Liver biopsy for assessment of suspected drug-induced liver injury in metabolic dysfunction-associated steatohepatitis clinical trials: Expert consensus from the Liver Forum

BACKGROUND

Causality assessment of suspected drug-induced liver injury (DILI) during metabolic dysfunction-associated steatohepatitis (MASH) clinical trials can be challenging, and liver biopsies are not routinely performed as part of this evaluation. While the field is moving away from liver biopsy as a diagnostic and prognostic tool, information not identified by non-invasive testing may be provided on histology.

AIM

To address the appropriate utilisation of liver biopsy as part of DILI causality assessment in this setting.

METHODS

From 2020 to 2022, the Liver Forum convened a series of webinars on issues pertaining to liver biopsy during MASH trials. The Histology Working Group was formed to generate a series of consensus documents addressing these challenges. This manuscript focuses on liver biopsy as part of DILI causality assessment.

RESULTS

Expert opinion, guidance and recommendations on the role of liver biopsy as part of causality assessment of suspected DILI occurring during clinical trials for a drug(s) being developed for MASH are provided. Lessons learned from prior MASH programs are reviewed and gaps identified.

CONCLUSIONS

Although there are no pathognomonic features, histologic evaluation of suspected DILI during MASH clinical trials may alter patient management, define the pattern and severity of injury, detect findings that favour a diagnosis of DILI versus MASH progression, identify prognostic features, characterise the clinicopathological phenotype of DILI, and/or define lesions that influence decisions about trial discontinuation and further development of the drug.

Zafirlukast is a broad-spectrum thiol isomerase inhibitor that inhibits thrombosis without altering bleeding times

BACKGROUND AND PURPOSE

Multiple members of the thiol isomerase (TI) family of enzymes are present in and released by platelets. Inhibition of these enzymes results in diminished platelet responses, aggregation, adhesion and thrombus formation. Recently, the therapeutic potential of TI inhibition has been recognised and drug-development technologies were used to identify selective small molecule inhibitors. To date, few pan-TI inhibitors have been characterised and the most studied, bacitracin, is known to be nephrotoxic, which prohibits its systemic therapeutic usage.

EXPERIMENTAL APPROACH

We therefore sought to identify novel broad-spectrum inhibitors of these enzymes and test their effects in vivo. A total of 3,641 compounds were screened for inhibitory effects on the redox activity of ERp5, protein disulphide isomerase (PDI), ERp57, ERp72 and thioredoxin in an insulin turbidity assay. Of the lead compounds identified, zafirlukast was selected for further investigation.

KEY RESULTS

When applied to platelets, zafirlukast diminished platelet responses in vitro. Zafirlukast was antithrombotic in murine models of thrombosis but did not impair responses in a model of haemostasis. Since TIs are known to modulate adhesion receptor function, we explored the effects of zafirlukast on cell migration. This was inhibited independently of cysteinyl LT receptor expression and was associated with modulation of cell-surface free thiol levels consistent with alterations in redox activity on the cell surface.

CONCLUSION AND IMPLICATIONS

We identify zafirlukast to be a novel, potent, broad-spectrum TI inhibitor, with wide-ranging effects on platelet function, thrombosis and integrin-mediated cell migration. Zafirlukast is antithrombotic but does not cause bleeding.

MAFLD: A Consensus-Driven Proposed Nomenclature for Metabolic Associated Fatty Liver Disease

Fatty liver associated with metabolic dysfunction is common, affects a quarter of the population, and has no approved drug therapy. Although pharmacotherapies are in development, response rates appear modest. The heterogeneous pathogenesis of metabolic fatty liver diseases and inaccuracies in terminology and definitions necessitate a reappraisal of nomenclature to inform clinical trial design and drug development. A group of experts sought to integrate current understanding of patient heterogeneity captured under the acronym nonalcoholic fatty liver disease (NAFLD) and provide suggestions on terminology that more accurately reflects pathogenesis and can help in patient stratification for management. Experts reached consensus that NAFLD does not reflect current knowledge, and metabolic (dysfunction) associated fatty liver disease "MAFLD" was suggested as a more appropriate overarching term. This opens the door for efforts from the research community to update the nomenclature and subphenotype the disease to accelerate the translational path to new treatments.

