Suppression of cytokine release syndrome during CAR-T-cell therapy via a subcutaneously injected interleukin-6-adsorbing hydrogel.

The infusion of chimaeric antigen receptor (CAR) T cells can trigger the release of life-threatening supraphysiological levels of pro-inflammatory cytokines. However, uncertainty regarding the timing and severity of such cytokine release syndrome (CRS) demands careful monitoring of the conditions required for the administration of neutralizing antibodies. Here we show that a temperature-sensitive hydrogel conjugated with antibodies for the pro-inflammatory cytokine interleukin-6 (IL-6) and subcutaneously injected before the infusion of CAR-T cells substantially reduces the levels of IL-6 during CRS while maintaining the therapy's antitumour efficacy. In immunodeficient mice and in mice with transplanted human haematopoietic stem cells, the subcutaneous IL-6-adsorbing hydrogel largely suppressed CAR-T-cell-induced CRS, substantially improving the animals' survival and alleviating their levels of fever, hypotension and weight loss relative to the administration of free IL-6 antibodies. The implanted hydrogel, which can be easily removed with a syringe following a cooling-induced gel-sol transition, may allow for a shift in the management of CRS, from monitoring to prevention.

CCL2 is required for initiation but not persistence of HIV infection mediated neurocognitive disease in mice.

HIV enters the brain within days of infection causing neurocognitive impairment (NCI) in up to half of infected people despite suppressive antiretroviral therapy. The virus is believed to enter the brain in infected monocytes through chemotaxis to the major monocyte chemokine, CCL2, but the roles of CCL2 in established NCI are not fully defined. We addressed this question during infection of conventional and CCL2 knockout mice with EcoHIV in which NCI can be verified in behavioral tests. EcoHIV enters mouse brain within 5 days of infection, but NCI develops gradually with established cognitive disease starting 25 days after infection. CCL2 knockout mice infected by intraperitoneal injection of virus failed to develop brain infection and NCI. However, when EcoHIV was directly injected into the brain, CCL2 knockout mice developed NCI. Knockout of CCL2 or its principal receptor, CCR2, slightly reduced macrophage infection in culture. Treatment of mice prior to and during EcoHIV infection with the CCL2 transcriptional inhibitor, bindarit, prevented brain infection and NCI and reduced macrophage infection. In contrast, bindarit treatment of mice 4 weeks after infection affected neither brain virus burden nor NCI. Based on these findings we propose that HIV enters the brain mainly through infected monocytes but that resident brain cells are sufficient to maintain NCI. These findings suggest that NCI therapy must act within the brain.

The third-generation anti-CD30 CAR T-cells specifically homing to the tumor and mediating powerful antitumor activity.

CAR T-cell therapy is well tolerated and effective in patients with Hodgkin lymphoma (HL) and anaplastic large cell lymphoma (ALCL). However, even second- generation anti-CD30 CAR T-cells with CD28 (28z) costimulatory domains failed to achieve the desired rate of complete responses. In the present study, we developed second-generation (CD28z) and third-generation (CD28BBz) CAR T-cells targeting CD30 and investigated their efficacy in vitro and in vivo. Both of CD28z and CD28BBz anti-CD30 CAR T cells were similar regarding amplification, T cell subsets distribution, T cell activity, effector/memory and exhaustion. However, we found that the 28BBz anti-CD30 CAR T-cells persist long-term, specifically homing to the tumor and mediating powerful antitumor activity in tumor xenograft models. Subsequently, we also demonstrated that the third generation anti-CD30 CAR T-cells have miner side effects or potential risks of tumorigenesis. Thus, anti-CD30 CAR T-cells represent a safe and effective treatment for Hodgkin lymphoma.

miR-142-5p Inhibits Cell Invasion and Migration by Targeting DNMT1 in Breast Cancer.

Abnormal cell proliferation caused by abnormal transcription regulation mechanism seems to be one of the reasons for the progression of breast cancer and also the pathological basis. MicroRNA-142-5p (miR-142-5p) is a low-expressed miRNA in breast cancer. The role of MKL-1s regulation of DNMT1 in breast cancer cell proliferation and migration is still unclear. MKL-1 (myocardin related transcription factor A) can bind to the conserved cis-regulatory element CC (A/T) 6GG (called CarG box) in the promoter to regulate the transcription of miR-142-5p. The expressions of miR-142-5p and MKL-1 are positively correlated. In addition, it has been proved that DNMT1 is the target of miR-142-5p, which inhibits the expression of DNMT1 by targeting the 3-UTR of DNMT1, thereby forming a feedback loop and inhibiting the migration and proliferation of breast cancer. Our data provide important and novel insights into the MKL-1/miR-142-5p/DNMT1/maspin signaling pathway and may become a new idea for breast cancer diagnosis, treatment, and prognosis.

