Resistance of HIV-infected macrophages to CD8+ T lymphocyte-mediated killing drives activation of the immune system.

CD4+ T lymphocytes are the principal target of human immunodeficiency virus (HIV), but infected macrophages also contribute to viral pathogenesis. The killing of infected cells by CD8+ cytotoxic T lymphocytes (CTLs) leads to control of viral replication. Here we found that the killing of macrophages by CTLs was impaired relative to the killing of CD4+ T cells by CTLs, and this resulted in inefficient suppression of HIV. The killing of macrophages depended on caspase-3 and granzyme B, whereas the rapid killing of CD4+ T cells was caspase independent and did not require granzyme B. Moreover, the impaired killing of macrophages was associated with prolonged effector cell-target cell contact time and higher expression of interferon-γ by CTLs, which induced macrophage production of pro-inflammatory chemokines that recruited monocytes and T cells. Similar results were obtained when macrophages presented other viral antigens, suggestive of a general mechanism for macrophage persistence as antigen-presenting cells that enhance inflammation and adaptive immunity. Inefficient killing of macrophages by CTLs might contribute to chronic inflammation, a hallmark of chronic disease caused by HIV.

Functional impairment of HIV-specific CD8+ T cells precedes aborted spontaneous control of viremia.

Spontaneous control of HIV infection has been repeatedly linked to antiviral CD8+ T cells but is not always permanent. To address mechanisms of durable and aborted control of viremia, we evaluated immunologic and virologic parameters longitudinally among 34 HIV-infected subjects with differential outcomes. Despite sustained recognition of autologous virus, HIV-specific proliferative and cytolytic T cell effector functions became selectively and intrinsically impaired prior to aborted control. Longitudinal transcriptomic profiling of functionally impaired HIV-specific CD8+ T cells revealed altered expression of genes related to activation, cytokine-mediated signaling, and cell cycle regulation, including increased expression of the antiproliferative transcription factor KLF2 but not of genes associated with canonical exhaustion. Lymphoid HIV-specific CD8+ T cells also exhibited poor functionality during aborted control relative to durable control. Our results identify selective functional impairment of HIV-specific CD8+ T cells as prognostic of impending aborted HIV control, with implications for clinical monitoring and immunotherapeutic strategies.

Concanamycin A counteracts HIV-1 Nef to enhance immune clearance of infected primary cells by cytotoxic T lymphocytes.

Nef is an HIV-encoded accessory protein that enhances pathogenicity by down-regulating major histocompatibility class I (MHC-I) expression to evade killing by cytotoxic T lymphocytes (CTLs). A potent Nef inhibitor that restores MHC-I is needed to promote immune-mediated clearance of HIV-infected cells. We discovered that the plecomacrolide family of natural products restored MHC-I to the surface of Nef-expressing primary cells with variable potency. Concanamycin A (CMA) counteracted Nef at subnanomolar concentrations that did not interfere with lysosomal acidification or degradation and were nontoxic in primary cell cultures. CMA specifically reversed Nef-mediated down-regulation of MHC-I, but not CD4, and cells treated with CMA showed reduced formation of the Nef:MHC-I:AP-1 complex required for MHC-I down-regulation. CMA restored expression of diverse allotypes of MHC-I in Nef-expressing cells and inhibited Nef alleles from divergent clades of HIV and simian immunodeficiency virus, including from primary patient isolates. Lastly, we found that restoration of MHC-I in HIV-infected cells was accompanied by enhanced CTL-mediated clearance of infected cells comparable to genetic deletion of Nef. Thus, we propose CMA as a lead compound for therapeutic inhibition of Nef to enhance immune-mediated clearance of HIV-infected cells.

Vpr Promotes Macrophage-Dependent HIV-1 Infection of CD4+ T Lymphocytes.

Vpr is a conserved primate lentiviral protein that promotes infection of T lymphocytes in vivo by an unknown mechanism. Here we demonstrate that Vpr and its cellular co-factor, DCAF1, are necessary for efficient cell-to-cell spread of HIV-1 from macrophages to CD4+ T lymphocytes when there is inadequate cell-free virus to support direct T lymphocyte infection. Remarkably, Vpr functioned to counteract a macrophage-specific intrinsic antiviral pathway that targeted Env-containing virions to LAMP1+ lysosomal compartments. This restriction of Env also impaired virological synapses formed through interactions between HIV-1 Env on infected macrophages and CD4 on T lymphocytes. Treatment of infected macrophages with exogenous interferon-alpha induced virion degradation and blocked synapse formation, overcoming the effects of Vpr. These results provide a mechanism that helps explain the in vivo requirement for Vpr and suggests that a macrophage-dependent stage of HIV-1 infection drives the evolutionary conservation of Vpr.