cHCC-CCA: Consensus terminology for primary liver carcinomas with both hepatocytic and cholangiocytic differentation

Primary liver carcinomas with both hepatocytic and cholangiocytic differentiation have been referred to as "combined (or mixed) hepatocellular-cholangiocarcinoma." These tumors, although described over 100 years ago, have attracted greater attention recently because of interest in possible stem cell origin and perhaps because of greater frequency and clinical recognition. Currently, because of a lack of common terminology in the literature, effective treatment and predictable outcome data have been challenging to accrue. This article represents a consensus document from an international community of pathologists, radiologists, and clinicians who have studied and reported on these tumors and recommends a working terminology for diagnostic and research approaches for further study and evaluation.

CONCLUSION

It is recommended that diagnosis is based on routine histopathology with hematoxylin and eosin (H&E); immunostains are supportive, but not essential for diagnosis. (Hepatology 2018;68:113-126).

Outcome analysis of primary liver carcinomas

438

Background: Treatments for hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (IHCCa) are established. Significant debate exists over optimal treatment for biphenotypic primary liver carcinomas (PLC) with combined HCC and IHCCa (B-PLC) and is considered to be a contraindication for transplantation. The purpose of this analysis is to determine single center outcomes of patients with B-PLC compared to HCC and IHCCa. Methods: A prospective database was reviewed to determine treatments and survivals of patients with HCC, IHCCa and B-PLC. Results: From 1/1/2009 to 12/31/2014, 810 patients with PLC were treated with resection (LRx) (n = 117), liver transplant (OLT) (n = 224) or liver directed therapy (LDT) (n = 469). 723 patients had HCC, 34 had IHCCa and 53 had B-PLC. Overall Survival (OS) in the LDT group, was similar comparing all tumor types at 1 yr (61.7%) and 3 yrs. (23.8%) (p =.3) Median survival (MS) was 16.2 months. OS in the LRx group was also similar between tumor types (1yr 81.1% and 5yrs. 41.1%, p =.2) and MS was 40.9 months. Comparing OLT patients with HCC (n = 212, 77% within Milan) to B-PLC (n = 10, 70% within Milan), OS (1yr 92.5% and 5 yrs. 77.0%, p =.8) was comparable and so also were disease-specific (1yr 99.0% and 5yr 97.3%, p =.6) and disease-free (1yr 88.7% and 5yrs. 73.5%, p =.4) survivals. OS for patients with B-PLC was significantly greater in patients receiving OLT vs. LRx or LDT (p =.005). Conclusions: Biphenotypic PLC has a poor prognosis and has been considered a contraindication for OLT. In this limited series, however, outcomes with transplantation appear acceptable.

Biphenotypic Primary Liver Carcinomas: Assessing Outcomes of Hepatic Directed Therapy

BACKGROUND

Primary liver carcinomas with hepatocellular and cholangiocellular differentiation (b[HB]-PLC) are rare. Surgery offers the best prognosis, but there is a paucity of literature to guide therapy for patients with advanced or unresectable disease. This study aimed to evaluate outcomes of hepatic-directed therapy compared with those of systemic chemotherapy and surgery.

METHODS

A retrospective evaluation of patients with b(HB)-PLC from 1 January 2008 to 1 September 2014 was conducted. The patients were divided into the following four groups: transplantation (TX) group, surgical resection (SX) group, hepatic directed (HD) group, and systemic chemotherapy alone (SC) group. Overall and progression-free survival, treatment response, and clinicopathologic data were analyzed.

