Molecular analysis of inflammatory markers in trauma patients at risk of postinjury complications.

BACKGROUND: Genetic differences associated with individual's immune responses appear to be a major contributing factor to the development of trauma- induced sepsis. Thus, effective treatment of sepsis requires the identification of the patients who are at increased risk for sepsis. METHODS: Sixty-eight patients, of which the majority had an injury severity score >15, and 118 controls from the same geographic region were genotyped. Cytokine and Toll-like receptor (TLR) genotypes and expressions were tested using polymerase chain reaction (PCR). RESULTS: Fifty percent of African American and 42% of Caucasian patients developed posttrauma sepsis. Frequency distribution of the polymorphism for some cytokine genes such as Interleukin (IL)-10 low/high and interferon (IFN)-gamma low producer were statistically different between the septic and aseptic patients, for others, such as tumor necrosis factor (TNF)-alpha, IL-6, and IL-18, there was no statistical difference. The TLR-2 genotypes (A/G) were considered a sepsis risk marker as compared with A/A (62.5% versus 37.5%, p < 0.03; relative risk = 2.5) in African American patients. Cytokine mRNA levels correlated with genotype definition, particularly, for IL-10, IL-6, IL-18, and TNF-alpha. A time course study demonstrated a significant difference in cytokines expression profile in septic and aseptic patients before the development of sepsis. CONCLUSION: Monitoring cytokine expression levels before the disease might predict the outcome of sepsis. A large cohort study is needed to assess the diagnostic potential of the genotypes.

Frequency distribution of cytochrome P450 3A4 gene polymorphism in ethnic populations and in transplant recipients.

CYP 3A4 plays a vital role in the metabolism of many drugs including immunosuppressants. An association between a transition of A --> G at position -290 of the 5'-regulatory region of the CYP 3A4 gene and an effect on the level of transcription has been reported. The CYP 3A4-G variant frequency varies substantially in different populations. In addition it has been demonstrated in association with several disease conditions, including clinical grades of prostate cancer, breast cancer, secondary leukemia, hypercholesterolemia and diabetes. We sought to determine the frequency distributions, in African American (AFAM) and Caucasian (CAU) populations as well as patients with multiple complex diseases, such as those that had undergone cardiac or renal transplantation. Sequence-specific primers and PCR were used to determine genotype variation in 206 AFAM and 108 CAU individuals. CYP 3A4-G genotype was present with a higher frequency in AFAM individuals as compared with CAU (83% vs. 3%, p < 0.0001, RR = 3.9). The homozygous AA allele was predominantly present in CAU (97%) but only 17% in AFAM (p < 0.0001, RR = 2.5). In contrast, the homozygous GG allele was only detected in AFAM group (14.6%). The frequency distribution of homozygous GG and AA alleles were inversely present in male vs. female patients with CTx or RTx. Pre-transplantation clinical conditions demonstrated that hypertension (HTN), hyperlipidemia and to a lesser extent diabetes (DM) were present in CTx and RTx patients with homozygous GG alleles. In addition, 75% of AFAM patients with homozygous GG genotype experienced multiple rejection episodes with severity grades of 3A after cardiac transplantation, and 31.5% of homozygous GG patients with RTx suffered from rejections (p < 0.05; RR = 2.4). In conclusion, CYP 3A4 genotype demonstrated a remarkable interindividual variation between AFAM and CAU populations, and furthermore CTx patients with homozygous GG genotype were at higher risk of developing rejection as compared with RTx patients. This indicates an underlying heterogeneity with regard to the disease characteristics as well as the therapy regimen.

Neurotrophin and GDNF family ligands promote survival and alter excitotoxic vulnerability of neurons derived from murine embryonic stem cells.

