CCR5 knockout prevents neuronal injury and behavioral impairment induced in a transgenic mouse model by a CXCR4-using HIV-1 glycoprotein 120.

The innate immune system has been implicated in several neurodegenerative diseases, including HIV-1-associated dementia. In this study, we show that genetic ablation of CCR5 prevents microglial activation and neuronal damage in a transgenic model of HIV-associated brain injury induced by a CXCR4-using viral envelope gp120. The CCR5 knockout (KO) also rescues spatial learning and memory in gp120-transgenic mice. However, the CCR5KO does not abrogate astrocytosis, indicating it can occur independently from neuronal injury and behavioral impairment. To characterize further the neuroprotective effect of CCR5 deficiency we performed a genome-wide gene expression analysis of brains from HIVgp120tg mice expressing or lacking CCR5 and nontransgenic controls. A comparison with a human brain microarray study reveals that brains of HIVgp120tg mice and HIV patients with neurocognitive impairment share numerous differentially regulated genes. Furthermore, brains of CCR5 wild-type and CCR5KO gp120tg mice express markers of an innate immune response. One of the most significantly upregulated factors is the acute phase protein lipocalin-2 (LCN2). Using cerebrocortical cell cultures, we find that LCN2 is neurotoxic in a CCR5-dependent fashion, whereas inhibition of CCR5 alone is not sufficient to abrogate neurotoxicity of a CXCR4-using gp120. However, the combination of pharmacologic CCR5 blockade and LCN2 protects neurons from toxicity of a CXCR4-using gp120, thus recapitulating the finding in CCR5-deficient gp120tg mouse brain. Our study provides evidence for an indirect pathologic role of CCR5 and a novel protective effect of LCN2 in combination with inhibition of CCR5 in HIV-associated brain injury.

Outcome data from 15 years of cystic fibrosis newborn screening in a large UK region.

BACKGROUND: The West Midlands Newborn Bloodspot Screening Laboratory is one of 16 in the UK and serves two tertiary paediatric cystic fibrosis (CF) centres (Staffordshire Children's Hospital at Royal Stoke and Birmingham Children's Hospital). CF newborn bloodspot screening (NBS) in this region started in November 2006 prior to the UK national roll-out in 2007. It uses an immunoreactive trypsinogen (IRT)/DNA/IRT protocol. We report the outcomes from 15 years of CF screening. METHODS: The West Midlands CF NBS outcomes from 1 November 2006 to 31 October 2021 were reviewed. Clinical data were also obtained for babies referred to the CF centres as 'CF suspected'. RESULTS: 1 075 161 babies were screened, with 402 referred as 'CF suspected' and 205 identified as CF carriers. Of the 'CF suspected' babies, 268 were diagnosed with CF, 33 with CF screen positive, inconclusive diagnosis (CFSPID) and 17 as a CF carrier. Any CF-related diagnosis was excluded in 67. Outcome data were not available for 17, of whom 14 had died. Eighteen children with a negative CF NBS have subsequently been diagnosed with CF, 10 had meconium ileus and 8 were true 'affected not detected', presenting with respiratory symptoms or failure to thrive. This gives the West Midlands a CF birth prevalence of 1 in 4012 live births and the NBS protocol a sensitivity of 97.1% and a positive predictive value of 66.7%. CONCLUSIONS: This large regional data set has excellent case ascertainment and demonstrates successful performance of the CF NBS protocol, with low numbers identified as CFSPID or CF carriers.

OMERACT 2023 Systemic Lupus Erythematosus Special Interest Group: Winnowing and Binning Preliminary Candidate Domains for the Core Outcome Set.

BACKGROUND: The Outcome Measures in Rheumatology (OMERACT) Systemic Lupus Erythematosus (SLE) Working Group held a Special Interest Group (SIG) at the OMERACT 2023 conference in Colorado Springs where SLE collaborators reviewed domain sub-themes generated through qualitative research and literature review. OBJECTIVE: The objective of the SIG and the subsequent meetings of the SLE Working Group was to begin the winnowing and binning of candidate domain sub-themes into a preliminary list of candidate domains that will proceed to the consensus Delphi exercise for the SLE COS. METHODS: Four breakout groups at the SLE SIG in Colorado Springs winnowed and binned 132 domain sub-themes into candidate domains, which was continued with a series of virtual meetings by an advisory group of SLE patient research partners (PRPs), members of the OMERACT SLE Working Group Steering Committee, and other collaborators. RESULTS: The 132 domain sub-themes were reduced to a preliminary list of 20 candidate domains based on their clinical and research relevance for clinical trials and research studies. CONCLUSION: A meaningful and substantial winnowing and binning of candidate domains for the SLE COS was achieved resulting in a preliminary list of 20 candidate domains.

