Zinc-chelating BET bromodomain inhibitors equally target islet endocrine cell types

Inhibition of the bromodomain and extraterminal domain (BET) protein family is a potential strategy to prevent and treat diabetes; however, the clinical use of BET bromodomain inhibitors (BETi) is associated with adverse effects. Here, we explore a strategy for targeting BETi to β-cells by exploiting the high zinc (Zn2+) concentration in β-cells relative to other cell types. We report the synthesis of a novel, Zn2+-chelating derivative of the pan-BETi (+)-JQ1, (+)-JQ1-DPA, in which (+)-JQ1 was conjugated to dipicolyl amine (DPA). As controls, we synthesized (+)-JQ1-DBA, a non-Zn2+-chelating derivative, and (-)-JQ1-DPA, an inactive enantiomer that chelates Zn2+. Molecular modeling and biophysical assays showed that (+)-JQ1-DPA and (+)-JQ1-DBA retain potent binding to BET bromodomains in vitro. Cellular assays demonstrated (+)-JQ1-DPA attenuated NF-ĸB target gene expression in β-cells stimulated with the pro-inflammatory cytokine interleukin 1β. To assess β-cell selectivity, we isolated islets from a mouse model that expresses green fluorescent protein in insulin-positive β-cells and mTomato in insulin-negative cells (non-β-cells). Surprisingly, Zn2+-chelation did not confer β-cell selectivity as (+)-JQ1-DPA was equally effective in both β- and α-cells; however, (+)-JQ1-DPA was less effective in macrophages, a non-endocrine islet cell type. Intriguingly, the non-Zn2+-chelating derivative (+)-JQ1-DBA displayed the opposite selectivity, with greater effect in macrophages compared to (+)-JQ1-DPA, suggesting potential as a macrophage-targeting molecule. These findings suggest that Zn2+-chelating small molecules confer endocrine cell selectivity rather than β-cell selectivity in pancreatic islets and provide valuable insights and techniques to assess Zn2+-chelation as an approach to selectively target small molecules to pancreatic β-cells.

N-terminal BET bromodomain inhibitors disrupt a BRD4-p65 interaction and reduce inducible nitric oxide synthase transcription in pancreatic β-cells

Chronic inflammation of pancreatic islets is a key driver of β-cell damage that can lead to autoreactivity and the eventual onset of autoimmune diabetes (T1D). In the islet, elevated levels of proinflammatory cytokines induce the transcription of the inducible nitric oxide synthase (iNOS) gene, NOS2, ultimately resulting in increased nitric oxide (NO). Excessive or prolonged exposure to NO causes β-cell dysfunction and failure associated with defects in mitochondrial respiration. Recent studies showed that inhibition of the bromodomain and extraterminal domain (BET) family of proteins, a druggable class of epigenetic reader proteins, prevents the onset and progression of T1D in the non-obese diabetic mouse model. We hypothesized that BET proteins co-activate transcription of cytokine-induced inflammatory gene targets in β-cells and that selective, chemotherapeutic inhibition of BET bromodomains could reduce such transcription. Here, we investigated the ability of BET bromodomain small molecule inhibitors to reduce the β-cell response to the proinflammatory cytokine interleukin 1 beta (IL-1β). BET bromodomain inhibition attenuated IL-1β-induced transcription of the inflammatory mediator NOS2 and consequent iNOS protein and NO production. Reduced NOS2 transcription is consistent with inhibition of NF-κB facilitated by disrupting the interaction of a single BET family member, BRD4, with the NF-κB subunit, p65. Using recently reported selective inhibitors of the first and second BET bromodomains, inhibition of only the first bromodomain was necessary to reduce the interaction of BRD4 with p65 in β-cells. Moreover, inhibition of the first bromodomain was sufficient to mitigate IL-1β-driven decreases in mitochondrial oxygen consumption rates and β-cell viability. By identifying a role for the interaction between BRD4 and p65 in controlling the response of β-cells to proinflammatory cytokines, we provide mechanistic information on how BET bromodomain inhibition can decrease inflammation. These studies also support the potential therapeutic application of more selective BET bromodomain inhibitors in attenuating β-cell inflammation.

Spinal muscular atrophy astrocytes exhibit abnormal calcium regulation and reduced growth factor production

Spinal muscular atrophy (SMA) is a genetic disorder caused by the deletion of the survival motor neuron 1 (SMN1) gene that leads to loss of motor neurons in the spinal cord. Although motor neurons are selectively lost during SMA pathology, selective replacement of SMN in motor neurons does not lead to full rescue in mouse models. Due to the ubiquitous expression of SMN, it is likely that other cell types besides motor neurons are affected by its disruption and therefore may contribute to disease pathology. Here we show that astrocytes in SMAΔ7 mouse spinal cord and from SMA-induced pluripotent stem cells exhibit morphological and cellular changes indicative of activation before overt motor neuron loss. Furthermore, our in vitro studies show mis-regulation of basal calcium and decreased response to adenosine triphosphate stimulation indicating abnormal astrocyte function. Together, for the first time, these data show early disruptions in astrocytes that may contribute to SMA disease pathology.

