Loss of cytomegalovirus-specific CD4+ T cell responses in human immunodeficiency virus type 1-infected patients with high CD4+ T cell counts and recurrent retinitis

Murine cytomegalovirus localization and uveitic cell infiltration might both contribute to trabecular meshwork impairment in Posner-Schlossman syndrome: Evidence from an open-angle rat model

As a special type of glaucoma, Posner-Schlossman syndrome (PSS) is characterized by elevated intraocular pressure (IOP) and anterior uveitis. Cytomegalovirus (CMV) anterior chamber infection has now been considered the leading cause of PSS. We used murine CMV (MCMV) intracameral injection to establish a rat model manifested in IOP elevation and mild anterior uveitis, much like PSS; viral localization and gene expression at various time points and inflammatory cell infiltration derived from innate and adaptive immunity were investigated, as well as pathogenetic changes of the trabecular meshwork (TM). The IOP and uveitic manifestations peaked at 24 h post-infection (p.i.) and returned to normal after 96 h; the iridocorneal angle remained open consistently. At 24 h p.i., leucocytes gathered at the chamber angle. Maximum transcription of MCMV immediate early 1 (IE1) was reached at 24 h in the cornea and 48 h in the iris and ciliary body. MCMV localized in aqueous humor outflow facilities and the iris from 24 h to 28 d p.i. and was detected by in situ hybridization, though it did not transcribe after 7 d p.i. TM and iris pigment epithelial cells harboring viral inclusion bodies and autophagosomes were present at 28 d p.i. These findings shed light on how and where innate and adaptive immunity reacted after MCMV was found and transcribed in a highly ordered cascade, as well as pathogenetic changes in TM as a result of virus and uveitis behaviors.

Classification Criteria for Cytomegalovirus Retinitis

PURPOSE

The purpose of this study was to determine classification criteria for cytomegalovirus (CMV) retinitis.

DESIGN

Machine learning of cases with CMV retinitis and 4 other infectious posterior/ panuveitides.

METHODS

Cases of infectious posterior/panuveitides were collected in an informatics-designed preliminary database, and a final database was constructed of cases achieving supermajority agreement on diagnosis using formal consensus techniques. Cases were split into a training set and a validation set. Machine learning using multinomial logistic regression was used in the training set to determine a parsimonious set of criteria that minimized the misclassification rate among the infectious posterior/panuveitides. The resulting criteria were evaluated in the validation set.

RESULTS

A total of 803 cases of infectious posterior/panuveitides, including 211 cases of CMV retinitis, were evaluated by machine learning. Key criteria for CMV retinitis included: 1) necrotizing retinitis with indistinct borders due to numerous small satellites; 2) evidence of immune compromise; and either 3) a characteristic clinical appearance, or 4) positive polymerase chain reaction assay results for CMV from an intraocular specimen. Characteristic appearances for CMV retinitis included: 1) wedge-shaped area of retinitis; 2) hemorrhagic retinitis; or 3) granular retinitis. Overall accuracy for infectious posterior/panuveitides was 92.1% in the training set and 93.3% (95% confidence interval: 88.2-96.3) in the validation set. The misclassification rates for CMV retinitis were 6.9% in the training set and 6.3% in the validation set.

CONCLUSIONS

The criteria for CMV retinitis had a low misclassification rate and appeared to perform sufficiently well for use in clinical and translational research.

Use of maintenance therapy and incidence of recurrent Cytomegalovirus DNAemia among allogeneic hematopoietic cell transplant recipients

BACKGROUND

Cytomegalovirus (CMV) infection is the most common infection following hematopoietic cell transplantation (HCT). Preemptive antiviral therapy is highly effective at halting viral replication and preventing CMV disease; however, recurrence rates after clearance of CMV DNAemia are high (50-70%). Current treatment guidelines recommend maintenance therapy after initial clearance. Yet, the effectiveness of this intervention to prevent recurrence is not well defined.

OBJECTIVES

We aimed to assess the impact of maintenance therapy on the probability of recurrent CMV in allogeneic HCT recipients with early CMV reactivation.

STUDY DESIGN

Sixty-six patients with an initial episode of early CMV reactivation who achieved viral clearance in response to preemptive therapy were included. We compared the incidence of recurrent CMV DNAemia in patients who received maintenance therapy vs those who underwent early discontinuation of antiviral therapy.

RESULTS

Recurrence occurred in 47/64 (73%) patients, including 11/14 (79%) patients without maintenance therapy and 36/50 (72%) of patients who received maintenance therapy (P = 0.74). The propensity score adjusted risk ratio for the effect of maintenance therapy on recurrence was 0.89 (95% CI 0.64-1.25; P = 0.41). In a time to event analysis using the unweighted cohort, the 90-day probability of CMV recurrence was similar between patient groups independent of maintenance therapy administration (54% vs 64% for maintenance vs non-maintenance groups, respectively; log-rank P = 0.37).

CONCLUSION

These data suggest that maintenance antiviral therapy does not reduce the incidence of CMV recurrence while off therapy and is of limited value in HCT recipients who have successfully eradicated CMV DNAemia in response to preemptive therapy. Larger studies in this area are needed.

Active cytomegalovirus retinitis after the start of antiretroviral therapy

Patients with AIDS-related cytomegalovirus (CMV) retinitis receiving combined antiretroviral therapy (cART), but not specific anti-CMV therapy, consistently showed active retinitis for several months. Delayed diagnosis and treatment of CMV retinitis may have severe consequences. Patients first entering care with advanced HIV infection and vulnerability to reactivation of latent CMV infection should be screened immediately for CMV retinitis by dilated indirect ophthalmoscopy and treated with specific anti-CMV therapy without delay, in addition to cART.

Deep functional immunophenotyping predicts risk of cytomegalovirus reactivation after hematopoietic cell transplantation

Cytomegalovirus (CMV) is the most common viral infection in hematopoietic cell transplantation (HCT) recipients. We performed deep phenotyping of CMV-specific T cells to predict CMV outcomes following allogeneic HCT. By using 13-color flow cytometry, we studied ex vivo CD8⁺ T-cell cytokine production in response to CMV-pp65 peptides in 3 clinically distinct subgroups of CMV-seropositive HCT patients: (1) Elite Controllers (n = 19): did not have evidence of CMV DNAemia on surveillance testing; (2) Spontaneous Controllers (n = 16): spontaneously resolved low-grade CMV DNAemia without antiviral therapy; and (3) Noncontrollers (NC; n = 21): experienced clinically significant CMV. Two CMV-specific CD8⁺ T-cell functional subsets were strongly associated with risk of CMV: (i) the nonprotective signature (NPS; IL-2^-IFN-γ⁺TNF-α^-MIP-1β⁺), found at increased levels among NC; and (ii) the protective signature (PS; IL-2⁺IFN-γ⁺TNF-α⁺MIP-1β⁺) found at low levels among NC. High levels of the NPS and low levels of PS were associated with an increased 100-day cumulative incidence of clinically significant CMV infection (35% vs 5%; P = .02; and 40% vs 12%; P = .05, respectively). The highest predictive value was observed when these signatures were combined into a composite biomarker consisting of low levels of the PS and high levels of the NPS (67% vs 10%; P < .001). After adjusting for steroid use or donor type, this composite biomarker remained associated with a fivefold increase in the risk of clinically significant CMV infection. CMV-specific CD8⁺ T-cell cytokine signatures with robust predictive value for risk of CMV reactivation should prove useful in guiding clinical decision making in HCT recipients.

Emerging concepts in cytomegalovirus infection following hematopoietic stem cell transplantation

Despite the refinements in molecular methods for the detection of cytomegalovirus (CMV) and the advent of highly effective preemptive strategies, CMV remains a leading cause of morbidity and mortality in hematopoietic cell transplant (HCT) recipients. CMV can cause tissue-invasive disease including pneumonia, hepatitis, colitis, retinitis, and encephalitis. Mortality in HCT recipients with CMV disease can be as high as 60%. CMV infection has been associated with increased risk of secondary bacterial and fungal infections, increased risk of graft-versus-host disease, and high rates of non-relapse mortality following HCT. The risk of CMV is highly dependent on the donor (D) and the recipient (R) serostatus (D^-/R⁺>D⁺/R⁺>D⁺/R^->D^-/R^-). Among allogeneic HCT recipients, high-dose corticosteroids, T-cell depletion, graft-versus-host disease, and mismatched or unrelated donors constitute the main predisposing factors. However, not all seropositive individuals with these risk factors develop CMV, which strongly suggests that host factors, such as those regulating CMV-specific T-cell responses, play a major role in predisposition to CMV in HCT recipients. Here, we discuss emerging concepts in CMV infection in HCT with emphasis on immunological factors that govern CMV reactivation and the applicability of immune monitoring to understand correlates of pathogenesis and its potential to guide clinical decision making.