CD19/CD22 Chimeric Antigen Receptor T Cell Cocktail Therapy following Autologous Transplantation in Patients with Relapsed/Refractory Aggressive B Cell Lymphomas.

High-dose chemotherapy followed by autologous stem cell transplantation (HDT-ASCT) is the standard of care for chemosensitive relapsed or refractory (R/R) aggressive B cell lymphoma. Patients with a positive positron emission tomography (PET) scan before ASCT have a poor prognosis, and those who fail to achieve a therapeutic response better than partial remission after salvage treatment are ineligible candidates for ASCT. We conducted this open-label single-arm prospective clinical study to evaluate the safety and efficacy of sequential infusion of CD19/22 chimeric antigen receptor (CAR) T cells following HDT-ASCT. Eligibility for this study included patients with R/R aggressive B cell non-Hodgkin lymphoma (B-NHL) with 18F-fluorodeoxyglucose-PET positivity and patients with stable or progressive disease after salvage chemotherapy. Between November 14, 2016, and August 15, 2019, 42 patients underwent HDT-ASCT followed by CD19/22 CAR T cell infusion. Grade 3 cytokine release syndrome (CRS) occurred in only 2 patients. Twenty-one percent of patients experienced any grade of neurotoxicity, 5% with severe grade 3. All cases of CRS and neurotoxicity were reversible. The overall response rate was 90.5% (95% confidence interval [CI], 77.4% to 97.3%). At a median follow-up of 24.3 months, the median progression-free survival (PFS) and overall survival were not reached. The 2-year PFS rate was 83.3 % (95% CI, 68.2% to 91.7%). No patients were found to be CD19- and CD22-negative at the time of progression; 97.1% and 68.6% of patients with ongoing complete remission (CR) had consistently detectable levels of CD19 and CD22 CAR transgene, respectively, at 3 months. The median time to onset of sustained B cell recovery was 8.2 months. The high durable CR rates and favorable safety profiles support the strong potential of the HDT-ASCT plus CD19/CD22 CAR T cell cocktail therapy for the suboptimal group of patients with R/R aggressive B-NHL who are less sensitive or fail salvage chemotherapy. These early data are encouraging and informative for future trials to further test the efficacy and safety of HDT-ASCT plus CAR T cell therapy in a larger population. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

A phase I study of anti-BCMA CAR T cell therapy in relapsed/refractory multiple myeloma and plasma cell leukemia.

BACKGROUND: Relapsed/refractory (R/R) multiple myeloma (MM) patients and primary plasma cell leukemia (PCL) have an unfavorable prognosis and no effective treatment. This study was designed to assess the safety and preliminary efficacy of a novel anti-B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T cell in R/R MM and PCL. METHODS: Between February 22, 2017, and June 25, 2018, 28 R/R and two R/R primary PCL patients received a median dose of 11.2 × 106 CAR+ cells/kg. The subjects were refractory to a proteasome inhibitor and/or an immunomodulatory agent. Fludarabine and cyclophosphamide were given as lymphodepletion chemotherapy. RESULTS: Results for these 30 consecutive patients who received an anti-BCMA CAR T cell infusion are reported. The patients had received a median of four prior lines of therapy. A total of 44 different types of adverse events were recorded, and hematologic toxic effects were the most common events of any grade during treatment. Hematologic toxic effects were also the most common events of grade 3 or higher. A total of 29 patients (96.7%) had cytokine release syndrome, which was of grade 1 or 2 in 24 patients (80%) and grade 3 in five patients (16.7%). Neurologic toxic effects only occurred in one patient (3.3%) and were of grade 1. The objective response rate was 90%, and the complete response rate was 43.3%. With a median follow-up of 12.6 months, the median progression-free survival (PFS) and overall survival were 5.2 months and 14.0 months. One of the two primary PCL achieved a complete response with a PFS of 307 days. The other patients achieved a very good partial response with a PFS of 117 days. CONCLUSIONS: Anti-BCMA CAR T cell treatment is safe and highly active in R/R multiple myeloma.

STAT3/miR-15a-5p/CX3CL1 Loop Regulates Proliferation and Migration of Vascular Endothelial Cells in Atherosclerosis.

