Beta-lactam allergy risk stratification in a maternity population in Australia: Scope for allergy de-labelling.

BACKGROUND: Unconfirmed beta-lactam allergy in pregnant people has been associated with higher morbidity, unnecessary exposure to broad-spectrum antibiotics and prolonged hospitalisation. There are no published data on beta-lactam allergies in pregnant people in Australia. AIMS: The aim was to describe patient-reported beta-lactam allergies and appropriateness for antibiotic allergy de-labelling in a maternity cohort in Australia. METHODS: Maternity patients aged ≥18 years admitted to our institution between March 2021 and June 2021 with a beta-lactam allergy documented in their electronic medical record were interviewed for details of their allergy. The documented allergies were compared to the allergy history obtained from the interview. Severity of the allergy was rated, and appropriateness for allergy de-labelling was assessed using the Victorian Therapeutics Advisory Group beta-lactam antibiotic allergy assessment tool. RESULTS: One hundred and fifty-three beta-lactam allergies (182 reactions) were reported by 145 patients. Penicillin class antibiotics were the most frequently implicated, including unspecified penicillins (95/153, 62%), amoxicillin (19/153, 13%) and amoxicillin-clavulanate (8/153, 5%). Allergy documentation required amending in 52 of 145 patients (36%); 85 of 153 (56%) of the beta-lactam allergies were considered low risk and potentially appropriate for direct oral re-challenge. CONCLUSION: Beta-lactam allergies were inaccurately documented in more than one third of the maternity patients included in our study. As such, education of maternity care providers about the importance of accurate allergy history taking remains an urgent unmet need. Furthermore, allergy assessment and de-labelling during pregnancy should be considered in maternity patients to optimise antibiotic prescribing and to improve maternal and neonatal health outcomes.

Neonatal outcomes following antenatal corticosteroid administration prior to elective caesarean delivery in women with pre-gestational diabetes: A retrospective cohort study.

BACKGROUND: The benefit of antenatal corticosteroid (ACS) administration for the prevention of neonatal morbidity and mortality has been well described for preterm infants. Some studies have demonstrated a benefit for infants born by elective caesarean section (CS) at late preterm or term gestations. However, the neonatal benefits of ACS are not well described when given to pregnant women with diabetes. AIMS: The aim of this study was to evaluate the neonatal outcomes following ACS administration in women with pre-gestational diabetes mellitus (PGDM) when administered prior to elective CS after 36 weeks gestation. METHODS: This retrospective observational study included all women with PGDM who gave birth by elective CS between 36+0 and 38+6 weeks gestation. Neonatal outcomes for exposed participants were compared to outcomes for non-exposed participants. RESULTS: Of the 306 women identified, 65 (21.2%) were exposed to ACS within seven days prior to birth and 241 (78.8%) were not. Although not statistically significant, ACS-exposed infants born prior to 38+0 weeks were less likely to require respiratory support or neonatal nursery admission compared to those who were not exposed; however, exposed infants born after 37+0 weeks were more likely to require parenteral treatment for neonatal hypoglycaemia. CONCLUSION: This study did not demonstrate any statistically significant beneficial or harmful effects of ACS in neonates of women with PGDM who are born by elective CS. While it is plausible that ACS could reduce neonatal respiratory morbidity in this population, further prospective studies evaluating the benefits and harms are required before recommending this practice.

Postpartum contraceptive planning of women with substance abuse disorders.