Embryonic stem (ES) cells are genetically manipulable pluripotential cells that can be differentiated in vitro into neurons, oligodendrocytes, and astrocytes. Given their potential utility as a source of replacement cells for the injured nervous system and the likelihood that transplantation interventions might include co-application of growth factors, we examined the effects of neurotrophin and GDNF family ligands on the survival and excitotoxic vulnerability of ES cell-derived neurons (ES neurons) grown in vitro. ES cells were differentiated down a neural lineage in vitro using the 4-/4+ protocol (Bain et al., Dev Biol 168:342-57, 1995). RT-PCR demonstrated expression of receptors for neurotrophins and GDNF family ligands in ES neural lineage cells. Neuronal expression of GFRalpha1, GFRalpha2, and ret was confirmed by immunocytochemistry. Exposure to 30-100 ng/ml GDNF or neurturin (NRTN) resulted in activation of ret. Addition of NT-3 and GDNF did not increase cell division but did increase the number of neurons in the cultures 7 days after plating. Pretreatment with NT-3 enhanced the vulnerability of ES neurons to NMDA-induced death (100 microM NMDA for 10 min) and enhanced the NMDA-induced increase in neuronal [Ca2+]i, but did not alter expression of NMDA receptor subunits NR2A or NR2B. In contrast, pretreatment with GDNF reduced the vulnerability of ES neurons to NMDA-induced death while modestly enhancing the NMDA-induced increase in neuronal [Ca2+]i. These findings demonstrate that the response of ES-derived neurons to neurotrophins and GDNF family ligands is largely similar to that of other cultured central neurons.

A proteasomal stress response: pre-treatment with proteasome inhibitors increases proteasome activity and reduces neuronal vulnerability to oxidative injury.

We report here that exposure to low concentrations of proteasome inhibitors (e.g. 10-100 nm MG-132, 0.1-3 nm epoxomicin or 10-30 nm clasto-lactacystin beta-lactone) resulted in an enhancement, rather than an inhibition, of proteasome activity in cultured neocortical neurons. Size-fractionation chromatography confirmed that the enhanced peptide cleavage activity was associated with proteasome-sized complexes. This sub toxic exposure reduced neuronal death caused by subsequent exposure to oxidative stress (100-200 microm H(2)O(2) for 30 min, 24-h exposure to 100 microm paraquat or 7.5 microm menadione), but did not alter vulnerability to excitotoxicity (5-min exposure to 30-100 microm NMDA or 24 exposure to 12 microm NMDA). Sub toxic proteasome inhibitor exposure caused an increase in levels of proteasome core subunit proteins and mRNAs, but not in levels of potentially cytoprotective heat shock proteins (hsp70, hsp90 and hsp40). The neuroprotective effects of proteasome inhibitor pre-treatment were blocked by coapplication of proteasome inhibitors during the oxidative insult. These findings support a model in which sublethal proteasome inhibition induces neurons to increase proteasome activity and promotes resistance to oxidative injury and suggests that enhancement of proteasome activity is a potential therapeutic target for diseases in which oxidative stress has been implicated.

NMDA antagonists exacerbate neuronal death caused by proteasome inhibition in cultured cortical and striatal neurons.

The proteasome is involved in multiple cellular processes including control of the cell cycle, apoptosis and intracellular signalling; loss of proteasome function has been postulated to participate in the pathogenesis of triplet repeat diseases. We examined the vulnerability of central neurons to proteasome inhibition and tested the ability of anti-excitotoxic and anti-apoptotic treatments to attenuate proteasome inhibition-induced neuronal death. Exposure of murine neocortical cultures to proteasome inhibitors (0.1-10 microm clasto-lactacystin beta-lactone or MG-132) for 48 h resulted in widespread neuronal death associated with a reduction in intracellular free calcium; higher inhibitor concentrations killed astrocytes. Cultured striatal neurons were more vulnerable than cortical neurons. Within each population, the NADPH diaphorase-positive neuronal subpopulation was more vulnerable than the general neuronal population. Enhancing calcium entry with S(-)BayK8644 or kainate, or blocking apoptosis with cycloheximide, actinomycin D or Z-VAD.FMK attenuated neuronal death, whereas, reducing calcium entry with NMDA antagonists or R(+)BayK8644 potentiated neuronal death. These findings suggest that proteasome inhibition can induce selective neuronal apoptosis associated with intracellular calcium starvation, and point to manipulation of intracellular calcium as a specific therapeutic strategy. In particular, concern is raised that glutamate receptor antagonists might exacerbate, rather than attenuate, proteasome inhibition-induced neuronal death.