Cytomegalovirus Retinitis in Patients With Acquired Immunodeficiency Syndrome After Initiating Antiretroviral Therapy

PURPOSE

To evaluate the rates of new-onset cytomegalovirus (CMV) retinitis and worsening existing CMV retinitis in patients with AIDS after initiating combination antiretroviral therapy (cART) and the role of an immune recovery inflammatory syndrome (IRIS).

DESIGN

Cohort study.

METHODS

Immune recovery was defined as an increase in CD4⁺ T cells to ≥100 cells/μL; rates of new-onset CMV retinitis and of worsening of CMV retinitis (either increasing border activity or retinitis progression) were compared between those with and without immune recovery.

RESULTS

Among patients without CMV retinitis, 1 of 75 patients with immune recovery developed CMV retinitis in the first 6 months after initiating cART vs 1 of 31 without immune recovery (P = .14). Among patients with CMV retinitis, the rates of retinitis progression and increasing retinitis border activity among patients during the first 6 months after initiating cART in those with immune recovery were 0.11 per person-year (PY; 95% confidence interval [CI] 0-0.62) and 0.11 per PY (95% CI 0-0.62), respectively, vs 0.67 per PY (95% CI 0.22-1.56) and 0.40 per PY (95% CI 0.08-1.17), respectively, for those without immune recovery (P = .11 and .47).

CONCLUSIONS

Among persons with AIDS who experience immune recovery, there was neither an increased rate of new-onset CMV retinitis nor worsening of existing CMV retinitis in the first 6 months after initiating cART vs those without immune recovery. These data are consistent with the known 3- to 6-month lag in recovery of specific immunity to CMV after initiating cART and suggest that "immune recovery retinitis," a proposed immune recovery inflammatory syndrome phenomenon, is rare.

Cytomegalovirus Infection Leads to Development of High Frequencies of Cytotoxic Virus-Specific CD4+ T Cells Targeted to Vascular Endothelium

Cytomegalovirus (CMV) infection elicits a very strong and sustained intravascular T cell immune response which may contribute towards development of accelerated immune senescence and vascular disease in older people. Virus-specific CD8+ T cell responses have been investigated extensively through the use of HLA-peptide tetramers but much less is known regarding CMV-specific CD4+ T cells. We used a range of HLA class II-peptide tetramers to investigate the phenotypic and transcriptional profile of CMV-specific CD4+ T cells within healthy donors. We show that such cells comprise an average of 0.45% of the CD4+ T cell pool and can reach up to 24% in some individuals (range 0.01–24%). CMV-specific CD4+ T cells display a highly differentiated effector memory phenotype and express a range of cytokines, dominated by dual TNF-α and IFN-γ expression, although substantial populations which express IL-4 were seen in some donors. Microarray analysis and phenotypic expression revealed a profile of unique features. These include the expression of CX3CR1, which would direct cells towards fractalkine on activated endothelium, and the β2-adrenergic receptor, which could permit rapid response to stress. CMV-specific CD4+ T cells display an intense cytotoxic profile with high level expression of granzyme B and perforin, a pattern which increases further during aging. In addition CMV-specific CD4+ T cells demonstrate strong cytotoxic activity against antigen-loaded target cells when isolated directly ex vivo. PD-1 expression is present on 47% of cells but both the intensity and distribution of the inhibitory receptor is reduced in older people. These findings reveal the marked accumulation and unique phenotype of CMV-specific CD4+ T cells and indicate how such T cells may contribute to the vascular complications associated with CMV in older people.

Cytomegalovirus (CMV) is a member of the herpesvirus family and most humans carry chronic CMV infection. This drives the development of large expansions of CD8+ CMV-specific T cells, which increase further during ageing. CMV infection is associated with vascular disease and increased risk of mortality in older people, which may be related to damage from this CMV-specific immune response. Here we used a set of novel reagents called HLA class II tetramers to make a detailed study of CMV-specific CD4+ T cells. We show that CMV-specific CD4+ T cells are found at remarkably high frequencies within blood, representing up to a quarter of all such white cells. In addition they demonstrate a range of unique features. Firstly they carry a chemokine receptor that directs the cells to activated endothelial cells within blood vessels. Secondly, they express epinephrine receptors which would allow them to respond rapidly to stress. Finally, these CD4+ T cells are unique as they are strongly cytotoxic and equipped with the ability to directly kill virally-infected cells. HLA class II tetramers therefore reveal a profile of unique features which provide insight into how CMV-specific CD4+ T cells may be involved in vascular immunopathology.

Long-Term Follow-up of a Cohort of HIV-Infected Patients Who Discontinued Maintenance Therapy for Cytomegalovirus Retinitis

PURPOSE

To determine the long-term safety of discontinuation of maintenance therapy for cytomegalovirus retinitis (CMVR) and to identify predictors for relapse.

METHOD

This was a prospective cohort study. Patients with treated CMVR who responded to HAART were followed by ophthalmologic assessment, markers for CMV replication (blood and urine cultures, CMV antigenemia, CMV DNA by PCR), and in vitro lymphoproliferative responses to CMV and other antigens after discontinuation of CMVR maintenance therapy.

RESULTS

23 patients were followed a median of 34 (range, 5-61) months. Median CD4 count was 321/mm3 at enrollment and 395/mm3 at last follow-up. HIV RNA was <50 copies/mL in 78% of patients at enrollment and 65% at last follow-up. One CMVR reactivation occurred at 12 months at a CD4 count of 395/mm3 (21%) and HIV RNA <50 copies/mL. Urine cultures were a poor predictive marker for reactivation. Other CMV replication markers had good negative predictive value. 96% of patients had a good lymphoproliferative response to CMV antigen in vitro.

CONCLUSION

Maintenance therapy for CMVR can safely be discontinued in patients who have responded to HAART. Combining our results with the published literature, the risk of reactivation is estimated at 0.016 per person year of follow-up. Markers to predict relapse and the need for re-initiation of maintenance therapy are not yet identified.

Chronic retinal necrosis: cytomegalovirus necrotizing retinitis associated with panretinal vasculopathy in non-HIV patients

PURPOSE

To characterize a unique cytomegalovirus (CMV)-associated retinopathy in patients with limited immune dysfunction.

METHODS

Retrospective observational case series. CMV was confirmed as the pathogenic agent via polymerase chain reaction analysis of aqueous or vitreous humor samples or via immunohistochemical analysis of retinal biopsy specimens.

RESULTS

Five non-HIV patients with granular necrotizing retinitis, vitritis, and severe occlusive vasculopathy were identified. Patient histories all suggested a basis for limited immune dysfunction including advanced age (n = 4), diabetes mellitus (n = 4), and noncytotoxic immunotherapy (n = 3). Diagnosis of CMV retinitis was delayed in all cases and patients received either no antiviral therapy (n = 2) or incorrect antiviral therapy (n = 3) for presumed herpes simplex/varicella zoster-related acute retinal necrosis. Retinitis subsequently regressed in all cases with introduction of systemic ganciclovir/valganciclovir (n = 5) and/or intravitreal foscarnet (n = 2). Four of five patients developed neovascularization because of extensive retinal ischemia.

CONCLUSION

The clinical expression of CMV-associated retinopathy is strongly related to immune status. In patients with limited immune dysfunction, a mixed clinical picture of intraocular inflammation with panretinal occlusive vasculopathy, more characteristic of acute retinal necrosis, and peripheral slowly progressive granular retinitis, more characteristic of classic CMV retinitis, is observed. Recognition of this atypical clinical presentation, which the authors term chronic retinal necrosis, should prompt molecular testing for CMV to determine the appropriate antiviral therapy. Consideration should also be given to prophylactic panretinal photocoagulation in such eyes, given the high risk of neovascular complications.

