Skin microbiome sampling in the preterm neonate

Despite advances in our understanding of the human microbiome, there exist significant knowledge gaps in our understanding of the skin microbiome of the preterm neonate. Herein, we describe skin microbiome sampling of six preterm neonates at multiple timepoints, and compare the skin microbiome samples to environmental (crib/isolette swabs) and negative controls. Samples of the same type (skin, crib, control) were more similar than when compared by week or by patient.

Effect of Routine Gastric Residual Aspiration on the Preterm Infant Fecal Microbiome

OBJECTIVE

 Enteral feeding tubes are used in neonatal intensive care units (NICUs) to assess feeding tolerance by utilizing preprandial gastric residual aspiration. This study evaluates the effect of gastric residual aspiration on the preterm infant fecal microbiome and gastrointestinal inflammation.

STUDY DESIGN

 Fifty-one very low birth weight (VLBW) infants (≤32 weeks' gestational age and ≤1,250 g) enrolled in a larger single-center randomized controlled trial evaluating the effects of routine and nonroutine gastric residual aspiration were selected for further analysis. Of those infants, 30 had microbiome analysis performed on stools collected at 6 weeks by sequencing the bacterial V1 to V3 variable regions of the genes encoding for 16S rRNA. In an additional 21 infants, stool samples collected at 3 and 6 weeks were analyzed for intestinal inflammation using a cytokine multiplex panel.

RESULTS

 Microbial communities between groups were not distinct from each other and there was no difference in intestinal inflammation between groups. Analyses using gene expression packages DESeq2 and edgeR produced statistically significant differences in several taxa, possibly indicating a more commensal intestinal microbiome in infants not undergoing gastric residual aspiration.

CONCLUSION

 Omission of routine gastric residual aspiration was not associated with intestinal dysbiosis or inflammation, providing additional evidence that monitors preprandial gastric residuals is unnecessary.

KEY POINTS

· Omission of routine gastric residual aspiration was not associated with intestinal dysbiosis or inflammation.. · Existing literature indicates preprandial gastric aspiration does not reliably correlate with development of necrotizing enterocolitis but does correlate with delayed enteral nutrition.. · Further study is required but this data that suggest monitoring preprandial gastric residuals are unnecessary..

The gut microbiome of COVID-19 recovered patients returns to uninfected status in a minority-dominated United States cohort

To investigate the relationship between intestinal microbiota and SARS-CoV-2-mediated pathogenicity in a United States, majority African American cohort. We prospectively collected fecal samples from 50 SARS-CoV-2 infected patients, 9 SARS-CoV-2 recovered patients, and 34 uninfected subjects seen by the hospital with unrelated respiratory medical conditions (controls). 16S rRNA sequencing and qPCR analysis was performed on fecal DNA/RNA. The fecal microbial composition was found to be significantly different between SARS-CoV-2 patients and controls (PERMANOVA FDR-P = .004), independent of antibiotic exposure. Peptoniphilus, Corynebacterium and Campylobacter were identified as the three most significantly enriched genera in COVID-19 patients compared to controls. Actively infected patients were also found to have a different gut microbiota than recovered patients (PERMANOVA FDR-P = .003), and the most enriched genus in infected patients was Campylobacter, with Agathobacter and Faecalibacterium being enriched in the recovered patients. No difference in microbial community structure between recovered patients and uninfected controls was observed, nor a difference in alpha diversity between the three groups. 24 of the 50 COVID-19 patients (48%) tested positive via RT-qPCR for fecal SARS-CoV-2 RNA. A significant difference in gut microbial composition between SARS-CoV-2 positive and negative samples was observed, with Klebsiella and Agathobacter being enriched in the positive cohort. No significant associations between microbiome composition and disease severity was found. The intestinal microbiota is sensitive to the presence of SARS-CoV-2, with increased relative abundance of genera (Campylobacter, Klebsiella) associated with gastrointestinal (GI) disease. Further studies are needed to investigate the functional impact of SARS-CoV-2 on GI health.