Low dose interferon-alpha therapy for HIV-associated multicentric Castleman's disease

Successful maintenance therapy with weekly interferon-alpha for HIV-associated multicentric Castleman's disease is described.

Obstacles to penicillin use in treating pneumococcal infection

OBJECTIVES

To determine the pattern of penicillin use in the treatment of pneumococcal pneumonia, and factors contributing to the use of alternative antibiotics.

METHODS

This study included all adult inpatients of St. Vincent's Hospital and Medical Center who had documented pneumococcal pneumonia between December 1998 and October 1999. St. Vincent's is a 600 bed tertiary teaching hospital in New York City. Patients who had Streptococcus pneumoniae isolated from a respiratory tract specimen were identified through microbiology laboratory records. A retrospective chart review of these patients was conducted, and those identified with clinical pneumonia were included in this study. Antibiotic use, patient demographics, resistance data, and clinician awareness of the antibiotic susceptibility results were noted.

RESULTS

Sixty adult patients hospitalized with documented pneumococcal pneumonia were identified. Thirteen (21.6%) of the 60 patients received penicillin or ampicillin. Susceptibility results were not noted in the medical record in 21 (35.0%) of the 60 patients, and none received penicillin. High rates of reported penicillin allergy in 8 (13.3%) of the 60 patients, and reluctance to use penicillin when isolates demonstrated intermediate susceptibility in 8 (13.3%) of the 60 patients were observed.

CONCLUSIONS

Several remediable obstacles to penicillin use were identified in this study. An increased awareness of susceptibility results by physicians and education of practitioners could have increased the use of penicillin as therapy to two-thirds of these patients.

Lung cancer in HIV-infected patients: a one-year experience

The relative incidence and rate of lung cancer in HIV-infected patients compared with the general US population has been a source of controversy. We sought to establish these parameters in a cohort of 2616 HIV-infected patients. Tumour type, stage of disease, patient demographics and immune parameters including viral loads were ascertained. An annual rate of 191 cases/100,000 population was found, which is 3.01 times greater (95% confidence interval [CI]=1.3-7.0) when compared with the general US population and 7.4 times the rate in US males between ages 35 and 54 (95% CI=3.1-17.8). Three patients had CD4 counts greater than 200 cells/mm3 at diagnosis and 2 had undetectable viral loads. The mean age was 44 years and all had advanced disease and short survival. In conclusion, the incidence of primary lung cancer was increased in this cohort of HIV-infected patients and occurred over a wide range of immunosuppression and viral replication.

The ESP culture system for drug susceptibilities of Mycobacterium avium complex

OBJECTIVE

To validate the non-radiometric, broth-based ESP system for determining Mycobacterium avium complex (MAC) susceptibilities.

METHODS

MAC isolates from sterile body sites of 20 adult HIV-infected patients who were failing their present MAC regimen were identified. Susceptibilities were determined and comparisons made between the agar proportion method and the ESP system for clarithromycin, ethambutol, sparfloxacin and cycloserine.

RESULTS

Ninety-nine percent of the MICS generated by the ESP system user identical to or lower than the MICs determined by the agar proportion

METHOD

In vitro resistance was documented by the ESP system for 86% of the drugs that patients were taking at the time of breakthrough, and no resistance was seen to cycloserine, a drug that no patient was taking.

CONCLUSIONS

The ESP system, a fast and reliable method for determining MAC susceptibilities, could be used to optimize MAC regimens in a timely fashion, avoid the use of ineffective drugs, minimize emerging resistance and ultimately improve outcome.

The emergence of resistant strains of Acinetobacter baumannii: clinical and infection control implications

A prospective study was undertaken to determine colonization rates, susceptibility profiles, and outcomes in patients with clinical isolates of Acinetobacter baumannii. Fifty percent of patients became colonized with A. baumannii, and 29% of these patients had clinical and colonizing isolates with discordant susceptibility profiles, without apparent relation to antibiotic use. Barrier infection control measures are necessary to prevent nosocomial transmission.

Amoxicillin-clavulanic acid for treating drug-resistant Mycobacterium tuberculosis

This report describes two patients with multidrug resistant tuberculosis who were successfully treated with the addition of amoxicillin-clavulanic acid to second-line drugs. Mycobacterium tuberculosis possesses a beta-lactamase contributing to its resistance to beta-lactam antibiotics. The combination of clavulanic acid, a beta-lactamase inhibitor, and amoxicillin has been shown bactericidal for M tuberculosis in vitro. These data suggest that resistant tuberculosis may warrant a trial of treatment including amoxicillin-clavulanic acid.

Prehatch color stimulation effects on color pecking preferences and color discrimination learning in white leghorn chicks

Four experiments assessed the effects of stimulating chick embryos with colored light at 2 intensity levels. Both posthatch color pecking preferences (Experiments 1 and 2) and color discrimination learning (Experiments 3 and 4) were unaffected. These results affirm and extend a prior finding of no pre- and posthatch colored light stimulation effect on posthatch color preferences in ducklings. The color pecking preferences found replicated prior findings with chicks. However, they differed from the approach color preferences observed in color discrimination learning.