Expanded Antigen-Specific Elimination Assay to Measure Human CD8+ T Cell Cytolytic Potential.

Durable cellular immunity against pathogens is dependent upon a coordinated recall response to antigen by memory CD8+ T cells, involving their proliferation and the generation of secondary cytotoxic effector cells. Conventional assays measuring ex vivo cytotoxicity fail to capture this secondary cytolytic potential, especially in settings where cells have not been recently exposed to their cognate antigen in vivo. Here we describe the expanded antigen-specific elimination assay (EASEA), a flow cytometric endpoint assay to measure the capacity of human CD8+ T cells to expand in vitro upon antigen re-exposure and generate secondary effector cells capable of selectively eliminating autologous antigen-pulsed target cells across a range of effector-to-target ratios. Unlike alternative assays, EASEA avoids the hazards of radioactive labeling and viral infection and can be used to study responses to individual or pooled antigens of interest. © 2024 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Expanded antigen-specific elimination assay.

Impact of HLA class I functional divergence on HIV control.

Heterozygosity of Human leukocyte antigen (HLA) class I genes is linked to beneficial outcomes after HIV infection, presumably through greater breadth of HIV epitope presentation and cytotoxic T cell response. Distinct allotype pairs, however, differ in the extent to which they bind shared sets of peptides. We developed a functional divergence metric that measures pairwise complementarity of allotype-associated peptide binding profiles. Greater functional divergence for pairs of HLA-A and/or HLA-B allotypes was associated with slower AIDS progression and independently with enhanced viral load control. The metric predicts immune breadth at the peptide level rather than gene level and redefines HLA heterozygosity as a continuum differentially affecting disease outcome. Functional divergence may affect response to additional infections, vaccination, immunotherapy, and other diseases where HLA heterozygote advantage occurs.

Cytolytic CD8+ T cells infiltrate germinal centers to limit ongoing HIV replication in spontaneous controller lymph nodes.

Follicular CD8+ T cells (fCD8) mediate surveillance in lymph node (LN) germinal centers against lymphotropic infections and cancers, but the precise mechanisms by which these cells mediate immune control remain incompletely resolved. To address this, we investigated functionality, clonotypic compartmentalization, spatial localization, phenotypic characteristics, and transcriptional profiles of LN-resident virus-specific CD8+ T cells in persons who control HIV without medications. Antigen-induced proliferative and cytolytic potential consistently distinguished spontaneous controllers from noncontrollers. T cell receptor analysis revealed complete clonotypic overlap between peripheral and LN-resident HIV-specific CD8+ T cells. Transcriptional analysis of LN CD8+ T cells revealed gene signatures of inflammatory chemotaxis and antigen-induced effector function. In HIV controllers, the cytotoxic effectors perforin and granzyme B were elevated among virus-specific CXCR5+ fCD8s proximate to foci of HIV RNA within germinal centers. These results provide evidence consistent with cytolytic control of lymphotropic infection supported by inflammatory recruitment, antigen-specific proliferation, and cytotoxicity of fCD8s.

Molecular basis of differential HLA class I-restricted T cell recognition of a highly networked HIV peptide.

Cytotoxic-T-lymphocyte (CTL) mediated control of HIV-1 is enhanced by targeting highly networked epitopes in complex with human-leukocyte-antigen-class-I (HLA-I). However, the extent to which the presenting HLA allele contributes to this process is unknown. Here we examine the CTL response to QW9, a highly networked epitope presented by the disease-protective HLA-B57 and disease-neutral HLA-B53. Despite robust targeting of QW9 in persons expressing either allele, T cell receptor (TCR) cross-recognition of the naturally occurring variant QW9_S3T is consistently reduced when presented by HLA-B53 but not by HLA-B57. Crystal structures show substantial conformational changes from QW9-HLA to QW9_S3T-HLA by both alleles. The TCR-QW9-B53 ternary complex structure manifests how the QW9-B53 can elicit effective CTLs and suggests sterically hindered cross-recognition by QW9_S3T-B53. We observe populations of cross-reactive TCRs for B57, but not B53 and also find greater peptide-HLA stability for B57 in comparison to B53. These data demonstrate differential impacts of HLAs on TCR cross-recognition and antigen presentation of a naturally arising variant, with important implications for vaccine design.