RESULTS

The study included 79 patients (37 females) with an average age of 62 years. The number of patients in each group were as follows: TX group (n = 6), SX group (n = 27), HD group (n = 18), and SC group (n = 28). The mean follow-up periods were 33 months for the TX group, 17 months for the SX group, 14 months for the HD group, and 7 months for the SX group. Overall, 28 % of the patients had cirrhosis and 35 % had viral hepatitis. The candidates for surgery comprised 42 % of the patients. The HD group (n = 18) had a significantly greater objective response than the SC group (n = 28) (47 vs. 6 %; p = 0.02). Two patients who underwent hepatic arterial infusion pump treatment were downstaged to resection. A trend toward improved OS/PFS was observed in the HD group versus the SC group, although statistically significant. The SX group had significantly improved survival (p < 0.001) as did the transplanted patients.

CONCLUSIONS

Although surgery offers the best survival for b(HB)-PLC patients, only a minority are candidates for surgery. Because HD therapy showed a superior objective response over SC therapy, it may offer a survival advantage and may downstage patients for surgical resection or transplantation.

Independent predictors of overall survival and recurrence in biphenotypic hepatocellular cancer

291

Background: Biphenotypic hepatocellular cancer (BPHCC), which is a combined hepatocellular cancer (HCC) and cholangiocarcinoma (CC), is a rare form of primary liver cancer, whose long term prognosis is extremely poor as compared to either HCC or CC alone. Little is known about the recurrence rates and predictors of recurrence in BPHCC. Our objective was to 1) identify both overall survival and recurrence rates after primary resection or systemic and liver directed therapies and 2) to evaluate the independent predictors of survival and recurrence. Methods: Our Hepatobiliary Registry identified 65 patients with BPHCC from February 1999 till April 2013 at Siteman Cancer Center, Washington University, St. Louis MO. We conducted univariate Kaplan-Meier survival analysis and multivariable Cox proportional hazards regression to identify factors independently associated with overall survival. We also conducted multivariable logistic regression analysis to identify factors independently associated with recurrence. Results: Of the 65 patients in our study, 18 (28 %) with prior resection, 2 (3 %) after OLT, 45 (69 %) ineligible for surgery, 40 (62 %) were treated with chemotherapy, 17 (26%) with liver directed therapies. Overall survival was 39.2 % at 1 year. Independent factors associated with survival were: smoking (HR 2.84, 95% CI 1.29-6.23, p = 0.0089), tumor thrombus (HR 5.45, 95% CI 2.05-14.50, p = 0.0007), any liver directed treatment (HR 3.01, 95% CI 1.21-7.48, p = 0.0175), multiple satellite lesions (HR 3.17, 95% CI 1.71-8.58, p = 0.025) and prior tumor resection (HR 2.65, 95% CI 1.16-6.03, p = 0.020). Risk of recurrence was independently predicted by male sex (OR 3.98, 95% CI 1.30-12.15, p = 0.015) and multiple satellite lesions (OR 15.42, 95% CI 2.68-88.62, p = 0.0076). Conclusions: Patients with biphenotypic cancers have a devastating overall survival. Tumor thrombus and satellite lesions were the strongest predictors of poor survival; satellite lesions also strongly predicted recurrence. In this rare form of cancer, this is the largest study to identify factors associated with overall survival and recurrence. These factors should help guide clinical care of patients with BPHCC.

Analysis of the genomic profile of biphenotypic tumors compared to cholangiocarcinoma and hepatocellular carcinoma

226

Background: Biphenotypic (combined HCC/Cholangiocarcinoma) tumors represent a minority of primary liver cancers. While databases such as the Catalog of Somatic Mutations in Cancer (COSMIC) have genetic information on a large number of cases of HCC and Cholangiocarcinoma, there is little known about rarer Biphenotypic tumors. In this analysis we examine the results of targeted next-generation sequencing to assess genomic differences between these tumors. We utilize the COSMIC database for comparison. Methods: The database of theIRB-approved Washington University Hepatobiliary Registry identified patients with HCC, cholangiocarcinoma and biphenotypic tumors with specimens evaluated utilizing next generation sequencing via a Comprehensive Cancer Gene Set. Further data on corresponding genes was collected from the COSMIC database (v66) for comparison. Results: In this descriptive analysis 15 patients with biphenotypic tumors, 7 patients with HCC and 6 patients with cholangiocarcinoma are presented. The percent of samples with corresponding genetic mutations are outlined (table). These are compared to existing COSMIC data. Conclusions: Biphenotypic tumors had high levels of mutations in EGFR, P53 and Flt3. Mutations in MET, BRAF, CSF1, and MAPK1 were largely isolated to biphenotypic tumors. Mutations in CTNBB1 were isolated to cases of HCC. Notably, mutations in EGFR, Flt3 and FGFR4 were found in all three tumors in higher numbers than seen via review of COSMIC data. Overall, Biphenotypic tumors are genetically complex tumors that share many features of HCC and cholangiocarcinoma. [Table: see text]

