Important Inflammatory Factor Research Articles

Interleukin‐1β and tumor necrosis factor α inhibit chondrogenesis by human mesenchymal stem cells through NF‐κB–dependent pathways

The differentiation of mesenchymal stem cells (MSCs) into chondrocytes provides an attractive basis for the repair and regeneration of articular cartilage. Under clinical conditions, chondrogenesis will often need to occur in the presence of mediators of inflammation produced in response to injury or disease. The purpose of this study was to examine the effects of 2 important inflammatory cytokines, interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNFalpha), on the chondrogenic behavior of human MSCs. Aggregate cultures of MSCs recovered from the femoral intermedullary canal were used. Chondrogenesis was assessed by the expression of relevant transcripts by quantitative reverse transcription-polymerase chain reaction analysis and examination of aggregates by histologic and immunohistochemical analyses. The possible involvement of NF-kappaB in mediating the effects of IL-1beta was examined by delivering a luciferase reporter construct and a dominant-negative inhibitor of NF-kappaB (suppressor-repressor form of IkappaB [srIkappaB]) with adenovirus vectors. Both IL-1beta and TNFalpha inhibited chondrogenesis in a dose-dependent manner. This was associated with a marked activation of NF-kappaB. Delivery of srIkappaB abrogated the activation of NF-kappaB and rescued the chondrogenic response. Although expression of type X collagen followed this pattern, other markers of hypertrophic differentiation responded differently. Matrix metalloproteinase 13 was induced by IL-1beta in a NF-kappaB-dependent manner. Alkaline phosphatase activity, in contrast, was inhibited by IL-1beta regardless of srIkappaB delivery. Cell-based repair of lesions in articular cartilage will be compromised in inflamed joints. Strategies for enabling repair under these conditions include the use of specific antagonists of individual pyrogens, such as IL-1beta and TNFalpha, or the targeting of important intracellular mediators, such as NF-kappaB.

ADMA induces monocyte adhesion via activation of chemokine receptors in cultured THP-1 cells

Asymmetric dimethylarginine (ADMA), an endogenous NOS inhibitor, is also an important inflammatory factor contributing to the development of atherosclerosis (AS). The present study was to test the effect of ADMA on angiotensin (Ang) II-induced monocytic adhesion. Human monocytoid cells (THP-1) or isolated peripheral blood monocyte cells (PBMCs) were incubated with Ang II (10−6M) or exogenous ADMA (30μM) for 4 or 24h in the absence or presence of losartan or antioxidant PDTC. In cultured THP-1 cells, Ang II (10−6M) for 24h elevated the level of ADMA in the medium, upregulated the protein expression of protein arginine methyltransferase (PRMT) and decreased the activity of dimethylarginine dimethylaminohydrolase (DDAH). Both of Ang II and ADMA increased monocytic adhesion to human umbilical vein endothelial cells (HUVECs), elevated the levels of monocyte chemoattractant protein (MCP)-1, interleukin (IL)-8 and tumor necrosis factor (TNF)-α and upregulated CCR2 and CXCR2 mRNA expression, concomitantly with increase in reactive oxygen species (ROS) generation and activation of nuclear factor (NF)-κB. Pretreatment with losartan (10μM) or PDTC (10μM) abolished the effects mediated by Ang II or ADMA. In isolated PBMCs from healthy individuals, ADMA upregulated the expression of CXCR2 mRNA, which was attenuated by losartan (10μM), however, ADMA had no effect on surface protein expression of CCR2. The present results suggest that ADMA may be involved in monocytic adhesion induced by Ang II via activation of chemokine receptors by ROS/NF-κB pathway.

Proinflammatory Role of Leukocyte-Derived Egr-1 in the Development of Murine Postoperative Ileus

Early growth response gene-1 (Egr-1) is an important inflammatory transcription factor. We hypothesize that leukocyte-derived Egr-1 plays a key inflammatory role in causing postoperative ileus. Wild-type, Egr-1 knockout, and chimera mice (constructed by irradiation followed by injection with Egr-1(+/+) or Egr-1(-/-) bone marrow) were subjected to surgical manipulation of the gastrointestinal tract to induce ileus. Reverse-transcription polymerase chain reaction, Western blot, and immunohistochemistry quantified and localized Egr-1. Lumenal transit of nonabsorbable fluorescein isothiocyanate-labeled dextran and in vitro organ bath techniques measured functional gastrointestinal motility. Inflammatory mediator expressions were measured by Griess reaction, enzyme-linked immunosorbent assay, and multiplex Luminex assay. Intestinal manipulation rapidly and significantly induced Egr-1 messenger RNA and protein within the inflamed muscularis externa. Egr-1 was colocalized early to smooth muscle and enteric neurons and later in extravasated monocytes after surgery when postoperative ileus was functionally prominent. The functional severity of postoperative ileus was significantly ameliorated in mice deficient in Egr-1(-/-) and chimera wild-type mice transplanted with Egr-1(-/-) bone marrow, whereas knockout mice with Egr-1(+/+) bone marrow again displayed significant ileus. Motility was mechanistically associated in Egr-1(-/-) gene deficiency with a down-regulation in the release of nitric oxide, prostanoids, monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha, interleukin-6, interleukin-1, and granulocyte colony-stimulating factor, as well as a decrease in the recruitment of leukocytes into the manipulated muscle wall of the intestine compared with wild-type mice. Leukocyte-derived Egr-1 plays an early critical inflammatory role in the initiation of the postoperative inflammatory response, which leads to a prolonged decreased in gastrointestinal motility after intestinal surgery.

