Morphine, but not trauma, sensitizes to systemic Acinetobacter baumannii infection

Blocking IL-17A prevents oxycodone-induced depression-like effects and elevation of IL-6 levels in the ventral tegmental area and reduces oxycodone-derived physical dependence in rats

Oxycodone is the most prescribed opioid for pain management and has been available in clinics for almost a century, but effects of chronic oxycodone have been studied less than morphine in preclinical and clinical studies. Newly developed depression has been coupled with chronic oxycodone use in a few clinical studies, but no preclinical studies have investigated the pathogenesis of oxycodone-induced depression. Gut microbiome changes following oxycodone use is an understudied area, and interleukin-17A (IL-17A) is linked to both the development of mood disorders and regulation of gut microbiome. The present study investigated effects of chronic oxycodone exposure on mood-related behaviors (depression and anxiety), pain hypersensitivity, physical dependence, immune markers, and the gut microbiome and tested the hypothesis that blocking IL-17A with a systemically administered monoclonal antibody reduces oxycodone-derived effects. Oxycodone (using an incremental dosing regimen) or saline was injected twice a day for 12 days. IL-17A Ab (200 µg/100 µl) or saline was administered every 3rd day during the 12-day interval. Chronic oxycodone induced a depression-like effect, but not anxiogenic- or anxiolytic-like effects; promoted hyperalgesia; increased IL-17A and IL-6 levels in the ventral tegmental area (VTA); and induced physical dependence. IL-17A Ab co-administration with oxycodone prevented the depression-like effect and hyperalgesia, reduced naloxone-precipitated withdrawal signs, and normalized the increase in cytokine levels. Chronic oxycodone exposure did not affect gut microbiome and integrity. Our results identify a role for IL-17A in oxycodone-related behavioral and neuroimmune effects and show that IL-17A Ab has potential therapeutic value in blocking these effects. Given that humanized IL-17A Ab is approved for treatment of psoriasis and psoriatic arthritis, our findings point toward studying it for use in the treatment of oxycodone use disorder.

Insights into the Current and Possible Future Use of Opioid Antagonists in Relation to Opioid-Induced Constipation and Dysbiosis

Opioid receptor agonists, particularly those that activate µ-opioid receptors (MORs), are essential analgesic agents for acute or chronic mild to severe pain treatment. However, their use has raised concerns including, among others, intestinal dysbiosis. In addition, growing data on constipation-evoked intestinal dysbiosis have been reported. Opioid-induced constipation (OIC) creates an obstacle to continuing treatment with opioid analgesics. When non-opioid therapies fail to overcome the OIC, opioid antagonists with peripheral, fast first-pass metabolism, and gastrointestinal localized effects remain the drug of choice for OIC, which are discussed here. At first glance, their use seems to only be restricted to constipation, however, recent data on OIC-related dysbiosis and its contribution to the appearance of several opioid side effects has garnered a great of attention from researchers. Peripheral MORs have also been considered as a future target for opioid analgesics with limited central side effects. The properties of MOR antagonists counteracting OIC, and with limited influence on central and possibly peripheral MOR-mediated antinociception, will be highlighted. A new concept is also proposed for developing gut-selective MOR antagonists to treat or restore OIC while keeping peripheral antinociception unaffected. The impact of opioid antagonists on OIC in relation to changes in the gut microbiome is included.

Compound 511 ameliorates MRSA-induced lung injury by attenuating morphine-induced immunosuppression in mice via PI3K/AKT/mTOR pathway

BACKGROUND

Opioids are widely used in clinical practice. However, their long-term administration causes respiratory depression, addiction, tolerance, and severe immunosuppression. Traditional Chinese medicine (TCM) can alleviate opioid-induced adverse effects. Compound 511 is particularly developed for treating opioid addiction, based on Jiumi Liangfang, an ancient Chinese drug treatment and rehabilitation monograph completed in 1833 A.D. It is an herbal formula containing eight plants, each of them contributing to the overall pharmacological effect of the product: Panax ginseng C. A. Meyer (8.8%), Astragalus membranaceus (Fisch.) (18.2%), Datura metel Linn. (10.95%), Corydalis yanhusuo W. T. Wang (14.6%), Acanthopanar gracilistμlus W. W. Smith (10.95%), Ophiopogon japonicus (Linn. f.) Ker-Gawl. (10.95%), Gynostemma pentaphyllum (Thunb.) Makino (10.95%), Polygala arvensis Willd. (14.6%). This formula effectively ameliorates opioid-induced immunosuppression. However, the underlying mechanism remains unclear.

PURPOSE

To reveal the effects of Compound 511 on the immune response of morphine-induced immunosuppressive mice and their potential underlying molecular mechanism. This study provides information for a better clinical approach and scientific use of opioids.

METHODS

Immunosuppression was induced in mice by repeated morphine administration. Th1/Th2/Th17/Treg cell levels were measured using flow cytometry. Splenic transcription factors of Th1/Th2/Th17/Treg and outputs of the regulatory PI3K/AKT/mTOR signaling pathway were determined. Subsequently, methicillin-resistant Staphylococcus aureus (MRSA) was administered intranasally to morphine-induced immunosuppressive mice pretreated with Compound 511. Their lung inflammatory status was assessed using micro-computer tomography (CT), hematoxylin and eosin (H&E) staining, and enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared to morphine, Compound 511 significantly decreased the immune organ indexes of mice, corrected the Th1/Th2 and Treg/Th17 imbalance in the immune organs and peripheral blood, reduced the mRNA levels of FOXP3 and GATA3, and increased those of STAT3 and T-bet in the spleen. It improved immune function and reduced MRSA-induced lung inflammation.

CONCLUSION

Compound 511 ameliorates opioid-induced immunosuppression by regulating the balance of Th1/Th2 and Th17/Treg via PI3K/AKT/mTOR signaling pathway. Thus, it effectively reduces susceptibility of morphine-induced immunosuppressive mice to MRSA infection.