Endothelial cell proliferation disorder caused by vascular injury seems to be one of the causes of atherosclerosis, which is the pathological basis of coronary heart disease. The role of STAT3 in the regulation of microRNAs and endothelial dysfunction in atherosclerosis is unclear. STAT3 can be activated by cytokine IL-6 and up regulate the expression of CX3CL1. In addition, microRNA-15a-5p (miR-15a-5p) inhibited the transcription of CX3CL1, the proliferation of vascular endothelial cells and the proliferation of STAT3 regulated vascular endothelial cells. STAT3 positively regulates the expression of CX3CL1, and then down-regulates the inhibition of CX3CL1 by over-expression of miR-15a-5p, thus forming an elimination feedback loop to control the proliferation of HUVECs and affect the progression of atherosclerosis. In conclusion, miR-15a-5p may be the therapeutic target of the pathological basis of coronary atherosclerosis.

Efficacy and safety of CAR19/22 T-cell cocktail therapy in patients with refractory/relapsed B-cell malignancies.

Antigen-escape relapse has emerged as a major challenge for long-term disease control after CD19-directed therapies, to which dual-targeting of CD19 and CD22 has been proposed as a potential solution. From March 2016 through January 2018, we conducted a pilot study in 89 patients who had refractory/relapsed B-cell malignancies, to evaluate the efficacy and safety of sequential infusion of anti-CD19 and anti-CD22, a cocktail of 2 single-specific, third-generation chimeric antigen receptor-engineered (CAR19/22) T cells. Among the 51 patients with acute lymphoblastic leukemia, the minimal residual disease-negative response rate was 96.0% (95% confidence interval [CI], 86.3-99.5). With a median follow-up of 16.7 months (range, 1.3-33.3), the median progression-free survival (PFS) was 13.6 months (95% CI, 6.5 to not reached [NR]), and the median overall survival (OS) was 31.0 months (95% CI, 10.6-NR). Among the 38 patients with non-Hodgkin lymphoma, the overall response rate was 72.2% (95% CI, 54.8-85.8), with a complete response rate of 50.0% (95% CI, 32.9-67.1). With a median follow-up of 14.4 months (range, 0.4-27.4), the median PFS was 9.9 months (95% CI, 3.3-NR), and the median OS was 18.0 months (95% CI, 6.1-NR). Antigen-loss relapse occurred in 1 patient during follow-up. High-grade cytokine release syndrome and neurotoxicity occurred in 22.4% and 1.12% patients, respectively. In all except 1, these effects were reversible. Our results indicated that sequential infusion of CAR19/22 T cell was safe and efficacious and may have reduced the rate of antigen-escape relapse in B-cell malignancies. This trial was registered at www.chictr.org.cn as #ChiCTR-OPN-16008526.

Efficient Expression of HIV in Immunocompetent Mouse Brain Reveals a Novel Nonneurotoxic Viral Function in Hippocampal Synaptodendritic Injury and Memory Impairment.

HIV causes neurodegeneration and dementia in AIDS patients, but its function in milder cognitive impairments in virologically suppressed patients on antiretroviral therapy is unknown. Such patients are immunocompetent, have low peripheral and brain HIV burdens, and show minimal brain neuropathology. Using the model of HIV-related memory impairment in EcoHIV-infected conventional mice, we investigated the neurobiological and cognitive consequences of efficient EcoHIV expression in the mouse brain after intracerebral infection. HIV integrated and persisted in an expressed state in brain tissue, was detectable in brain monocytic cells, and caused neuroinflammatory responses and lasting spatial, working, and associative memory impairment. Systemic antiretroviral treatment prevented direct brain infection and memory dysfunction indicating the requirement for HIV expression in the brain for disease. Similarly inoculated murine leukemia virus used as a control replicated in mouse brain but not in monocytic cells and was cognitively benign, linking the disease to HIV-specific functions. Memory impairment correlated in real time with hippocampal dysfunction shown by defective long-term potentiation in hippocampal slices ex vivo and with diffuse synaptodendritic injury in the hippocampus reflected in significant reduction in microtubule-associated protein 2 and synapsin II staining. In contrast, there was no evidence of overt neuronal loss in this region as determined by neuron-specific nuclear protein quantification, TUNEL assay, and histological observations. Our results reveal a novel capacity of HIV to induce neuronal dysfunction and memory impairment independent of neurotoxicity, distinct from the neurotoxicity of HIV infection in dementia.IMPORTANCE HIV neuropathogenesis has been attributed in large measure to neurotoxicity of viral proteins and inflammatory factors produced by infected monocytic cells in the brain. We show here that HIV expression in mouse brain causes lasting memory impairment by a mechanism involving injury to hippocampal synaptodendritic arbors and neuronal function but not overt neuronal loss in the region. Our results mirror the observation of minimal neurodegeneration in cognitively impaired HIV patients on antiretroviral therapy and demonstrate that HIV is nonneurotoxic in certain brain abnormalities that it causes. If neurons comprising the cognition-related networks survive HIV insult, at least for some time, there is a window of opportunity for disease treatment.