Prevention of HIV-associated opportunistic infections and diseases in the age of highly active antiretroviral therapy

Since the introduction of highly active antiretroviral therapy (HAART), the rates of opportunistic infections have decreased markedly as has overall morbidity and mortality from HIV infection in developed countries. However, opportunistic infections remain the most important cause of death in HIV-infected people due to both late presentation of HIV infections and failure of HAART to adequately restore cell-mediated immunity in all individuals. While prophylaxis may be discontinued in patients who have responded to HAART with sustained increases of their CD4 counts above risk thresholds, for those patients who fail HAART, those who are unable to tolerate it, or whose treatments are interrupted, opportunistic-infection prophylaxis remains essential. Some HIV-associated diseases, such as anogenital human papilloma virus-induced neoplasia and hepatitis C infection, have not decreased in frequency with the advent of HAART. For these conditions, effective screening and treatment programs will be necessary to prevent ongoing morbidity. This review will provide an update on HIV-associated opportunistic infections and their prevention in the age of HAART, as well as discuss novel presentations of opportunistic illnesses, such as immune restoration syndromes.

Restoration of CMV-specific-CD4 T cells with ART occurs early and is greater in those with more advanced immunodeficiency

Objectives

Restoration of Cytomegalovirus-specific-CD4 T cell (CMV-Sp-CD4) responses partly accounts for the reduction of CMV-disease with antiretroviral-therapy (ART), but CMV-Sp-CD4 may also drive immune activation and immunosenescence. This study characterized the dynamics of CMV-Sp-CD4 after ART initiation and explored associations with CD4 T cell recovery as well as frequency of naïve CD4 T cells at week 96.

Methods

Fifty HIV-infected, ART-naïve Thai adults with CD4 T cell count ≤350cells/µL and starting ART were evaluated over 96 weeks (ClinicalTrials.gov identifier NCT01296373). CMV-Sp-CD4 was detected by co-expression of CD25/CD134 by flow cytometry after CMV-antigen stimulation.

Results

All subjects were CMV sero-positive, 4 had quantifiable CMV-DNA (range 2.3-3.9 log₁₀ copies/mL) at baseline but none had clinically apparent CMV-disease. Baseline CMV-Sp-CD4 response was positive in 40 subjects. Those with CD4 T cell count <100cells/µL were less likely to have positive baseline CMV-Sp-CD4 response (P=0.003). Positive baseline CMV-Sp-CD4 response was associated with reduced odds of quantifiable CMV-DNA (P=0.022). Mean CD4 T cell increase at week 96 was 213 cells/µL. This was associated positively with baseline HIV-VL (P=0.001) and negatively with age (P=0.003). The frequency of CMV-Sp-CD4 increased at week 4 (P=0.008), then declined. Those with lower baseline CMV-Sp-CD4 (P=0.009) or CDC category C (P<0.001) had greater increases in CMV-Sp-CD4 at week 4. At week 96, CD4 T cell count was positively (P<0.001) and the frequency of CMV-Sp-CD4 was negatively (P=0.001) associated with the percentage of naïve CD4 T cells.

Conclusions

Increases in CMV-Sp-CD4 with ART occurred early and were greater in those with more advanced immunodeficiency. The frequency of CMV-Sp-CD4 was associated with reduced naïve CD4 T cells, a marker associated with immunosenescence.

Toxoplasma encephalitis in an HIV-infected patient on highly active antiretroviral therapy despite sustained immune response

Toxoplasma encephalitis (TE) is usually diagnosed in advanced stages of HIV infection when the CD4+ count is <100–200 cells/µl. A 55-year-old woman with HIV/AIDS, well controlled on antiretroviral therapy (ART), CD4+ count in the 300 cells/μl range for >1 year presented with acute onset of headache, nausea and vomiting. She had been on her current ART regimen consisting of raltegravir, co-formulated emtricitabine/tenofovir and etravirine for three years and had been off Pneumocystis prophylaxis for 10 months (trimethoprim-sulfamethoxazole). Brain MRI showed multiple ring-enhancing, supratentorial and infra-tentorial parenchymal lesions suspicious for metastases. She had no other evidence of metastatic disease in her body. The possibilities of TE and primary CNS lymphoma were considered but deemed unlikely given the high CD4+ count. A brain biopsy demonstrated Toxoplasma tachyzoites. There was no evidence of lymphoma or carcinoma. Anti-toxoplasma treatment yielded good initial clinical and radiographic responses. While on TE maintenance therapy, she developed similar symptoms. Repeat MRI showed progression of lesions. Further work-up including CSF Epstein-Barr virus PCR and SPECT Th 201 imaging was not conclusive for CNS lymphoma. The patient’s clinical condition deteriorated and she died. We postulate that functional immunological dysfunction is a possible mechanism by which our patient developed TE despite demonstrating sustained immune response on ART.

CD4 T cell responses in latent and chronic viral infections

The spectrum of tasks which is fulfilled by CD4 T cells in the setting of viral infections is large, ranging from support of CD8 T cells and humoral immunity to exertion of direct antiviral effector functions. While our knowledge about the differentiation pathways, plasticity, and memory of CD4 T cell responses upon acute infections or immunizations has significantly increased during the past years, much less is still known about CD4 T cell differentiation and their beneficial or pathological functions during persistent viral infections. In this review we summarize current knowledge about the differentiation, direct or indirect antiviral effector functions, and the regulation of virus-specific CD4 T cells in the setting of persistent latent or active chronic viral infections with a particular emphasis on herpes virus infections for the former and chronic lymphocytic choriomeningitis virus infection for the latter.

Peptide library-based evaluation of T-cell receptor breadth detects defects in global and regulatory activation in human immunologic diseases

The ability of T-cells to respond to foreign antigens and to appropriately regulate this response is crucial for maintaining immune homeostasis. Using combinatorial peptide libraries, we functionally measured broad T-cell reactivity and observed impaired reactivity in established models of T-cell receptor repertoire restriction and in previously unrecognized disease contexts. By concurrently analyzing T-regulatory and T-effector cells, we show strong functional correlation between these subsets in healthy individuals and, strikingly, that alterations of this balance are associated with T helper type 2 (Th2)-mediated disease in a lymphopenic setting. Finally, we demonstrate that peptide-based priming of polyclonal naive cells with relatively low concentrations skews toward Th2 differentiation. These findings provide unique insight into the pathophysiology and functional consequences of abnormal T-cell repertoires and into differentiation of human naive T-cells.

MEK inhibitors selectively suppress alloreactivity and graft-versus-host disease in a memory stage-dependent manner

Immunosuppressive strategies currently used in hematopoietic stem cell transplantation reliably decrease graft-versus-host disease (GVHD) rates, but also impair pathogen-specific immunity. Experimental transplant studies indicate that GVHD-initiating alloreactive T cells reside primarily in naive and central memory T-cell compartments. In contrast, virus-specific T cells comprise a more differentiated memory population. After finding that the rat sarcoma/mitogen-activated protein kinase kinase/extracellular receptor kinase (RAS/MEK/ERK) pathway is preferentially activated in naive and central memory human T cells, we hypothesized that MEK inhibitors would preferentially inhibit alloreactive T cells, while sparing more differentiated virus-specific T cells. Confirming our hypothesis, we found that MEK inhibitors including selumetinib preferentially inhibited cytokine production and alloreactivity mediated by naive and central memory human CD4(+) and CD8(+) T cells while sparing more differentiated T cells specific for the human herpesviruses cytomegalovirus and Epstein-Barr virus. We then demonstrated that short-term posttransplant administration of selumetinib in a major histocompatibility complex major- and minor-mismatched murine model significantly delayed the onset of GVHD-associated mortality without compromising myeloid engraftment, demonstrating the in vivo potential of MEK inhibitors in the setting of hematopoietic stem cell transplantation. These findings demonstrate that targeting memory-dependent differences in T-cell signaling is a potent and selective approach to inhibition of alloreactivity.

Interaction between HIV and Mycobacterium tuberculosis: HIV-1-induced CD4 T-cell depletion and the development of active tuberculosis

PURPOSE OF REVIEW

HIV infection is the main driver of the HIV/tuberculosis (TB) syndemic in southern Africa since the early 1990s, when HIV infection rates started to increase exponentially and TB incidence rates quadruplet simultaneously. Here, we discuss pathogenic mechanisms of HIV-induced CD4 T-cell depletion and their potential impact on immune control of Mycobacterium tuberculosis.

RECENT FINDINGS

Depletion of effector memory CD4 T cells from the air-tissue interphase, their dysfunctional regeneration and the preferential depletion of MTB-specific CD4 T cells from circulation and from the air-tissue interphase might be key factors for the increased susceptibility to develop active TB after HIV infection.