BACKGROUND: Women with substance abuse disorders have lower use of contraception. Unplanned pregnancies increase risk of fetal exposure to addictive and teratogenic substances. Postpartum inpatient periods for these women can be challenging times to facilitate contraception planning. OBJECTIVE: To explore postnatal contraceptive planning practices, patient preferences for contraception, and supply challenges, and to identify how clinical pharmacists may best provide care in this context. SETTING: A tertiary maternity referral hospital in metropolitan Victoria, Australia (January 2015-December 2018). METHOD: A retrospective cohort study was conducted on postnatal women with substance abuse disorders. Patients were excluded if they had delivered at another health service, had inadequate documented evidence of a substance abuse disorder, or had incomplete or unavailable medical records. Records were reviewed for demographic data, admission details, and documented contraceptive planning. MAIN OUTCOME MEASURES: Documented contraceptive planning, patient contraception preferences and identified supply challenges. RESULTS: Ninety-three women were included. Seventy-one (76.3%) had psychiatric disorders or impairments, and 92 (98.9%) had identifiable follow-up challenges (eg. Homelessness). Nine (9.7%) self-discharged/absconded. Eighty-seven (93.5%) had documented postnatal contraception discussions. Sixty-two of 87 (71.3%) considered a medicine/device, three (3.4%) preferred condoms, 10 (11.5%) considered sterilisation, 2 (2.3%) preferred no contraception, and 16 (18.4%) undecided. Etonogestral 68 mg implants were most commonly prescribed (28 of 42; 66.7%). CONCLUSION: Inpatient postpartum periods for this cohort were characterised by psycho-social complexities, inconsistent contraceptive planning documentation, and patients seemingly unprepared to consider contraception. This study highlights a need for an earlier decision-making process and pragmatic counselling with antenatal pharmacists.

Creation of a novel trigeminal tractography atlas for automated trigeminal nerve identification.

Diffusion MRI (dMRI) tractography has been successfully used to study the trigeminal nerves (TGNs) in many clinical and research applications. Currently, identification of the TGN in tractography data requires expert nerve selection using manually drawn regions of interest (ROIs), which is prone to inter-observer variability, time-consuming and carries high clinical and labor costs. To overcome these issues, we propose to create a novel anatomically curated TGN tractography atlas that enables automated identification of the TGN from dMRI tractography. In this paper, we first illustrate the creation of a trigeminal tractography atlas. Leveraging a well-established computational pipeline and expert neuroanatomical knowledge, we generate a data-driven TGN fiber clustering atlas using tractography data from 50 subjects from the Human Connectome Project. Then, we demonstrate the application of the proposed atlas for automated TGN identification in new subjects, without relying on expert ROI placement. Quantitative and visual experiments are performed with comparison to expert TGN identification using dMRI data from two different acquisition sites. We show highly comparable results between the automatically and manually identified TGNs in terms of spatial overlap and visualization, while our proposed method has several advantages. First, our method performs automated TGN identification, and thus it provides an efficient tool to reduce expert labor costs and inter-operator bias relative to expert manual selection. Second, our method is robust to potential imaging artifacts and/or noise that can prevent successful manual ROI placement for TGN selection and hence yields a higher successful TGN identification rate.

Anatomical assessment of trigeminal nerve tractography using diffusion MRI: A comparison of acquisition b-values and single- and multi-fiber tracking strategies.