Immunogenicity of loop 3 of Omp34 from A. Baumannii in loopless C-lobe of TbpB of N. meningitidis

Acinetobacter baumannii is a common causative agent of nosocomial infections, with a mortality rate of 43% in infected patients. Due to the emergence of multidrug-resistant (MDR) strains, vaccine development has become necessary. Since the 34 kDa outer membrane protein Omp34 has been identified as a potential vaccine target, we implemented a hybrid antigen approach to target its extracellular loops. Using bioinformatic and structural analyses, we selected Loop 3 from Omp34 and displayed it on the loopless C-lobe (LCL) of TbpB of Neisseria meningitidis. The hybrid antigen and the LCL were produced and used to immunize mice for passive and active immunization and challenge experiments in which the reactivity of the sera was assessed by ELISAs, the bacterial load in the tissues measured and the survival of immunized mice compared. LCL was ineffective in immunization against A. baumannii thus the resulting immunity was due to the presence of Omp34 loop 3. It resulted in increased survival and a reduced bacterial load in the tissues compared to the control groups. The findings indicate that the immunogenicity of Omp34 loops can induce protection against A. baumannii infection, and it could probably be used as a vaccine candidate to control the pathogenesis of A. baumannii.

Dynamic Gene Clusters Mediating Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates

Acinetobacter baumanni (A. baumannii), a nonfermenting Gram-negative bacterium, has recently been associated with a broad range of nosocomial infections. To gain more meaningful insight into the problem of nosocomial illnesses caused by the multidrug-resistant (MDR) A. baumannii, as well as the factors that increase the risk of catching these infections, this investigation included a total of 86 clinical A. baumannii infections. Repetitive extragenic palindromic (REP)-PCR was used to investigate imipenem-resistant A. baumannii isolates for dynamic gene clusters causing carbapenem resistance. Four distinct A. baumannii lineages were found in the REP-PCR-DNA fingerprints of all isolates, with 95% of the samples coming from two dominant lineages. Imipenem, amikacin, and ciprofloxacin were less effective against genotype (A) isolates because of enhanced antibiotic tolerance. Lastly, to gain more insight into the mode of action of imipenem, we explored the binding affinity of imipenem toward different Acinetobacter baumannii OXA beta-lactamase class enzymes.

Opioid-Mediated HIV-1 Immunopathogenesis

Despite the ability of combination antiretroviral therapy to dramatically suppress viremia, the brain continues to be a reservoir of HIV-1 low-level replication. Adding further complexity to this is the comorbidity of drug abuse with HIV-1 associated neurocognitive disorders and neuroHIV. Among several abused drugs, the use of opiates is highly prevalent in HIV-1 infected individuals, both as an abused drug as well as for pain management. Opioids and their receptors have attained notable attention owing to their ability to modulate immune functions, in turn, impacting disease progression. Various cell culture, animal and human studies have implicated the role of opioids and their receptors in modulating viral replication and virus-mediated pathology both positively and negatively. Further, the combinatorial effects of HIV-1/HIV-1 proteins and morphine have demonstrated activation of inflammatory signaling in the host system. Herein, we summarized the current knowledge on the role of opioids on peripheral immunopathogenesis, viral immunopathogenesis, epigenetic profiles of the host and viral genome, neuropathogenesis of SIV/SHIV-infected non-human primates, blood-brain-barrier, HIV-1 viral latency, and viral rebound. Overall, this review provides recent insights into the role of opioids in HIV-1 immunopathogenesis. Graphical abstract.

Host Innate Immune Responses to Acinetobacter baumannii Infection

Acinetobacter baumannii has emerged as a major threat to global public health and is one of the key human pathogens in healthcare (nosocomial and community-acquired)-associated infections. Moreover, A. baumannii rapidly develops resistance to multiple antibiotics and is now globally regarded as a serious multidrug resistant pathogen. There is an urgent need to develop novel vaccines and immunotherapeutics as alternatives to antibiotics for clinical management of A. baumannii infection. However, our knowledge of host immune responses to A. baumannii infection and the identification of novel therapeutic targets are significantly lacking. This review highlights the recent advances and critical gaps in our understanding how A. baumannii interacts with the host innate pattern-recognition receptors, induces a cascade of inflammatory cytokine and chemokine responses, and recruits innate immune effectors (such as neutrophils and macrophages) to the site of infection for effective control of the infection. Such knowledge will facilitate the identification of new targets for the design and development of effective therapeutics and vaccines to fight this emerging threat.

La batalla contra las superbacterias: No más antimicrobianos, no hay ESKAPE

La resistencia a los antimicrobianos es uno de los más grandes retos de la medicina moderna. Durante la última década, un grupo de seis bacterias han probado no sólo su capacidad para relativamente “escapar” de los efectos de casi cualquier antimicrobiano, sino también por ser la causa principal de las infecciones hospitalarias. Estos organismos en conjunto se les conoce como ESKAPE, siglas que derivan de la primera letra de la categoría taxonómica género, o sea, del nombre científico de cada una de estas bacterias (Enterococcus spp, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa y Enterobacter spp.). La presente revisión tiene como objetivo describir los principales mecanismos de resistencia asociados a este grupo de bacterias y el impacto que han tenido en el desarrollo de nuevas estrategias antimicrobianas.

