. The anthropometric parameters measured were weight, height, skin folds, body circumferences, and body fat percentage. Biochemical measures were performed for glucose, cholesterol, triglycerides, cholesterol HDL-c, and LDL-c. The presence of HAd36 DNA was performed by conventional PCR. Adipocyte morphology was analyzed in H&E-stained sections using ImageJ/Fiji software. The expression of genes C/EBPβ, HIF-1α and β-actin was determined using TaqMan probes.

Results: HAd36 DNA was detected in 31% of adipose tissue samples. The presence of viral DNA was not significantly associated with anthropometric, clinical, or metabolic measurements, or with changes in adipose tissue morphology. The levels of mRNA expression for C/EBPβ and HIF-1α did not show significant differences between positive and negative samples for HAd36 (p>0.05).

Conclusion: The presence of HAd36 DNA in adipose tissue was identified, but it was not related to morphological changes of adipocytes, or the expression of C/EBPβ and HIF-1α. Further studies are needed to confirm these findings.

Keywords: adipose tissue; gene expression; human adenovirus 36; obesity.

Figure 1

Identification of HAd36 DNA in 6% polyacrylamide gel stained with 0.3% AgNO₃. (A) Lanes 1–6, negative samples for HAd36 and lanes 7–12, positive samples for HAd36. The PCR products correspond to an amplified fragment of 171 bp. (B) PCR products for β-actin, amplified fragment of 290 pb. M corresponds to the molecular marker of 50 bp. C+ indicates the positive control and N indicates the negative control.

Figure 2

Morphological analysis and distribution of adipose tissue from women who underwent abdominal lipectomy. (A) Distribution (%) of positive and negative samples for HAd36 in relation to the number of adipose cells per field. (B) Distribution (%) of positive and negative samples for HAd36 in relation with cell diameter. (C) Representative photograph of an adipose tissue sample positive for HAd36, showing greater cellularity and adipocytes of variable size. (D) Representative photograph of an adipose tissue sample negative for HAd36, showing a more homogeneous distribution in the number and size of adipocytes.

Figure 3

Morphological changes of subcutaneous adipose tissue from women subjected to abdominal lipectomy. (A) Frequency of fat cell hyperplasia in positive and negative women for HAd36. (B) Frequency of fat cell hypertrophy in positive and negative women for HAd36. The P value was calculated using Fisher’s exact test.

Figure 4

Relative mRNA expression of the C/EBPβ and HIF-1α genes is shown. (A, B) C/EBPβ mRNA expression between HAd36-positive and -negative samples by BMI category. (C, D) HIF-1α mRNA expression between HAd36-positive and -negative samples by BMI category. Relative expression analysis for each gene of interest was performed using 2^−ΔCt (A and C) and 2^−ΔΔCt (B and D) methods and β-actin was the reference gene. The P value was calculated using the Welch’s t-test.