BACKGROUND: The trigeminal nerve (TGN) is the largest cranial nerve and can be involved in multiple inflammatory, compressive, ischemic or other pathologies. Currently, imaging-based approaches to identify the TGN mostly rely on T2-weighted magnetic resonance imaging (MRI), which provides localization of the cisternal portion of the TGN where the contrast between nerve and cerebrospinal fluid (CSF) is high enough to allow differentiation. The course of the TGN within the brainstem as well as anterior to the cisternal portion, however, is more difficult to display on traditional imaging sequences. An advanced imaging technique, diffusion MRI (dMRI), enables tracking of the trajectory of TGN fibers and has the potential to visualize anatomical regions of the TGN not seen on T2-weighted imaging. This may allow a more comprehensive assessment of the nerve in the context of pathology. To date, most work in TGN tracking has used clinical dMRI acquisitions with a b-value of 1000 s/mm2 and conventional diffusion tensor MRI (DTI) tractography methods. Though higher b-value acquisitions and multi-tensor tractography methods are known to be beneficial for tracking brain white matter fiber tracts, there have been no studies conducted to evaluate the performance of these advanced approaches on nerve tracking of the TGN, in particular on tracking different anatomical regions of the TGN. OBJECTIVE: We compare TGN tracking performance using dMRI data with different b-values, in combination with both single- and multi-tensor tractography methods. Our goal is to assess the advantages and limitations of these different strategies for identifying the anatomical regions of the TGN. METHODS: We proposed seven anatomical rating criteria including true and false positive structures, and we performed an expert rating study of over 1000 TGN visualizations, as follows. We tracked the TGN using high-quality dMRI data from 100 healthy adult subjects from the Human Connectome Project (HCP). TGN tracking performance was compared across dMRI acquisitions with b = 1000 s/mm2, b = 2000 s/mm2 and b = 3000 s/mm2, using single-tensor (1T) and two-tensor (2T) unscented Kalman filter (UKF) tractography. This resulted in a total of six tracking strategies. The TGN was identified using an anatomical region-of-interest (ROI) selection approach. First, in a subset of the dataset we identified ROIs that provided good TGN tracking performance across all tracking strategies. Using these ROIs, the TGN was then tracked in all subjects using the six tracking strategies. An expert rater (GX) visually assessed and scored each TGN based on seven anatomical judgment criteria. These criteria included the presence of multiple expected anatomical segments of the TGN (true positive structures), specifically branch-like structures, cisternal portion, mesencephalic trigeminal tract, and spinal cord tract of the TGN. False positive criteria included the presence of any fibers entering the temporal lobe, the inferior cerebellar peduncle, or the middle cerebellar peduncle. Expert rating scores were analyzed to compare TGN tracking performance across the six tracking strategies. Intra- and inter-rater validation was performed to assess the reliability of the expert TGN rating result. RESULTS: The TGN was selected using two anatomical ROIs (Meckel's Cave and cisternal portion of the TGN). The two-tensor tractography method had significantly better performance on identifying true positive structures, while generating more false positive streamlines in comparison to the single-tensor tractography method. TGN tracking performance was significantly different across the three b-values for almost all structures studied. Tracking performance was reported in terms of the percentage of subjects achieving each anatomical rating criterion. Tracking of the cisternal portion and branching structure of the TGN was generally successful, with the highest performance of over 98% using two-tensor tractography and b = 1000 or b = 2000. However, tracking the smaller mesencephalic and spinal cord tracts of the TGN was quite challenging (highest performance of 37.5% and 57.07%, using two-tensor tractography with b = 1000 and b = 2000, respectively). False positive connections to the temporal lobe (over 38% of subjects for all strategies) and cerebellar peduncles (100% of subjects for all strategies) were prevalent. High joint probability of agreement was obtained in the inter-rater (on average 83%) and intra-rater validation (on average 90%), showing a highly reliable expert rating result. CONCLUSIONS: Overall, the results of the study suggest that researchers and clinicians may benefit from tailoring their acquisition and tracking methodology to the specific anatomical portion of the TGN that is of the greatest interest. For example, tracking of branching structures and TGN-T2 overlap can be best achieved with a two-tensor model and an acquisition using b = 1000 or b = 2000. In general, b = 1000 and b = 2000 acquisitions provided the best-rated tracking results. Further research is needed to improve both sensitivity and specificity of the depiction of the TGN anatomy using dMRI.

The hepatitis B birth-dose immunisation: Exploring parental refusal.

