Identification and stratification of systemic lupus erythematosus patients into two transcriptionally distinct clusters based on IFN-I signature.

OBJECTIVE: Despite the significant advancement in the understanding of the pathophysiology of systemic lupus erythematosus (SLE) variable clinical response to newer therapies remain a major concern, especially for patients with lupus nephritis and neuropsychiatric systemic lupus erythematosus (NPSLE). We performed this study with an objective to comprehensively characterize Indian SLE patients with renal and neuropsychiatric manifestation with respect to their gene signature, cytokine profile and immune cell phenotypes. METHODS: We characterized 68 Indian SLE subjects with diverse clinical profiles and disease activity and tried to identify differentially expressed genes and enriched pathways. To understand the temporal profile, same patients were followed at 6 and 12-months intervals. Additionally, auto-antibody profile, levels of various chemokines, cytokines and the proportion of different immune cells and their activation status were captured in these subjects. RESULTS: Multiple IFN-related pathways were enriched with significant increase in IFN-I gene signature in SLE patients as compared to normal healthy volunteers (NHV). We identified two transcriptionally distinct clusters within the same cohort of SLE patients with differential immune cell activation status, auto-antibody as well as plasma chemokines and cytokines profile. CONCLUSIONS: Identification of two distinct clusters of patients based on IFN-I signature provided new insights into the heterogeneity of underlying disease pathogenesis of Indian SLE cohort. Importantly, patient within those clusters retain their distinct expression dynamics of IFN-I signature over the time course of one year despite change in disease activity. This study will guide clinicians and researchers while designing future clinical trials on Indian SLE cohort.

Selective IRAK4 Inhibition Attenuates Disease in Murine Lupus Models and Demonstrates Steroid Sparing Activity.

The serine/threonine kinase IL-1R-associated kinase (IRAK)4 is a critical regulator of innate immunity. We have identified BMS-986126, a potent, highly selective inhibitor of IRAK4 kinase activity that demonstrates equipotent activity against multiple MyD88-dependent responses both in vitro and in vivo. BMS-986126 failed to inhibit assays downstream of MyD88-independent receptors, including the TNF receptor and TLR3. Very little activity was seen downstream of TLR4, which can also activate an MyD88-independent pathway. In mice, the compound inhibited cytokine production induced by injection of several different TLR agonists, including those for TLR2, TLR7, and TLR9. The compound also significantly suppressed skin inflammation induced by topical administration of the TLR7 agonist imiquimod. BMS-986126 demonstrated robust activity in the MRL/lpr and NZB/NZW models of lupus, inhibiting multiple pathogenic responses. In the MRL/lpr model, robust activity was observed with the combination of suboptimal doses of BMS-986126 and prednisolone, suggesting the potential for steroid sparing activity. BMS-986126 also demonstrated synergy with prednisolone in assays of TLR7- and TLR9-induced IFN target gene expression using human PBMCs. Lastly, BMS-986126 inhibited TLR7- and TLR9-dependent responses using cells derived from lupus patients, suggesting that inhibition of IRAK4 has the potential for therapeutic benefit in treating lupus.

Coproporphyrins in Plasma and Urine Can Be Appropriate Clinical Biomarkers to Recapitulate Drug-Drug Interactions Mediated by Organic Anion Transporting Polypeptide Inhibition.

In the present study, an open-label, three-treatment, three-period clinical study of rosuvastatin (RSV) and rifampicin (RIF) when administered alone and in combination was conducted in 12 male healthy subjects to determine if coproporphyrin I (CP-I) and coproporphyrin III (CP-III) could serve as clinical biomarkers for organic anion transporting polypeptide 1B1 (OATP1B1) and 1B3 that belong to the solute carrier organic anion gene subfamily. Genotyping of the human OATP1B1 gene was performed in all 12 subjects and confirmed absence of OATP1B1*5 and OATP1B1*15 mutations. Average plasma concentrations of CP-I and CP-III prior to drug administration were 0.91 ± 0.21 and 0.15 ± 0.04 nM, respectively, with minimum fluctuation over the three periods. CP-I was passively eliminated, whereas CP-III was actively secreted from urine. Administration of RSV caused no significant changes in the plasma and urinary profiles of CP-I and CP-III. RIF markedly increased the maximum plasma concentration (Cmax) of CP-I and CP-III by 5.7- and 5.4-fold (RIF) or 5.7- and 6.5-fold (RIF+RSV), respectively, as compared with the predose values. The area under the plasma concentration curves from time 0 to 24 h (AUC0-24h) of CP-I and CP-III with RIF and RSV increased by 4.0- and 3.3-fold, respectively, when compared with RSV alone. In agreement with this finding, Cmax and AUC0-24h of RSV increased by 13.2- and 5.0-fold, respectively, when RIF was coadministered. Collectively, we conclude that CP-I and CP-III in plasma and urine can be appropriate endogenous biomarkers specifically and reliably reflecting OATP inhibition, and thus the measurement of these molecules can serve as a useful tool to assess OATP drug-drug interaction liabilities in early clinical studies.