OMERACT systemic lupus erythematosus domain survey.

BACKGROUND: Since the development of the OMERACT Systemic Lupus Erythematosus (SLE) Core Outcome Set (COS) in 1998, many new SLE domains have been identified and measures developed, creating a need to update the SLE COS. To revisit the 1998 SLE COS and research agenda domains, and generate new candidate domains, we conducted this study of patients with SLE and collaborators. OBJECTIVE: (1) To evaluate existing candidate SLE domains for inclusion in the SLE COS. (2) To generate additional candidate SLE domains for COS consideration. (3) To engage SLE collaborators, including patients, in developing the updated SLE COS. METHODS: The OMERACT SLE Working Group's steering committee developed a survey to assess the importance of candidate SLE domains and generate additional domains for consideration towards the SLE COS. Patients with SLE followed at the University of Toronto Lupus Clinic (patient group) and members of the OMERACT SLE Working Group (collaborator group) were invited to complete the survey between August 2022 and February 2023. RESULTS: A total of 175 patients were invited and 100 completed the survey. Of 178 collaborators invited, 145 completed the survey. Patients tended to prioritize life-impact domains while collaborators prioritized clinical domains. Both patients and collaborators recommended additional domains to those included in the 1998 SLE COS and research agenda. CONCLUSION: The domain inclusion and importance results demonstrate that patients and collaborators prioritize different domains, so capturing the perspectives of both groups is essential to ensure a holistic assessment of SLE. The results of the study identify domains that already have a high level of agreement for potential inclusion in the SLE COS, domains that require further explanation, and novel domains that warrant consideration.

Activation of p38 MAPK is required in monocytic and neuronal cells for HIV glycoprotein 120-induced neurotoxicity.

HIV-1 envelope protein gp120 has been implicated in neurotoxin production by monocytic cells (i.e., macrophages and microglia), as well as in the pathogenesis of HIV-1-associated neurocognitive disorders. We previously showed in cerebrocortical cell cultures from rodents containing microglia, astrocytes, and neurons that overall inhibition of p38 MAPK signaling abrogated the neurotoxic effect of HIV-1 gp120. However, the time course of p38 MAPK activation and the contribution of this kinase in the various cell types remained unknown. In this study, we found that active p38 MAPK is required in monocytic lineage cells (i.e., macrophages and microglia) and neuronal cells for HIV gp120-induced neurotoxicity to occur. In cerebrocortical cell cultures, HIV-1 gp120 stimulated a time-dependent overall increase in active p38 MAPK, and the activated kinase was primarily detected in microglia and neurons. Interestingly, increased activation of p38 MAPK and neuronal death in response to gp120 were prevented by prior depletion of microglia or the presence of CCR5 ligand CCL4 or p38 MAPK inhibitors. In human monocytic THP-1 cells and primary monocyte-derived macrophages, HIV gp120-stimulated production of neurotoxins was abrogated by prior introduction into the cells of a dominant-negative p38 MAPK mutant or p38 MAPK small interfering RNA. In addition, the neurotoxic effects of cell-free supernatants from gp120-stimulated monocytic THP-1 cells were prevented in microglia-depleted cerebrocortical cells pretreated with a pharmacological inhibitor of p38 MAPK. Thus, p38 MAPK signaling was critical, upon exposure to HIV gp120, for the neurotoxic phenotype of monocytic cells and subsequent toxin-initiated neuronal apoptosis.

A systematic review of lung clearance index in non-cystic fibrosis, non-primary ciliary dyskinesia bronchiectasis.