BACKGROUND: Hepatitis B virus (HBV) immunisation is the first vaccine of infant life and one of the most commonly refused immunisations on the Australian Immunisation Schedule. AIMS: To quantify the frequency of declined HBV immunisation birth-doses, investigate reasons for refusal, and determine information sources used by parents. MATERIALS AND METHODS: A cross-sectional study using a questionnaire was conducted on postnatal women who declined their newborn's HBV birth-dose immunisation during December 2016-July 2017 at an Australian tertiary referral hospital. Mothers who were non-English-speaking, unwell or medically unstable, or otherwise unavailable were excluded. RESULTS: One hundred and thirty-seven of the 1574 (8.7%) eligible reviewed infants had HBV immunisation birth-doses documented as declined; 113 mothers consented to complete the questionnaire. The most common reasons for declining the dose were: 'baby too young' (55.8%); preference for two, four and six-month HBV immunisations only (56.6%); perceived low risk of contracting HBV (45.1%); and a fear of 'overloading' their baby's immune system (42.5%). General practitioners or nurses/midwives (43.3%) and the internet/media (33.6%) were the predominant information sources consulted, and 58.4% felt satisfied with the information they received antenatally. Eighty-eight of 113 mothers (77.9%) would still consider future immunisations for their infant. CONCLUSIONS: The majority of postnatal women decline HBV birth-dose immunisation for their newborns citing age-related safety concerns and vaccine misconceptions. Informal information sources such as the internet and media are often consulted. Addressing the need for antenatal and health professional education toward the birth-dose may be instrumental in improving uptake.

Prescription opioid use in pregnancy.

Prescription medications, including opioid analgesics, are increasingly prescribed in Australia and internationally. More women are presenting in pregnancy with prescription opioid use which can potentially cause harm to the mother and fetus. This article outlines the different types of prescription opioids, defines how prescription opioid use disorder presents clinically and suggests a rational clinical approach to assess and manage patients in the context of pregnancy and their infants.

Retrospective cohort study comparing the adverse reactions and efficacy of intravenous iron polymaltose with ferric carboxymaltose for iron deficiency anemia.

OBJECTIVE: To examine the adverse drug reactions (ADRs) and the efficacy of intravenous iron polymaltose and ferric carboxymaltose (FCM) among gynecology/obstetric patients with anemia. METHODS: The present retrospective observational study examined data from anemic obstetrics and gynecology patients who received either iron polymaltose or FCM between January 1, 2011, and April 30, 2015, at The Royal Women's Hospital, Victoria, Australia. Patient demographic data, dosage, ADR documentation, and hemoglobin levels were collected from medical records and compared. RESULTS: The study included 221 patients; 111 and 110 received iron polymaltose and FCM, respectively. ADRs were documented for 18 (16.2%) patients in the iron polymaltose group and 2 (1.8%) in the FCM group (P<0.001), with no incidences of anaphylaxis. Both formulations achieved increased hemoglobin levels within 12 weeks (P<0.001 for both). Mean hemoglobin level increases were similar in both groups among non-pregnant patients (P=0.186), but were greater in the iron polymaltose cohort among pregnant patients (P=0.005). FCM dose compliance was suboptimal, with 8 of 57 (14%) patients who required second visits for doses greater than 1000 mg returning for the infusion. CONCLUSION: FCM was associated with a lower incidence of ADRs than iron polymaltose. Patients receiving FCM infusions were less likely to receive their total required iron dose. Further randomized prospective studies are required to compare clinical efficacy of iron polymaltose versus FCM.

Complementary medicines in pregnancy: recommendations and information sources of healthcare professionals in Australia.

Background The use of oral complementary and alternative medicines, including herbal supplements, has been increasing in pregnant women worldwide despite limited safety data. The decision of healthcare professionals to recommend these products to pregnant patients is controversial and not well documented. Objective To explore the recommendations and information sources that healthcare professionals use to determine the safety of oral non-prescribed supplements during pregnancy. Setting An Australian metropolitan maternity hospital. Method An electronic survey was distributed to doctors, midwives, pharmacists, dietitians, lactation consultants and physiotherapists. Main outcome measure The nature of recommendations and information sources that healthcare professionals use to determine the safety of oral non-prescribed supplements during pregnancy. Results Responses were received from 54 healthcare professionals. Forty of 54 (74.1%) were concerned about the safety of their patients' supplements, while 35 of 54 (64.8%) felt that they had access to trustworthy safety information. Supplements most commonly recommended as safe to use were ginger (40.7%), probiotics (29.6%) and raspberry leaf (22.2%). Participants specifically requested further safety information for raspberry leaf, evening primrose oil, fish oil, probiotics, ginger, vitamin C, valerian, turmeric, blue cohosh and colloidal silver. Written resources most frequently consulted included MIMS® (61.1%) and 'Google Searches' (29.6%), and healthcare professionals most referred to were pharmacists (74.1%), doctors (22.2%), and naturopaths or herbalists (3.7%). Conclusion The recommendations of maternity heath care professionals and quality of information sources used varied. Further education and access to unbiased safety information is required to empower healthcare professionals to provide informed recommendations to pregnant patients.

