Stiffness-Activated GEF-H1 Expression Exacerbates LPS-Induced Lung Inflammation

The critical first step in finding an effective treatment for any medical condition is understanding how the condition in question works. Careful analysis of the mechanisms that bring on the condition and exacerbate it can reveal effective strategies for its mitigation. One good example of this is with acute respiratory distress syndrome (ARDS), a condition with dangerously high rates of morbidity and mortality. To date, quite a bit is known about ARDS pathology, but not enough to be able to develop a truly effective treatment, particularly for muscular stiffness and inflammation. For example, excess lysyl oxidase (LOX)-dependent cross-linking leads to excess extracellular matrix (ECM) accumulation and muscular stiffening. As such, inhibiting LOX with antibodies or the chemical inhibitor β-aminopropyl nitrile (BAPN) reduces cross-linking and impedes tumor progression. The effectiveness of stiffness modulation in pathologic conditions comes from the fundamental role of cell detection of the microenvironment, yet the relation between stiffness and modulation of inflammation is still unknown. Some previous studies have indicated that cell differentiation and cell motility are controlled by small GTPAse Rho, activated by varying levels of stiffness.

To build on this, Mambetsariev et al. wanted to look at the relationship of LPS-induced inflammation, increased ECM synthesis and activation of Rho signaling in stiffness-dependent mechanisms. To do this, the team needed to examine LPS effects on ECM proteins and ECM-modifying enzyme LOX, and also tested the role of Guanine nucleotide exchange factor H1 (GEF-H1). Performing this experiment required researchers to carefully measure LOX levels, something they did using the Amplite Fluorimetric Lysyl Oxidase Assay Kit. By using Amplite's proprietary LOX substrate that releases hydrogen peroxide upon LOX oxidation, this assay kit produces a vibrant fluorescence that allows researchers to carefully and accurately measure LOX activity. This method also allows for the detection of sub ng/mL LOX, making it far more sensitive than other assay kits and also eliminating unwanted interference, increasing the reliability of the results.

The results of this study have led the research team to conclude that GEF-H1 plays an essential role in stiffness-dependent enhancement of LPS-induced inflammation and forms a positive feedback loop of inflammation, a relationship previously unknown to the medical community. Armed with this knowledge, researchers can now move forward in attempts to control the type of lung inflammation and muscular stiffness so common in ARDS. They can do this by employing GEF-H1 inhibition, something that may be able to break the vicious cycle of inflammation propagation. This study represents the value of understanding all the mechanisms involved in a biological phenomenon, and was made possible in part by the measurement accuracy provided by tools such as the Amplite Fluorimetric Lysyl Oxidase Assay Kit. Being able to accurately and confidently measure LOX activity was essential to seeing the role of GEF-H1 on muscle inflammation and stiffness. Employing the proper tools allows for breakthrough studies, which facilitate the further advance of the medical field.

References

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1. Mambetsariev, Isa, et al. "Stiffness-activated GEF-H1 expression exacerbates LPS-induced lung inflammation." PLoS One 9.4 (2014): e92670.