BACKGROUND: Non cystic fibrosis, non primary ciliary dyskinesia bronchiectasis (nCFnPCD-BE) results in significant morbidity with few evidence-based treatments. OBJECTIVE: assessments are required to assess severity and evaluate treatment. Lung clearance index (LCI) measures ventilation inhomogeneity and is a sensitive test of disease in CF; its use in nCFnPCD-BE is unclear. METHODS: A systematic review of LCI in nCFnPCD-BE was performed using standard methodology (protocol registered on PROSPERO, University of York). RESULTS: Of 276 records identified, 12 articles, describing 519 adult and paediatric patients in cross-sectional studies were included, addressing several domains. 1: What is the utility of LCI in detecting disease and severity? LCI detected disease in adults, differentiating bronchiectasis from controls (AUC 0.90 to 0.96) and mild from moderate/severe bronchiectasis on CT (AUC 0.73). 2: Does LCI correlate with spirometry and imaging? LCI correlated with spirometry in adult (r = -0.37 to -0.61) and paediatric (r = -0.6) groups, signs of bronchiectasis on CT, and CT scoring systems (modified Reiff). 3: Does LCI relate to subjective scores of severity? In adults, LCI correlated with St. George's Respiratory Questionnaire (r = 0.18) and Bronchiectasis Severity Index (r = 0.45). 4: Does LCI identify response to intervention? LCI did not change in studies examining LCI pre-post intervention (adults treated for exacerbation and undergoing physiotherapy). Overall study quality was variable. CONCLUSION: Contrary to data in CF, the review did not identify good quality studies defining the role of LCI in children with bronchiectasis. In adults, LCI was a sensitive measure of disease severity and correlated with clinical assessment tools.

Globe dislocation and optic nerve avulsion following all-terrain vehicle accidents.

Purpose: Open-air motor vehicles present unique trauma risks to the eyes and face. We describe two patients who suffered a crash while riding an all-terrain vehicle (ATV), leading to globe dislocation with optic nerve avulsion in order to raise awareness about the risks associated with ATV accidents. Observations: In both cases, the injury was caused by high-speed trauma to the orbit involving a tree branch. One patient sustained a life threatening arrythmia requiring a short stay in the intensive care unit, and both patients required emergent surgical management and eventual socket reconstruction. Conclusions and Importance: These cases highlight the need for greater advocacy on behalf of rider safety. The authors encourage ophthalmologists to counsel patients who use ATVs to wear helmets, seatbelts, and protective eyewear to prevent these types of injuries in the future.

Who are the 10%? - Non eligibility of cystic fibrosis (CF) patients for highly effective modulator therapies.

BACKGROUND: The availability of mutation-specific cystic fibrosis modulator therapies has the potential to improve the lives of children and adults with cystic fibrosis. The frequency of mutations causing defects in the cystic fibrosis transmembrane conductance regulator (CFTR) function varies between sub-groups in multi-ethnic populations. The profile of patients eligible for CFTR modulator ivacaftor/tezacaftor/elexacaftor (Kaftrio™) therapy based on ethnicity has not been reported in the United Kingdom CF population. METHODS: We conducted a descriptive cross-sectional analysis of patients in the UK CF Registry who had annual review data submissions in 2019. Data analysed included demographic characteristics, spirometry, chronic Pseudomonas status, nutrition, and CF related diabetes status. The genotype data was stratified by whether there was at least one copy of F508del or no copy of F508del as current eligibility for ivacaftor/tezacaftor/elexacaftor, or projected future eligibility, is defined as having at least one copy of F508del mutation. RESULTS: Data from 9887 patients were reviewed, 46.7% female, mean age 22.5 years. 8.6% (n = 852) patients had no copy of F508del making them ineligible for ivacaftor/tezacaftor/elexacaftor. Overall, 93.4% of patients were of white ethnicity, with a similar proportion of those with at least one F508del being white (95.6%). This was reduced to 70.0% of those with no F508del. The proportion of people of Asian ethnicity was much higher in the no F508del group (19.2% vs 1.2%). Compared with one F508del patients, the no F508del group were older (25.2 years vs 22.2 years, p < 0.001), had higher prevalence of pancreatic sufficiency (39.0% vs 14.9% p < 0.001), lower prevalence of chronic Pseudomonas infection (21.1% vs. 26.6%, p < 0.001), and higher best FEV1 from the previous year (proportion with greater than 70% FEV1 predicted, 66.1% vs 63.0%, p = 0.005). CONCLUSION: Patients from black, Asian and minority ethnic backgrounds are significantly less likely to be eligible for ivacaftor/tezacaftor/elexacaftor based on the current prescribing policy in the UK. At present this is the most highly effective CF modulator therapy available to treat people with CF. The CF community should urgently address the unmet need for effective targeted therapies for patients without F508del.

An Alzheimer's disease-relevant presenilin-1 mutation augments amyloid-beta-induced oligodendrocyte dysfunction.

