The persistence of HIV-1 viral reservoirs in the brain, despite treatment with combination antiretroviral therapy (cART), remains a critical roadblock for the development of a novel cure strategy for HIV-1. To enhance our understanding of viral reservoirs, two complementary studies were conducted to (1) evaluate the HIV-1 mRNA distribution pattern and major cell type expressing HIV-1 mRNA in the HIV-1 transgenic (Tg) rat, and (2) validate our findings by developing and critically testing a novel biological system to model active HIV-1 infection in the rat. First, a restricted, region-specific HIV-1 mRNA distribution pattern was observed in the HIV-1 Tg rat. Microglia were the predominant cell type expressing HIV-1 mRNA in the HIV-1 Tg rat. Second, we developed and critically tested a novel biological system to model key aspects of HIV-1 by infusing F344/N control rats with chimeric HIV (EcoHIV). In vitro, primary cultured microglia were treated with EcoHIV revealing prominent expression within 24 h of infection. In vivo, EcoHIV expression was observed seven days after stereotaxic injections. Following EcoHIV infection, microglia were the major cell type expressing HIV-1 mRNA, results that are consistent with observations in the HIV-1 Tg rat. Within eight weeks of infection, EcoHIV rats exhibited neurocognitive impairments and synaptic dysfunction, which may result from activation of the NogoA-NgR3/PirB-RhoA signaling pathway and/or neuroinflammation. Collectively, these studies enhance our understanding of HIV-1 viral reservoirs in the brain and offer a novel biological system to model HIV-associated neurocognitive disorders and associated comorbidities (i.e., drug abuse) in rats.

Acute pancreatitis (AP) is an aseptic inflammation characterized with an annual incidence rate, and ~20% patients progressing to severe AP (SAP) with a high mortality rate. Although Qingyi decoction has been frequently used for SAP treatment over the past 3 decades in clinic, the actual mechanism of its protective effects remains unknown. As the major active ingredient of Qingyi decoction, emodin was selected in the present study to investigate the effect of emodin against severe acute pancreatitis (SAP) in rats through NOD‑like receptor protein 3 (NLRP3) inflammasomes. The rats were randomly divided into a sham operation group, an SAP model group induced by a standard retrograde infusion of 5.0% sodium taurocholate into the biliopancreatic duct, and low‑dose (30 mg/kg) and high‑dose (60 mg/kg) emodin‑treated groups. At 12 h after the event, the plasma amylase, lipase, interleukin (IL)‑1β, IL‑18 and myeloperoxidase (MPO) activities were examined. Furthermore, the pathological scores of pancreases were evaluated by hematoxylin and eosin staining. The expression levels of P2X ligand‑gated ion channel 7 (P2X7), NLRP3, apoptosis‑associated speck‑like protein containing a C‑terminal caspase recruitment domain and caspase‑1 were also analyzed by western blot analysis. The data demonstrated that, compared with the SAP group, emodin could significantly relieve the pancreatic histopathology and acinar cellular structure injury, and notably downregulate the plasma amylase and lipase levels, as well as the MPO activities in pancreatic tissues, in a dose‑dependent manner. Furthermore, emodin inhibited the P2X7/NLRP3 signaling pathway followed by the decrease of pro‑inflammatory factors, and the latter is beneficial for the recovery of SAP. Collectively, the data indicated that emodin may be an efficient candidate natural product for SAP treatment.

The prevalence of HIV-1 associated neurocognitive disorders (HAND) is significantly greater in older, relative to younger, HIV-1 seropositive individuals; the neural pathogenesis of HAND in older HIV-1 seropositive individuals, however, remains elusive. To address this knowledge gap, abnormal protein aggregates (i.e., β-amyloid) were investigated in the brains of aging (>12 months of age) HIV-1 transgenic (Tg) rats. In aging HIV-1 Tg rats, double immunohistochemistry staining revealed abnormal intraneuronal β-amyloid accumulation in the prefrontal cortex (PFC) and hippocampus, relative to F344/N control rats. Notably, in HIV-1 Tg animals, increased β-amyloid accumulation occurred in the absence of any genotypic changes in amyloid precursor protein (APP). Furthermore, no clear amyloid plaque deposition was observed in HIV-1 Tg animals. Critically, β-amyloid was co-localized with neurons in the cortex and hippocampus, supporting a potential mechanism underlying synaptic dysfunction in the HIV-1 Tg rat. Consistent with these neuropathological findings, HIV-1 Tg rats exhibited prominent alterations in the progression of temporal processing relative to control animals; temporal processing relies, at least in part, on the integrity of the PFC and hippocampus. In addition, in post-mortem HIV-1 seropositive individuals with HAND, intraneuronal β-amyloid accumulation was observed in the dorsolateral PFC and hippocampal dentate gyrus. Consistent with observations in the HIV-1 Tg rat, no amyloid plaques were found in these post-mortem HIV-1 seropositive individuals with HAND. Collectively, intraneuronal β-amyloid aggregation observed in the PFC and hippocampus of HIV-1 Tg rats supports a potential factor underlying HIV-1 associated synaptodendritic damage. Further, the HIV-1 Tg rat provides a biological system to model HAND in older HIV-1 seropositive individuals.