Glycogenic hepatopathy: an underrecognized hepatic complication of diabetes mellitus

Reported are the clinical and pathologic features of glycogenic hepatopathy, a pathologic overloading of hepatocytes with glycogen that is associated with poorly controlled diabetes mellitus. Fourteen cases were studied by stains, including hematoxylin and eosin, trichrome, periodic acid-Schiff, and periodic acid-Schiff with diastase. Ultrastructural analysis was performed in 2 cases. Medical records were reviewed for clinical presentations, laboratory findings, and clinical outcomes. The individuals ranged from 8 to 25 years of age. All had type I diabetes mellitus with poor glycemic control. The clinical presentations included hepatomegaly, abdominal pain, and elevated transaminases (range, 50-1600 IU/L). The transaminases were dramatically elevated in 3 cases to greater than 10 times the upper limit of normal. All biopsies showed diffusely pale staining hepatocytes on hematoxylin and eosin stains, with excessive glycogen accumulation demonstrated by periodic acid-Schiff stains. Ultrastructural examination revealed marked glycogen accumulation in the cytoplasm and nuclei. Most cases showed no evidence for fatty liver disease: steatosis was absent in 12 of 14 cases, simple steatosis was seen in 1 of 14 cases, and mild steatohepatitis was present in 1 of 14 cases. Mallory hyaline was absent in all cases, acidophil bodies were only rarely seen, and inflammation was absent or minimally present. Fibrosis was typically absent, with only 2 cases demonstrating focal mild fibrosis. Three patients had adequate follow-up and demonstrated improvement of liver enzyme levels with control of blood glucose. We conclude that glycogenic hepatopathy can cause hepatomegaly and significant transaminase elevations in individuals with type I diabetes mellitus. The pathology is distinct from steatohepatitis.

Oral treatments for toenail onychomycosis: a systematic review

OBJECTIVE

To identify and synthesize the evidence for the efficacy of oral treatments for fungal infections of the toenails.

DESIGN

Systematic review of randomized controlled trials.

INTERVENTIONS

Oral treatments for dermatophyte infections of the toenails.

MAIN OUTCOME MEASURES

Cure confirmed by microscopy and culture results in patients with clinically diagnosed fungal infections. Data relating to the clinical cure rates were also extracted from the trials.

RESULTS

A pooled analysis of 2 trials comparing mycological cure rates from continuous treatment with terbinafine (250 mg/d for 12 weeks) and continuous treatment with itraconazole (200 mg/d for 12 weeks) found a statistically significant difference in 11- and 12-month outcomes in favor of terbinafine (risk difference, -0.23 [95% confidence interval, -0.32 to -0.15]; number needed to treat, 5 [95% confidence interval, 4 to 8]). An analysis of clinical cure rates was not possible because of the diversity of definitions used in researching the effectiveness of oral antifungal drugs for onychomycosis. Only 3 trials gave a clear definition of clinical cure and presented data for these outcomes.

CONCLUSIONS

There is good evidence that a continuous regimen of terbinafine (250 mg/d) for 3 months is the most effective oral treatment for fungally infected toenails. Consensus among researchers evaluating oral antifungal drugs for onychomycosis is needed to establish meaningful definitions of clinical cure. Most trials were funded by the pharmaceutical industry; we found little independent research, and this may have introduced bias to the review.