SUMMARY

Early initiation of antiretroviral therapy or the development of an efficacious HIV vaccine would be the best options to reduce morbidity and mortality associated with the HIV/TB syndemic.

Incidence of cytomegalovirus retinitis in the era of highly active antiretroviral therapy

PURPOSE

To estimate the incidence of cytomegalovirus (CMV) retinitis in the era of highly active antiretroviral therapy (HAART) and to characterize the factors associated with increased risk of CMV retinitis.

DESIGN

Prospective cohort study.

METHODS

A total of 1600 participants with acquired immunodeficiency syndrome (AIDS) but without CMV retinitis at enrollment who completed at least 1 follow-up visit in the Longitudinal Study of the Ocular Complications of AIDS (LSOCA) were seen every 6 months to obtain disease and treatment history, ophthalmic examination, and laboratory testing. Incidence of CMV retinitis and risk factors for incident CMV retinitis were assessed.

RESULTS

The incidence rate of CMV retinitis in individuals with AIDS was 0.36/100 person-years (PY) based upon 29 incident cases during 8134 PY of follow-up. The rate was higher for those with a CD4+ T cell count at the immediately prior visit below 50 cells/μL (3.89/100 PY, P < .01), whereas only 1 individual with a CD4+ T cell count of 50 to 99 cells/μL and 2 individuals with a CD4+ T cell count >100 cells/μL developed CMV retinitis. Having a CD4+ T cell count below 50 cells/μL at the clinical visit prior to CMV retinitis evaluation was the single most important risk factor (HR: 136, 95% CI: 30 to 605, P < .0001) for developing retinitis.

CONCLUSIONS

Patients with AIDS, especially those with severely compromised immune systems, remain at risk for developing CMV retinitis in the HAART era, although the incidence rate is reduced from that observed in the pre-HAART era.

Ocular manifestations of acquired immunodeficiency syndrome in Korea

The clinical features of HIV/AIDS-related ocular manifestations in Korean patients were investigated in this study. Data on 200 consecutive Korean patients diagnosed with AIDS who visited the Seoul National University Hospital from January 2003 to June 2008 were reviewed. Fifty-seven patients (28.5%) had ocular manifestations, and they showed significantly lower CD4+ T cell count than patients without ocular manifestations. Among them, 23 (40.3%) patients showed retinal microvasculopathy, and 22 (38.5%) patients showed cytomegalovirus (CMV) retinitis. Other manifestations included retinal vein occlusion (n = 4), herpes zoster ophthalmicus (n = 4), syphilitic uveitis (n = 2), acute retinal necrosis (n = 1), and progressive outer retinal necrosis (n = 1). The mean CD4+ lymphocyte counts of the patients with retinal microvasculopathy and cytomegalovirus retinitis were 108.5 cells/µL and 69.4 cells/µL, respectively. In conclusion, ocular manifestations including CMV retinitis are common complications in Korean patients with AIDS even in the era of highly active anti-retroviral therapy. Compared to previous reports in western countries, prevalence of CMV retinitis is relatively low and CD4+ lymphocytes count at the time of diagnosis is relatively high.

Pathogen-specific T cell depletion and reactivation of opportunistic pathogens in HIV infection

During HIV infection, it is unclear why different opportunistic pathogens cause disease at different CD4 T cell count thresholds. Early work has shown that CD4 T cell depletion is influenced both by cellular activation status and expression of viral entry receptors. More recently, functional characteristics of the CD4 T cells, such as cytokine and chemokine production, have also been shown to influence cellular susceptibility to HIV. Here, we examine how functional differences in pathogen-specific CD4 T cells could lead to their differential loss during HIV infection. This may have implications for when different opportunistic infections occur, and a better understanding of the mechanisms for functional imprinting of antigen-specific T cells may lead to improvements in design of vaccines against HIV and opportunistic pathogens.

Blood T-cell receptor diversity decreases during the course of HIV infection, but the potential for a diverse repertoire persists

HIV infection results in a decrease in circulating CD4(+) T-cell and naive T-cell numbers. If such losses were associated with an erosion of T-cell receptor (TCR) repertoire diversity in the peripheral T-cell pool, this might exacerbate the state of persistent immunodeficiency. Existing methods for the analysis of the TCR repertoire have demonstrated skewed distributions of TCR genes in HIV-infected subjects but cannot directly measure TCR diversity. Here we used AmpliCot, a quantitative assay based on DNA hybridization kinetics, to measure TCR diversity in a cross-sectional comparison of 19 HIV-infected persons to 18 HIV-uninfected controls. HIV-infected persons had a 10-fold decrease in total TCR repertoire diversity in 1.5 mL of blood compared with uninfected controls, with decreased diversity correlating most closely with a lower CD4(+) T-cell percentage. Nonetheless, the TCR repertoire diversity of sort-purified T-cell subpopulations in HIV-infected and HIV-uninfected subjects was comparable. These observations suggest that the TCR repertoire diversity changes in whole blood during HIV disease progression are primarily the result of changes in the number and proportion of T-cell subpopulations and that most HIV-infected persons may retain a sufficiently diverse TCR repertoire to permit immune reconstitution with antiretroviral therapy alone, without thymopoiesis.

Association of host genetic risk factors with the course of cytomegalovirus retinitis in patients infected with human immunodeficiency virus

PURPOSE

To evaluate the effects of previously reported host genetics factors that influence cytomegalovirus (CMV) retinitis incidence, progression to acquired immune deficiency syndrome (AIDS), and efficacy of highly active antiretroviral therapy (HAART) for mortality, retinitis progression, and retinal detachment in patients with CMV retinitis and AIDS in the era of HAART.

DESIGN

Prospective, multicenter, observational study.

METHODS

Cox proportional hazards model based genetic association tests examined the influence of IL-10R1_S420L, CCR5-Δ32, CCR2-V64I, CCR5 promoter, and SDF-3'A polymorphisms among patients with mortality, retinitis progression, and retinal detachment. Participants were 203 European-American and 117 African-American patients with AIDS and CMV retinitis.

RESULTS

European-American patients with the CCR5 +.P1.+ promoter haplotype showed increased risk for mortality (hazard ratio [HR] = 1.83; 95% confidence interval [CI]: 1.00-3.40; P = .05). Although the same haplotype also trended for increased risk for mortality in African-American patients, the result was not significant (HR = 2.28; 95% CI: 0.93-5.60; P = .07). However, this haplotype was associated with faster retinitis progression in African Americans (HR = 5.22; 95% CI: 1.54-17.71; P = .007). Increased risk of retinitis progression was also evident for African-American patients with the SDF1-3'A variant (HR = 3.89; 95% CI: 1.42-10.60; P = .008). In addition, the SDF1-3'A variant increased the retinal detachment risk in this patient group (HR = 3.05; 95% CI: 1.01-9.16; P = .05).

CONCLUSION

Besides overall immune health, host genetic factors influence mortality, retinitis progression, and retinal detachment in patients with AIDS and CMV retinitis that are receiving HAART.

Cytomegalovirus retinitis and the acquired immunodeficiency syndrome--bench to bedside: LXVII Edward Jackson Memorial Lecture

PURPOSE

To update information on cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS) and to integrate information on its pathogenesis and clinical outcomes.

DESIGN

Literature review.

METHODS

Selected articles from the medical literature, particularly large epidemiologic studies, including the Johns Hopkins Cytomegalovirus Retinitis Cohort Study, the Longitudinal Study of the Ocular Complications of AIDS, and the Cytomegalovirus Retinitis and Viral Resistance Study, were reviewed. Clinical information is discussed in light of knowledge on CMV, its pathogenesis, and its interactions with human immunodeficiency virus (HIV).

RESULTS

Cytomegalovirus uses several mechanisms to evade the immune system and establish latent infection in immunologically normal hosts. With immune deficiency, such as late-stage AIDS, CMV reactivates, is disseminated to the eye, and establishes a productive infection, resulting in retinal necrosis. HIV and CMV potentiate each other: CMV accelerates HIV disease, and CMV retinitis is associated with increased mortality. Randomized clinical trials have demonstrated the efficacy of treatments for CMV retinitis. Systemically administered treatment for CMV retinitis decreases AIDS mortality. Highly active antiretroviral therapy (HAART) effectively suppresses HIV replication, resulting in immune recovery, which, if sufficient, controls retinitis without anti-CMV therapy. Resistant CMV, detected in the blood, correlates with resistant virus in the eye and is associated with worse clinical outcomes, including mortality. Host factors, including host genetics and access to care, play a role in the development of CMV retinitis.