Baseline Gut Microbiota Composition Is Associated with Major Infections Early after Hematopoietic Cell Transplantation

Infection is a major cause of morbidity and mortality after hematopoietic cell transplantation (HCT). Gut microbiota (GM) composition and metabolites provide colonization resistance against dominance of potential pathogens, and GM dysbiosis following HCT can be deleterious to immune reconstitution. Little is known about the composition, diversity, and evolution of GM communities in HCT patients and their association with subsequent febrile neutropenia (FN) and infection. Identification of markers before HCT that predict subsequent infection could be useful in developing individualized antimicrobial strategies. Fecal samples were collected prospectively from 33 HCT recipients at serial time points: baseline, post-conditioning regimen, neutropenia onset, FN onset (if present), and hematologic recovery. GM was assessed by 16S rRNA sequencing. FN and major infections (ie, bloodstream infection, typhlitis, invasive fungal infection, pneumonia, and Clostridium difficile enterocolitis) were identified. Significant shifts in GM composition and diversity were observed during HCT, with the largest alterations occurring after initiation of antibiotics. Loss of diversity persisted without a return to baseline at hematologic recovery. GM in patients with FN was enriched in Mogibacterium, Bacteroides fragilis, and Parabacteroides distasonis, whereas increased abundance of Prevotella, Ruminococcus, Dorea, Blautia, and Collinsella was observed in patients without fever. A baseline protective GM profile (BPGMP) was predictive of protection from major infection. The BPGMP was associated with subsequent major infections with 77% accuracy and an area under the curve of 79%, with sensitivity, specificity, and positive and negative predictive values of 0.71, 0.91, 0.77, and 0.87, respectively. Our data show that large shifts in GM composition occur early after HCT, and differences in baseline GM composition are associated with the development of subsequent major infections.

Human Colon Mucosal Biofilms and Murine Host Communicate via Altered mRNA and microRNA Expression during Cancer

Disrupted interactions between host and intestinal bacteria are implicated in colorectal cancer (CRC) development. However, activities derived from these bacteria and their interplay with the host are unclear. Here, we examine this interplay by performing mouse and microbiota RNA sequencing on colon tissues and 16S and small RNA sequencing on stools from germfree (GF) and gnotobiotic ApcMin Δ 850/+ ;Il10-/- mice associated with microbes from biofilm-positive human CRC tumor (BF+T) and biofilm-negative healthy (BF-bx) tissues. The bacteria in BF+T mice differentially expressed (DE) >2,900 genes, including genes related to bacterial secretion, virulence, and biofilms but affected only 62 host genes. Small RNA sequencing of stools from these cohorts revealed eight significant DE host microRNAs (miRNAs) based on biofilm status and several miRNAs that correlated with bacterial taxon abundances. Additionally, computational predictions suggest that some miRNAs preferentially target bacterial genes while others primarily target mouse genes. 16S rRNA sequencing of mice that were reassociated with mucosa-associated communities from the initial association revealed a set of 13 bacterial genera associated with cancer that were maintained regardless of whether the reassociation inoculums were initially obtained from murine proximal or distal colon tissues. Our findings suggest that complex interactions within bacterial communities affect host-derived miRNA, bacterial composition, and CRC development.IMPORTANCE Bacteria and bacterial biofilms have been implicated in colorectal cancer (CRC), but it is still unclear what genes these microbial communities express and how they influence the host. MicroRNAs regulate host gene expression and have been explored as potential biomarkers for CRC. An emerging area of research is the ability of microRNAs to impact growth and gene expression of members of the intestinal microbiota. This study examined the bacteria and bacterial transcriptome associated with microbes derived from biofilm-positive human cancers that promoted tumorigenesis in a murine model of CRC. The murine response to different microbial communities (derived from CRC patients or healthy people) was evaluated through RNA and microRNA sequencing. We identified a complex interplay between biofilm-associated bacteria and the host during CRC in mice. These findings may lead to the development of new biomarkers and therapeutics for identifying and treating biofilm-associated CRCs.