Anti-BCMA CAR-T cells for treatment of plasma cell dyscrasia: case report on POEMS syndrome and multiple myeloma.

BACKGROUND: POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome still has no standard treatment. On the basis that both POEMS syndrome and myeloma have an underlying plasma cell dyscrasia, anti-myeloma therapy can be expected to be useful for POEMS syndrome. Chimeric antigen receptor T (CAR-T) cells targeting B cell maturation antigen (BCMA) has been used in the treatment of relapsed and refractory multiple myeloma (RRMM). No POEMS syndrome cases treated with anti-BCMA CAR-T cells have been reported. CASE PRESENTATION: Here, we, for the first time, report a POEMS syndrome case treated with anti-BCMA CAR-T cells. A 49-year-old female with incapacitating POEMS syndrome that progressed on lenalidomide treatment was enrolled in a phase I study involving anti-BCMA CAR-T cells (ChiCTR-OPC-16009113). Another patient with RRMM who had undergone six prior lines treatments was also enrolled in the study. They received infusions of anti-BCMA CAR-T cells. Both patients achieved a stringent complete response. Complete remission persisted in the patient with POEMS syndrome and lasted for 7.6 months before a relapse in RRMM patient. Both patients had toxicity consistent with the grade 1 cytokine release syndrome. CONCLUSIONS: This is the first report of treatment by anti-BCMA CAR-T cells in POEMS syndrome. Our findings demonstrate the anti-BCMA CAR-T cell treatment may be a feasible therapeutic option for patients with POEMS syndrome and RRMM who do not respond well to traditional therapies. TRIAL REGISTRATION: ChiCTR-OPC, ChiCTR-OPC-16009113 . Registered 29 August 2016.

EcoHIV infection of mice establishes latent viral reservoirs in T cells and active viral reservoirs in macrophages that are sufficient for induction of neurocognitive impairment.

Suppression of HIV replication by antiretroviral therapy (ART) or host immunity can prevent AIDS but not other HIV-associated conditions including neurocognitive impairment (HIV-NCI). Pathogenesis in HIV-suppressed individuals has been attributed to reservoirs of latent-inducible virus in resting CD4+ T cells. Macrophages are persistently infected with HIV but their role as HIV reservoirs in vivo has not been fully explored. Here we show that infection of conventional mice with chimeric HIV, EcoHIV, reproduces physiological conditions for development of disease in people on ART including immunocompetence, stable suppression of HIV replication, persistence of integrated, replication-competent HIV in T cells and macrophages, and manifestation of learning and memory deficits in behavioral tests, termed here murine HIV-NCI. EcoHIV established latent reservoirs in CD4+ T lymphocytes in chronically-infected mice but could be induced by epigenetic modulators ex vivo and in mice. In contrast, macrophages expressed EcoHIV constitutively in mice for up to 16 months; murine leukemia virus (MLV), the donor of gp80 envelope in EcoHIV, did not infect macrophages. Both EcoHIV and MLV were found in brain tissue of infected mice but only EcoHIV induced NCI. Murine HIV-NCI was prevented by antiretroviral prophylaxis but once established neither persistent EcoHIV infection in mice nor NCI could be reversed by long-acting antiretroviral therapy. EcoHIV-infected, athymic mice were more permissive to virus replication in macrophages than were wild-type mice, suffered cognitive dysfunction, as well as increased numbers of monocytes and macrophages infiltrating the brain. Our results suggest an important role of HIV expressing macrophages in HIV neuropathogenesis in hosts with suppressed HIV replication.