CONCLUSIONS

Clinical outcomes of CMV retinitis in patients with AIDS are dependent on characteristics of the virus and host and on HIV-CMV interactions.

Effect of nucleoside and nucleotide analog reverse transcriptase inhibitors on cell-mediated immune functions

Nucleoside analog reverse transcriptase inhibitors (NRTIs) constitute the most commonly used drugs in antiretroviral therapy. NRTIs differ with respect to their host cell toxicity. We compared the in vitro effect of zidovudine (AZT; 2 μg/ml), lamivudine (3TC; 5 μg/ml), stavudine (d4T; 1 μg/ml), and tenofovir (TFV; 1 μg/ml) on Candida cell-mediated immunity (CMI) of peripheral blood mononuclear cells (PBMCs). The concentrations of the active derivative AZT-triphosphate were 4-fold higher in Candida-stimulated compared with unstimulated PBMCs (p = 0.01), but those of 3TC-triphosphate and TFV-diphosphate did not differ significantly. AZT treatment decreased proliferation of unstimulated and Candida-stimulated PBMCs and IFN-γ ELISPOT responses; 3TC decreased proliferation of unstimulated PBMCs only; d4T and TFV decreased proliferation of Candida-stimulated PBMCs only. AZT, but not the other NRTIs, increased unstimulated PBMC apoptosis measured by caspase 3 activity. All NRTIs increased annexin-V-measured apoptosis of Candida-stimulated PBMCs. The effect of d4T on apoptosis of Candida-stimulated PBMCs strongly correlated with its inhibitory effect on mitochondrial DNA synthesis (r² = 0.94; p = 0.007). The other NRTIs did not significantly decrease the mitochondrial:nuclear DNA ratios in Candida-stimulated or unstimulated cultures, suggesting that other mechanisms mediated their effect on apoptosis and CMI. In conclusion, AZT had the most pronounced inhibitory effect on CMI. Further studies are warranted to determine the clinical significance of this observation.

Preferential infection and depletion of Mycobacterium tuberculosis-specific CD4 T cells after HIV-1 infection

HIV-1 preferentially infects M. tuberculosis-specific CD4+ T cells due to their increased production of IL-2.

HIV-1 infection results in the progressive loss of CD4 T cells. In this study, we address how different pathogen-specific CD4 T cells are affected by HIV infection and the cellular parameters involved. We found striking differences in the depletion rates between CD4 T cells to two common opportunistic pathogens, cytomegalovirus (CMV) and Mycobacterium tuberculosis (MTB). CMV-specific CD4 T cells persisted after HIV infection, whereas MTB-specific CD4 T cells were depleted rapidly. CMV-specific CD4 T cells expressed a mature phenotype and produced very little IL-2, but large amounts of MIP-1β. In contrast, MTB-specific CD4 T cells were less mature, and most produced IL-2 but not MIP-1β. Staphylococcal enterotoxin B–stimulated IL-2–producing cells were more susceptible to HIV infection in vitro than MIP-1β–producing cells. Moreover, IL-2 production was associated with expression of CD25, and neutralization of IL-2 completely abrogated productive HIV infection in vitro. HIV DNA was found to be most abundant in IL-2–producing cells, and least abundant in MIP-1β–producing MTB-specific CD4 T cells from HIV-infected subjects with active tuberculosis. These data support the hypothesis that differences in function affect the susceptibility of pathogen-specific CD4 T cells to HIV infection and depletion in vivo, providing a potential mechanism to explain the rapid loss of MTB-specific CD4 T cells after HIV infection.

Effect of host genetics on the development of cytomegalovirus retinitis in patients with AIDS

BACKGROUND

Cytomegalovirus (CMV) retinitis is a common opportunistic infection among patients with AIDS and still causes visual morbidity despite the wide spread usage of highly active antiretroviral therapy (HAART). The ubiquitous CMV pathogen contains a human interleukin-10 (IL-10) homolog in its genome and utilizes it to evade host immune reactions through an IL-10 receptor mediated immune-suppression pathway.

METHODS

Effects of IL-10R1, IL-10 and previously described AIDS restriction gene variants are investigated on the development of CMV retinitis in the Longitudinal Study of the Ocular Complications of AIDS (LSOCA) cohort (N = 1284).

RESULTS

In European Americans (n = 750), a haplotype carrying an amino acid changing variation in the cytoplasmic domain (S420L) of IL-10R1 can be protective (OR, 0.14; 95% CI, 0.02-0.94; P = .04) against, whereas another haplotype carrying an amino acid changing variation in the extracellular domain (I224V) of IL-10R1 can be more susceptible (OR, 6.21; 95% CI, 1.22- 31.54; P = .03) to CMV retinitis. In African Americans (n = 534), potential effects of IL-10 variants are observed.

CONCLUSION

Host genetics may have a role in the occurrence of CMV retinitis in patients infected with HIV.

Course of cytomegalovirus retinitis in the era of highly active antiretroviral therapy: five-year outcomes

PURPOSE

To describe the 5-year outcomes of patients with cytomegalovirus (CMV) retinitis and AIDS in the era of highly active antiretroviral therapy (HAART).

DESIGN

Prospective, multicenter, observational study.

PARTICIPANTS

A total of 503 patients with AIDS and CMV retinitis.

METHODS

Follow-up every 3 months with medical history, ophthalmologic examination, laboratory testing, and retinal photographs. Participants were classified as having previously diagnosed CMV retinitis and immune recovery (CD4+ T cells ≥ 100 cells/μl), previously diagnosed retinitis and immune compromise, and newly diagnosed CMV retinitis (diagnosis <45 days before enrollment).

MAIN OUTCOME MEASURES

Mortality, retinitis progression (movement of the border of a CMV lesion ≥ ½ disc diameter or occurrence of a new lesion), retinal detachment, immune recovery uveitis (IRU), and visual loss (< 20/40 and ≥ 20/200).

RESULTS

Overall mortality was 9.8 deaths/100 person-years (PY). Rates varied by group at enrollment from 3.0/100 PY for those with previously diagnosed retinitis and immune recovery to 26.1/100 PY for those with newly diagnosed retinitis. The rate of retinitis progression was 7.0/100 PY and varied from 1.4/100 PY for those with previously diagnosed retinitis and immune recovery to 28.0/100 PY for those with newly diagnosed retinitis. The rate of retinal detachment was 2.3/100 eye-years (EY) and varied from 1.2/100 EY for those with previously diagnosed retinitis and immune recovery to 4.9/100 EY for those with newly diagnosed retinitis. The rate of IRU was 1.7/100 PY and varied from 1.3/100 PY for those with previously diagnosed retinitis and immune recovery at enrollment to 3.6/100 PY for those with newly diagnosed retinitis who subsequently experienced immune recovery. The rates of visual loss to < 20/40 and to ≤ 20/200 were 7.9/100 EY and 3.4/100 EY, respectively; they varied from 6.1/100 EY and 2.7/100 EY for those with previously diagnosed retinitis and immune recovery to 11.8/100 EY and 5.1/100 EY for those with newly diagnosed retinitis. Although the event rates tended to decline with time, in general, at no time did they reach zero.

CONCLUSIONS

Despite the availability of HAART, patients with AIDS and CMV retinitis remain at increased risk for mortality, retinitis progression, complications of the retinitis, and visual loss over a 5-year period.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Treatment with recombinant growth hormone is associated with modest improvement in CD4 lymphocyte reconstitution in HIV-infected persons on antiretroviral therapy: results of ACTG A5174

Pilot studies have suggested that treatment with recombinant human growth hormone (rhGH) is associated with increased T-lymphocyte restoration and enhanced thymic output. We evaluated the immunologic effects of rhGH on HIV(+) subjects with incomplete immune reconstitution on antiretroviral therapy (ART). Sixty subjects were randomized to receive rhGH 1.5 mg scqd and ART for 48 weeks (Arm A) or continue ART alone for 24 weeks then add rhGH 3.0 mg scqd for 24 weeks (Arm B). Median baseline CD4 for Arms A and B were 223 and 219, respectively. There was little difference between Arm A and Arm B in change in total or naive CD4 cells or percentage from baseline to week 24. Only one subject in Arm A met the primary endpoint, an increase in naive CD4 percentage of at least 10 percentage points. By week 48 both Arms had statistically significant increases in naive CD4 cell count and percentage and thymus size. Within Arm B, treatment with rhGH was associated with significant increases in naive CD4(+) cell count and percentage compared with ART alone. Treatment with rhGH +ART may be associated with modest increases in CD4 lymphocytes over ART alone in subjects with CD4 <350, yet the origin of these naive cells and their impact on immune function require further investigation.