Human colon mucosal biofilms from healthy or colon cancer hosts are carcinogenic

Mucus-invasive bacterial biofilms are identified on the colon mucosa of approximately 50% of colorectal cancer (CRC) patients and approximately 13% of healthy subjects. Here, we test the hypothesis that human colon biofilms comprise microbial communities that are carcinogenic in CRC mouse models. Homogenates of human biofilm-positive colon mucosa were prepared from tumor patients (tumor and paired normal tissues from surgical resections) or biofilm-positive biopsies from healthy individuals undergoing screening colonoscopy; homogenates of biofilm-negative colon biopsies from healthy individuals undergoing screening colonoscopy served as controls. After 12 weeks, biofilm-positive, but not biofilm-negative, human colon mucosal homogenates induced colon tumor formation in 3 mouse colon tumor models (germ-free ApcMinΔ850/+;Il10-/- or ApcMinΔ850/+ and specific pathogen-free ApcMinΔ716/+ mice). Remarkably, biofilm-positive communities from healthy colonoscopy biopsies induced colon inflammation and tumors similarly to biofilm-positive tumor tissues. By 1 week, biofilm-positive human tumor homogenates, but not healthy biopsies, displayed consistent bacterial mucus invasion and biofilm formation in mouse colons. 16S rRNA gene sequencing and RNA-Seq analyses identified compositional and functional microbiota differences between mice colonized with biofilm-positive and biofilm-negative communities. These results suggest human colon mucosal biofilms, whether from tumor hosts or healthy individuals undergoing screening colonoscopy, are carcinogenic in murine models of CRC.

Initial microbial community of the neonatal stomach immediately after birth

The purpose of this prospective cross-sectional cohort pilot study is to explore the initial microbial community of gastric aspirate fluid as collected immediately after birth and its relationships with mode of delivery and preterm birth. Twenty-nine gastric aspirate samples collected immediately after birth from infants born between 24-40 weeks gestation were analyzed for microbial composition. Total microbial content was low in many samples, with a substantial number sharing taxonomic composition with negative controls. qPCR targeting the 16S rRNA gene showed that infants delivered vaginally had a higher microbial load than infants delivered by C-section. Some pre-term samples showed high relative abundance of genus Ureaplasma, consistent with previous literature that has implicated infections with this taxon as a potential cause of pre-term birth. Vaginally born term infant samples, by contrast, had significantly higher levels of genus Lactobacillus with Lactobacillus crispatus the most dominant species. Microbial evaluation showed that vaginally born term infant gastric aspirate samples had higher levels of lactobacilli than pre-terms. Samples from many infants had low microbial load near the edge of the detection limit.

Rare susceptibility variants for bipolar disorder suggest a role for G protein-coupled receptors

Bipolar disorder (BD) is a prevalent mood disorder that tends to cluster in families. Despite high heritability estimates, few genetic susceptibility factors have been identified over decades of genetic research. One possible interpretation for the shortcomings of previous studies to detect causative genes is that BD is caused by highly penetrant rare variants in many genes. We explored this hypothesis by sequencing the exomes of affected individuals from 40 well-characterized multiplex families. We identified rare variants segregating with affected status in many interesting genes, and found an enrichment of deleterious variants in G protein-coupled receptor (GPCR) family genes, which are important drug targets. Furthermore, we showed targeted downstream GPCR dysregulation for some of the variants that may contribute to disease pathology. Particularly interesting was the finding of a rare and functionally relevant nonsense mutation in the corticotropin-releasing hormone receptor 2 (CRHR2) gene that tracked with affected status in one family. By focusing on rare variants in informative families, we identified key biochemical pathways likely implicated in this complex disorder.

Intestinal microbiota enhances pancreatic carcinogenesis in preclinical models

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer death in the United States yet data are scant regarding host factors influencing pancreatic carcinogenesis. Increasing evidence support the role of the host microbiota in carcinogenesis but its role in PDAC is not well established. Herein, we report that antibiotic-mediated microbial depletion of KrasG12D/PTENlox/+ mice showed a decreased proportion of poorly differentiated tumors compared to microbiota-intact KrasG12D/PTENlox/+ mice. Subsequent 16S rRNA PCR showed that ~50% of KrasG12D/PTENlox/+ mice with PDAC harbored intrapancreatic bacteria. To determine if a similar observation in humans correlates with presence of PDAC, benign and malignant human pancreatic surgical specimens demonstrated a microbiota by 16S bacterial sequencing and culture confirmation. However, the microbial composition did not differentiate PDAC from non-PDAC tissue. Furthermore, murine pancreas did not naturally acquire a pancreatic microbiota, as germ-free mice transferred to specific pathogen-free housing failed to acquire intrapancreatic bacteria over time, which was not augmented by a murine model of colitis. Finally, antibiotic-mediated microbial depletion of Nod-SCID mice, compared to microbiota-intact, showed increased time to PDAC xenograft formation, smaller tumors, and attenuated growth. Interestingly, both xenograft cohorts were devoid of intratumoral bacteria by 16S rRNA PCR, suggesting that intrapancreatic/intratumoral microbiota is not the sole driver of PDAC acceleration. Xenografts from microbiota-intact mice demonstrated innate immune suppression by immunohistochemistry and differential regulation of oncogenic pathways as determined by RNA sequencing. Our work supports a long-distance role of the intestinal microbiota on PDAC progression and opens new research avenues regarding pancreatic carcinogenesis.