Mutations in Kir2.1 Cause the Developmental and Episodic Electrical Phenotypes of Andersen's Syndrome

Andersen's syndrome is characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. We have mapped an Andersen's locus to chromosome 17q23 near the inward rectifying potassium channel gene KCNJ2. A missense mutation in KCNJ2 (encoding D71V) was identified in the linked family. Eight additional mutations were identified in unrelated patients. Expression of two of these mutations in Xenopus oocytes revealed loss of function and a dominant negative effect in Kir2.1 current as assayed by voltage-clamp. We conclude that mutations in Kir2.1 cause Andersen's syndrome. These findings suggest that Kir2.1 plays an important role in developmental signaling in addition to its previously recognized function in controlling cell excitability in skeletal muscle and heart.

Ancestral origins of the Machado-Joseph disease mutation: a worldwide haplotype study

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder originally described in families of Portuguese-Azorean ancestry. The cloning of the MJD1 gene allowed identification of the disease in many other populations, and MJD is now known to be the most common cause of dominant spinocerebellar ataxia. The hypothesis that its present world distribution could result from the spread of an original founder mutation has been raised, both at historical and molecular levels. In the present study, we tested this hypothesis by linkage-disequilibrium analysis of tightly linked polymorphisms and by haplotype comparison, in 249 families from different countries. We typed five microsatellite markers surrounding the MJD1 locus (D14S1015, D14S995, D14S973, D14S1016, and D14S977), and three intragenic single-base-pair polymorphisms (A(669)TG/G(669)TG, C(987)GG/G(987)GG, and TAA(1118)/TAC(1118)). The results show two different haplotypes, specific to the island of origin, in families of Azorean extraction. In families from mainland Portugal, both Azorean haplotypes can be found. The majority of the non-Portuguese families also share the same intragenic haplotype seen in the families coming from the island of Flores, but at least three other haplotypes were seen. These findings suggest two introductions of the mutation into the Portuguese population. Worldwide, the sharing of one intragenic haplotype by the majority of the families studied implies a founder mutation in MJD.

Hepatic lipid peroxidation in hereditary hemochromatosis and alcoholic liver injury

Studies in experimental animals have indicated that enhanced lipid peroxidation may play a role in the hepatic injury produced by iron overload or by excessive alcohol consumption. The aim of this study was to compare the formation of lipid peroxidation-derived aldehydes in the liver of patients with hereditary hemochromatosis (HH) and alcohol abuse. Liver biopsy specimens from 10 nondrinking patients with HH were evaluated. These patients were classified as having HH based on hepatic iron index or human leukocyte antigen identity with a known proband. All patients were homozygous for the Cys282Tyr mutation. In addition, 8 patients with alcoholic liver disease were examined, 2 of whom also had hemochromatosis. For comparison, 17 patients with liver diseases unrelated to iron overload or alcohol abuse were studied. Liver biopsy specimens were immunostained for protein adducts with malondialdehyde and 4-hydroxynonenal. Both malondialdehyde- and 4-hydroxynonenal-protein adducts were found from liver specimens of patients with HH and alcohol abuse in more abundant amounts than from patients in a control group. In alcoholics the adducts were primarily in zone 3, whereas in hemochromatosis staining had an acinar zone 1 predominance, which followed the localization of iron. The most abundant amounts of protein adducts were noted in patients with alcohol abuse plus iron overload. The data support the concept that both chronic alcohol use and iron overload induce hepatic lipid peroxidation. Through formation of reactive aldehydic products, excessive alcohol consumption and iron overload may have additive hepatotoxic effects.

The safety of ropinirole, a selective nonergoline dopamine agonist, in patients with Parkinson's disease