Killing effect of NK92 cells modified with CD33-CAR on CD33+ acute myeloid leukemia cells / 中国肿瘤生物治疗杂志

@#[Abstract] Objective: To construct CD33-CAR modified NK92 cells based on CD33-scFv sequence, and to explore its killing effect on CD33+ AML (acute myeloid leukemia) cells. Methods: DNA fragment encoding CD33-CAR was synthesized by gene synthesis and molecular cloning technology and then cloned into lentiviral vector. Lentivirus were packaged and used to transfect NK92 cells. The transfection efficiency was detected by flow cytometry, and puromycin was used to screen NK92 cells stably expressing CD33-CAR (CD33-CAR-NK92). Killing effect of CD33-CAR-NK92 cells on AML cells in vitro was examined with calcein-AM release assays. IFN-γ secretions of NK92 cells and CD33-CAR-NK92 cells were measured by ELISA. Results: The pCDH-CD33-CAR lentiviral vector was successfully constructed. After lentiviral transfection, about 18.7% of NK92 cells express CD33-CAR (referred as CD33-CARNK92 cells). The percentage of CD33-CAR+ NK92 cells was about 86.3% after puromycin selection. In contrast to unmodified NK92 cells, significantly higher cytotoxic effect against CD33+ MOLM-13 cells was found in CD33-CAR-NK92 cells (P<0.01); however, there was no significant difference in cytotoxicity against CD33- JURKAT cells between NK92 cells and CD33-CAR-NK92 cells (P> 0.05). After co-culture at an effect-target ratio of 2∶1 for 6 hours, the level of IFN-γ secreted by the CD33-CAR modified NK92 cells was significantly higher than that of the unmodified ([190.97±11.52] vs [88.41±2.75]pg/ml, P<0.01). Conclusion: The CD33-CARNK92 cells could specifically recognize CD33 antigen and kill CD33+ AML cells in comparison with the unmodified NK92 cells, which provides experimental basis for clinical transformation of CD33-CAR-NK92 cells in treatingAML.

Myocardin and Stat3 act synergistically to inhibit cardiomyocyte apoptosis.

Signal transducer and activator of transcription 3 (Stat3) and Myocardin regulate cardiomyocyte differentiation, proliferation, and apoptosis. We report a novel aspect of the cellular function of Myocardin and Stat3 in the regulation of cardiomyocyte apoptosis. Myocardin and Stat3 showed anti-apoptotic function by increasing the expression of Bcl-2 while reducing expression of the pro-apoptotic genes Bax, Apaf-1, caspase-9, and caspase-3. Moreover, myocardin/Stat3-mediated activation of Bcl-2 and Mcl-1 transcription is contingent on the CArG box. Myocardin and Stat3 synergistically inhibited staurosporine-induced cardiomyocyte apoptosis by up-regulating expression of anti-apoptotic Bcl-2 and Mcl-1 in neonatal rat cardiomyocytes. These results describe a novel anti-apoptotic Myocardin/Stat3 signaling pathway operating during cardiomyocyte apoptosis. This provides a molecular explanation for cardiomyocyte apoptosis inhibition as a critical component of myocardial protection.

MRTF-A-miR-206-WDR1 form feedback loop to regulate breast cancer cell migration.

Breast cancer is the leading cause of cancer death in women worldwide which is closely related to metastasis. Our previous study has shown that MRTF-A promote the migration of MDA-MB-231 cells and WDR1 promotes breast cancer cell migration. But the exact molecular mechanism on metastasis is still not fully understood, we now report that WDR1 enhanced the effect of MRTF-A induced-MDA-MB-231 cell migration by promoting the expression of the EMT markers and migration markers via RhoA-MRTF-A signaling pathway. Importantly, WDR1 promoted the nuclear importion of MRTF-A by affecting the expression of nuclear transport protein importin. But WDR1 did not affect the expression of MRTF-A. Interestingly, MRTF-A promoted the expression of miR-206 via its promoter CArG box but miR-206 inhibits the migration of breast cancer cells through suppressing the expression of WDR1 and MRTF-A via targeted their 3'UTR. Our data thus provide important and novel insights into MRTF-A-miR-206-WDR1 form feedback loop to regulate breast cancer cell migration.

MiR-93-5p inhibits the EMT of breast cancer cells via targeting MKL-1 and STAT3.

Epithelial-mesenchymal transition (EMT) plays an important role in breast cancer cell metastasis. Both (megakaryoblastic leukemia)/myocardin-like 1 (MKL-1) and Signal transducer and activator of transcription 3 (STAT3) have been implicated in the control of cellular metabolism, survival and growth. Our previous study has shown that cooperativity of MKL-1 and STAT3 promoted breast cancer cell migration. Herein, we demonstrate a requirement for MKL-1 and STAT3 in miRNA-mediated cellular EMT to affect breast cancer cell migration. Here we show that cooperativity of MKL-1 and STAT3 promoted the EMT of MCF-7 cells. Importantly, MKL-1 and STAT3 promoted the expression of Vimentin via its promoter CArG box. Interestingly, miR-93-5p inhibits the EMT of breast cancer cells through suppressing the expression of MKL-1 and STAT3 via targeted their 3'UTR. These results demonstrated a novel pathway through which miR-93-5p regulates MKL-1 and STAT3 to affect EMT controlling breast cancer cell migration.