Co-engagement of alpha(4)beta(1) integrin (VLA-4) and CD4 or CD8 is necessary to induce maximal Erk1/2 phosphorylation and cytokine production in human T cells

The alpha(4)beta(1) integrin VLA-4 (very-late activation antigen-4) and the lineage-specific CD4 and CD8 receptors have been proposed as putative co-stimulatory receptors on T cells. To assess the relative contribution of signaling through the TCR, CD28 and these accessory molecules, we activated human T cells using soluble antibodies recognizing all four of these T-cell receptor classes (CD3, CD28, CD4/CD8, and VLA-4), and we assessed the degree of activation using higher-order flow cytometry detecting intracellular Erk1/2 phosphorylation and production of IL-2 and IFN-gamma. We found that: (1) co-stimulation via CD4/CD8, in addition to CD28, is required for optimal T-cell activation; (2) VLA-4 binding consistently potentiates CD4(+) and CD8(+) T-cell activation; (3) augmentation of T-cell activation through VLA-4 binding is most pronounced following engagement of CD4/CD8. These results confirm that multiple signals, including VLA-4 engagement, are necessary for maximal T-cell activation beyond that induced via the TCR and CD28.

Autocrine production of beta-chemokines protects CMV-Specific CD4 T cells from HIV infection

Induction of a functional subset of HIV-specific CD4⁺ T cells that is resistant to HIV infection could enhance immune protection and decrease the rate of HIV disease progression. CMV-specific CD4⁺ T cells, which are less frequently infected than HIV-specific CD4⁺ T cells, are a model for such an effect. To determine the mechanism of this protection, we compared the functional response of HIV gag-specific and CMV pp65-specific CD4⁺ T cells in individuals co-infected with CMV and HIV. We found that CMV-specific CD4⁺ T cells rapidly up-regulated production of MIP-1α and MIP-1β mRNA, resulting in a rapid increase in production of MIP-1α and MIP-1β after cognate antigen stimulation. Production of β-chemokines was associated with maturational phenotype and was rarely seen in HIV-specific CD4⁺ T cells. To test whether production of β-chemokines by CD4⁺ T cells lowers their susceptibility to HIV infection, we measured cell-associated Gag DNA to assess the in vivo infection history of CMV-specific CD4⁺ T cells. We found that CMV-specific CD4⁺ T cells which produced MIP-1β contained 10 times less Gag DNA than did those which failed to produce MIP-1β. These data suggest that CD4⁺ T cells which produce MIP-1α and MIP-1β bind these chemokines in an autocrine fashion which decreases the risk of in vivo HIV infection.

HIV infection results in a significant loss of CD4⁺ T cells, particularly HIV-specific CD4⁺ T cells. In contrast to this, CMV-specific CD4⁺ T cells persist in large numbers, even in individuals with AIDS. We compared the functional profile of HIV-specific and CMV-specific CD4⁺ T cells and found that unlike HIV-specific CD4⁺ T cells, CMV-specific CD4⁺ T cells rapidly produce MIP-1β when stimulated with cognate antigen. CMV specific CD4⁺ T cells also produce another β chemokine when stimulated with cognate antigen, MIP-1α. Addition of both of these chemokines to in vitro incubations protects CD4⁺ T cells from HIV infection. To determine if the production of these two chemokines could protect the CD4⁺ T cells that produce them in vivo, we analyzed peripheral blood cells from HIV infected individuals and separated CMV-specific CD4⁺ T cells that produced MIP-1β from CMV-specific CD4⁺ T cells that did not. We found that cells that produced MIP-1β were less frequently infected with HIV than those that did not produce MIP-1β. These data, and recent advances in vaccine design, suggest that it may be possible to design a vaccine in which vaccine-induced HIV-specific CD4⁺ T cells are less susceptible to infection than those usually produced during HIV infection.

Immune recovery uveitis associated with highly active antiretroviral therapy in a patient with CMV retinitis and AIDS despite a low CD4+ T cell count: case report and a review of the literature

An unusual case of CMV retinitis and AIDS who developed immune recovery uveitis (IRU) despite a low CD4+ T cell count achieved during HAART is reported. A 36-year-old female complained of blurred vision in both eyes six months after initiation of anti-CMV retinitis therapy and HAART. Ocular examination revealed a substantial intraocular inflammation causing a dense vitreous haze and frosted branch angiitis. Consecutive CD4+ T cell counts were 20 cells/mm(3) or less and plasma HIV mRNA was undetectable. The laboratory test for Cytomegalovirus was positive whereas those for infections known to cause uveitis were negative. The inflammatory reaction resolved with treatment, but she developed retinal detachment just before she died of pulmonary complications. A review of the literature led us to propose that our patient developed an intraocular inflammation which may probably be a form of IRU and it might be appropriate to employ additional criteria in the definition and the diagnosis of IRU.

Restoration of Toxoplasma gondii-specific immune responses in patients with AIDS starting HAART

OBJECTIVE

To study the kinetics and identify factors associated with Toxoplasma-specific immune responses in patients with AIDS starting antiretroviral therapy.

METHODS

A prospective study of 38 HIV-infected patients seropositive for Toxoplasma who started antiretroviral therapy with CD4 T cells less than 200 cells/microl. T-cell and B-cell phenotypes, anti-Toxoplasma antibodies titers, Th-1 and Th-2 cytokine production and lymphocyte proliferative responses (LPRs) to Toxoplasma were assessed over 12 months.

RESULTS

Median CD4 cell count increased from 122 cells/microl at baseline to 260 cells/microl at 12 months, and the incidence of a positive LPR from 18.4 to 70.5%. A Toxoplasma IgG titer more than 150 IU/ml was the only baseline variable associated with a positive LPR (hazard ratio: 4.6, P = 0.003). Among time-dependent covariates, the number of effector memory (CD45RA-CCR7-) CD4 T cells was associated with a positive LPR (P < 0.02) and the number of terminally differentiated (CD45RA+CCR7-) CD8 T cells was associated with in-vitro production of gamma-IFN (P < 0.008).

CONCLUSION

Among patients with low CD4 cell counts, high anti-Toxoplasma IgG titers were associated with LPR to Toxoplasma antigen. After starting antiretroviral therapy, the number of effector memory CD4 T cells and terminally differentiated CD8 T cells were associated with the restoration of Toxoplasma LPR and gamma-IFN production, respectively.

Manifestations of human cytomegalovirus infection: proposed mechanisms of acute and chronic disease

Infections with human cytomegalovirus (HCMV) are a major cause of morbidity and mortality in humans with acquired or developmental deficits in innate and adaptive immunity. In the normal immunocompetent host, symptoms rarely accompany acute infections, although prolonged virus shedding is frequent. Virus persistence is established in all infected individuals and appears to be maintained by both a chronic productive infections as well as latency with restricted viral gene expression. The contributions of the each of these mechanisms to the persistence of this virus in the individual is unknown but frequent virus shedding into the saliva and genitourinary tract likely accounts for the near universal incidence of infection in most populations in the world. The pathogenesis of disease associated with acute HCMV infection is most readily attributable to lytic virus replication and end organ damage either secondary to virus replication and cell death or from host immunological responses that target virus-infected cells. Antiviral agents limit the severity of disease associated with acute HCMV infections, suggesting a requirement for virus replication in clinical syndromes associated with acute infection. End organ disease secondary to unchecked virus replication can be observed in infants infected in utero, allograft recipients receiving potent immunosuppressive agents, and patients with HIV infections that exhibit a loss of adaptive immune function. In contrast, diseases associated with chronic or persistent infections appear in normal individuals and in the allografts of the transplant recipient. The manifestations of these infections appear related to chronic inflammation, but it is unclear if poorly controlled virus replication is necessary for the different phenotypic expressions of disease that are reported in these patients. Although the relationship between HCMV infection and chronic allograft rejection is well known, the mechanisms that account for the role of this virus in graft loss are not well understood. However, the capacity of this virus to persist in the midst of intense inflammation suggests that its persistence could serve as a trigger for the induction of host-vs-graft responses or alternatively host responses to HCMV could contribute to the inflammatory milieu characteristic of chronic allograft rejection.