CD8+ T cells in HIV control, cure and prevention.

HIV infection can be effectively treated by lifelong administration of combination antiretroviral therapy, but an effective vaccine will likely be required to end the HIV epidemic. Although the majority of current vaccine strategies focus on the induction of neutralizing antibodies, there is substantial evidence that cellular immunity mediated by CD8+ T cells can sustain long-term disease-free and transmission-free HIV control and may be harnessed to induce both therapeutic and preventive antiviral effects. In this Review, we discuss the increasing evidence derived from individuals who spontaneously control infection without antiretroviral therapy as well as preclinical immunization studies that provide a clear rationale for renewed efforts to develop a CD8+ T cell-based HIV vaccine in conjunction with B cell vaccine efforts. Further, we outline the remaining challenges in translating these findings into viable HIV prevention, treatment and cure strategies.

Mannose receptor is an HIV restriction factor counteracted by Vpr in macrophages.

HIV-1 Vpr is necessary for maximal HIV infection and spread in macrophages. Evolutionary conservation of Vpr suggests an important yet poorly understood role for macrophages in HIV pathogenesis. Vpr counteracts a previously unknown macrophage-specific restriction factor that targets and reduces the expression of HIV Env. Here, we report that the macrophage mannose receptor (MR), is a restriction factor targeting Env in primary human monocyte-derived macrophages. Vpr acts synergistically with HIV Nef to target distinct stages of the MR biosynthetic pathway and dramatically reduce MR expression. Silencing MR or deleting mannose residues on Env rescues Env expression in HIV-1-infected macrophages lacking Vpr. However, we also show that disrupting interactions between Env and MR reduces initial infection of macrophages by cell-free virus. Together these results reveal a Vpr-Nef-Env axis that hijacks a host mannose-MR response system to facilitate infection while evading MR's normal role, which is to trap and destroy mannose-expressing pathogens.

Human cells have defense mechanisms against viral infection known as restriction factors. These are proteins that break down parts of a virus including its DNA or proteins. To evade these defenses, viruses in turn make proteins that block or break down restriction factors. This battle between human and viral proteins determines which types of cells are infected and how quickly a virus can multiply and spread to new cells. HIV produces a protein called Vpr that counteracts a restriction factor found in immune cells called macrophages. However, the identity of the restriction factor targeted by Vpr is a mystery. When Vpr is missing, this unknown restriction factor breaks down a virus protein called Env. Env is a glycoprotein, which is a protein with sugars attached. When Env levels are low, HIV cannot spread to other cells and multiply. Identifying the restriction factor that breaks down Env may lead to new ways of treating and preventing HIV infections. Now, Lubow et al. reveal that the unknown restriction factor in macrophages is a protein called the mannose receptor. This protein binds and destroys proteins containing mannose, a type of sugar found on bacteria and some viruses. The experiments revealed that the mannose receptor grabs mannose on the HIV protein Env. This causes Env to be broken down and stops HIV from spreading. Lubow et al. also find that Vpr works with another protein produced by HIV called Nef to reduce the number of mannose receptors on macrophages. The two proteins do this by targeting different steps in the assembly of mannose receptors, allowing the virus to multiply and spread more efficiently. The experiments suggest that drugs that simultaneously block Vpr and Nef might prevent or suppress HIV infections. More studies are needed to develop and test potential HIV-treatments targeting Vpr and Nef.

Structural topology defines protective CD8+ T cell epitopes in the HIV proteome.

Mutationally constrained epitopes of variable pathogens represent promising targets for vaccine design but are not reliably identified by sequence conservation. In this study, we employed structure-based network analysis, which applies network theory to HIV protein structure data to quantitate the topological importance of individual amino acid residues. Mutation of residues at important network positions disproportionately impaired viral replication and occurred with high frequency in epitopes presented by protective human leukocyte antigen (HLA) class I alleles. Moreover, CD8+ T cell targeting of highly networked epitopes distinguished individuals who naturally control HIV, even in the absence of protective HLA alleles. This approach thereby provides a mechanistic basis for immune control and a means to identify CD8+ T cell epitopes of topological importance for rational immunogen design, including a T cell-based HIV vaccine.

Predicting functional change from preintervention measures in selective dorsal rhizotomy.

