ABSTRACT
Cardiac arrest (CA) results in a central and systemic cytokine and inflammatory response. Thalidomide has been reported to be neuroprotective by selectively decreasing TNFα synthesis. We hypothesized that thalidomide would decrease the systemic and organ-specific TNFα/cytokine response and biomarkers of injury in rats subjected to 10 min CA. Naïves, CA treated with vehicle (CA) and CA treated with thalidomide (50 mg/kg; CA+T) were studied (n=6 per group). TNFα and key cytokines were assessed at 3 h after resuscitation in the cortex, hippocampus, striatum, cerebellum, plasma, heart and lung. Neuron specific enolase (NSE), S100b, cardiac troponin T (cTnT) and intestinal fatty acid binding protein (IFABP) were used to assess neuronal, glial, cardiac and intestinal damage, respectively. CA increased TNFα and multiple pro-inflammatory cytokines in plasma and selected tissues with no differences between the CA and CA+T groups in any region. NSE, S100b, cTnT and IFABP were increased after CA or CA+T vs. in the naïve group (all P<0.05) without significant differences between the CA and CA+T groups. In conclusion, CA resulted in a TNFα and cytokine response, with increased biomarkers of organ injury. Notably, thalidomide at a dose reported to improve the outcome in in vivo models of brain ischemia did not decrease TNFα or cytokine levels in plasma, brain or extracerebral organs, or biomarkers of injury. Although CA at 3 h post resuscitation produces a robust TNFα response, it cannot be ruled out that an alternative dosing regimen or assessment at other time-points might yield different results. The marked systemic and regional cytokine response to CA remains a potential therapeutic target.
ABSTRACT
Background Current postresuscitative care after cardiac arrest (CA) does not address the cause of CA. We previously reported that asphyxial CA (ACA) and ventricular fibrillation CA (VFCA) elicit unique injury signatures. We hypothesized that the early cytokine profiles of the serum, heart, and brain differ in response to ACA versus VFCA. Methods and Results Adult male rats were subjected to 10 minutes of either ACA or VFCA. Naives and shams (anesthesia and surgery without CA) served as controls (n=12/group). Asphyxiation produced an ≈4-minute period of progressive hypoxemia followed by a no-flow duration of ≈6±1 minute. Ventricular fibrillation immediately induced no flow. Return of spontaneous circulation was achieved earlier after ACA compared with VFCA (42±18 versus 105±22 seconds; P<0.001). Brain cytokines in naives were, in general, low or undetectable. Shams exhibited a modest effect on select cytokines. Both ACA and VFCA resulted in robust cytokine responses in serum, heart, and brain at 3 hours. Significant regional differences pinpointed the striatum as a key location of neuroinflammation. No significant differences in cytokines, neuron-specific enolase, S100b, and troponin T were observed across CA models. Conclusions Both models of CA resulted in marked systemic, heart, and brain cytokine responses, with similar degrees of change across the 2 CA insults. Changes in cytokine levels after CA were most pronounced in the striatum compared with other brain regions. These collective observations suggest that the amplitude of the changes in cytokine levels after ACA versus VFCA may not mediate the differences in secondary injuries between these 2 CA phenotypes.
