Background
We previously demonstrated in a 3T3L1cells in vitro model of adipogenesis, that Integrase Strand Transfer Inhibitors (INSTI) increase adipogenesis, while, tenofovir alafenamide fumarate (TAF) and tenofovir disoproxil fumarate (TDF), displayed an inhibitory effect, counteracting increased adipogenesis caused by INSTIs [dolutegravir (DTG), bictegravir (BIC)]. Deregulation of the expression levels of two families of adipocyte differentiation transcription factors, the CCAAT/enhancer-binding proteins (C/EBPs) and the peroxisome proliferator-activated receptors (PPARs), was also confirmed with a different degree of expression according to different antiviral drug. Morphological changes were also detected in cells treated by TDF/TAF with increased expression of E-TR7 a well-known fibroblastic marker. Presently it is not clear the effect of nucleoside reverse transcriptase inhibitors (NNRTIs), alone or in combination with TDF/TAF or INSTIs on adipocyte differentiation. Aim of the study was to evaluate in vitro these last potential activities as in routine clinical practice.
Methods
We used a 3T3-L1 cells in vitro model of adipogenesis to study the effects on adipocyte differentiation of the NNRTIs doravirine (DOR) and rilpivirine (RPV), alone or in combination with the previously evaluated DTG and the newer INSTI cabotegravir (CAB), or TDF or TAF. Expression levels of PPARɣ and C/EBP⍺, and the intracellular lipid accumulation by Red Oil staining, were used to monitor adipocyte differentiation (fig. 1). Immunoistochemistry for E-TR7 was also performed on terminally differentiated cells.
Results
CAB, DOR and RPV were all able to increase adipogenesis, compared to control, while cells showed some morphological changes. This last effect was more evident with CAB and DOR, and less with RPV. When used in combination, NNRTIs were able to increase the adipogenic effects of CAB and DTG, while TAF and TDF respectively combined with RPV and DOR displayed an inhibitory effect. Furthermore, NNRTIs and CAB enhanced the expression levels of ER-TR7 compared to control, being the combination DTG+DOR less effective in this activity.
Conclusions
Our data support the evidence that in-vitro challenge of 3T3-L1 cells with INSTIs and NNRTIs is able to increase adipocytic differentiation and to drive a number of these cells toward the expression of fibroblastic features, whereas TAF and TDF when combined to different ARV have an antagonistic role on this phenomenon confirming our previous report.
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