White matter pathology has been documented in the brains of familial Alzheimer's disease (FAD)-afflicted individuals during presymptomatic and preclinical stages of AD. How these defects in myelination integrity arise and what roles they may play in AD pathophysiology have yet to be fully elucidated. We previously demonstrated that triple-transgenic AD (3xTg-AD) mice, which harbor the human amyloid precursor Swedish mutation, presenilin-1 M146V (PS1(M146V) ) knock-in mutation, and tau(P301L) mutation, exhibit myelin abnormalities analogous to FAD patients and that Aß(1-42) contributes to these white matter deficits. Herein, we demonstrate that the PS1(M146V) mutation predisposes mouse oligodendrocyte precursor (mOP) cells to Aß(1-42) -induced alterations in cell differentiation in vitro. Furthermore, PS1(M146V) expression compromised mOP cell function and MBP protein distribution, a process that is further aggravated with exposure to Aß(1-42) . We found that the myelination defect and MBP subcellular mislocalization triggered by PS1(M146V) and Aß(1-42) can be effectively prevented by treatment with the GSK-3ß inhibitor, TWS119, thereby implicating GSK-3ß kinase activity in this pathogenic cascade. Overall, this work provides further mechanistic insights into PS1(M146V) and Aß(1-42) -driven oligodendrocyte dysfunction andmyelin damage during early presymptomatic stages of AD, and provides a new target in oligodendrocytes for developing therapies designed to avert AD-related white matter pathology.

Early oligodendrocyte/myelin pathology in Alzheimer's disease mice constitutes a novel therapeutic target.

The detection of myelin disruptions in Alzheimer's disease (AD)-affected brain raises the possibility that oligodendrocytes undergo pathophysiological assault over the protracted course of this neurodegenerative disease. Oligodendrocyte compromise arising from direct toxic effects imparted by pathological amyloid-beta peptides and/or through signals derived from degenerating neurons could play an important role in the disease process. We previously demonstrated that 3xTg-AD mice, which harbor the human amyloid precursor protein Swedish mutant transgene, presenilin knock-in mutation, and tau P301L mutant transgene, exhibit significant alterations in overall myelination patterns and oligodendrocyte status at time points preceding the appearance of amyloid and tau pathology. Herein, we demonstrate that Abeta(1-42) leads to increased caspase-3 expression and apoptotic cell death of both nondifferentiated and differentiated mouse oligodendrocyte precursor (mOP) cells in vitro. Through use of a recombinant adeno-associated virus serotype-2 (rAAV2) vector expressing an Abeta(1-42)-specific intracellular antibody (intrabody), oligodendrocyte and myelin marker expression, as well as myelin integrity, were restored in the vector-infused brain regions of 3xTg-AD mice. Overall, this work provides further insights into the impact of Abeta(1-42)-mediated toxicity on the temporal and spatial progression of subtle myelin disruption during the early presymptomatic stages of AD and may help to validate new therapeutic options designed to avert these early impairments.

In vitro efficacy of relebactam versus avibactam against Mycobacterium abscessus complex.

Infections resulting from Mycobacterium abscessus are increasing in prevalence worldwide, with the greatest risk posed to patients with underlying respiratory conditions. Treatment for infections is difficult due to wide ranging intrinsic antimicrobial resistance, which is compounded by the existence of a range of subspecies within the M. abscessus complex, each with varying additional antimicrobial resistance profiles. Previously, the use of ß-lactam/ß-lactamase inhibitors within a combination therapy has been proposed as an effective treatment option for pulmonary M. abscessus infections. Here, we assess the in vitro efficacy of two non-ß-lactam based inhibitors, relebactam and avibactam, as agents against M. abscessus with their respective partner drugs imipenem and ceftazidime, as well as in triplicate combinations with additional ß-lactam antibiotics against the M. abscessus complex. We have shown that the commercially available ratio of imipenem to relebactam is the appropriate ratio for bactericidal activity against M. abscessus, whereas the ratio between ceftazidime and avibactam is redundant, due to inactivity of ceftazidime to inhibit the bacteria. We have identified that the use of imipenem and meropenem alongside either relebactam or avibactam yield low minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) for each M. abscessus subspecies, which are within the therapeutically achievable concentration ranges within the epithelial lining fluid of the lungs. We propose the implementation of imipenem with relebactam in place of stand-alone imipenem into the current treatment regime, alongside meropenem, as a future front-line treatment option for M. abscessus complex infections.

Author Correction: Effect of Amoxicillin in combination with Imipenem-Relebactam against Mycobacterium abscessus.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Effect of Amoxicillin in combination with Imipenem-Relebactam against Mycobacterium abscessus.