The Role of Opioid Receptors in Immune System Function

Research on the effects of opioids on immune responses was stimulated in the 1980s by the intersection of use of intravenous heroin and HIV infection, to determine if opioids were enhancing HIV progression. The majority of experiments administering opioid alkaloids (morphine and heroin) in vivo, or adding these drugs to cell cultures in vitro, showed that they were immunosuppressive. Immunosuppression was reported as down-regulation: of Natural Killer cell activity; of responses of T and B cells to mitogens; of antibody formation in vivo and in vitro; of depression of phagocytic and microbicidal activity of neutrophils and macrophages; of cytokine and chemokine production by macrophages, microglia, and astrocytes; by sensitization to various infections using animal models; and by enhanced replication of HIV in vitro. The specificity of the receptor involved in the immunosuppression was shown to be the mu opioid receptor (MOR) by using pharmacological antagonists and mice genetically deficient in MOR. Beginning with a paper published in 2005, evidence was presented that morphine is immune-stimulating via binding to MD2, a molecule associated with Toll-like Receptor 4 (TLR4), the receptor for bacterial lipopolysaccharide (LPS). This concept was pursued to implicate inflammation as a mechanism for the psychoactive effects of the opioid. This review considers the validity of this hypothesis and concludes that it is hard to sustain. The experiments demonstrating immunosuppression were carried out in vivo in rodent strains with normal levels of TLR4, or involved use of cells taken from animals that were wild-type for expression of TLR4. Since engagement of TLR4 is universally accepted to result in immune activation by up-regulation of NF-κB, if morphine were binding to TLR4, it would be predicted that opioids would have been found to be pro-inflammatory, which they were not. Further, morphine is immunosuppressive in mice with a defective TLR4 receptor. Morphine and morphine withdrawal have been shown to permit leakage of Gram-negative bacteria and LPS from the intestinal lumen. LPS is the major ligand for TLR4. It is proposed that an occult variable in experiments where morphine is being proposed to activate TLR4 is actually underlying sepsis induced by the opioid.

Opioid use potentiates the virulence of hospital-acquired infection, increases systemic bacterial dissemination and exacerbates gut dysbiosis in a murine model of Citrobacter rodentium infection

Opioid analgesics are frequently prescribed in the United States and worldwide. However, serious side effects such as addiction, immunosuppression and gastrointestinal symptoms limit their use. It was recently demonstrated that morphine treatment results in a significant disruption in gut barrier function, leading to an increased translocation of gut commensal bacteria. Further studies have indicated distinct alterations in the gut microbiome and metabolome following morphine treatment, contributing to the negative consequences that are associated with opioid use. However, it is unclear how opioids modulate gut homeostasis in the context of a hospital-acquired bacterial infection. Citrobacter rodentium is an ideal murine model of human infections with enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC). In the current study, a mouse model of C. rodentium infection was used to investigate the role of morphine in the modulation of gut homeostasis in the context of a hospital-acquired bacterial infection. Morphine treatment resulted in 1) the promotion of C. rodentium systemic dissemination, 2) an increase in the expression of the virulence factors of C. rodentium colonization in intestinal contents, 3) altered gut microbiome, 4) damaged integrity of gut epithelial barrier function, 5) inhibition of the C. rodentium-induced increase in goblet cells, and 6) dysregulated IL-17A immune response. This study demonstrates and further validates a positive correlation between opioid drug use/abuse and an increased risk of infections, suggesting that the overprescription of opioids may increase the susceptibility to hospital-acquired infection.

Thioredoxin-A is a virulence factor and mediator of the type IV pilus system in Acinetobacter baumannii

The Gram-negative pathogen, Acinetobacter baumannii has emerged as a global nosocomial health threat affecting the majority of hospitals in the U.S. and abroad. The redox protein thioredoxin has been shown to play several roles in modulation of cellular functions affecting various virulence factors in Gram-negative pathogens. This study aims to explore the role of thioredoxin-A protein (TrxA) in A. baumannii virulence. We determined that deletion of the TrxA gene did not significantly affect resistance to environmental stressors such as temperature, salt, and pH. However, TrxA was critical for survival in the presence of elevated levels of hydrogen peroxide. Lack of TrxA was associated with decreased expression of type IV pili related genes and an inability to undergo normal twitching motility. Interestingly, the TrxA-null mutant was able to form biofilms better than the wildtype (WT) and was observed to be significantly less virulent than the WT in a pulmonary infection model. These results are supportive of thioredoxin playing a key role in A. baumannii virulence.

Sequence similarity searches for morphine biosynthesis enzymes in bacteria yield putative targets for understanding associations between infection and opiate administration

Exploiting the immunosuppressive, analgesic and highly addictive properties of morphine could increase the success of a bacterial pathogen. Therefore, we performed sequence similarity searches for two morphine biosynthesis demethylases in bacteria. For thebaine 6-O-demethylase and codeine O-demethylase, we found strong alignments to three (Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii) of the six ESKAPE pathogens (Enterococcus faecalis, Staphylococcus aureus, K. pneumoniae, A. baumannii, P. aeruginosa and Enterobacter species) that are commonly associated with drug resistance and nosocomial infections. Expression of the aligned sequence found in P. aeruginosa (NP_252880.1/PA4191) is upregulated in isolates obtained from cystic fibrosis patients. Our findings provide putative mechanistic targets for understanding the role of morphine in pathogenicity.

A potential role for the gut microbiome in substance use disorders

Pathological substance use disorders represent a major public health crisis with limited effective treatment options. While much work has been done to understand the neuronal signaling networks and intracellular signaling cascades associated with prolonged drug use, these studies have yielded few successful treatment options for substance use disorders. In recent years, there has been a growing interest to explore interactions between the peripheral immune system, the gut microbiome, and the CNS. In this review, we will present a summary of existing evidence, suggesting a potential role for gut dysbiosis in the pathogenesis of substance use disorders. Clinical evidence of gut dysbiosis in human subjects with substance use disorder and preclinical evidence of gut dysbiosis in animal models of drug addiction are discussed in detail. Additionally, we examine how changes in the gut microbiome and its metabolites may not only be a consequence of substance use disorders but may in fact play a role in mediating behavioral response to drugs of abuse. While much work still needs to be done, understanding the interplay of gut microbiome in substance use disorders may offer a promising avenue for future therapeutic development.