Ropinirole is a novel, nonergoline, selective D2-type dopamine agonist developed to treat Parkinson's disease. Safety data from therapeutic studies involving 1364 patients receiving ropinirole are reported (mean daily dose 8.7 mg, early therapy; 8.2 mg adjunct therapy). In early therapy, the emergent adverse experiences more common with the ropinirole group compared with placebo were nausea, somnolence, leg edema, abdominal pain, vomiting, dyspepsia, and hallucinations. In adjunct therapy, they were dyskinesia, nausea, hallucinations, and confusion. Most adverse experiences were mild and associated with a similar withdrawal rate compared with the placebo group. Except for hallucinations, the incidence of emergent adverse experiences decreased with time, despite increasing doses. Long-term adverse experiences particularly associated with ergoline-type dopamine agonists have so far not been observed with ropinirole. Only 1.2% of patients receiving ropinirole developed dyskinesia compared with 11.2% receiving L-dopa in early therapy over a mean period of 17 months. There were no clinically significant changes in cardiovascular parameters or laboratory data. The incidence of adverse experiences in the bromocriptine group was low, possibly because of a slow titration scheme and low average dose. Overall, the safety profile of ropinirole appears similar to that of other dopamine agonists. Clinical studies are continuing to assess the long-term safety and efficacy of ropinirole.

Lipopolysaccharide (LPS) neutralizing peptides reveal a lipid A binding site of LPS binding protein

Endotoxic shock follows a cascade of events initiated by release of lipopolysaccharide during infection with Gram-negative organisms. Two overlapping 15-mer peptides were identified, corresponding to residues 91-108 of human lipopolysaccharide binding protein that specifically bound the lipid A moiety of lipopolysaccharide with high affinity. The peptides inhibited binding of lipopolysaccharide to lipopolysaccharide binding protein, inhibited the chromogenic Limulus amebocyte lysate reaction, and blocked release of tumor necrosis factor alpha following lipopolysaccharide challenge both in vitro and in vivo. These results suggest lipopolysaccharide binding protein residues 91-108 form at least part of the lipopolysaccharide binding site. Moreover, derivatives of lipopolysaccharide binding protein residues 91-108 might modulate lipopolysaccharide toxicity in the clinical setting.

Rapid infarct imaging with a technetium-99m-labeled antimyosin recombinant single-chain Fv: evaluation in a canine model of acute myocardial infarction

Studies of monoclonal antibody-based imaging agents show that blood clearance is inversely proportional to molecular size, i.e., Fab or Fab' > F(ab')2 > IgG. Indium-111-antimyosin Fab-DTPA is a highly specific and sensitive marker for myocardial necrosis. An improvement on current antibody diagnostic imaging may result from the use of smaller labeled fragments. We report the first in vivo targeting of acute myocardial infarction with a novel recombinant single-chain Fv (sFv) antimyosin protein. The sFv (MW = 27,594) is approximately one-half the size of the Fab and is comprised of the heavy and light chain variable regions from the myosin-specific murine monoclonal antibody R11D10 which were joined by a 15-amino-acid linker and expressed as a fusion protein (sFv) in E. coli. The binding affinity of the sFv for cardiac myosin was similar to the affinity observed for the Fab fragment. Technetium-99m labeling of the sFv was accomplished by the attachment of a cleavable, ester-linked bifunctional chelator (RP-1). Comparative studies in mice showed 99mTc-sFv-RP-1 cleared significantly faster (p < 0.001) than 99mTc-Fab'-RP-1 and 111In-Fab-DTPA antimyosin fragments. Furthermore, measurement of 99mTc-sFv-RP-1 blood clearance in a canine model of acute myocardial infarction gave a mean T1/2 of 0.54 +/- 0.13 hr versus 2.80 +/- 0.57 and 2.58 +/- 0.64 hr for Fab-DTPA and Fab'-RP-1 (p < 0.05), respectively. Despite its comparatively rapid clearance, 99mTc sFv-RP-1 had similar uptake in the infarct compared to the Fab'-RP-1. In addition, infarct visualization was more rapid with the sFv. Thus, these data demonstrate antimyosin sFv possesses characteristics necessary for rapid imaging of myocardial necrosis.