OBJECT: In this investigation the authors attempted to predict change in function following selective dorsal rhizotomy (SDR) and intensive physical therapy in patients with spastic diplegic cerebral palsy (CP) based on multidomain preintervention measures. METHODS: Data pertaining to 22 children with CP were collected before the SDR and again 20 months afterward. Although equations for predicting change in gait speed and function (such as the Gross Motor Function Measure) were derived, the 95% confidence interval (CI) widths were too broad to make accurate predictions that were clinically useful outside the study group. CONCLUSIONS: Future work should be focused on developing additional measures such as lower-extremity motor control and balance in an attempt to reduce the CIs to more clinically relevant values.

Patterns of lumbar region movement during trunk lateral bending in 2 subgroups of people with low back pain.

BACKGROUND AND PURPOSE: The movement system impairment (MSI) system is one proposed system for classifying low back pain (LBP) problems. Prior clinical data and observations for the MSI system suggest that different LBP subgroups demonstrate different patterns of movement during clinical tests, such as trunk lateral bending (TLB). The purpose of this study, therefore, was to examine the validity of the observation that lumbar region (LR) movement patterns during TLB are different between 2 subgroups of people with LBP: lumbar rotation with extension (Rotation With Extension) and lumbar rotation (Rotation). SUBJECTS: Participants were 44 people (28 men and 16 women; age [X+/-SD], 28.5+/-8.4 years) with chronic or recurrent LBP. METHODS: Each participant's LBP problem was classified with the MSI system. Kinematic variables were measured, and LBP symptoms were recorded during the TLB test. RESULTS: People in the 2 LBP subgroups demonstrated different patterns of LR movement during TLB. People in the Rotation With Extension subgroup displayed an asymmetric (right versus left) pattern of LR movement across the TLB movement, whereas people in the Rotation subgroup displayed a symmetric pattern of LR movement. Equal proportions of people in the 2 subgroups reported an increase in symptoms with the TLB test. DISCUSSION AND CONCLUSION: The patterns of LR movement across the TLB movement were different in 2 subgroups of people with LBP. The difference in the LR movement patterns between subgroups may be an important factor to consider in specifying the details of the interventions for these 2 LBP problems.

Effect of selective dorsal rhizotomy in the treatment of children with cerebral palsy.

OBJECT: In this investigation the authors compared impairment and functional outcomes between two groups of children with cerebral palsy (CP): one group underwent selective dorsal rhizotomy (SDR) followed by intensive physical therapy (PT), and the other group underwent the latter only (PT group). Data from an age-matched group of children without disability (nondisabled [ND] group) were also collected. METHODS: Data pertaining to the 68 children with CP were collected before any intervention and again 8 and 20 months afterwards. Data regarding the 40 children in the ND group were collected in a single session. CONCLUSIONS: Although patients in both groups with CP were weaker than those in the ND group, they did have strength gains. Gait speed in the SDR-PT group was slower than that in the ND group preoperatively but not at 20 months postoperatively. Gait speed in the PT group remained slower than that in the ND group. The pre- to postoperative change in the Gross Motor Abilities Estimate score was significantly greater in the SDR-PT group than in the PT-only group. An effective treatment for children with CP, SDR offers gains in strength, gait speed, and overall gross motor function.

Gender differences in pattern of hip and lumbopelvic rotation in people with low back pain.

BACKGROUND: Findings from previous studies suggest gender may affect the pattern of hip and lumbopelvic motion during a multi-segmental movement. To date, no studies have examined movement patterns and low back pain symptom behavior during hip lateral rotation. METHODS: Forty-six people (27 males and 19 females) with low back pain were examined. Three-dimensional kinematic data and low back pain symptoms were recorded during active hip lateral rotation. Percent of maximum lumbopelvic rotation was calculated for each 10% increment of maximum active hip lateral rotation. FINDINGS: Men exhibited a greater percent of maximum lumbopelvic rotation (mean 49.3, SD 13.3) during the first 60% of hip lateral rotation than women (mean 36.2, SD 16.4) (P < 0.01). Nineteen (70.4%) of the men and seven (36.8%) of the women had pain with the hip lateral rotation test (P = 0.02). INTERPRETATION: Men exhibited more lumbopelvic rotation in the early part of hip lateral rotation than women, and hip lateral rotation was more likely to be associated with symptoms in men than women. Greater lumbopelvic motion, earlier in hip lateral rotation, may make men more vulnerable to low back pain associated with hip lateral rotation. Factors that contribute to these gender differences should be investigated further.

The effects of feedback self-consistency, therapist status, and attitude toward therapy on reaction to personality feedback.