Acute intraperitoneal infection with a hypervirulent Acinetobacter baumannii isolate in mice

Acinetobacter baumannii infection has become a major cause of healthcare-associated infection and a critical pathogen in the WHO antimicrobial resistance research and development priority list. Catheter-related septicemia is one of the major clinical manifestations of A. baumannii infection associated with high morbidity and mortality. In this study, we used a clinical A. baumannii strain (LAC-4) that is hypervirulent to immunocompetent C57BL/6 and BALB/c mice and established a mouse model of intraperitoneal (i.p.) A. baumannii infection. Our study showed that i.p. LAC-4 infection of C57BL/6 and BALB/c mice induces a lethal or sublethal infection with high bacterial burdens in peritoneal cavity, blood and tissues and the infected mice either succumbed to the infection within 24 hours or completely recovered from the infection. The infection induces acute peritoneal recruitment of neutrophils and other innate immune cells, and the local and systemic production of proinflammatory cytokines and chemokines (IL-1β, IL-5, IL-6, TNF-α, RANTES, MIP-1β, MCP-1, KC and IL-10). Mechanistic studies suggest an important role of macrophages in the host innate defense in this model in that in vitro stimulation of peritoneal macrophages with killed LAC-4 induced a similar pattern of cytokine/chemokine responses to those in the infected mice, and depletion of peritoneal macrophages rendered the mice significantly more susceptible to the infection. Thus, this mouse infection model will provide an alternative and useful tool for future pathogenesis studies of A. baumannii-associated septicemia and identification and characterization of important virulence factors, as well as serve as a surrogate model for rapid evaluation of novel therapeutics and vaccines for this emerging infectious agent.

Skin and Soft Tissue Models for Acinetobacter baumannii Infection

Multidrug-resistant A. baumannii are important Gram-negative pathogens causing persistent wound infections in both wounded and burned victims, which often result in secondary complications such as delayed wound healing, skin graft failure, and sometimes more serious outcomes such as sepsis and amputation. The choice of antibiotics to remediate these A. baumannii infections is becoming limited; and therefore, there has been a renewed interest in the research and development of new antibacterials targeting this pathogen. However, the evaluation of safety and efficacy is made more difficult by the lack of well-established in vivo models. This chapter describes established rodent and large animal models that have been used to investigate and develop treatments for A. baumannii skin and soft tissue infections.

A Porcine Wound Model of Acinetobacter baumannii Infection

Objective: To better understand Acinetobacter baumannii pathogenesis and to advance drug discovery against this pathogen, we developed a porcine, full-thickness, excisional, monospecies infection wound model.

Approach: The research was facilitated with AB5075, a previously characterized, extensively drug-resistant A. baumannii isolate. The model requires cyclophosphamide-induced neutropenia to establish a skin and soft tissue infection (SSTI) that persists beyond 7 days. Multiple, 12-mm-diameter full-thickness wounds were created in the skin overlying the cervical and thoracic dorsum. Wound beds were inoculated with 5.0 × 10⁴ colony-forming units (CFU) and covered with dressing.

Results:A. baumannii was observed in the wound bed and on the dressing in what appeared to be biofilm. When bacterial burdens were measured, proliferation to at least 10⁶ CFU/g (log₁₀6) wound tissue was observed. Infection was further characterized by scanning electron microscopy (SEM) and peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) staining. To validate as a treatment model, polymyxin B was applied topically to a subset of infected wounds every 2 days. Then, the treated and untreated wounds were compared using multiple quantitative and qualitative techniques to include gross pathology, CFU burden, histopathology, PNA-FISH, and SEM.

Innovation: This is the first study to use A. baumannii in a porcine model as the sole infectious agent.

Conclusion: The porcine model allows for an additional preclinical assessment of antibacterial candidates that show promise against A. baumannii in rodent models, further evaluating safety and efficacy, and serve as a large animal in preclinical assessment for the treatment of SSTI.

Part I: Minimum Quality Threshold in Preclinical Sepsis Studies (MQTiPSS) for Study Design and Humane Modeling Endpoints

Preclinical animal studies are mandatory before new treatments can be tested in clinical trials. However, their use in developing new therapies for sepsis has been controversial because of limitations of the models and inconsistencies with the clinical conditions. In consideration of the revised definition for clinical sepsis and septic shock (Sepsis-3), a Wiggers-Bernard Conference was held in Vienna in May 2017 to propose standardized guidelines on preclinical sepsis modeling. The participants conducted a literature review of 260 most highly cited scientific articles on sepsis models published between 2003 and 2012. The review showed, for example, that mice were used in 79% and euthanasia criteria were defined in 9% of the studies. Part I of this report details the recommendations for study design and humane modeling endpoints that should be addressed in sepsis models. The first recommendation is that survival follow-up should reflect the clinical time course of the infectious agent used in the sepsis model. Furthermore, it is recommended that therapeutic interventions should be initiated after the septic insult replicating clinical care. To define an unbiased and reproducible association between a new treatment and outcome, a randomization and blinding of treatments as well as inclusion of all methodological details in scientific publications is essential. In all preclinical sepsis studies, the high standards of animal welfare must be implemented. Therefore, development and validation of specific criteria for monitoring pain and distress, and euthanasia of septic animals, as well as the use of analgesics are recommended. A set of four considerations is also proposed to enhance translation potential of sepsis models. Relevant biological variables and comorbidities should be included in the study design and sepsis modeling should be extended to mammalian species other than rodents. In addition, the need for source control (in case of a defined infection focus) should be considered. These recommendations and considerations are proposed as "best practices" for animal models of sepsis that should be implemented.

Preoperative Opioids Increase the Risk of Periprosthetic Joint Infection After Total Joint Arthroplasty

BACKGROUND

Opioids have well-known immunosuppressive properties and preoperative opioid consumption is relatively common among patients undergoing total joint arthroplasty (TJA). The hypothesis of this study was that utilization of opioids preoperatively would increase the incidence of subsequent periprosthetic joint infection (PJI) in patients undergoing primary TJA.