Refining the phenotype associated with biallelic DNAJC21 mutations

Inherited bone marrow failure syndromes (IBMFS) are caused by mutations in genes involved in genomic stability. Although they may be recognized by the association of typical clinical features, variable penetrance and expressivity are common, and clinical diagnosis is often challenging. DNAJC21, which is involved in ribosome biogenesis, was recently linked to bone marrow failure. However, the specific phenotype and natural history remain to be defined. We correlate molecular data, phenotype, and clinical history of 5 unreported affected children and all individuals reported in the literature. All patients present features consistent with IBMFS: bone marrow failure, growth retardation, failure to thrive, developmental delay, recurrent infections, and skin, teeth or hair abnormalities. Additional features present in some individuals include retinal abnormalities, pancreatic insufficiency, liver cirrhosis, skeletal abnormalities, congenital hip dysplasia, joint hypermobility, and cryptorchidism. We suggest that DNAJC21-related diseases constitute a distinct IBMFS, with features overlapping Shwachman-Diamond syndrome and Dyskeratosis congenita, and additional characteristics that are specific to DNAJC21 mutations. The full phenotypic spectrum, natural history, and optimal management will require more reports. Considering the aplastic anemia, the possible increased risk for leukemia, and the multisystemic features, we provide a checklist for clinical evaluation at diagnosis and regular follow-up.

Microbiota-Derived Metabolic Factors Reduce Campylobacteriosis in Mice

BACKGROUND & AIMS

Campylobacter jejuni, a prevalent foodborne bacterial pathogen, exploits the host innate response to induce colitis. Little is known about the roles of microbiota in C jejuni-induced intestinal inflammation. We investigated interactions between microbiota and intestinal cells during C jejuni infection of mice.

METHODS

Germ-free C57BL/6 Il10-/- mice were colonized with conventional microbiota and infected with a single dose of C jejuni (109 colony-forming units/mouse) via gavage. Conventional microbiota were cultured under aerobic, microaerobic, or anaerobic conditions and orally transplanted into germ-free Il10-/- mice. Colon tissues were collected from mice and analyzed by histology, real-time polymerase chain reaction, and immunoblotting. Fecal microbiota and bile acids were analyzed with 16S sequencing and high-performance liquid chromatography with mass spectrometry, respectively.

RESULTS

Introduction of conventional microbiota reduced C jejuni-induced colitis in previously germ-free Il10-/- mice, independent of fecal load of C jejuni, accompanied by reduced activation of mammalian target of rapamycin. Microbiota transplantation and 16S ribosomal DNA sequencing experiments showed that Clostridium XI, Bifidobacterium, and Lactobacillus were enriched in fecal samples from mice colonized with microbiota cultured in anaerobic conditions (which reduce colitis) compared with mice fed microbiota cultured under aerobic conditions (susceptible to colitis). Oral administration to mice of microbiota-derived secondary bile acid sodium deoxycholate, but not ursodeoxycholic acid or lithocholic acid, reduced C jejuni-induced colitis. Depletion of secondary bile acid-producing bacteria with antibiotics that kill anaerobic bacteria (clindamycin) promoted C jejuni-induced colitis in specific pathogen-free Il10-/- mice compared with the nonspecific antibiotic nalidixic acid; colitis induction by antibiotics was associated with reduced level of luminal deoxycholate.

