Publications

Infection and inflammation affect adipose triglyceride metabolism, resulting in increased plasma free fatty acid (FFA) and VLDL levels during the acute-phase response. Lipin-1, a multifunctional protein, plays a critical role in adipose differentiation, mitochondrial oxidation, and triglyceride synthesis. Here, we examined whether LPS [a Toll-like receptor (TLR)-4 activator], zymosan (a TLR-2 activator), and proinflammatory cytokines regulate lipin-1 in adipose tissue. LPS administration caused a marked decrease in the levels of lipin-1 mRNA and protein in adipose tissue. The decrease in lipin-1 mRNA levels occurred rapidly and lasted for at least 24 h. In contrast, lipin-2 and -3 mRNA levels did not change, suggesting specific repression of lipin-1. Zymosan similarly decreased lipin-1 mRNA without affecting lipin-2 or lipin-3 mRNA levels. To determine the pathways by which LPS repressed lipin-1, we examined the effect of proinflammatory cytokines on cultured adipocytes. In 3T3-L1 adipocytes, TNF-alpha, IL-1beta, and IFN-gamma, but not LPS or IL-6, caused a decrease in lipin-1 mRNA levels. Furthermore, TNF-alpha and IL-1beta administration also decreased mRNA levels of lipin-1 in adipose tissue in mice. Importantly, the LPS-induced decrease in lipin-1 mRNA levels was significantly but not totally blunted in TNF-alpha/IL-1 receptor-null mice compared with controls, suggesting key roles for TNF-alpha/IL-1beta and other cytokines in mediating LPS-induced repression of lipin-1. Together, our results demonstrate that expression of lipin-1, one of the essential triglyceride synthetic enzymes, was suppressed by LPS, zymosan, and proinflammatory cytokines in mouse adipose tissue and in cultured 3T3-L1 adipocytes, which could contribute to a decrease in the utilization of FFA to synthesize triglycerides in adipose tissue, thus promoting the release of FFA into the circulation.

BACKGROUND

Partial External Biliary Diversion (PEBD) is a surgical intervention to treat children with Progressive Familial Intrahepatic Cholestasis (PFIC) and Alagille syndrome (AGS). PEBD can reduce disease progression, and examining the alterations in biliary lipid composition may be a prognostic factor for outcome.

METHODS

Biliary lipid composition and the clinical course of AGS and PFIC patients were examined before and after PEBD.

RESULTS

Pre-PEBD bile from AGS patients had greater chenodeoxycholic/cholic acid (CDCA/CA), bile salt, cholesterol and phospholipid concentrations than PFIC patients. AGS patients, and PFIC patients with familial intrahepatic cholestasis 1 (FIC1) genotype, responded better to PEBD than PFIC patients with bile salt export protein (BSEP) genotype. After successful PEBD, AGS patients have higher biliary lipid concentrations than PFIC patients and PEBD also increases biliary phospholipid concentrations in FIC1 patients.

CONCLUSION

Both AGS and FIC1 patients can benefit from PEBD, and preserved biliary phospholipid concentrations may be associated with better outcomes post-PEBD.

Rapid rebound of plasma viremia in patients after interruption of long-term combination antiretroviral therapy (cART) suggests persistence of low-level replicating cells or rapid reactivation of latently infected cells. To further characterize rebounding virus, we performed extensive longitudinal clonal evolutionary studies of HIV env C2-V3-C3 regions and exploited the temporal relationships of rebounding plasma viruses with regard to pretreatment sequences in 20 chronically HIV-1-infected patients having undergone multiple 2-week structured treatment interruptions (STI). Rebounding virus during the short STI was homogeneous, suggesting mono- or oligoclonal origin during reactivation. No evidence for a temporal structure of rebounding virus in regard to pretreatment sequences was found. Furthermore, expansion of distinct lineages at different STI cycles emerged. Together, these findings imply stochastic reactivation of different clones from long-lived latently infected cells rather than expansion of viral populations replicating at low levels. After treatment was stopped, diversity increased steadily, but pretreatment diversity was, on average, achieved only >2.5 years after the start of STI when marked divergence from preexisting quasispecies also emerged. In summary, our results argue against persistence of ongoing low-level replication in patients on suppressive cART. Furthermore, a prolonged delay in restoration of pretreatment viral diversity after treatment interruption demonstrates a surprisingly sustained evolutionary bottleneck induced by punctuated antiretroviral therapy.

The liganded vitamin D receptor (VDR) is thought to play an important role in controlling cardiac function. Specifically, this system has been implicated as playing an antihypertrophic role in the heart. Despite this, studies of VDR in the heart have been limited in number and scope. In the present study, we used a combination of real-time polymerase chain reaction, Western blot analysis, immunofluorescence, and transient transfection analysis to document the presence of functional VDR in both the myocytes and fibroblasts of the heart, as well as in the intact ventricular myocardium. We also demonstrated the presence of 1-alpha-hydroxylase and 24-hydroxylase in the heart, 2 enzymes involved in the synthesis and metabolism of 1,25 dihydroxyvitamin D. VDR is shown to interact directly with the human B-type natriuretic peptide gene promoter, a surrogate marker of the transcriptional response to hypertrophy. Of note, induction of myocyte hypertrophy either in vitro or in vivo leads to an increase in VDR mRNA and protein levels. Collectively, these findings suggest that the key components required for a functional 1,25 dihydroxyvitamin D-dependent signaling system are present in the heart and that this putatively antihypertrophic system is amplified in the setting of cardiac hypertrophy.