METHODS

A comparative cohort study design was set up that used a cohort of 23,754 TJA patients at a single institution. Patient records were reviewed to extract relevant information, in particular details of opioid consumption, and an internal institutional database of PJI was cross-referenced against the cohort to identify patients who developed a PJI within 2 years of index arthroplasty. Univariate and multivariate linear regression analyses were used to examine the potential association between preoperative opioid consumption and the development of PJI.

RESULTS

Among the total cohort of 23,754 patients, 5051 (21.3%) patients used opioids before index arthroplasty. Preoperative opioid usage overall was found to be a significant risk factor for development of PJI in the univariate (odds ratio, 1.63; P = .005) and multivariate analyses (adjusted odds ratio, 1.53 [95% confidence interval, 1.14-2.05], P = .005).

CONCLUSION

Preoperative opioid consumption is independently associated with a higher risk of developing a PJI after primary TJA. These findings underscore a need for caution when prescribing opioids in patients with degenerative joint disease who may later require arthroplasty.

Update of the Scientific Opinion on opium alkaloids in poppy seeds

Poppy seeds are obtained from the opium poppy (Papaver somniferum L.). They are used as food and to produce edible oil. The opium poppy plant contains narcotic alkaloids such as morphine and codeine. Poppy seeds do not contain the opium alkaloids, but can become contaminated with alkaloids as a result of pest damage and during harvesting. The European Commission asked EFSA to provide an update of the Scientific Opinion on opium alkaloids in poppy seeds. The assessment is based on data on morphine, codeine, thebaine, oripavine, noscapine and papaverine in poppy seed samples. The CONTAM Panel confirms the acute reference dose (ARfD) of 10 μg morphine/kg body weight (bw) and concluded that the concentration of codeine in the poppy seed samples should be taken into account by converting codeine to morphine equivalents, using a factor of 0.2. The ARfD is therefore a group ARfD for morphine and codeine, expressed in morphine equivalents. Mean and high levels of dietary exposure to morphine equivalents from poppy seeds considered to have high levels of opium alkaloids (i.e. poppy seeds from varieties primarily grown for pharmaceutical use) exceed the ARfD in most age groups. For poppy seeds considered to have relatively low concentrations of opium alkaloids (i.e. primarily varieties for food use), some exceedance of the ARfD is also seen at high levels of dietary exposure in most surveys. For noscapine and papaverine, the available data do not allow making a hazard characterisation. However, comparison of the dietary exposure to the recommended therapeutical doses does not suggest a health concern for these alkaloids. For thebaine and oripavine, no risk characterisation was done due to insufficient data. However, for thebaine, limited evidence indicates a higher acute lethality than for morphine and the estimated exposure could present a health risk.

Association between rs2275913 single-nucleotide polymorphism of the interleukin-17A gene and perioperative analgesic use in cosmetic orthognathic surgery

AIM

Interleukin-17A (IL-17A) plays an essential role in tissue inflammation by inducing proinflammatory cytokine and chemokine production and is related to innate immune reactions. IL-17A also contributes to neuroinflammation, neuropathic pain, and mechanical hypersensitivity after peripheral nerve injury in rodents. To clarify the contribution of IL-17A to pain-related phenotypes in humans, we investigated the association between pain-related phenotypes and the rs2275913 single-nucleotide polymorphism (SNP) of the IL-17A gene, which has been reported to be associated with rheumatoid arthritis, ulcerative colitis, and some cancers.

METHODS

The present study used a correlational design to examine the impact of the rs2275913 SNP on postoperative pain-related phenotypes in a group of patients who underwent cosmetic orthognathic surgery.

RESULTS

Carriers of the AA genotype had higher opioid requirements during and after surgery than carriers of the AG and GG genotypes (P = .009). Linear regression analysis indicated that opioid requirements linearly increased as the copy number of the A allele of the SNP increased (P = .008).

CONCLUSIONS

Opioid requirements during and after surgery are enhanced in carriers of the AA genotype of the rs2275913 SNP of the IL-17A gene, possibly through an enhancement of IL-17A function that induces inflammation that is related to the inflammatory pain stimulus.

Opioid Analgesic Use and Risk for Invasive Pneumococcal Diseases: A Nested Case-Control Study

BACKGROUND

Although certain opioid analgesics have immunosuppressive properties and increase the risk for infections in animals, the clinical effects of prescription opioid use on infection risk among humans are unknown.

OBJECTIVE

To test the hypothesis that prescription opioid use is an independent risk factor for invasive pneumococcal disease (IPD).

DESIGN

Nested case-control study.

SETTING

Tennessee Medicaid database linked to Medicare and Active Bacterial Core surveillance system databases (1995 to 2014).

PATIENTS

1233 case patients with IPD aged 5 years and older matched to 24 399 control participants by diagnosis date, age, and county of residence.

MEASUREMENTS

Opioid use was measured on the basis of pharmacy prescription fills. Invasive pneumococcal disease was defined by the isolation of Streptococcus pneumoniae from a normally sterile site. The odds of current opioid use were compared between the case and control groups, accounting for known IPD risk factors. Secondary analyses categorized opioid use by opioid characteristics, applied an IPD risk score to assure comparability between exposure groups, and analyzed pneumonia and nonpneumonia IPD cases separately.

RESULTS

Persons in the case group had greater odds than control participants of being current opioid users (adjusted odds ratio [aOR], 1.62 [95% CI, 1.36 to 1.92]). Associations were strongest for opioids that were long acting (aOR, 1.87 [CI, 1.24 to 2.82]), of high potency (aOR, 1.72 [CI, 1.32 to 2.25]), or were used at high dosages (50 to 90 morphine milligram equivalents [MME]/d: aOR, 1.71 [CI, 1.22 to 2.39]; ≥90 MME/d: aOR, 1.75 [CI, 1.33 to 2.29]). Results were consistent when the IPD risk score was taken into account and pneumonia and nonpneumonia IPD were analyzed separately.

