@article{ManowskyCamargoKippetal.2016, author = {Manowsky, Julia and Camargo, Rodolfo Gonzalez and Kipp, Anna Patricia and Henkel, Janin and P{\"u}schel, Gerhard Paul}, title = {Insulin-induced cytokine production in macrophages causes insulin resistance in hepatocytes}, series = {American journal of physiology : Endocrinology and metabolism}, volume = {310}, journal = {American journal of physiology : Endocrinology and metabolism}, publisher = {American Chemical Society}, address = {Bethesda}, issn = {0193-1849}, doi = {10.1152/ajpendo.00427.2015}, pages = {E938 -- E946}, year = {2016}, abstract = {Overweight and obesity are associated with hyperinsulinemia, insulin resistance, and a low-grade inflammation. Although hyperinsulinemia is generally thought to result from an attempt of the beta-cell to compensate for insulin resistance, there is evidence that hyperinsulinaemia itself may contribute to the development of insulin resistance and possibly the low-grade inflammation. To test this hypothesis, U937 macrophages were exposed to insulin. In these cells, insulin induced expression of the proinflammatory cytokines IL-1 beta, IL-8, CCL2, and OSM. The insulin-elicited induction of IL-1 beta was independent of the presence of endotoxin and most likely mediated by an insulin-dependent activation of NF-kappa B. Supernatants of the insulin-treated U937 macrophages rendered primary cultures of rat hepatocytes insulin resistant; they attenuated the insulin-dependent induction of glucokinase by 50\%. The cytokines contained in the supernatants of insulin-treated U937 macrophages activated ERK1/2 and IKK beta, resulting in an inhibitory serine phosphorylation of the insulin receptor substrate. In addition, STAT3 was activated and SOCS3 induced, further contributing to the interruption of the insulin receptor signal chain in hepatocytes. These results indicate that hyperinsulinemia per se might contribute to the low-grade inflammation prevailing in overweight and obese patients and thereby promote the development of insulin resistance particularly in the liver, because the insulin concentration in the portal circulation is much higher than in all other tissues.}, language = {en} } @article{HenkelOberlaenderKlauderStatzetal.2021, author = {Henkel-Oberl{\"a}nder, Janin and Klauder, Julia and Statz, Meike and Wohlenberg, Anne-Sophie and Kuipers, Sonja and Vahrenbrink, Madita and P{\"u}schel, Gerhard}, title = {Enhanced Palmitate-Induced Interleukin-8 Formation in Human Macrophages by Insulin or Prostaglandin E₂}, series = {Biomedicines : open access journal}, volume = {9}, journal = {Biomedicines : open access journal}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {2227-9059}, doi = {10.3390/biomedicines9050449}, pages = {10}, year = {2021}, abstract = {Macrophages in pathologically expanded dysfunctional white adipose tissue are exposed to a mix of potential modulators of inflammatory response, including fatty acids released from insulin-resistant adipocytes, increased levels of insulin produced to compensate insulin resistance, and prostaglandin E₂ (PGE₂) released from activated macrophages. The current study addressed the question of how palmitate might interact with insulin or PGE₂ to induce the formation of the chemotactic pro-inflammatory cytokine interleukin-8 (IL-8). Human THP-1 cells were differentiated into macrophages. In these macrophages, palmitate induced IL-8 formation. Insulin enhanced the induction of IL-8 formation by palmitate as well as the palmitate-dependent stimulation of PGE₂ synthesis. PGE₂ in turn elicited IL-8 formation on its own and enhanced the induction of IL-8 release by palmitate, most likely by activating the EP4 receptor. Since IL-8 causes insulin resistance and fosters inflammation, the increase in palmitate-induced IL-8 formation that is caused by hyperinsulinemia and locally produced PGE₂ in chronically inflamed adipose tissue might favor disease progression in a vicious feed-forward cycle.}, language = {en} } @article{HenkelKlauderStatzetal.2021, author = {Henkel, Janin and Klauder, Julia and Statz, Meike and Wohlenberg, Anne-Sophie and Kuipers, Sonja and Vahrenbrink, Madita and P{\"u}schel, Gerhard Paul}, title = {Enhanced Palmitate-Induced Interleukin-8 Formation in Human Macrophages by Insulin or Prostaglandin E-2}, series = {Biomedicines}, volume = {9}, journal = {Biomedicines}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {2227-9059}, doi = {10.3390/biomedicines9050449}, pages = {10}, year = {2021}, abstract = {Macrophages in pathologically expanded dysfunctional white adipose tissue are exposed to a mix of potential modulators of inflammatory response, including fatty acids released from insulin-resistant adipocytes, increased levels of insulin produced to compensate insulin resistance, and prostaglandin E-2 (PGE(2)) released from activated macrophages. The current study addressed the question of how palmitate might interact with insulin or PGE(2) to induce the formation of the chemotactic pro-inflammatory cytokine interleukin-8 (IL-8). Human THP-1 cells were differentiated into macrophages. In these macrophages, palmitate induced IL-8 formation. Insulin enhanced the induction of IL-8 formation by palmitate as well as the palmitate-dependent stimulation of PGE(2) synthesis. PGE(2) in turn elicited IL-8 formation on its own and enhanced the induction of IL-8 release by palmitate, most likely by activating the EP4 receptor. Since IL-8 causes insulin resistance and fosters inflammation, the increase in palmitate-induced IL-8 formation that is caused by hyperinsulinemia and locally produced PGE(2) in chronically inflamed adipose tissue might favor disease progression in a vicious feed-forward cycle.}, language = {en} }