Inhibition of the G9a/GLP histone methyltransferase complex modulates anxiety-related behavior in mice.

Epigenetic gene-regulation abnormalities have been implicated in various neuropsychiatric disorders including schizophrenia and depression, as well as in the regulation of mood and anxiety. In addition, epigenetic mechanisms are involved in the actions of psychiatric drugs. Current anxiolytic drugs have significant shortcomings, and development of new medications is warranted. Two proteins, G9a (also known as EHMT2 or KMT1C) and GLP (G9a-like protein, also known as EHMT1 or KMT1D), which methylate lysine 9 of histone H3 (H3K9), could be promising anxiolytic targets. Postnatal genetic knock-out of G9a reduces anxiety-related behavior, consistent with the reduction of G9a levels by some medications used to treat anxiety (amitriptyline, imipramine and paroxetine). Conversely, there is increased anxiety-like behavior in mice with GLP haplodeficiency. We sought to determine whether two pharmacological inhibitors of G9a/GLP, UNC0642 and A-366, would have similar effects to genetic G9a/GLP insufficiency. We found that G9a/GLP inhibition with either compound reduced anxiety-like behaviors when administered to adult mice, in conjunction with decreased H3K9 methylation in the brain. In contrast, exposure to these compounds from embryonic day 9.5 (E9.5) until birth increased anxiety-like behaviors and decreased social interaction in adulthood, while H3K9 methylation was at normal levels in the brains of the adult mice. These findings reinforce genetic evidence that G9a/GLP has different effects on anxiety-like behavior at different stages of brain development, and suggest that targeting this histone methyltransferase pathway could be useful for developing new anxiolytic drugs. These data also suggest that antidepressant exposure in utero could have negative effects in adulthood, and further investigation of these effects is warranted.

Managing opioid overdose in pregnancy with take-home naloxone.

Programs have recently been established in Australia and internationally to allow wider access to naloxone to people at risk of opioid overdose yet there are no guidelines relating to the administration of naloxone to pregnant women, particularly regarding dose requirements and resuscitative measures peculiar to pregnancy. This paper provides practical guidelines to health workers in relation to any complications that may arise during opioid overdose response (including the administration of naloxone) for pregnant women and the follow up required ensuring best possible outcomes for mother and baby.

Implementation of dextrose gel in the management of neonatal hypoglycaemia.

AIM: The aim of this study was to evaluate dextrose gel in the management of neonatal hypoglycaemia in the postnatal wards at an Australian tertiary level perinatal centre. METHODS: An audit was performed before and after implementation of dextrose gel. Pre-implementation, neonatal hypoglycaemia was managed with feed supplementation alone, and dextrose gel was used in addition to feed supplementation in the post-implementation phase. Outcomes included admission to neonatal intensive care unit (NICU) for management of hypoglycaemia, proportion of neonates who achieved normoglycaemia (defined as blood glucose ≥2.6 mmol/L, with no clinical signs after one or two treatment attempts) and proportion of neonates with hypoglycaemia recurrence after normoglycaemia and one or two treatment attempts. RESULTS: NICU admission for treatment of hypoglycaemia reduced significantly post-implementation of dextrose gel (29/100 (29%) vs. 14/100 (14%), P = 0.01). No significant difference was seen in the proportion of neonates achieving normoglycaemia (71/100 (71%) vs. 75/100 (75%), P = 0.52), but hypoglycaemia recurrence was higher in the post-implementation group (22/71 (31%) vs. 37/75 (49%), P = 0.02). CONCLUSIONS: Dextrose gel is effective in the management of neonatal hypoglycaemia in the postnatal ward setting, reducing admission to NICU and mother-infant separation.