LIMITATIONS

Unmeasured confounding and measurement error, although sensitivity analyses suggested that neither was likely to affect results. Actual opioid use and other nonprescription use (such as illicit opioid use) were not measured.

CONCLUSION

Opioid use is associated with an increased risk for IPD and represents a novel risk factor for these diseases.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Analgesia in clinically relevant rodent models of sepsis

Postoperative analgesia in rodent sepsis models has been considerably neglected in the past. However, intentions to model clinical practice, increasing awareness of animal ethics, efforts to apply the 3Rs (replacement, reduction, refinement), and stricter legislation argue for a change in this respect. In this review, we describe different concepts of analgesia in rodent models of sepsis focusing on opioid agonists as well as non-opioid analgesics. Advantages and pitfalls in study design and side-effects are discussed. Score sheets should be used to adapt analgesia or to terminate experiments using humane endpoints. Further research is needed to differentiate behavioral changes caused by sepsis and pain or as a consequence of analgesia. Information on the efficacy of analgesia in sepsis models is scarce. Hence, studies are needed to identify the best ways to reduce suffering of research animals and thereby optimize the clinically relevant rodent models of sepsis.

Clinical and Pathophysiological Overview of Acinetobacter Infections: a Century of Challenges

Acinetobacter is a complex genus, and historically, there has been confusion about the existence of multiple species. The species commonly cause nosocomial infections, predominantly aspiration pneumonia and catheter-associated bacteremia, but can also cause soft tissue and urinary tract infections. Community-acquired infections by Acinetobacter spp. are increasingly reported. Transmission of Acinetobacter and subsequent disease is facilitated by the organism's environmental tenacity, resistance to desiccation, and evasion of host immunity. The virulence properties demonstrated by Acinetobacter spp. primarily stem from evasion of rapid clearance by the innate immune system, effectively enabling high bacterial density that triggers lipopolysaccharide (LPS)-Toll-like receptor 4 (TLR4)-mediated sepsis. Capsular polysaccharide is a critical virulence factor that enables immune evasion, while LPS triggers septic shock. However, the primary driver of clinical outcome is antibiotic resistance. Administration of initially effective therapy is key to improving survival, reducing 30-day mortality threefold. Regrettably, due to the high frequency of this organism having an extreme drug resistance (XDR) phenotype, early initiation of effective therapy is a major clinical challenge. Given its high rate of antibiotic resistance and abysmal outcomes (up to 70% mortality rate from infections caused by XDR strains in some case series), new preventative and therapeutic options for Acinetobacter spp. are desperately needed.

Improving animal welfare using continuous nalbuphine infusion in a long-term rat model of sepsis

Background

Sepsis research relies on animal models to investigate the mechanisms of the dysregulated host response to infection. Animal welfare concerns request the use of potent analgesics for the Refinement of existing sepsis models, according to the 3Rs principle. Nevertheless, adequate analgesia is often missing, partly because the effects of analgesics in this particular condition are unknown. We evaluated the use of nalbuphine, an opioid with kappa agonistic and mu antagonistic effects, in rats with and without experimental sepsis.

Methods

Male Wistar rats were anesthetized with isoflurane and instrumented with a venous line for drug administration. Arterial cannulation allowed for blood pressure measurements and blood sampling in short-term experiments of non-septic animals. Nalbuphine (or placebo) was administered intravenously at a dose of 1 mg/kg/h. Long-term (48 h) experiments in awake septic animals included repetitive clinical scoring with the Rat Grimace Scale and continuous heart rate monitoring by telemetry. Sepsis was induced by intraperitoneal injection of faecal slurry. Nalbuphine plasma levels were measured by liquid chromatography—high resolution mass spectrometry.

Results

In anesthetized healthy animals, nalbuphine led to a significant reduction of respiratory rate, heart rate, and mean arterial pressure during short-term experiments. In awake septic animals, a continuous nalbuphine infusion did not affect heart rate but significantly improved the values of the Rat Grimace Scale. Nalbuphine plasma concentrations remained stable between 4 and 24 h of continuous infusion in septic rats.

Conclusions

In anaesthetised rats, nalbuphine depresses respiratory rate, heart rate, and blood pressure. In awake animals, nalbuphine analgesia improves animal welfare during sepsis.

Special Considerations for the Treatment of Pain from Torture and War

Pain care for survivors of torture and of war shows similarities and marked differences. For both, pain can be complex with unfamiliar presentations and the pains hard to assign to known disorders. For many survivors, pain and associated disability are overshadowed by psychological distress, often by post-traumatic stress symptoms that can be frightening and isolating. Pain medicine in war can exemplify best techniques and organisation, reducing suffering, but many military veterans have persistent pain that undermines their readjustment. By contrast, survivors of torture rarely have any acute health care; their risk for developing chronic pain is high. Even when settled as refugees in a well-resourced country, their access to healthcare may be restricted. Recent evidence is reviewed that informs assessment and treatment of pain in both groups, with the broader context of psychological distress addressed at the end. Clinical and research implications are briefly outlined.

Opioid Analgesics and the Risk of Serious Infections Among Patients With Rheumatoid Arthritis: A Self-Controlled Case Series Study

OBJECTIVE

Animal studies and in vitro human studies suggest that certain opioid analgesics impair crucial immune functions. This study was undertaken to determine whether opioid use is associated with increased risk of serious infection in patients with rheumatoid arthritis (RA).

METHODS

We conducted a self-controlled case series analysis on a retrospective cohort of 13,796 patients with RA enrolled in Tennessee Medicaid in 1995-2009. Within-person comparisons of the risk of hospitalization for serious infection during periods of opioid use versus non-use were performed using conditional Poisson regression. Fixed confounders were accounted for by design; time-varying confounders included age and use of disease-modifying antirheumatic drugs, glucocorticoids, and proton-pump inhibitors. In additional analyses, risks associated with new opioid use, use of opioids known to have immunosuppressive properties, use of long-acting opioids, and different opioid dosages were assessed. Sensitivity analyses were performed to account for potential protopathic bias and confounding by indication.