CONCLUSIONS

We identified a mechanism by which the microbiota controls susceptibility to C jejuni infection in mice, via bacteria-derived secondary bile acids.

Locoregional Effects of Microbiota in a Preclinical Model of Colon Carcinogenesis

Inflammation and microbiota are critical components of intestinal tumorigenesis. To dissect how the microbiota contributes to tumor distribution, we generated germ-free (GF) Apc^Min/+ and Apc^Min/+ ;Il10^-/- mice and exposed them to specific-pathogen-free (SPF) or colorectal cancer-associated bacteria. We found that colon tumorigenesis significantly correlated with inflammation in SPF-housed Apc^Min/+ ;Il10^-/- , but not in Apc^Min/+ mice. In contrast, small intestinal neoplasia development significantly correlated with age in both Apc^Min/+ ;Il10^-/- and Apc^Min/+ mice. GF Apc^Min/+ ;Il10^-/- mice conventionalized by an SPF microbiota had significantly more colon tumors compared with GF mice. Gnotobiotic studies revealed that while Fusobacterium nucleatum clinical isolates with FadA and Fap2 adhesins failed to induce inflammation and tumorigenesis, pks⁺Escherichia coli promoted tumorigenesis in the Apc^Min/+ ;Il10^-/- model in a colibactin-dependent manner, suggesting colibactin is a driver of carcinogenesis. Our results suggest a distinct etiology of cancers in different locations of the gut, where colon cancer is primarily driven by inflammation and the microbiome, while age is a driving force for small intestine cancer. Cancer Res; 77(10); 2620-32. ©2017 AACR.

Impact of Wilms' tumor 1 expression on outcome of patients undergoing allogeneic stem cell transplantation for AML

The monitoring of the minimal residual disease by Wilms' tumor 1 expression (MRD^WT1) is a standardized test, which can be used in over 80% of patients with AML. To investigate the prognostic value of MRD^WT1 in patients undergoing allogeneic stem cell transplantation (allo-SCT) for AML, MRD^WT1 was monitored 3 months after transplantation in 139 patients. MRD^WT1 positivity did not lead to any therapeutic intervention. Median follow-up was 39.3 (6.4-99.8) months. Patients with positive MRD^WT1 at 3 months experienced more often post-transplant relapse (27/30, 90%) than those with negative MRD^WT1 (16/109, 14.7%) (P<0.0001). Similarly, a shorter 3-year event-free survival (EFS) was observed in MRD^WT1-positive patients (10% vs 72.3% in MRD^WT1-negative patients, P<0.0001). The correlation between relapse and MRD^WT1 was stronger in blood than in bone marrow samples. Multivariate analysis confirmed the detrimental role of 3-month positive MRD^WT1 for relapse (hazard ratio (HR): 15.42; 95% confidence interval (CI): 7.53-31.59; P<0.0001) and EFS (HR: 10.71; 95% CI: 5.41-21.21; P<0.0001). Interestingly, 3-month chimerism was less predictive of relapse than positive MRD^WT1. In conclusion, our results demonstrate the usefulness of peripheral blood MRD^WT1 monitoring in identifying very high-risk patients, who could benefit from an early preemptive treatment, and those who do not need such an intervention.

Allogeneic stem cell transplantation for patients with mantle cell lymphoma who failed autologous stem cell transplantation: a national survey of the SFGM-TC

Poly-chemotherapy plus rituximab followed by autologous stem cell transplantation (auto-SCT) is standard care for untreated young patients with mantle cell lymphoma (MCL). Despite this intensive treatment, transplant patients remain highly susceptible to relapse over time. The French SFGM-TC performed a national survey on reduced-intensity conditioning allogeneic stem cell transplantation (RIC-allo-SCT) for fit relapsed/refractory patients who failed after auto-SCT (n=106). Median times of relapse after auto-SCT, and from auto-SCT to RIC-allo-SCT were 28 months and 3.6 years, respectively. Sixty per cent of patients received at least three lines of treatment before RIC-allo-SCT. Conditioning regimens for RIC-allo-SCT were heterogeneous. Twenty patients experienced grade III/IV aGvHD, extensive cGvHD was reported in 28 cases. Median follow-up after RIC-allo-SCT was 45 months. Median PFS after RIC-allo-SCT was 30.1 months and median overall survival was 62 months. Treatment-related mortality (TRM) at 1 year and 3 years were estimated at 28% and 32%, respectively. A total of 52 patients died; major causes of death were related to toxicity (n=34) and MCL (n=11). Patients in good response before RIC-allo-SCT experienced a better PFS and OS. Our work highlights the need for new RIC-allo-SCT MCL-tailored approaches to reduce TRM, and early and late relapse.