Relationship of Serum Cystatin C with C-Reactive Protein and Apolipoprotein A1 in Patients on Hemodialysis

Cystatin C is considered an indicator of acute renal failure and also a risk factor of cardiovascular disease. This study was undertaken to examine the relationship of serum cystatin C with C-reactive protein (CRP), lipids, and lipid-related compounds in patients on hemodialysis (HD). Cystatin C, CRP, total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, and apolipoprotein A1 and B were analyzed in serum of 30 patients on HD for 118 ± 18 months with low-flux dialyzers, before and after HD. The results were compared with those obtained by 21 healthy individuals (NC). Multiple regression analysis was performed to evaluate the association of cystatin C concentration before HD with clinical and laboratory parameters. The results showed that cystatin C before HD was not associated with age, body mass index (BMI), or duration of HD. However, it was significantly correlated with creatinine (r = 0.435, p = 0.021) and albumin (r = 0.483, p = 0.009) concentrations. Moreover, a highly significant association was shown with logCRP (r = 0.692, p < 0.0001). Among the lipid and lipid-related compounds studied, a significant correlation was found between cystatin C and apolipoprotein A1 concentrations (r = 0.402, p = 0.034). None of those correlations were observed in the NC group. In conclusion, it seems that cystatin C levels before HD are related with CRP, an important inflammatory factor, and also with apolipoprotein A1, which has been proved to accelerate the atherosclerosis process. However more studies are needed to confirm these findings.

TLRs are important inflammatory factors in atherosclerosis and may be a therapeutic target

Inflammation and immune reactions are implicated in atherogenesis and plaque disruption. The precise triggers for inflammation in atherosclerosis are not fully understood but may include hypercholesterolemia, modified lipoproteins and local or distant infections. TLRs play an important role in the innate and inflammatory signaling responses to microbial agents. Evidence from diverse sources has suggested that TLRs can affect atherosclerosis in multiple ways. Several reports have documented the expression of TLRs in atherosclerotic lesions and suggested that the TLR-NF-kappa B pathway is activated in the lesion, resulting in the transcription of a variety of genes involved in the inflammatory and proliferative responses of cells critical to atherogenesis and ultimately leading to the synthesis and release of antimicrobial peptides and inflammatory cytokines that provide a critical link to adaptive immunity. Moreover, TLR4 expression in macrophages is up-regulated by oxidized LDL, which suggests a potential mechanism for the synergistic effects of hypercholesterolemia and infection in acceleration of atherosclerosis. These findings indicate that TLRs provide additional new insights into the link among lipids, infection/inflammation and atherosclerosis, thus may be effective therapeutic target molecules. We speculate that TLRs are important for the development and progression of atherosclerosis, and hence blocking the expression of TLRs may serve as new targets for antiatherogenic therapy.

D‐4F, an apoA‐I mimetic, protects Endothelium‐dependent vasodilation and endothelial cell proliferation against the inhibitory effects of POVPC

Oxidized phospholipids are important atherogenic and inflammatory factors in the vessel wall. Several studies show the levels of oxidized lipids in the atherosclerotic plaque are increased and proportionally related to the premature development of coronary heart disease. However, their direct effects on vasodilation and endothelial cell (EC) function remain unclear. Here we use isolated and pressurized (60 mmHg) facialis arteries of C57BL/6 mice to test the in vitro effects of 1-palmitoyl-2-oxovaleroyl-sn-glycero-3-phosphorylcholine (POVPC) on endothelium-dependent vasodilation by videomicroscopy. Endothelium-dependent vasodilation in response to acetylcholine (Ach, 10−7 – 10−4 M) was impaired by 10 μM of POVPC (40% of controls, n = 5, p < 0.05). D-4F, an apo A-I mimetic, reversed, in part, the inhibitory effects of POVPC on vasodilation (increased vasodilation to 84% of control, n = 5, p < 0.05). Next, we examined the effects of POVPC on VEGF-stimulated EC proliferation in human umbilical vein endothelial cells (HUVEC). Proliferation was determined by incorporation of [3H]-thymidine into HUVEC DNA. We found 25 μM of POVPC significantly inhibited VEGF (10 ng/ml)-induced EC proliferation. D-4F restored, in part, VEGF-stimulated EC proliferation up to 50% of the VEGF control value (n = 3, p < 0.05). These data indicate D-4F protects vascular EC function with respect to vasodilation and EC proliferation against the proinflammatory effects of POVPC.