An infectious murine model for studying the systemic effects of opioids on early HIV pathogenesis in the gut.

Opioids are known to exacerbate HIV pathogenesis, however current studies have been limited by models of HIV infection. Given that HIV causes many systemic effects via direct infection of host cells as well as indirect bystander effects, it is important to establish a systemic infection model in a small animal so that genetic tools can be utilized to elucidate the mechanisms of action. In this study, the systemic effects of EcoHIV infection, a modified HIV which can infect mouse cells, are examined in conjunction with morphine. EcoHIV infection with opioid treatment induced bacterial translocation from the lumen of the gut into systemic compartments such as liver, which is similar to observations in human patients with LPS. Bacterial translocation corresponds with alterations in gut morphology, disorganization of the tight junction protein occludin, and a concurrent increase in systemic inflammation in both IL-6 and TNFα. Long term infection also had increased expression of inflammatory cytokines in the CNS when co-treated with morphine. Overall, this study shows that EcoHIV is an appropriate model to study the effects of opioids on HIV pathogenesis, including the HIV-induced pathology at early stages of pathogenesis in the gut.

Enhanced human immunodeficiency virus Type 1 expression and neuropathogenesis in knockout mice lacking Type I interferon responses.

The roles of Type I interferon (IFN) in human immunodeficiency virus Type 1 (HIV-1) neuropathogenesis are poorly understood; both protective and deleterious effects of IFN signaling have been described. We used genetically modified mice deficient in the Type I IFN receptor (IFNRKO) to analyze the progress of HIV-1 brain infection and neuropathogenesis in the absence of IFN signaling. IFNRKO and wild-type (WT) mice on the 129xSv/Ev or C57BL/6 strain backgrounds were infected systemically with EcoHIV, a chimeric HIV-1 that productively infects mice. IFNRKO mice showed higher HIV-1 expression in spleen and peritoneal macrophages and greater virus infiltration into the brain compared to WT mice. Neuropathogenesis was studied by histopathological, immunohistochemical, immunofluorescence, and polymerase chain reaction analyses of brain tissues after the virus was inoculated into the brain by stereotaxic intracerebral injection. Both IFNRKO and WT mice showed readily detectable HIV-1 and brain lesions, including microglial activation, astrocytosis, and increased expression of genes coding for inflammatory cytokines and chemokines typical of human HIV-1 brain disease. Parameters of HIV-1 neuropathogenesis, including HIV-1 expression in microglia/macrophages, were significantly greater in IFNRKO than in WT mice. Our results show unequivocally that Type I IFN signaling and responses limit HIV-1 infection and pathogenesis in the brains of mice.

Mice chronically infected with chimeric HIV resist peripheral and brain superinfection: a model of protective immunity to HIV.

Infection by some viruses induces immunity to reinfection, providing a means to identify protective epitopes. To investigate resistance to reinfection in an animal model of HIV disease and its control, we employed infection of mice with chimeric HIV, EcoHIV. When immunocompetent mice were infected by intraperitoneal (IP) injection of EcoHIV, they resisted subsequent secondary infection by IP injection, consistent with a systemic antiviral immune response. To investigate the potential role of these responses in restricting neurotropic HIV infection, we established a protocol for efficient EcoHIV expression in the brain following intracranial (IC) inoculation of virus. When mice were inoculated by IP injection and secondarily by IC injection, they also controlled EcoHIV replication in the brain. To investigate their role in EcoHIV antiviral responses, CD8+ T lymphocytes were isolated from spleens of EcoHIV infected and uninfected mice and adoptively transferred to isogenic recipients. Recipients of EcoHIV primed CD8+ cells resisted subsequent EcoHIV infection compared to recipients of cells from uninfected donors. CD8+ spleen cells from EcoHIV-infected mice also mounted modest but significant interferon-γ responses to two HIV Gag peptide pools. These findings suggest EcoHIV-infected mice may serve as a useful system to investigate the induction of anti-HIV protective immunity for eventual translation to human beings.