RESULTS

Among 1,790 patients with RA who had at least 1 hospitalization for serious infection, the adjusted incidence rate of serious infection was higher during periods of current opioid use compared to non-use, with an incidence rate ratio (IRR) of 1.39 (95% confidence interval [95% CI] 1.19-1.62). The incidence rate was also higher during periods of long-acting opioid use, immunosuppressive opioid use, and new opioid use compared to non-use (IRR 2.01 [95% CI 1.52-2.66], IRR 1.72 [95% CI 1.33-2.23], and IRR 2.38 [95% CI 1.65-3.42], respectively). Results of sensitivity analyses were consistent with the main findings.

CONCLUSION

In within-person comparisons of patients with RA, opioid use was associated with an increased risk of hospitalization for serious infection.

Molecular Epidemiology of Carbapenem-Resistant Acinetobacter Baumannii Complex Isolates from Patients that were Injured During the Eastern Ukrainian Conflict

This study addressed carbapenem-resistant Acinetobacter baumannii complex (ABC) isolates from patients that were injured during the military conflict in the Eastern Ukraine and treated at German Armed Forces Hospitals in 2014 and 2015. Clonal diversity of the strains and potential ways of transmission were analyzed.

Patients with one or several isolation events of carbapenem-resistant ABC were included. Isolates were characterized by VITEK II-based identification and resistance testing, molecular screening for frequent carbapenemase genes, and DiversiLab rep-PCR-based typing. Available clinical information of the patients was assessed.

From 21 young male Ukrainian patients with battle injuries, 32 carbapenem- and fluoroquinolone-resistant ABC strains were isolated. Four major clonal clusters were detected. From four patients (19%), ABC isolates from more than one clonal cluster were isolated. The composition of the clusters suggested transmission events prior to the admission to the German hospitals.

The infection and colonization pressure in the conflict regions of the Eastern Ukraine with ABC of low clonal diversity is considerable. Respective infection risks have to be considered in case of battle-related injuries in these regions. The low number of local clones makes any molecular exclusion of transmission events difficult.

Gut failure in critical care: old school versus new school

The concept of bacterial translocation and gut-origin sepsis as causes of systemic infectious complications and multiple organ deficiency syndrome in surgical and critically ill patients has been a recurring issue over the last decades attracting the scientific interest. Although gastrointestinal dysfunction seemingly arises frequently in intensive care unit patients, it is usually underdiagnosed or underestimated, because the pathophysiology involved is incompletely understood and its exact clinical relevance still remains controversial with an unknown yet probably adverse impact on the patients' outcome. The purpose of this review is to define gut-origin sepsis and related terms, to describe the mechanisms leading to gut-derived complications, and to illustrate the therapeutic options to prevent or limit these untoward processes.

Disruption of gut homeostasis by opioids accelerates HIV disease progression

Cumulative studies during the past 30 years have established the correlation between opioid abuse and human immunodeficiency virus (HIV) infection. Further studies also demonstrate that opioid addiction is associated with faster progression to AIDS in patients. Recently, it was revealed that disruption of gut homeostasis and subsequent microbial translocation play important roles in pathological activation of the immune system during HIV infection and contributes to accelerated disease progression. Similarly, opioids have been shown to modulate gut immunity and induce gut bacterial translocation. This review will explore the mechanisms by which opioids accelerate HIV disease progression by disrupting gut homeostasis. Better understanding of these mechanisms will facilitate the search for new therapeutic interventions to treat HIV infection especially in opioid abusing population.

Morphine compromises bronchial epithelial TLR2/IL17R signaling crosstalk, necessary for lung IL17 homeostasis

Opportunistic lung infection and inflammation is a hallmark of chronic recreational/clinical use of morphine. We show that early induction of IL17 from the bronchial epithelium, following pathogenic encounter is a protective response, which contributes to pathogenic clearance and currently attributed to TLR2 activation in immune cells. Concurrent activation of TLR2 and IL17R in bronchial epithelium results in the sequestration of MyD88 (TLR2 adapter) by Act1/CIKS (IL17R adapter), thereby turning off TLR2 signaling to restore homeostasis. Morphine inhibits the early IL17 release and interaction between Act1 and MyD88, leading to decreased pathogenic clearance and sustained inflammation. Hence, we propose that therapeutically targeting either TLR2 or IL17 in bronchial epithelia, in the context of morphine, can restore inflammatory homeostasis.

Validation of a novel murine wound model of Acinetobacter baumannii infection

Patients recovering from traumatic injuries or surgery often require weeks to months of hospitalization, increasing the risk for wound and surgical site infections caused by ESKAPE pathogens, which include A. baumannii (the ESKAPE pathogens are Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). As new therapies are being developed to counter A. baumannii infections, animal models are also needed to evaluate potential treatments. Here, we present an excisional, murine wound model in which a diminutive inoculum of a clinically relevant, multidrug-resistant A. baumannii isolate can proliferate, form biofilms, and be effectively treated with antibiotics. The model requires a temporary, cyclophosphamide-induced neutropenia to establish an infection that can persist. A 6-mm-diameter, full-thickness wound was created in the skin overlying the thoracic spine, and after the wound bed was inoculated, it was covered with a dressing for 7 days. Uninoculated control wounds healed within 13 days, whereas infected, placebo-treated wounds remained unclosed beyond 21 days. Treated and untreated wounds were assessed with multiple quantitative and qualitative techniques that included gross pathology, weight loss and recovery, wound closure, bacterial burden, 16S rRNA community profiling, histopathology, peptide nucleic acid-fluorescence in situ hybridization, and scanning electron microscopy assessment of biofilms. The range of differences that we are able to identify with these measures in antibiotic- versus placebo-treated animals provides a clear window within which novel antimicrobial therapies can be assessed. The model can be used to evaluate antimicrobials for their ability to reduce specific pathogen loads in wounded tissues and clear biofilms. Ultimately, the mouse model approach allows for highly powered studies and serves as an initial multifaceted in vivo assessment prior to testing in larger animals.