CD8+ T lymphocytes control murine cytomegalovirus replication in the central nervous system of newborn animals

Human CMV infection of the neonatal CNS results in long-term neurologic sequelae. To define the pathogenesis of fetal human CMV CNS infections, we investigated mechanisms of virus clearance from the CNS of neonatal BALB/c mice infected with murine CMV (MCMV). Virus titers peaked in the CNS between postnatal days 10-14 and infectious virus was undetectable by postnatal day 21. Congruent with virus clearance was the recruitment of CD8(+) T cells into the CNS. Depletion of CD8(+) T cells resulted in death by postnatal day 15 in MCMV-infected animals and increased viral loads in the liver, spleen, and the CNS, suggesting an important role for these cells in the control of MCMV replication in the newborn brain. Examination of brain mononuclear cells revealed that CD8(+) T cell infiltrates expressed high levels of CD69, CD44, and CD49d. IE1(168)-specific CD8(+) T cells accumulated in the CNS and produced IFN-gamma and TNF-alpha but not IL-2 following peptide stimulation. Moreover, adoptive transfer of brain mononuclear cells resulted in decreased virus burden in immunodepleted MCMV-infected syngeneic mice. Depletion of the CD8(+) cell population following transfer eliminated control of virus replication. In summary, these results show that functionally mature virus-specific CD8(+) T cells are recruited to the CNS in mice infected with MCMV as neonates.

In vitro cell-mediated immune responses of human immunodeficiency virus-infected and -uninfected individuals to whole cytomegalovirus antigens and their subunits

The aim of this study was to optimize the ability to detect cytomegalovirus (CMV)-specfic cell-mediated immunity (CMI) in human immunodeficiency virus (HIV)-infected individuals by comparing different assays (the lymphocyte proliferation assay [LPA] and assays for gamma interferon [IFN-gamma] and interleukin-2 [IL-2] production) and CMV antigenic preparations. Thresholds discriminating positive from negative CMI results were developed with specimens from 36 CMV-seropositive and 21 CMV-seronegative healthy individuals. The analysis showed that the CMI elicited by any of the four CMV whole lysates tested in this study tended to be more robust and sensitive than the responses to the subunit antigens gB and pp65. LPA and inducible IFN-gamma but not IL-2 were highly sensitive measures of CMV-specific CMI in HIV-infected and -uninfected individuals. The ability to detect CMV-specific LPA or IFN-gamma responses in HIV-infected individuals significantly increased with higher CD4 cell numbers. Nevertheless, the proportion of HIV-infected subjects with CD4 counts of >or=500 cells/mul who had a detectable CMV-specific CMI remained significantly lower than that of healthy adults. The ability to detect CMV-specific CMI in HIV-infected individuals decreased with higher levels of HIV replication, with discriminative thresholds of 10(3) to 10(4) HIV RNA copies/ml of plasma, for LPA or inducible IFN-gamma production elicited by different antigens. The LPA responses obtained with CMV whole lysate and phytohemagglutinin were significantly correlated in HIV-infected subjects but not uninfected controls, indicating a novel characteristic of the CMI defect caused by HIV. The intrasubject variabilities of the CMV-specific CMI were similar in HIV-infected and -uninfected individuals. These data show that LPA and the inducible IFN-gamma production elicited by CMV whole lysates may be used to assess modifications of the immune competency of HIV-infected individuals.

Distinctive in vitro effects of T-cell growth cytokines on cytomegalovirus-stimulated T-cell responses of HIV-infected HAART recipients

Functional immune reconstitution is limited after HAART, maintaining the interest in adjunctive immune-modulators. We compared in vitro the effects of the gamma-chain T-cell growth cytokines IL-2, IL-4, IL-7 and IL-15 on cytomegalovirus-stimulated cell-mediated immunity. IL-2 and IL-15 increased cytomegalovirus-specific lymphocyte proliferation in HAART recipients, whereas IL-4 and IL-7 did not. The boosting effect of IL-2 and IL-15 on proliferation correlated with their ability to prevent late apoptosis. However, IL-2 increased the frequency of cells in early apoptosis, whereas IL-15 increased the frequency of fully viable cells. Both IL-2 and IL-15 increased cytomegalovirus-induced CD4+ and CD8+ T-cell proliferation and the synthesis of Th1 and pro-inflammatory cytokines and chemokines. However, only IL-2 increased the frequency of regulatory T cells and Th2 cytokine production, both of which have the potential to attenuate antiviral immune responses. Overall, compared to other gamma-chain cytokines, IL-15 had the most favorable profile for boosting antiviral cell-mediated immunity.

Growth hormone enhances thymic function in HIV-1-infected adults

Growth hormone (GH) is an underappreciated but important regulator of T cell development that can reverse age-related declines in thymopoiesis in rodents. Here, we report findings of a prospective randomized study examining the effects of GH on the immune system of HIV-1-infected adults. GH treatment was associated with increased thymic mass. In addition, GH treatment enhanced thymic output, as measured by both the frequency of T cell receptor rearrangement excision circles in circulating T cells and the numbers of circulating naive and total CD4(+) T cells. These findings provide compelling evidence that GH induces de novo T cell production and may, accordingly, facilitate CD4(+) T cell recovery in HIV-1-infected adults. Further, these randomized, prospective data have shown that thymic involution can be pharmacologically reversed in humans, suggesting that immune-based therapies could be used to enhance thymopoiesis in immunodeficient individuals.

Delayed immune reconstitution after cord blood transplantation is characterized by impaired thymopoiesis and late memory T-cell skewing

Advances in immune assessment, including the development of T-cell receptor excision circle (TREC) assays of thymopoiesis, cytokine-flow cytometry assays of T-cell function, and higher-order phenotyping of T-cell maturation subsets have improved our understanding of T-cell homeostasis. Limited data exist using these methods to characterize immune recovery in adult cord blood (CB) transplant recipients, in whom infection is a leading cause of mortality. We now report the results of a single-center prospective study of T-cell immune recovery after cord blood transplantation (CBT) in a predominantly adult population. Our primary findings include the following: (1) Prolonged T lymphopenia and compensatory expansion of B and natural killer (NK) cells was evident; (2) CB transplant recipients had impaired functional recovery, although we did observe posttransplantation de novo T-cell responses to cytomegalovirus (CMV) in a subset of patients; (3) Thymopoietic failure characterized post-CBT immune reconstitution, in marked contrast to results in other transplant recipients; and (4) Thymopoietic failure was associated with late memory T-cell skewing. Our data suggest that efforts to improve outcomes in adult CB transplant recipients should be aimed at optimizing T-cell immune recovery. Strategies that improve the engraftment of lymphoid precursors, protect the thymus during pretransplant conditioning, and/or augment the recovery of thymopoiesis may improve outcomes after CBT.

Evolving characteristics of toxoplasmosis in patients infected with human immunodeficiency virus-1: clinical course and Toxoplasma gondii-specific immune responses

Toxoplasmic encephalitis (TE) is the most important opportunistic infection of the central nervous system in patients infected with human immunodeficiency virus (HIV)-1. This study evaluated the effect of highly active anti-retroviral therapy (HAART) and Toxoplasma gondii-specific immune responses on the occurrence of TE. The clinical characteristics of all patients diagnosed with TE in two centres since 1990 (n = 140) were analysed. Patients were grouped according to the date of diagnosis (period 1, 1990-1993; period 2, 1994-1996; period 3, 1997 onwards). Immune responses to T. gondii were evaluated in a subgroup (n = 12) by interferon (IFN)-gamma-specific ELISPOT tests. There were marked differences in the estimated Kaplan-Meier overall survival (OS), with a 1-year OS (5-year OS) of 41% (7%) in period 1, 56% (29%) in period 2, and 90% (78%) in period 3 (p <0.0001). In period 3, TE was found to be the first AIDS-defining illness more frequently than in earlier periods (74% vs. 38%, p 0.0002). Persistent neurological deficits caused by TE were present in 37% of the patients. Patients with an acute episode of TE or a TE relapse had significantly lower responses in the T. gondii-specific ELISPOT than patients who discontinued maintenance therapy and were relapse-free (p 0.0044). Survival of HIV patients with TE has improved markedly since the introduction of HAART, but persistent neurological deficits are often present in surviving patients. While preventive therapy remains essential, evaluation of T. gondii-specific immune responses may be an important step in improving estimates of the individual risk of TE and TE relapses.