Tumor-specific HSP90 inhibition as a therapeutic approach in JAK-mutant acute lymphoblastic leukemias.

The development of the dual Janus kinase 1/2 (JAK1/2) inhibitor ruxolitinib for the treatment of myeloproliferative neoplasms (MPNs) has led to studies of ruxolitinib in other clinical contexts, including JAK-mutated acute lymphoblastic leukemia (ALL). However, the limited ability of JAK inhibition to induce molecular or clinicopathological responses in MPNs suggests a need for development of better therapies for JAK kinase-dependent malignancies. Here, we demonstrate that heat shock protein 90 (HSP90) inhibition using a purine-scaffold HSP90 inhibitor in early clinical development is an effective therapeutic approach in JAK-dependent ALL and can overcome persistence to JAK-inhibitor therapy in ALL cells.

Apolipoprotein E4 produced in GABAergic interneurons causes learning and memory deficits in mice.

Apolipoprotein (apo) E4 is expressed in many types of brain cells, is associated with age-dependent decline of learning and memory in humans, and is the major genetic risk factor for AD. To determine whether the detrimental effects of apoE4 depend on its cellular sources, we generated human apoE knock-in mouse models in which the human APOE gene is conditionally deleted in astrocytes, neurons, or GABAergic interneurons. Here we report that deletion of apoE4 in astrocytes does not protect aged mice from apoE4-induced GABAergic interneuron loss and learning and memory deficits. In contrast, deletion of apoE4 in neurons does protect aged mice from both deficits. Furthermore, deletion of apoE4 in GABAergic interneurons is sufficient to gain similar protection. This study demonstrates a detrimental effect of endogenously produced apoE4 on GABAergic interneurons that leads to learning and memory deficits in mice and provides a novel target for drug development for AD related to apoE4.

Genetic correction of tauopathy phenotypes in neurons derived from human induced pluripotent stem cells.

Tauopathies represent a group of neurodegenerative disorders characterized by the accumulation of pathological TAU protein in brains. We report a human neuronal model of tauopathy derived from induced pluripotent stem cells (iPSCs) carrying a TAU-A152T mutation. Using zinc-finger nuclease-mediated gene editing, we generated two isogenic iPSC lines: one with the mutation corrected, and another with the homozygous mutation engineered. The A152T mutation increased TAU fragmentation and phosphorylation, leading to neurodegeneration and especially axonal degeneration. These cellular phenotypes were consistent with those observed in a patient with TAU-A152T. Upon mutation correction, normal neuronal and axonal morphologies were restored, accompanied by decreases in TAU fragmentation and phosphorylation, whereas the severity of tauopathy was intensified in neurons with the homozygous mutation. These isogenic TAU-iPSC lines represent a critical advancement toward the accurate modeling and mechanistic study of tauopathies with human neurons and will be invaluable for drug-screening efforts and future cell-based therapies.

Cellular source-specific effects of apolipoprotein (apo) E4 on dendrite arborization and dendritic spine development.

Apolipoprotein (apo) E4 is the leading genetic risk factor for Alzheimer's disease (AD), and it has a gene dose-dependent effect on the risk and age of onset of AD. Although apoE4 is primarily produced by astrocytes in the brain, neurons can also produce apoE4 under stress conditions. ApoE4 is known to inhibit neurite outgrowth and spine development in vitro and in vivo, but the potential influence of apoE4's cellular source on dendritic arborization and spine development has not yet been investigated. In this study, we report impairments in dendritic arborization and a loss of spines, especially thin (learning) and mushroom (memory) spines, in the hippocampus and entorhinal cortex of 19-21-month-old female neuron-specific-enolase (NSE)-apoE4 and apoE4-knockin (KI) mice compared to their respective apoE3-expressing counterparts. In general, NSE-apoE4 mice had more severe and widespread deficits in dendritic arborization as well as spine density and morphology than apoE4-KI mice. The loss of dendritic spines, especially mushroom spines, occurred in NSE-apoE4 mice as early as 7-8 months of age. In contrast, glial fibrillary acidic protein (GFAP)-apoE4 mice, which express apoE4 solely in astrocytes, did not have impairments in their dendrite arborization or spine density and morphology compared to GFAP-apoE3 mice at both ages. These results indicate that the effects of apoE4 on dendrite arborization, spine density, and spine morphology depend critically on its cellular source, with neuronal apoE4 having more detrimental effects than astrocytic apoE4.