Pathophysiology of endotoxin tolerance: mechanisms and clinical consequences

Endotoxin tolerance was first described in a study that exposed animals to a sublethal dose of bacterial endotoxin. The animals subsequently survived a lethal injection of endotoxin. This refractory state is associated with the innate immune system and, in particular, with monocytes and macrophages, which act as the main participants. Several mechanisms are involved in the control of endotoxin tolerance; however, a full understanding of this phenomenon remains elusive. A number of recent reports indicate that clinical examples of endotoxin tolerance include not only sepsis but also diseases such as cystic fibrosis and acute coronary syndrome. In these pathologies, the risk of new infections correlates with a refractory state. This review integrates the molecular basis and clinical implications of endotoxin tolerance in various pathologies.

Trauma is associated with a better prognosis in intensive care patients with Acinetobacter infections

PURPOSE

Acinetobacter baumannii has emerged as a common cause of infection in war-related trauma, civilian trauma and other surgical emergencies. The aim of this study was to determine prognostic factors especially trauma, in critically ill surgical patients with Acinetobacter spp. infection in a reference emergency ICU.

METHODS

A retrospective review of medical records was conducted for all patients admitted to the ICU who developed Acinetobacter spp. infection from January 2007 to December 2009. Bivariate and multivariate analyses were made for 36 patients. The end-point analyzed was the in-hospital mortality.

RESULTS

The initial analysis revealed a majority of young (43.6 years ± 17.1) men (92 %), trauma victims (78 %) and an in-hospital mortality of 30 %. Patients who had not suffered trauma presented with other surgical conditions and were on average older than trauma patients (57 ± 12 versus 40 ± 16 years). The overall APACHE II score average was 15.3. The ventilator-associated pneumonia was the main Acinetobacter infection diagnosed. In bivariate analysis lower Glasgow coma scale (p = 0.01) was associated with increased chance of death and being victim of trauma was a protecting factor (OR: 0.16; 95 % CI: 0.03-0.89). Receiving adequate treatment made no difference to outcome (OR: 0.55; 95 % CI: 0.05-3.15). Multivariate analysis showed that only the presence of trauma was independently associated with prognosis and was a protecting factor.

CONCLUSION

Trauma was a marker of good prognosis in emergency ICU patients with Acinetobacter spp. infection.

Morphine induces bacterial translocation in mice by compromising intestinal barrier function in a TLR-dependent manner

Opiates are among the most prescribed drugs for pain management. However, morphine use or abuse results in significant gut bacterial translocation and predisposes patients to serious infections with gut origin. The mechanism underlying this defect is still unknown. In this report, we investigated the mechanisms underlying compromised gut immune function and bacterial translocation following morphine treatment. We demonstrate significant bacterial translocation to mesenteric lymph node (MLN) and liver following morphine treatment in wild-type (WT) animals that was dramatically and significantly attenuated in Toll-like receptor (TLR2 and 4) knockout mice. We further observed significant disruption of tight junction protein organization only in the ileum but not in the colon of morphine treated WT animals. Inhibition of myosin light chain kinase (MLCK) blocked the effects of both morphine and TLR ligands, suggesting the role of MLCK in tight junction modulation by TLR. This study conclusively demonstrates that morphine induced gut epithelial barrier dysfunction and subsequent bacteria translocation are mediated by TLR signaling and thus TLRs can be exploited as potential therapeutic targets for alleviating infections and even sepsis in morphine-using or abusing populations.

Endogenous opiates and behavior: 2011

This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).

Battlefield analgesia: a brief review of current trends and concepts in the treatment of pain in US military casualties from the conflicts in Iraq and Afghanistan

SUMMARY Battlefield analgesia and post-injury pain management is a high priority within the military medical community. The combined military services of the USA have developed a Pain Task Force and clinical practice guidelines to ensure that adequate analgesia is provided to our wounded soldiers as far forward as the point of injury on the battlefield. As a result of this emphasis, novel analgesic techniques and equipment have led to improved pain management. Continuous peripheral nerve blocks, intranasal ketamine, battlefield acupuncture and other adjuncts have all been utilized safely and successfully. The ability to provide rapid analgesia as early in the course of injury as possible not only helps with the immediate pain of the soldier, but potentially minimizes the risk of developing chronic postinjury pain. During the long medical evacuation system the risks of both undertreatment and overtreatment of pain are very real. Future studies and observation will help to delineate best treatment regimens and pave the way for the next generation of medical providers to positively impact a soldier’s recovery. This article is written from the perspective of the USA with a focus on the conflicts in Afghanistan (Operation Enduring Freedom) and Iraq (Operation Iraqi Freedom).

Acinetobacter in modern warfare

Increasing appreciation of the role of Acinetobacter baumannii in the aetiology of severe nosocomial infections, together with its ability to employ several mechanisms to rapidly develop resistance to multiple classes of antimicrobial agents, has led to growing interest in this organism over recent years. Recognition and subsequent investigation of the significance of pathogenic Acinetobacter infections in military personnel sustaining injuries during the conflicts in Afghanistan and Iraq has provided an important contribution to the epidemiology of infections with Acinetobacter spp. The following review examines this recent military experience.

Drugs of abuse effects on immunity and microbial pathogenesis

Substance abuse remains a serious medical, public health, and social problem. The impact on destructive public health and health costs compounded with the negative consequences of drugs abuse poses a significant toll on the economy. Despite significant advancement of research in the field treatment of and care of patients with substance abuse has lagged behind because of limited education and training of clinicians on substance abuse problems. The goal of the special issue is to provide the current status on the mechanisms underlying the increased prevalence of opportunistic infections in the drug abuse population, to identify important areas where further research would be beneficial and to open new avenues of investigation for therapeutic development. We aimed these articles for the benefit of both basic and clinical researchers.