Low-attenuation periportal collar in transplanted liver is not reliable CT evidence of acute allograft rejection

Recent reports indicate that the presence or absence of a periportal low-attenuation rim ("periportal collar" sign) on CT scans is of variable reliability in predicting rejection after liver transplantation. To study this matter further, we reviewed 178 CT scans in 68 patients (74 allografts) after hepatic transplantation. One hundred twenty-one scans were obtained within 7 days of liver biopsy. The presence or absence of a central or peripheral periportal collar on these scans was correlated with the presence or absence of acute rejection found at biopsy. A central periportal collar was defined as an abnormally large amount of low-attenuation material surrounding the main portal vein, the right portal vein, or the left portal vein. A peripheral periportal collar was defined as a low-attenuation area surrounding a portal vein branch distal to the left or right portal veins. A weak, but statistically significant correlation between the presence of a peripheral periportal collar and acute allograft rejection was shown in patients in whom CT scans were obtained within 3 days of biopsy. However, the sensitivity, specificity, accuracy, and positive predictive value of the presence of a peripheral collar in this group were 60%, 67%, 64%, and 63%, respectively. The sensitivity, specificity, accuracy, and positive predictive value of the presence of a central collar in patients scanned within 3 days of biopsy were 74%, 35%, 54%, and 52%, respectively. Negative predictive values of peripheral and central collars were 65% and 59%, respectively. Our study shows that a periportal collar is seen more commonly in patients with recently transplanted allografts (mean interval after transplantation, 46 days for peripheral collars and 57 days for central collars) and in patients with ascites. The presence of a central or peripheral periportal collar on CT is not sufficiently sensitive, specific, or accurate to reliably diagnose or exclude acute allograft rejection.

High-performance liquid chromatographic assay and erythrocyte partitioning of fleroxacin, a new fluoroquinolone antibiotic

A rapid technique for sample preparation and HPLC was developed to study in vitro the erythrocyte binding and plasma protein binding of fleroxacin in the concentration range 0.2-15 micrograms ml-1. The red blood cell partition coefficient of fleroxacin was 1.45 +/- 0.18 at 25 degrees C and was independent of concentration, incubation time and temperature. The in vitro plasma protein binding of fleroxacin in humans, determined by two independent methods, was 47-51%. Partition studies using erythrocytes as a simple in vitro model may be useful to predict the degree of tissue uptake and the volume of distribution.

Mucosal arachidonate metabolism and intestinal ischemia-reperfusion injury

Mucosal arachidonic acid metabolism was examined after 3 h of ischemia and 1 h of reperfusion in isolated ileal segments in the dog. The cyclooxygenase products thromboxane B2, 6-ketoprostaglandin F1 alpha, and prostaglandin E2 increased by 365%, 97%, and 158%, respectively, after ischemia and reperfusion but were not altered after 3 h of ischemia alone. The potent chemotactic lipoxygenase product leukotriene B4 (LTB4) increased by 687% after ischemia and reperfusion and was not affected by ischemia without reperfusion. In addition, tissue production of the thiol ether leukotrienes (LTC4, LTD4, and LTE4) increased threefold after ischemia and reperfusion. Quantitation of regionally isomeric hydroxy acids produced from arachidonate revealed a 300% increase in 12-hydroxyeicosatetraenoate (12-HETE) after intestinal ischemia and reperfusion without a change in other isomers (15-HETE and 5-HETE). Stereochemical analysis of 12-HETE demonstrated exclusive synthesis of the S-enantiomer. A significant and time-dependent decrease in intestinal blood flow also occurred during reperfusion. Administration of the dual cyclooxygenase-lipoxygenase synthesis inhibitor BW755C (1 mg/kg ia) did not alter time-dependent decreases in blood flow and failed to inhibit eicosanoid synthesis. Histologic examinations of intestinal samples revealed significant mucosal damage associated with ischemia alone and ischemia after reperfusion. This study indicates that intestinal ischemia-reperfusion injury is associated with dramatic alterations in mucosal production of vasoactive eicosanoids and with changes in blood flow that occur during reperfusion but not during ischemia alone. These events may be involved in the pathology characteristic of this injury.

Thromboxane synthesis inhibition and renal allograft function

These data indicate that chronic administration of CGS-12970 to renal allograft recipients maintains renal allograft function. These effects are probably due to selective inhibition of local tissue TXA2 production. These data also suggest that elevations in renal allograft tissue prostacyclin production may be secondary to ischemia since improving renal blood flow and GFR with selective thromboxane synthesis inhibitors leads to normalization of renal prostacyclin synthesis. The possible utility of using CGS-12970 as an adjunct therapy in human renal allotransplantation should be strongly considered.