Infections caused by Mycobacterium abscessus are increasing in prevalence in cystic fibrosis patients. This opportunistic pathogen's intrinsic resistance to most antibiotics has perpetuated an urgent demand for new, more effective therapeutic interventions. Here we report a prospective advance in the treatment of M. abscessus infection; increasing the susceptibility of the organism to amoxicillin, by repurposing the ß-lactamase inhibitor, relebactam, in combination with the front line M. abscessus drug imipenem. We establish by multiple in vitro methods that this combination works synergistically to inhibit M. abscessus. We also show the direct competitive inhibition of the M. abscessus ß-lactamase, BlaMab, using a novel assay, which is validated kinetically using the nitrocefin reporter assay and in silico binding studies. Furthermore, we reverse the susceptibility by overexpressing BlaMab in M. abscessus, demonstrating relebactam-BlaMab target engagement. Finally, we highlight the in vitro efficacy of this combination against a panel of M. abscessus clinical isolates, revealing the therapeutic potential of the amoxicillin-imipenem-relebactam combination.

Triple-transgenic Alzheimer's disease mice exhibit region-specific abnormalities in brain myelination patterns prior to appearance of amyloid and tau pathology.

Alzheimer's disease (AD) is a progressively debilitating brain disorder pathologically defined by extracellular amyloid plaques, intraneuronal neurofibrillary tangles, and synaptic disintegrity. AD has not been widely considered a disease of white matter, but more recent evidence suggests the existence of abnormalities in myelination patterns and myelin attrition in AD-afflicted human brains. Herein, we demonstrate that triple-transgenic AD (3xTg-AD) mice, which harbor the human amyloid precursor protein Swedish mutant transgene, presenilin knock-in mutation, and tau P301L mutant transgene, exhibit significant region-specific alterations in myelination patterns and in oligodendrocyte marker expression profiles at time points preceding the appearance of amyloid and tau pathology. These immunohistochemical signatures are coincident with age-related alterations in axonal and myelin sheath ultrastructure as visualized by comparative electron microscopic examination of 3xTg-AD and nontransgenic mouse brain tissue. Overall, these findings indicate that 3xTg-AD mice represent a viable model in which to examine mechanisms underlying AD-related myelination and neural transmission defects that occur early during presymptomatic stages of the disease process.

Mycobacterium abscessus: Environmental Bacterium Turned Clinical Nightmare.

Mycobacteria are a large family of over 100 species, most of which do not cause diseases in humans. The majority of the mycobacterial species are referred to as nontuberculous mycobacteria (NTM), meaning they are not the causative agent of tuberculous (TB) or leprosy, i.e., Mycobacterium tuberculous complex and Mycobacterium leprae, respectively. The latter group is undoubtedly the most infamous, with TB infecting an estimated 10 million people and causing over 1.2 million deaths in 2017 alone TB and leprosy also differ from NTM in that they are only transmitted from person to person and have no environmental reservoir, whereas NTM infections are commonly acquired from the environment. It took until the 1950's for NTM to be recognised as a potential lung pathogen in people with underlying pulmonary disease and another three decades for NTM to be widely regarded by the medical community when Mycobacterium avium complex was identified as the most common group of opportunistic pathogens in AIDS patients. This review focuses on an emerging NTM called Mycobacterium abscessus (M. abs). M. abs is a rapidly growing NTM that is responsible for opportunistic pulmonary infections in patients with structural lung disorders such as cystic fibrosis and bronchiectasis, as well as a wide range of skin and soft tissue infections in humans. In this review, we discuss how we came to understand the pathogen, how it is currently treated and examine drug resistance mechanisms and novel treatments currently in development. We highlight the urgent need for new and effective treatments for M. abs infection as well as improved in vivo methods of efficacy testing.

REVIEW OF INDEPENDENT NURSE PRESCRIBING IN A PAEDIATRIC CYSTIC FIBROSIS (CF) AND RESPIRATORY POPULATION.

