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Biomedical subjects

Gideon M Hirschfield

Publications and source records attributed to Gideon M Hirschfield.

8 recordsLinked to original sources
PubMed2024

Identifying a therapeutic window of opportunity for people living with primary sclerosing cholangitis: Embryology and the overlap of inflammatory bowel disease with immune-mediated liver injury.

Primary sclerosing cholangitis (PSC) is a variably progressive, fibrosis-causing autoimmune disorder of the intrahepatic and extrahepatic bile ducts of unclear etiology. PSC is commonly (in 60%-90% of cases) associated with an inflammatory bowel disease (IBD) like PSC-IBD and less commonly with an autoimmune hepatitis (AIH) like PSC-AIH or AIH-overlap disorder. Hepatologists and Gastroenterologists often consider these combined conditions as distinctly different from the classical forms in isolation. Here, we review recent epidemiologic observations and highlight that PSC-IBD and PSC-AIH overlap appear to represent aspects of a common PSC clinico-pathological pathway and manifest in an age-of-presentation-dependent manner. Particularly from the pediatric experience, we hypothesize that all cases of PSC likely originate from a complex "Early PSC"-"IBD"-"AIH" overlap in which PSC defines the uniquely and variably associated "AIH" and "IBD" components along an individualized lifetime continuum. We speculate that a distinctly unique, "diverticular autoimmunity" against the embryonic cecal- and hepatic diverticulum-derived tissues may be the origin of this combined syndrome, where "AIH" and "IBD" variably commence then variably fade while PSC progresses with age. Our hypothesis provides an explanation for the age-dependent variation in the presentation and progression of PSC. This is critical for the optimal targeting of studies into PSC etiopathogenesis and emphasizes the concept of a "developmental window of opportunity for therapeutic mitigation" in what is currently recognized as an irreversible disease process. The discovery of such a window would be critically important for the targeting of interventions, both the administration of current therapies and therapeutic trial planning.

Humans↗
PubMed2006

Targeting C-reactive protein for the treatment of cardiovascular disease.

Complement-mediated inflammation exacerbates the tissue injury of ischaemic necrosis in heart attacks and strokes, the most common causes of death in developed countries. Large infarct size increases immediate morbidity and mortality and, in survivors of the acute event, larger non-functional scars adversely affect long-term prognosis. There is thus an important unmet medical need for new cardioprotective and neuroprotective treatments. We have previously shown that human C-reactive protein (CRP), the classical acute-phase protein that binds to ligands exposed in damaged tissue and then activates complement, increases myocardial and cerebral infarct size in rats subjected to coronary or cerebral artery ligation, respectively. Rat CRP does not activate rat complement, whereas human CRP activates both rat and human complement. Administration of human CRP to rats is thus an excellent model for the actions of endogenous human CRP. Here we report the design, synthesis and efficacy of 1,6-bis(phosphocholine)-hexane as a specific small-molecule inhibitor of CRP. Five molecules of this palindromic compound are bound by two pentameric CRP molecules, crosslinking and occluding the ligand-binding B-face of CRP and blocking its functions. Administration of 1,6-bis(phosphocholine)-hexane to rats undergoing acute myocardial infarction abrogated the increase in infarct size and cardiac dysfunction produced by injection of human CRP. Therapeutic inhibition of CRP is thus a promising new approach to cardioprotection in acute myocardial infarction, and may also provide neuroprotection in stroke. Potential wider applications include other inflammatory, infective and tissue-damaging conditions characterized by increased CRP production, in which binding of CRP to exposed ligands in damaged cells may lead to complement-mediated exacerbation of tissue injury.

Animals↗
PubMed2005

Transgenic human C-reactive protein is not proatherogenic in apolipoprotein E-deficient mice.

The association between circulating concentrations of C-reactive protein (CRP) and future atherothrombotic events has provoked speculation about a possible pathogenetic role of CRP. However, we show here that transgenic expression of human CRP had no effect on development, progression, or severity of spontaneous atherosclerosis, or on morbidity or mortality, in male apolipoprotein E (apoE)-deficient C57BL/6 mice up to 56 weeks, despite deposition of human CRP and mouse complement component 3 in the plaques. Although female apoE knockouts develop atherosclerosis more rapidly than males, the human CRP transgene is under sex hormone control and is expressed at human levels only in males. We therefore studied only male mice. The concentration of mouse serum amyloid P component, an extremely sensitive systemic marker of inflammation, remained normal throughout except for transient spikes in response to fighting in a few animals, indicating that atherogenesis in this model is not associated with an acute-phase response. However, among human CRP transgenic mice, the circulating CRP concentration was higher in apoE knockouts than in wild-type controls. The higher CRP values were associated with substantially lower estradiol concentrations in the apoE-deficient animals. Human CRP transgene expression is thus up-regulated in apoE-deficient mice, apparently reflecting altered estrogen levels, despite the absence of other systemic signs of inflammation. Extrapolation to human pathology from this xenogeneic combination of human CRP with apoE deficiency-mediated mouse atherosclerosis must be guarded. Nevertheless, the present results do not suggest that human CRP is either proatherogenic or atheroprotective in vivo.

Acute-Phase Reaction↗
PubMed2005

Inflammation and endothelial function: direct vascular effects of human C-reactive protein on nitric oxide bioavailability.