Individuals' reactions to interpersonal feedback may depend on characteristics of the feedback and the feedback source. The present authors examined the effects of experimentally manipulated personality feedback that they--in the guise of therapists--e-mailed to participants on the degree of their acceptance of the feedback. Consistent with Self-Verification Theory (W. B. Swann Jr., 1987), participants accepted feedback that was consistent with their self-views more readily than they did feedback that was inconsistent with their self-views. Furthermore, the authors found main effects for therapist's status and participant's attitude toward therapy. Significant interactions showed effects in which high-status therapists and positive client attitudes increased acceptance of self-inconsistent feedback, effects that were only partially mediated by clients' perceptions of therapist competence. The present results indicate the possibility that participants may be susceptible to self-concept change or to self-fulfilling prophecy effects in therapy when they have a positive attitude toward therapy or are working with a high-status therapist.

Endoscopic third ventriculostomy: an outcome analysis of primary cases and procedures performed after ventriculoperitoneal shunt malfunction.

OBJECT: The authors analyzed the role of endoscopic third ventriculostomy (ETV) as a primary treatment for hydrocephalus and also as an alternative to shunt revision for malfunctioning and infected ventriculoperitoneal (VP) shunts. METHODS: A retrospective analysis of clinical notes, operation records, and magnetic resonance imaging procedures before and after ventriculostomy was performed to determine the success or failure of ETVs in 170 patients who underwent a primary ETV and in 63 patients who underwent an ETV for shunt malfunction (secondary ETV). The patients' data were derived from an endoscopy database inaugurated in 1998. Of the 63 patients with shunt malfunctions, 49 patients (78%) had mechanical malfunction only and 14 patients (22%) had both infection and malfunction. Seventy-four percent (126 of 170) of patients in the primary ETV group and 70% (44 of 63) of patients in the secondary ETV had a successful outcome at the time of analysis. The success rate for ETVs in cases involving a mechanical shunt malfunction alone was 67% (33 of 49) compared with 79% (11 of 14) in those cases involving an infected shunt. The origin of the hydrocephalus in the primary and shunt malfunction groups was evaluated as a factor contributing to the success of the ETV. In the primary group, patients with a history of intraventricular hemorrhage (IVH) and meningitis as a cause for hydrocephalus had a poor rate of success after the ETV--27% (four of 15) and 0% (none of two), respectively. This pattern was not seen in the series involving shunt malfunction after the ETV, with 71% (five of seven) and 75% (three of four) of cases having a hydrocephalus origin of IVH and meningitis, respectively, in which a successful outcome was attained. A two-way mixed-model analysis of variance yielded a significant effect for origin (p = 0.011), a significant interaction between group and origin (p = 0.028), and a marginally nonsignificant effect of group (p = 0.0686). More than 95% of failures were evident within 1 month of the ETV in both groups. Complications were minimal in both groups, and there were no procedure-related deaths. CONCLUSIONS: An ETV is a safe procedure with few complications and a high success rate in both primary and secondary groups. An ETV to address shunt malfunction, unlike a primary ETV, is not particularly origin specific. A bonus is its success in dealing with infected shunts. Most failures will be evident early, but long-term follow up is vital.

Orthopedic surgery after selective dorsal rhizotomy for spastic diplegia in relation to ambulatory status and age.

OBJECT: A retrospective study was performed to determine the following: 1) whether children who walk independently after selective dorsal rhizotomy (SDR) undergo fewer subsequent orthopedic operations than those who walk with assistance; and 2) the effect of age at SDR on the rate of orthopedic operations. METHODS: The cases of 158 children with spastic diplegia who were 2 to 14 years of age when they underwent SDR were followed over a 5- to 9-year period. Patients were grouped by age at the time of SDR as follows: 2 to 3 years (Group 1), 4 to 7 years (Group 2), and 8 to 14 years (Group 3). Follow-up data showed that children in all age groups who walked independently after SDR underwent fewer orthopedic operations than did children who walked with assistance. Overall rates of orthopedic surgery 5 to 9 years after SDR at last follow up were 24% for independent walkers and 51% for assisted walkers. Two-way categorical analysis (age group by ambulation) yielded a highly significant effect of ambulation (p = 0.0003). Children in Group 1 needed the fewest orthopedic operations at follow-up evaluation. In the older age groups (Groups 2 and 3), those who walked independently at the time of SDR underwent fewer orthopedic operations after SDR than did walkers who required assistance (p = 0.01). CONCLUSIONS: These data are of value in advising parents about the likelihood of orthopedic surgery based on the child's gait status both at the time of SDR and at follow-up evaluation. Orthopedic surgery is more likely in patients destined to be nonambulators.