Heterodimeric JAK-STAT activation as a mechanism of persistence to JAK2 inhibitor therapy.

The identification of somatic activating mutations in JAK2 (refs 1­4) and in the thrombopoietin receptor gene (MPL) in most patients with myeloproliferative neoplasm (MPN) led to the clinical development of JAK2 kinase inhibitors. JAK2 inhibitor therapy improves MPN-associated splenomegaly and systemic symptoms but does not significantly decrease or eliminate the MPN clone in most patients with MPN. We therefore sought to characterize mechanisms by which MPN cells persist despite chronic inhibition of JAK2. Here we show that JAK2 inhibitor persistence is associated with reactivation of JAK­STAT signalling and with heterodimerization between activated JAK2 and JAK1 or TYK2, consistent with activation of JAK2 in trans by other JAK kinases. Further, this phenomenon is reversible: JAK2 inhibitor withdrawal is associated with resensitization to JAK2 kinase inhibitors and with reversible changes in JAK2 expression. We saw increased JAK2 heterodimerization and sustained JAK2 activation in cell lines, in murine models and in patients treated with JAK2 inhibitors. RNA interference and pharmacological studies show that JAK2-inhibitor-persistent cells remain dependent on JAK2 protein expression. Consequently, therapies that result in JAK2 degradation retain efficacy in persistent cells and may provide additional benefit to patients with JAK2-dependent malignancies treated with JAK2 inhibitors.

Apolipoprotein E4 causes age- and sex-dependent impairments of hilar GABAergic interneurons and learning and memory deficits in mice.

Apolipoprotein (apo) E4 is the major genetic risk factor for Alzheimer's disease (AD). ApoE4 has sex-dependent effects, whereby the risk of developing AD is higher in apoE4-expressing females than males. However, the mechanism underlying the sex difference, in relation to apoE4, is unknown. Previous findings indicate that apoE4 causes age-dependent impairments of hilar GABAergic interneurons in female mice, leading to learning and memory deficits. Here, we investigate whether the detrimental effects of apoE4 on hilar GABAergic interneurons are sex-dependent using apoE knock-in (KI) mice across different ages. We found that in female apoE-KI mice, there was an age-dependent depletion of hilar GABAergic interneurons, whereby GAD67- or somatostatin-positive--but not NPY- or parvalbumin-positive-interneuron loss was exacerbated by apoE4. Loss of these neuronal populations was correlated with the severity of spatial learning deficits at 16 months of age in female apoE4-KI mice; however, this effect was not observed in female apoE3-KI mice. In contrast, we found an increase in the numbers of hilar GABAergic interneurons with advancing age in male apoE-KI mice, regardless of apoE genotype. Moreover, male apoE-KI mice showed a consistent ratio of hilar inhibitory GABAergic interneurons to excitatory mossy cells approximating 1.5 that is independent of apoE genotype and age, whereas female apoE-KI mice exhibited an age-dependent decrease in this ratio, which was exacerbated by apoE4. Interestingly, there are no apoE genotype effects on GABAergic interneurons in the CA1 and CA3 subregions of the hippocampus as well as the entorhinal and auditory cortexes. These findings suggest that the sex-dependent effects of apoE4 on developing AD is in part attributable to inherent sex-based differences in the numbers of hilar GABAergic interneurons, which is further modulated by apoE genotype.