BACKGROUND: Circulating concentrations of the sensitive inflammatory marker C-reactive protein (CRP) predict future cardiovascular events, and CRP is elevated during sepsis and inflammation, when vascular reactivity may be modulated. We therefore investigated the direct effect of CRP on vascular reactivity. METHODS AND RESULTS: The effects of isolated, pure human CRP on vasoreactivity and protein expression were studied in vascular rings and cells in vitro, and effects on blood pressure were studied in rats in vivo. The temporal relationship between changes in CRP concentration and brachial flow-mediated dilation was also studied in humans after vaccination with Salmonella typhi capsular polysaccharide, a model of inflammatory endothelial dysfunction. In contrast to some previous reports, highly purified and well-characterized human CRP specifically induced hyporeactivity to phenylephrine in rings of human internal mammary artery and rat aorta that was mediated through physiological antagonism by nitric oxide (NO). CRP did not alter endothelial NO synthase protein expression but increased protein expression of GTP cyclohydrolase-1, the rate-limiting enzyme in the synthesis of tetrahydrobiopterin, the NO synthase cofactor. In the vaccine model of inflammatory endothelial dysfunction in humans, increased CRP concentration coincided with the resolution rather than the development of endothelial dysfunction, consistent with the vitro findings; however, administration of human CRP to rats had no effect on blood pressure. CONCLUSIONS: Pure human CRP has specific, direct effects on vascular function in vitro via increased NO production; however, further clarification of the effect, if any, of CRP on vascular reactivity in humans in vivo will require clinical studies using specific inhibitors of CRP.

Animals↗
PubMed2004

C-reactive protein and other circulating markers of inflammation in the prediction of coronary heart disease.

BACKGROUND: C-reactive protein is an inflammatory marker believed to be of value in the prediction of coronary events. We report data from a large study of C-reactive protein and other circulating inflammatory markers, as well as updated meta-analyses, to evaluate their relevance to the prediction of coronary heart disease. METHODS: Measurements were made in samples obtained at base line from up to 2459 patients who had a nonfatal myocardial infarction or died of coronary heart disease during the study and from up to 3969 controls without a coronary heart disease event in the Reykjavik prospective study of 18,569 participants. Measurements were made in paired samples obtained an average of 12 years apart from 379 of these participants in order to quantify within-person fluctuations in inflammatory marker levels. RESULTS: The long-term stability of C-reactive protein values (within-person correlation coefficient, 0.59; 95 percent confidence interval, 0.52 to 0.66) was similar to that of both blood pressure and total serum cholesterol. After adjustment for base-line values for established risk factors, the odds ratio for coronary heart disease was 1.45 (95 percent confidence interval, 1.25 to 1.68) in a comparison of participants in the top third of the group with respect to base-line C-reactive protein values with those in the bottom third, and similar overall findings were observed in an updated meta-analysis involving a total of 7068 patients with coronary heart disease. By comparison, the odds ratios in the Reykjavik Study for coronary heart disease were somewhat weaker for the erythrocyte sedimentation rate (1.30; 95 percent confidence interval, 1.13 to 1.51) and the von Willebrand factor concentration (1.11; 95 percent confidence interval, 0.97 to 1.27) but generally stronger for established risk factors, such as an increased total cholesterol concentration (2.35; 95 percent confidence interval, 2.03 to 2.74) and cigarette smoking (1.87; 95 percent confidence interval, 1.62 to 2.16). CONCLUSIONS: C-reactive protein is a relatively moderate predictor of coronary heart disease. Recommendations regarding its use in predicting the likelihood of coronary heart disease may need to be reviewed.

Aged↗
PubMed2004

Amyloidosis: a clinico-pathophysiological synopsis.

Amyloidosis encompasses a spectrum of diseases in which there is disordered folding of certain proteins that leads to them being deposited as insoluble fibrils in the extracellular space. The result of this process is impaired tissue structure and function. Amyloidosis may be acquired or hereditary and local or systemic, and is defined according to the identity of the fibril precursor protein. Over 20 unrelated proteins can form amyloid fibrils in vivo, which all share a lamellar cross-beta-sheet structure composed of non-covalently associated protein or peptide subunits. Glycosaminoglycans and the pentraxin protein, serum amyloid P component, are universal non-fibrillar constituents of amyloid deposits that are believed to play a role in fibrillogenesis and fibril persistence. Greater understanding of the processes underlying amyloidogenesis, at all levels from cellular to clinical, has led to improvements in diagnosis, monitoring and treatment of this group of diseases, as well as pointing to possible future therapies.

Acetylglucosamine↗
PubMed2003

Human C-reactive protein does not protect against acute lipopolysaccharide challenge in mice.

The physiological and pathophysiological functions of C-reactive protein (CRP), the classical acute-phase protein, are not well established, despite many reports of biological effects of CRP in vitro and in model systems in vivo. Limited, small scale experiments have suggested that rabbit and human CRP may both protect mice against lethal toxicity of Gram-negative bacterial LPS. However, in substantial well-controlled studies in C57BL/6 mice challenged with Escherichia coli O111:B4 LPS, we show in this work that significant protection against lethality was conferred neither by an autologous acute-phase response to sterile inflammatory stimuli given to wild-type mice 24 h before LPS challenge, nor by human CRP, whether passively administered or expressed transgenically. Male mice transgenic for human CRP, which mount a major acute-phase response of human CRP after LPS injection, were also not protected against the lethality of LPS from either E. coli O55:B5 or Salmonella typhimurium. Even when the acute-phase human CRP response was actively stimulated in transgenic mice before LPS challenge, no protection against LPS toxicity was observed. Indeed, male mice transgenic for human CRP that were pretreated with casein to stimulate an acute-phase response 24 h before LPS challenge suffered significantly greater mortality than unstimulated human CRP transgenic controls. Rather than being protective in this situation, human CRP may thus have pathogenic proinflammatory effects in vivo.

Acute-Phase Reaction↗