Due to the widespread access to, and implementation of, combination antiretroviral therapy, individuals perinatally infected with human immunodeficiency virus type 1 (HIV-1) are living into adolescence and adulthood. Perinatally infected adolescents living with HIV-1 (pALHIV) are plagued by progressive, chronic neurocognitive impairments; the pathophysiological mechanisms underlying these deficits, however, remain understudied. A longitudinal experimental design from postnatal day (PD) 30 to PD 180 was utilized to establish the development of pyramidal neurons, and associated dendritic spines, from layers II-III of the medial prefrontal cortex (mPFC) in HIV-1 transgenic (Tg) and control animals. Three putative neuroinflammatory markers (i.e., IL-1β, IL-6, and TNF-α) were evaluated early in development (i.e., PD 30) as a potential mechanism underlying synaptic dysfunction in the mPFC. Constitutive expression of HIV-1 viral proteins induced prominent neurodevelopmental alterations and progressive synaptodendritic dysfunction, independent of biological sex, in pyramidal neurons from layers II-III of the mPFC. From a neurodevelopmental perspective, HIV-1 Tg rats exhibited prominent deficits in dendritic and synaptic pruning. With regards to progressive synaptodendritic dysfunction, HIV-1 Tg animals exhibited an age-related population shift towards dendritic spines with decreased volume, increased backbone length, and decreased head diameter; parameters associated with a more immature dendritic spine phenotype. There was no compelling evidence for neuroinflammation in the mPFC during early development. Collectively, progressive neuronal and dendritic spine dysmorphology herald synaptodendritic dysfunction as a key neural mechanism underlying chronic neurocognitive impairments in pALHIV.

Independently, chronic cocaine use and HIV-1 viral protein exposure induce neuroadaptations in the frontal-striatal circuit as evidenced by both clinical and preclinical studies; how the frontal-striatal circuit responds to HIV-1 infection following chronic drug use, however, has remained elusive. After establishing experience with both sucrose and cocaine self-administration, a pretest-posttest experimental design was utilized to evaluate preference judgment, a simple form of decision-making dependent upon the integrity of frontal-striatal circuit function. During the pretest assessment, male rats exhibited a clear preference for cocaine, whereas female animals preferred sucrose. Two posttest evaluations (3 days and 6 weeks post inoculation) revealed that, independent of biological sex, inoculation with chimeric HIV (EcoHIV), but not saline, disrupted decision-making. Prominent structural alterations in the frontal-striatal circuit were evidenced by synaptodendritic alterations in pyramidal neurons in the medial prefrontal cortex. Thus, the EcoHIV rat affords a valid animal model to critically investigate how the frontal-striatal circuit responds to HIV-1 infection following chronic drug use.

Emodin (EMO), an anthraquinone derivative from roots and leaves of various plants, has been widely used in many inflammatory diseases. Alveolar macrophages (AMs) play a critical role in maintaining alveolar homeostasis in the lung. To investigate the pathophysiological mechanism of AMs in acute pancreatitis-associated lung injury (AP-ALI) and the potential protective therapeutic of EMO for AP-ALI, AMs isolated from AP-ALI mice, murine cell line MH-S and RAW264.7 were pre-treated with EMO to assess its protective roles on regulating inflammation, pyroptosis, and mitophagy of macrophages in AP-ALI. The results showed that 1) in vivo, the relative quantity of AMs was significantly decreased across the time in API-ALI; however, the mitochondria flux presented earlier changes than the resident AMs alteration in our experimental system. EMO pretreatment significantly alleviated the severity of lung injury and improved the damaged alveolar structure, and further reversed the reduction of mitochondria impairment in AMs in mice. 2) In vitro, EMO significantly suppressed LPS/ATP associated NLRP3 inflammasome activation, enhanced mitophagy, and protected mitochondria damage. Furthermore, the data of mitophagy inhibition by 3-MA demonstrated that EMO protective effects were partially via manipulating mitophagy-mitochondria-alveolar macrophage axis. Our data shed light on the comprehensive understanding on EMO therapeutics in AP-ALI.