AIM: With pressures on junior doctors' availability in the NHS, non-medical prescribing is topical. Independent Nurse Prescribers (INPs) can prescribe any licensed medicine for any medical condition within their level of competence.1 An audit was undertaken of the four INPs employed by the Respiratory Department evaluating current prescribing practices. METHOD: The requirement for this audit was identified by the multidisciplinary team (MDT) and Trust approval was obtained. A data collection form was designed capturing patient demographics and full details of prescribed items.Over a 3 month period (August to October 2014) outpatient cystic fibrosis (CF) and respiratory prescriptions were studied using cluster sampling. Over a 6 week period prescription requests by CF INPs faxed to General Practitioners (GPs) were reviewed. INPs also prescribe via telephone, documenting advice on trust forms; these were preliminarily audited. All data was analysed using Microsoft Excel. Legality of prescriptions and adherence to national and local guidelines were evaluated. Reference keys were used to designate non-adherence post-application of exclusion criteria. RESULTS: A total of 77 outpatient prescriptions (45 CF and 32 respiratory) were completed by the 4 INPs, containing 122 items (72 CF and 50 respiratory). Of the CF prescribed items 21 were oral antibiotics (29%). Respiratory INPs mainly prescribed 14 inhaler devices (28%) and 12 inhaled bronchodilators (24%).All INP prescriptions met legal requirements. Basic details of medicinal products (drug name and dose) were documented for all items. A key finding was that duration/quantity was not indicated for 27 (54%) respiratory items.After applying exclusion criteria, of the CF prescribed items, 56/59 (95%) adhered to national guidelines and 47/66 (71%) followed local guidelines. The leading reason for not following local guidelines was not documenting allergy status. Of the respiratory prescribed items, 34 (100%) adhered to national guidelines and 31/32 (97%) followed local guidelines.A total of 33 faxes (with 38 items) were completed and 35 items (92%) were oral antibiotics. Drug name, dose and frequency were stated for all items. From the faxed items, 38 (100%) adhered to national guidelines and 32/33 (97%) followed local guidelines.Over 5 days, CF INPs provided telephone advice for 12 patients. Of these, 6 patients had respiratory exacerbation. Telephone advice led to faxes being sent to GPs for 9 patients. This was preliminary data with a re-audit planned after amendment of trust form. CONCLUSION: Overall INP prescribing was found to be safe and effective. This review enabled education of the respiratory team of prescribing practices via a local audit meeting. The positive contribution that INPs provide to patient care was highlighted as they improve the patient journey and support the MDT. The demand for INP prescribing in particular with CF has provided opportunity for a pharmacist prescriber to join the CF MDT. It is recommended medical and pharmacist prescribing to be reviewed.

Emergence and spread of a human-transmissible multidrug-resistant nontuberculous mycobacterium.

Lung infections with Mycobacterium abscessus, a species of multidrug-resistant nontuberculous mycobacteria, are emerging as an important global threat to individuals with cystic fibrosis (CF), in whom M. abscessus accelerates inflammatory lung damage, leading to increased morbidity and mortality. Previously, M. abscessus was thought to be independently acquired by susceptible individuals from the environment. However, using whole-genome analysis of a global collection of clinical isolates, we show that the majority of M. abscessus infections are acquired through transmission, potentially via fomites and aerosols, of recently emerged dominant circulating clones that have spread globally. We demonstrate that these clones are associated with worse clinical outcomes, show increased virulence in cell-based and mouse infection models, and thus represent an urgent international infection challenge.

Genetic knockouts suggest a critical role for HIV co-receptors in models of HIV gp120-induced brain injury.

Infection with HIV-1 frequently affects the brain and causes NeuroAIDS prior to the development of overt AIDS. The HIV-1 envelope protein gp120 interacts with host CD4 and chemokine co-receptors to initiate infection of macrophages and lymphocytes. In addition, the virus or fragments of it, such as gp120, cause macrophages to produce neurotoxins and trigger neuronal injury and apoptosis. Moreover, the two major HIV co-receptors, the chemokine receptors CCR5 and CXCR4, serve numerous physiological functions and are widely expressed beyond immune cells, including cells in the brain. Therefore, HIV co-receptors are poised to play a direct and indirect part in the development of NeuroAIDS. Although rodents are not permissive to infection with wild type HIV-1, viral co-receptors - more than CD4 - are highly conserved between species, suggesting the animals can be suitable models for mechanistic studies addressing effects of receptor-ligand interaction other than infection. Of note, transgenic mice expressing HIV gp120 in the brain share several pathological hallmarks with NeuroAIDS brains. Against this background, we will discuss recently completed or initiated, ongoing studies that utilize HIV co-receptor knockout and viral gp120-transgenic mice as models for in vitro and in vivo experimentation in order to address the potential roles of HIV gp120 and its co-receptors in the development of NeuroAIDS.