Similar levels of pain are reported in forefoot surgery after management as a day case and admission for 48 hours

While many forefoot procedures may be performed as a day case, there are no specific guidelines as to which procedures are suitable. This study assessed the early post-operative pain after forefoot surgery performed a day case, compared with conventional inpatient management.

A total of 317 consecutive operations performed by a single surgeon were included in the study. Those eligible according to the criteria of the French Society of Anaesthesia (SFAR) were managed as day cases (127; 40%), while the remainder were managed as inpatients.

The groups were comparable in terms of gender, body mass index and smoking status, although the mean age of the inpatients was higher (p < 0.001) and they had higher mean American Society of Anaesthesiologists scores (p = 0.002). The most severe daily pain was on the first post-operative day, but the levels of pain were similar in the two groups; (4.2/10, sd 2.5 for day cases, 4.4/10, sd 2.4 for inpatients; p = 0.53). Overall, 28 (9%) of patients who had their surgery as a day case and 34 (11%) of inpatients reported extreme pain (≥ 8/10). There were more day case patients rather than inpatients that declared their pain disappeared seven days after the surgery (p = 0.02). One day-case patient with excessive bleeding was admitted post-operatively.

Apart from the most complicated cases, forefoot surgery can safely be performed as a day case without an increased risk of pain, or complications compared with management as an inpatient.

Cite this article: Bone Joint J 2015;97-B:1645–50.

Differential Regulation of 6- and 7-Transmembrane Helix Variants of μ-Opioid Receptor in Response to Morphine Stimulation

The pharmacological effect of opioids originates, at the cellular level, by their interaction with the μ-opioid receptor (mOR) resulting in the regulation of voltage-gated Ca2+ channels and inwardly rectifying K+ channels that ultimately modulate the synaptic transmission. Recently, an alternative six trans-membrane helix isoform of mOR, (6TM-mOR) has been identified, but its function and signaling are still largely unknown. Here, we present the structural and functional mechanisms of 6TM-mOR signaling activity upon binding to morphine. Our data suggest that despite the similarity of binding modes of the alternative 6TM-mOR and the dominant seven trans-membrane helix variant (7TM-mOR), the interaction with morphine generates different dynamic responses in the two receptors, thus, promoting the activation of different mOR-specific signaling pathways. We characterize a series of 6TM-mOR-specific cellular responses, and observed that they are significantly different from those for 7TM-mOR. Morphine stimulation of 6TM-mOR does not promote a cellular cAMP response, while it increases the intracellular Ca2+ concentration and reduces the cellular K+ conductance. Our findings indicate that 6TM-mOR has a unique contribution to the cellular opioid responses. Therefore, it should be considered as a relevant target for the development of novel pharmacological tools and medical protocols involving the use of opioids.

Differences in the Antinociceptive Effects and Binding Properties of Propranolol and Bupranolol Enantiomers

Recent efforts have suggested that the β-adrenergic receptor (β-AR) system may be a novel and viable therapeutic target for pain reduction; however, most of the work to date has focused on the β(2)-adrenergic receptor (AR). Here, we compared the antinociceptive effects of enantiomeric configurations of propranolol and bupranolol, two structurally similar nonselective β-blocking drugs, against mouse models of inflammatory and chronic pain. In addition, we calculated in silico docking and measured the binding properties of propranolol and bupranolol for all 3 β-ARs. Of the agents examined, S-bupranolol is superior in terms of its antinociceptive effect and exhibited fewer side effects than propranolol or its associated enantiomers. In contrast to propranolol, S-bupranolol exhibited negligible β-AR intrinsic agonist activity and displayed a full competitive antagonist profile at β(1)/β(2)/β(3)-ARs, producing a unique blockade of β(3)-ARs. We have shown that S-bupranolol is an effective antinociceptive agent in mice without negative side effects. The distinctive profile of S-bupranolol is most likely mediated by its negligible β-AR intrinsic agonist activity and unique blockade of β(3)-AR. These findings suggest that S-bupranolol instead of propranolol may represent a new and effective treatment for a variety of painful conditions.

