Cerebral haemodynamics and carbon dioxide reactivity during sepsis syndrome

peer reviewed[en] BACKGROUND: Most patients with sepsis develop potentially irreversible cerebral dysfunctions. It is yet not clear whether cerebral haemodynamics are altered in these sepsis patients at all, and to what extent. We hypothesized that cerebral haemodynamics and carbon dioxide reactivity would be impaired in patients with sepsis syndrome and pathological electroencephalogram patterns. METHODS: After approval of the institutional ethics committee, 10 mechanically ventilated patients with sepsis syndrome and pathological electroencephalogram patterns underwent measurements of cerebral blood flow and jugular venous oxygen saturation before and after reduction of the arterial carbon dioxide partial pressure by 0.93 +/- 0.7 kPa iu by hyperventilation. The cerebral capillary closing pressure was determined from transcranial Doppler measurements of the arterial blood flow of the middle cerebral artery and the arterial pressure curve. A t test for matched pairs was used for statistical analysis (P < 0.05). RESULTS: During stable mean arterial pressure and cardiac index, reduction of the arterial carbon dioxide partial pressure led to a significant increase of the capillary closing pressure from 25 +/- 11 mmHg to 39 +/- 15 mmHg (P < 0.001), with a consecutive decrease of blood flow velocity in the middle cerebral artery of 21.8 +/- 4.8%/kPa (P < 0.001), of cerebral blood flow from 64 +/- 29 ml/100 g/min to 39 +/- 15 ml/100 g/min (P < 0.001) and of jugular venous oxygen saturation from 75 +/- 8% to 67 +/- 14% (P < 0.01). CONCLUSION: In contrast to other experimental and clinical data, we observed no pathological findings in the investigated parameters of cerebral perfusion and oxygenation

Toll-like receptor 4 deficiency: Smaller infarcts, but nogain in function

<p>Abstract</p> <p>Backgound</p> <p>It has been reported that Toll-like receptor 4 (TLR4) deficiency reduces infarct size after myocardial ischemia/reperfusion (MI/R). However, measurement of MI/R injury was limited and did not include cardiac <b>function</b>. In a chronic closed-chest model we assessed whether cardiac <b>function </b>is preserved in TLR4-deficient mice (C3H/HeJ) following MI/R, and whether myocardial and systemic cytokine expression differed compared to wild type (WT).</p> <p>Results</p> <p>Infarct size (IS) in C3H/HeJ assessed by TTC staining after 60 min ischemia and 24h reperfusion was significantly smaller than in WT. Despite a smaller infarct size, echocardiography showed no functional difference between C3H/HeJ and WT. Left-ventricular developed pressure measured with a left-ventricular catheter was lower in C3H/HeJ (63.0 ± 4.2 mmHg vs. 77.9 ± 1.7 mmHg in WT, p < 0.05). Serum cytokine levels and myocardial IL-6 were higher in WT than in C3H/HeJ (p < 0.05). C3H/HeJ MI/R showed increased myocardial IL-1β and IL-6 expression compared to their respective shams (p < 0.05), indicating TLR4-independent cytokine activation due to MI/R.</p> <p>Conclusion</p> <p>These results demonstrate that, although a mutant TLR4 signaling cascade reduces myocardial IS and serum cytokine levels, it <b>does not preserve myocardial function</b>. The change in inflammatory response, secondary to a non-functional TLR-4 receptor, may contribute to the observed dichotomy between infarct size and function in the TLR-4 mutant mouse.</p

Synergistic Stimulation with Different TLR7 Ligands Modulates Gene Expression Patterns in the Human Plasmacytoid Dendritic Cell Line CAL-1

Objective. TLR7 ligation in plasmacytoid dendritic cells is promising for the treatment of cancer, allergy, and infectious diseases; however, high doses of ligands are required. We hypothesized that the combination of structurally different TLR7 ligands exponentiates the resulting immune response. Methods. CAL-1 (human pDC line) cells were incubated with the TLR7-specific adenine analog CL264 and single-stranded 9.2s RNA. Protein secretion was measured by ELISA. Microarray technique was used to detect modified gene expression patterns upon synergistic stimulation, revealing underlying functional groups and networks. Cell surface binding properties were studied using FACS analysis. Results. CL264 in combination with 9.2s RNA significantly enhanced cytokine and interferon secretion to supra-additive levels. This effect was due to a stronger stimulation of already regulated genes (by monostimulation) as well as to recruitment of thus far unregulated genes. Top scoring canonical pathways referred to immune-related processes. Network analysis revealed IL-1β, IL-6, TNF, and IFN-β as major regulatory nodes, while several minor regulatory nodes were also identified. Binding of CL264 to the cell surface was enhanced by 9.2s RNA. Conclusion. Structurally different TLR7 ligands act synergistically on gene expression patterns and on the resulting inflammatory response. These data could impact future strategies optimizing TLR7-targeted drug design