Anti-inflammatory drugs suppress ultrasound-mediated mesenchymal stromal cell tropism to kidneys

Abstract

Mesenchymal stromal cells (MSC) are potential renal therapeutics. Clinically, results are mixed partly because MSC tropism to kidneys is minimal following infusion. Ultrasound augmentation of the renal microenvironment is becoming increasingly-important in renal MSC therapies. We demonstrated pulsed-focused-ultrasound (pFUS) increases enhanced homing permeability and retention of MSC in mouse kidneys. Here, we characterized the temporal proteomic response to pFUS in mouse kidneys and its association with MSC tropism. pFUS induced molecular cascades of initial increases in tumor necrosis factor-α (TNFα) and interleukin (IL)-1α, that activated nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) and cyclooxygenase-2 (COX2) pathways without cell death. This was followed by a 24–48 hour-long response of increased cell adhesion molecules (CAM), trophic and anti-inflammatory factors. Pretreating animals with anti-inflammatory drugs etanercept (TNFα inhibitor), anakinra (IL-1 receptor antagonist), prednisone (NFκB translocation inhibitor), or ibuprofen (COX inhibitor) suppressed molecular changes and inhibited renal MSC tropism. We further examined the role of COX2 using a COX2-knock-out mouse where pFUS was unable to increase MSC tropism. These results demonstrate that renal micro-environmental changes induce MSC tropism and could influence the therapeutic efficacy of MSC. Optimizing the microenvironment and understanding drug effects will enable improvements in MSC therapies for renal disease.

Pulsed focused ultrasound enhances the therapeutic effect of mesenchymal stromal cell-derived extracellular vesicles in acute kidney injury

“…These discrepancies suggest that there are different molecular mechanisms by which pFUS operates, depending on ultrasound parameters. The studies by Burks et al show that pFUS transiently activates TNF-α and IL-1α expression in the sonicated tissue, which act through NF-κB signaling to drive cyclooxygenase-2 (COX2) activity; in turn, this promotes the expression of several homing factors and increases the local accumulation of MSCs, thus augmenting their therapeutic effect [43,44]. Our previous studies have shown, however, that pFUS can improve MSC therapy independently of improved homing [29].…”

Mesenchymal Stromal Cell Homing: Mechanisms and Strategies for Improvement

“…Parallel results have been achieved in the kidney, where pFUS created a similar chemical gradient without any physiological damage to the host tissue, and dramatically increased MSC homing (Ziadloo et al., 2012). Similar to muscle, pFUS causes initial activation of TNFα and IL-1α in the kidney, which drive signaling through the nuclear factor-κB and COX2 pathways (Burks et al., 2017). In a mouse model of cisplatin-induced AKI, pFUS + MSCs significantly enhanced kidney homing and clinical outcomes compared with MSCs alone (Burks et al., 2015).…”

Acoustic Radiation or Cavitation Forces From Therapeutic Ultrasound Generate Prostaglandins and Increase Mesenchymal Stromal Cell Homing to Murine Muscle

“…For this study, production of the prostaglandins PGH 2 and PGE 2 were investigated serving as proxy indicators of microenvironmental changes. We have previously demonstrated that COX2 upregulation by NFκB is a critical component of the molecular signaling cascade within 4–6 h following pFUS at 4 MPa ( Tebebi et al, 2015 ; Burks et al, 2017 , 2019 ). While we have investigated COX2 expression in multiple studies, we have never investigated enzyme activity by quantifying metabolites.…”

“…Previous US studies characterized the molecular microenvironmental changes in tissues post-sonication and overwhelmingly observe increased expression of cytokines, chemokines, trophic factors and adhesion molecules (CAM) which would facilitate stem cell tethering and rolling across the activated endothelium followed by diapedesis into the parenchyma ( Liu et al, 2020 ). Several of our previous studies have investigated microenvironmental changes alone ( Burks et al, 2011 ) or in context of stem cell homing to skeletal muscle and kidney using 1 MHz pFUS at a peak negative pressure (PNP) of ∼4 MPa without microbubble (MB) infusions ( Ziadloo et al, 2012 ; Burks et al, 2013 , 2017 ; Tebebi et al, 2015 ). We have demonstrated that microenvironmental changes to facilitate stem cell homing require nuclear factor kappa B (NFκB) activation and subsequent cyclooxygenase-2 (COX2) upregulation ( Tebebi et al, 2015 ; Burks et al, 2017 ).…”

“…This study examined molecular changes in murine skeletal muscle following sonication at different frequencies and intensities, with and without IV MB infusions, to emphasize different mechanical US forces while measuring acoustic emissions. Having previously identified COX2 expression as a critical molecular mediator of US bioeffects ( Burks et al, 2015 , 2017 , 2019 ), we directly investigated COX2 activity following sonication by quantifying prostaglandin-H 2 (PGH 2 ), the direct metabolite of COX2, and PGE 2 , which our previous studies identified as a potential effector molecule and is known to enhance MSC homing ( Lu et al, 2017 ). Investigating US-induced prostaglandin production as a function of frequency and intensity revealed a strong correlation between prostaglandin levels and mechanical index (MI), suggesting cavitation forces are particularly effective at eliciting bioeffects in tissues.…”