Disorders of immune reconstitution in patients with HIV infection responding to antiretroviral therapy

Patients with HIV infection who were very immunodeficient before achieving a virologic response to antiretroviral therapy (ART) may experience various disorders of immune reconstitution. Immune restoration disease occurs in approximately 10% to 50% of patients and results from the restoration of a pathogen-specific immune response that causes immunopathology and presents as tissue inflammation or cellular proliferative disease. Opportunistic infections occur in no more than 5% of patients, but approximately one half of these patients have higher than expected CD4 T-cell counts and appear to have residual immune dysfunction. Autoimmune disease may arise because the reconstituted immune system confers an increased susceptibility to immune dysregulation but there may be different mechanisms because Graves' disease presents after a median time of about 2 years of ART whereas systemic lupus erythematosus presents earlier. Persistent CD4 T-cell deficiency (< 500/microL) affects up to 60% of patients and appears to reflect depletion of the naïve T-cell pool that results from low production and/or increased turnover of cells.

Susceptibility to opportunistic infections in HIV-infected patients with increased CD4 T-cell counts on antiretroviral therapy may be predicted by markers of dysfunctional effector memory CD4 T cells and B cells

OBJECTIVES

HIV-infected patients responding to combination antiretroviral therapy (ART) after experiencing severe immunodeficiency may exhibit persistent immune defects and occasionally experience opportunistic infections (OIs) despite increased CD4 T-cell counts. The investigation of immune defects in such patients was examined in this study.

METHODS

CD4 effector memory T-cell (T(em)-cell) function [assessed by blood cytomegalovirus (CMV) interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot-forming cell assay (ELISPOT) counts] and B-cell dysregulation [assessed by serum immunoglobulin A (IgA) and IgE levels] were examined in 27 patients with increased CD4 T-cell counts after receiving ART for over 2 years. Two of these patients and one other had developed OIs on ART and are described in detail.

RESULTS

Serum levels of IgA and IgE were higher than reference intervals (P<0.001) and CMV IFN-gamma ELISPOT counts were lower than those in non-HIV-infected controls (P<0.001) in the HIV-infected patients. Low CMV IFN-gamma ELISPOT counts were associated with high IgA levels (r=-0.5, P=0.01, Spearman's correlation test) and segregated with high IgE levels (P=0.06, Fisher's test). CMV IFN-gamma ELISPOT counts and serum IgA and IgE levels did not change significantly over a median time of 35 (range 8-60) months after the first measurement, whereas CD4 T-cell counts increased. All three patients who experienced OIs had repeatedly low CMV IFN-gamma ELISPOT counts and increased serum levels of IgA and/or IgE.

CONCLUSION

Low CD4 T(em)-cell function and B-cell dysregulation are immune defects that may persist independently of changes in the CD4 T-cell count in HIV-1-infected patients responding to ART and are associated with an increased risk of developing an OI.

Longitudinal Study of the Ocular Complications of AIDS

OBJECTIVE

To report the prevalence of ocular complications of AIDS in the era of highly active antiretroviral therapy (HAART).

DESIGN

Cohort study.

PARTICIPANTS

Patients with AIDS, 13 years or older.

METHODS

History, eye examination, and laboratory testing at enrollment.

MAIN OUTCOME MEASURE

Frequency of ocular complications at enrollment.

RESULTS

As of March 31, 2003, 1632 participants with AIDS were enrolled. The cohort had a history of severe immune deficiency, as evidenced by a median nadir CD4+ T-cell count of 30 cells per microliter. At enrollment, the median CD4+ T-cell count was 164 cells per microliter. CD4+ T-cell counts were <50 in 24.1% but > or =100 in 63.6% and > or =200 in 43.0%. Cytomegalovirus (CMV) retinitis was present in 22.1%, whereas other ocular opportunistic infections each were present in < or =0.6%. The incidence of CMV retinitis estimated from retrospective data was 5.60/100 person-years. Of the 360 patients with CMV retinitis, 22.5% were newly diagnosed at enrollment, and the remainder had more long-standing CMV retinitis (median, 2.8 years).

CONCLUSIONS

Although there is the possibility of oversampling patients with AIDS and ocular complications (as compared with a random sample), which would lead to increased estimates of prevalent and incident ocular morbidities, these data still suggest a substantial decline in the incidence of CMV retinitis from the pre-HAART era. Nevertheless, new cases of CMV retinitis continue to occur, and there is a population of patients with long-standing retinitis who will require management.

HIV patients developing primary CNS lymphoma lack EBV-specific CD4+ T cell function irrespective of absolute CD4+ T cell counts

BACKGROUND

In chronic HIV infection, antiretroviral therapy-induced normalization of CD4(+) T cell counts (immune reconstitution [IR]) is associated with a decreased incidence of opportunistic diseases. However, some individuals remain at risk for opportunistic diseases despite prolonged normalization of CD4(+) T cell counts. Deficient Epstein-Barr virus (EBV)-specific CD4(+) T cell function may explain the occurrence of EBV-associated opportunistic malignancy-such as primary central nervous system (PCNS) lymphoma-despite recovery of absolute CD4(+) T cell counts.

METHODS AND FINDINGS

Absolute CD4(+) T cell counts and EBV-specific CD4(+) T cell-dependent interferon-gamma production were assessed in six HIV-positive individuals prior to development of PCNS lymphoma ("cases"), and these values were compared with those in 16 HIV-infected matched participants with no sign of EBV-associated pathology ("matched controls") and 11 nonmatched HIV-negative blood donors. Half of the PCNS lymphoma patients fulfilled IR criteria (defined here as CD4(+) T cell counts >or=500/microl blood). EBV-specific CD4(+) T cells were assessed 0.5-4.7 y prior to diagnosis of lymphoma. In 0/6 cases versus 13/16 matched controls an EBV-specific CD4(+) T cell response was detected (p = 0.007; confidence interval for odds ratio [0-0.40]). PCNS lymphoma patients also differed with regards to this response significantly from HIV-negative blood donors (p < 0.001, confidence interval for odds ratio [0-0.14]), but there was no evidence for a difference between HIV-negative participants and the HIV-positive matched controls (p = 0.47).

CONCLUSIONS

Irrespective of absolute CD4(+) T cell counts, HIV-positive patients who subsequently developed PCNS lymphoma lacked EBV-specific CD4(+) T cell function. Larger, ideally prospective studies are needed to confirm these preliminary data, and clarify the impact of pathogen-specific versus surrogate marker-based assessment of IR on clinical outcome.

Regulatory T cells generated during cytomegalovirus in vitro stimulation of mononuclear cells from HIV-infected individuals on HAART correlate with decreased lymphocyte proliferation

HIV-infected patients fail to fully recover cell-mediated immunity despite HAART. To identify regulatory factors, we studied the phenotype and function of in vitro cytomegalovirus (CMV)-stimulated T cells from HAART recipients. CFSE-measured proliferation showed CD4+ and CD8+ cells dividing in CMV-stimulated cultures. Compared with healthy controls, CMV-stimulated lymphocytes from HAART recipients had lower 3H-thymidine incorporation; lower IFNgamma and TNFalpha production; higher CD4+ CD27- CD28- and CD8+ CD27- CD28- frequencies; lower CD4+ CD25hi; and higher FoxP3 expression in CD8+ CD25hi cells. CMV-specific proliferation correlated with higher IFNgamma, TNFalpha and IL10 levels and higher CD4+ perforin+ and CD8+ perforin+ frequencies. Decreased proliferation correlated with higher CD4+ CD27- CD28- frequencies and TGFbeta1 production, which also correlated with each other. Anti-TGFbeta1 neutralizing antibodies restored CMV-specific proliferation in a dose-dependent fashion. In HIV-infected subjects, decreased proliferation correlated with higher CMV-stimulated CD8+ CD25hi frequencies and their FoxP3 expression. These data indicate that FoxP3- and TGFbeta1-expressing regulatory T cells contribute to decreased immunity in HAART recipients.

Disseminate and fatal cytomegalovirus disease with thymitis in a naive HIV-patient after early initiation of HAART: Immune restoration disease?

We describe a naive HIV-infected patient who developed a Pneumocystis carinii pneumonia and disseminate and fatal cytomegalovirus disease within 3 months after initiation of HAART, suggesting due to coincidence in time, an immune restoration disease. We propose an alternative hypothesis.