Use of ricin A-chain to selectively deplete Kupffer cells

We used the A-chain of the toxin ricin (RTA) as a toxin specific to Kupffer cells in mice. RTA is specifically taken up by the mannose receptor present exclusively in macrophages. Kupffer cells were quantitated by shifts in beta-glucuronidase clearance and microscopic counts of cells which phagocytosed India ink. When compared to saline controls, 20 mg/kg of RTA intraperitoneally (divided over 4 days) or intraportally (single doses) significantly prolonged the t 1/2 half-life of beta-glucuronidase by 270 +/- 37 and 210 +/- 8%, respectively. Kupffer cell numbers were significantly decreased by 27 +/- 8 and 33 +/- 16%. This effect persisted for at least 3 days after toxin administration. Despite effects on Kupffer cell number, minimal histological damage to liver, spleen, lung, and heart was noted. Higher doses of RTA or doses potentiated by ureteral ligation to prevent renal clearance resulted in prohibitive mortalities and histologic liver damage. Doses of Hura crepitans inhibitor, a toxin similar to RTA but not mannose-receptor specific, did not affect Kupffer cell numbers. We conclude that RTA given both intraperitoneally and intraportally at low doses is toxic specifically to Kupffer cells. Kupffer cell numbers can be indirectly measured by beta-glucuronidase clearance.

Essential fatty acid depletion of renal allografts and prevention of rejection

A central hypothesis in transplantation biology is that resident leukocytes expressing class II histocompatibility antigens may determine the immunogenicity of an organ. By means of a novel method to deplete the kidney of resident leukocytes, essential fatty acid deficiency (EFAD), this hypothesis was tested in an intact, vascular organ. Kidneys subjected to EFAD and thus depleted of resident Ia-positive macrophages survived and functioned when transplanted across a major histocompatibility antigen barrier in the absence of immunosuppression of the recipient. Control allografts were rejected promptly. Allografts from donors subjected to EFAD normalized their lipid composition and were repopulated with host macrophages by 5 days. Administration of Ia-positive cells at the time of transplantation established that the resident leukocyte depletion induced by EFAD was responsible for the protective effect. These observations may provide insights into the mechanisms underlying tissue immunogenicity and the population of normal tissues with resident leukocytes.

Eicosanoid synthesis inhibition and renal allograft function during acute rejection

The effects of the dual cyclooxygenase-lipoxygenase inhibitor 3-amino-1-(m[trifluoromethyl]phenyl)-2-pyrazoline (BW755C) (10 mg/kg, p.o., b.i.d.) on renal blood flow, glomerular filtration rate (GFR), and eicosanoid production were examined in anesthetized dogs that had undergone unilateral renal allotransplantation. Rejecting renal allograft blood flow significantly declined over a 5-day period compared to the nonrejecting native kidney. In animals treated with BW755C, renal allograft blood flow was maintained over the postoperative 5-day period at levels comparable to blood flow to the native kidneys. While GFR and urine flow progressively declined in the rejecting kidney, treatment with BW755C prevented the fall in GFR and even augmented urine flow. Allograft renal cortical production or thromboxane B2 (TXB2) and leukotriene B4 (LTB4) in animals treated with BW755C was not significantly different than production by the native contralateral kidneys. Furthermore, BW755C reduced cellular infiltration and tissue damage in allografts compared to nontreated renal allografts. The selective cyclooxygenase inhibitor, indomethacin (5 mg/kg, p.o., b.i.d.) exerted no effect on renal allograft GFR or urine output but reduced allograft blood flow after 4 days compared to nontreated allografts. In conclusion, inhibition of arachidonate cyclooxygenase and lipoxygenase metabolism improves renal allograft function and reduces tissue damage while selective inhibition of the cyclooxygenase pathway does not improve renal allograft function. These data indicate that products of arachidonate-lipoxygenase metabolism potentiate the loss of renal function and tissue destruction associated with renal allograft rejection.