Expression and characterization of cynomolgus monkey cytochrome CYP3A4 in a novel human embryonic kidney cell-based mammalian system.

Cynomolgus monkeys are a commonly used species in preclinical drug discovery, and have high genetic similarity to humans, especially for the drug-metabolizing cytochrome P450s. However, species differences are frequently observed in the metabolism of drugs between cynomolgus monkeys and humans, and delineating these differences requires expressed CYPs. Toward this end, cynomolgus monkey CYP3A4 (c3A4) was cloned and expressed in a novel human embryonic kidney 293-6E cell suspension system. Following the preparation of microsomes, the kinetic profiles of five known human CYP3A4 (h3A4) substrates (midazolam, testosterone, terfenadine, nifedipine, and triazolam) were determined. All five substrates were found to be good substrates of c3A4, although some differences were observed in the Km values. Overall, the data suggest a strong substrate similarity between c3A4 and h3A4. Additionally, c3A4 exhibited no activity against non-h3A4 probe substrates, except for a known human CYP2D6 substrate (bufuralol), which suggests potential metabolism of human cytochrome CYP2D6-substrates by c3A4. Ketoconazole and troleandomycin showed similar inhibitory potencies toward c3A4 and h3A4, whereas non-h3A4 inhibitors did not inhibit c3A4 activity. The availability of a c3A4 preparation, in conjunction with commercially available monkey liver microsomes, will support further characterization of the cynomolgus monkey as a model to assess CYP3A-dependent clearance and drug-drug interactions.

Crystal structure of rat intestinal alkaline phosphatase--role of crown domain in mammalian alkaline phosphatases.

Intestinal alkaline phosphatases (IAPs) are involved in the cleavage of phosphate prodrugs to liberate the drug for absorption in the intestine. To facilitate in vitro characterization of phosphate prodrugs, we have cloned, expressed, purified and characterized IAPs from rat and cynomolgus monkey (rIAP and cIAP respectively) which are important pre-clinical species for drug metabolism studies. The recombinant rat and monkey enzymes expressed in Sf9 insect cells (IAP-Ic) were found to be glycosylated and active. Expression of rat IAP in Escherichia coli (rIAP-Ec) led to ~200-fold loss of activity that was partially recovered by the addition of external Zn(2+) and Mg(2+) ions. Crystal structures of rIAP-Ec and rIAP-Ic were determined and they provide rationale for the discrepancy in enzyme activities. Rat IAP-Ic retains its activity in presence of both Zn(2+) and Mg(2+) whereas activity of most other alkaline phosphatases (APs) including the cIAP was strongly inhibited by excess Zn(2+). Based on our crystal structure, we hypothesized the residue Q317 in rIAP, present within 7 Å of the Mg(2+) at M3, to be important for this difference in activity. The Q317H rIAP and H317Q cIAP mutants showed reversal in effect of Zn(2+), corroborating the hypothesis. Further analysis of the two structures indicated a close linkage between glycosylation and crown domain stability. A triple mutant of rIAP, where all the three putative N-linked glycosylation sites were mutated showed thermal instability and reduced activity.

Cynomolgus monkey as a potential model to assess drug interactions involving hepatic organic anion transporting polypeptides: in vitro, in vivo, and in vitro-to-in vivo extrapolation.

Organic anion-transporting polypeptides (OATP) 1B1, 1B3, and 2B1 can serve as the loci of drug-drug interactions (DDIs). In the present work, the cynomolgus monkey was evaluated as a potential model for studying OATP-mediated DDIs. Three cynomolgus monkey OATPs (cOATPs), with a high degree of amino acid sequence identity (91.9, 93.5, and 96.6% for OATP1B1, 1B3, and 2B1, respectively) to their human counterparts, were cloned, expressed, and characterized. The cOATPs were stably transfected in human embryonic kidney cells and were functionally similar to the corresponding human OATPs (hOATPs), as evident from the similar uptake rate of typical substrates (estradiol-17ß-d-glucuronide, cholecystokinin octapeptide, and estrone-3-sulfate). Moreover, six known hOATP inhibitors exhibited similar IC(50) values against cOATPs. To further evaluate the appropriateness of the cynomolgus monkey as a model, a known hOATP substrate [rosuvastatin (RSV)]-inhibitor [rifampicin (RIF)] pair was examined in vitro; the monkey-derived parameters (RSV K(m) and RIF IC(50)) were similar (within 3.5-fold) to those obtained with hOATPs and human primary hepatocytes. In vivo, the area under the plasma concentration-time curve of RSV (3 mg/kg, oral) given 1 hour after a single RIF dose (15 mg/kg, oral) was increased 2.9-fold in cynomolgus monkeys, consistent with the value (3.0-fold) reported in humans. A number of in vitro-in vivo extrapolation approaches, considering the fraction of the pathways affected and free versus total inhibitor concentrations, were also explored. It is concluded that the cynomolgus monkey has the potential to serve as a useful model for the assessment of OATP-mediated DDIs in a nonclinical setting.