PERSPECTIVE

The S enantiomer of bupranolol, a β-receptor antagonist, shows greater antinociceptive efficacy and a superior preclinical safety profile and it should be considered as a unique β-adrenergic receptor compound to advance future clinical pain studies.

μ-Opioid receptor 6-transmembrane isoform: A potential therapeutic target for new effective opioids

The μ-opioid receptor (MOR) is the primary target for opioid analgesics. MOR induces analgesia through the inhibition of second messenger pathways and the modulation of ion channels activity. Nevertheless, cellular excitation has also been demonstrated, and proposed to mediate reduction of therapeutic efficacy and opioid-induced hyperalgesia upon prolonged exposure to opioids. In this mini-perspective, we review the recently identified, functional MOR isoform subclass, which consists of six transmembrane helices (6 TM) and may play an important role in MOR signaling. There is evidence that 6 TM MOR signals through very different cellular pathways and may mediate excitatory cellular effects rather than the classic inhibitory effects produced by the stimulation of the major (7 TM) isoform. Therefore, the development of 6 TM and 7 TM MOR selective compounds represents a new and exciting opportunity to better understand the mechanisms of action and the pharmacodynamic properties of a new class of opioids.

Structural basis for μ-opioid receptor binding and activation

Opioids that stimulate the μ-opioid receptor (MOR1) are the most frequently prescribed and effective analgesics. Here we present a structural model of MOR1. Molecular dynamics simulations show a ligand-dependent increase in the conformational flexibility of the third intracellular loop that couples with the G protein complex. These simulations likewise identified residues that form frequent contacts with ligands. We validated the binding residues using site-directed mutagenesis coupled with radioligand binding and functional assays. The model was used to blindly screen a library of ∼1.2 million compounds. From the 34 compounds predicted to be strong binders, the top three candidates were examined using biochemical assays. One compound showed high efficacy and potency. Post hoc testing revealed this compound to be nalmefene, a potent clinically used antagonist, thus further validating the model. In summary, the MOR1 model provides a tool for elucidating the structural mechanism of ligand-initiated cell signaling and for screening novel analgesics.

Dose-response effects of TPI ASM8 in asthmatics after allergen

BACKGROUND

TPI ASM8 contains two modified antisense oligonucleotides (AON) targeting the beta subunit (β(c) ) of the IL-3, IL-5, GM-CSF receptors and the chemokine receptor CCR3. A previous study suggested that TPI ASM8 had broader effects than just inhibition of eosinophils in asthmatics.

OBJECTIVE

We assessed whether TPI ASM8 caused a dose-dependent attenuation in the inflammatory and physiological changes after inhaled allergen challenge (AIC).

METHODS

This single-center, open-label, stepwise-ascending dose study was conducted in fourteen stable, mild allergic asthmatics. Following placebo AIC, subjects underwent AIC after 4 days treatment with 1, 2, and 4 mg BID and finally 8 mg once daily (OD) of TPI ASM8, inhaled via the I-Neb™ nebuliser. Treatments were separated by 2-3-week washout periods.

RESULTS

TPI ASM8 was safe and well tolerated at all doses. TPI ASM8 8 mg OD reduced eosinophils in sputum after AIC (by 60.9% at 7 h and 68.4% at 24 h post-AIC, P=0.016 and P=0.007, respectively). Additionally, TPI ASM8 8 mg OD significantly attenuated the early and late airway responses as shown by the reduction in the area under the curve by 45% (P=0.016) and 59%, (P=0.0015), respectively, the increase in eosinophil cationic protein (ECP) by up to 57% (P=0.021), and airway responsiveness to methacholine by more than 1 doubling dose (P=0.012). A dose-response relationship was noted, and efficacy was maintained with once per day administration.

CONCLUSIONS

TPI ASM8 attenuated a broad range of inflammatory and physiological changes after AIC, suggesting that CCR3, IL-3, and GM-CSF also are important targets for the management of asthma.