Time to virological failure, treatment change and interruption for individuals treated within 12 months of HIV seroconversion and in chronic infection

The complexity of HIV persistence and pathogenesis in the lung under antiretroviral therapy: challenges beyond AIDS

Antiretroviral therapy (ART) represents a significant milestone in the battle against AIDS. However, we continue learning about HIV and confronting challenges 30 years after its discovery. HIV has cleverly tricked both the host immune system and ART. First, the many HIV subtypes and recombinant forms have different susceptibilities to antiretroviral drugs, which may represent an issue in countries where ART is just being introduced. Second, even under the suppressive pressures of ART, HIV still increases inflammatory mediators, deregulates apoptosis and proliferation, and induces oxidative stress in the host. Third, the preference of HIV for CXCR4 as a co-receptor may also have noxious outcomes, including potential malignancies. Furthermore, HIV still replicates cryptically in anatomical reservoirs, including the lung. HIV impairs bronchoalveolar T-lymphocyte and macrophage immune responses, rendering the lung susceptible to comorbidities. In addition, HIV-infected individuals are significantly more susceptible to long-term HIV-associated complications. This review focuses on chronic obstructive pulmonary disease (COPD), pulmonary arterial hypertension, and lung cancer. Almost two decades after the advent of highly active ART, we now know that HIV-infected individuals on ART live as long as the uninfected population. Fortunately, its availability is rapidly increasing in low- and middle-income countries. Nevertheless, ART is not risk-free: the developed world is facing issues with antiretroviral drug toxicity, resistance, and drug-drug interactions, while developing countries are confronting issues with immune reconstitution inflammatory syndrome. Several aspects of the complexity of HIV persistence and challenges with ART are discussed, as well as suggestions for new avenues of research.

Joint modeling of HIV data in multicenter observational studies: A comparison among different approaches

Disease process over time results from the combination of event history information and longitudinal process. Commonly, separate analyses of longitudinal and survival outcomes are performed. However, discharging the dependence between these components may cause misleading results. Separate analyses are difficult to interpret whenever one deals with observational retrospective multicenter cohort studies where the biomarkers are poorly monitored over time, while the survival component may be affected by several sources of bias, such as multiple endpoints, multiple time-scales, and informative censoring. We discuss how joint modeling of longitudinal and survival data represents an effective strategy to incorporate all information simultaneously and to provide valid and efficient inferences, thus allowing to produce a better insight into the biological mechanisms underlying the phenomenon under study. Accounting for the whole dynamics of the disease process is crucial in retrospective longitudinal studies. In this work, we present different approaches for modeling longitudinal and time-to-event data, retrieved from 648 HIV-infected patients enrolled in the Italian cohort of the CASCADE (Concerted Action on SeroConversion to AIDS and Death in Europe) study, one of the largest AIDS collaborative cohort studies. In particular, we evaluate CD4 lymphocyte evolution over time (from the date of seroconversion) and overall survival, CD4 being one of the most important immunologic biomarker for HIV progression. Besides a standard separate modeling approach, we consider two alternative joint models: the traditional joint model and the joint latent class mixed model. Advantages and disadvantages of the different approaches are discussed. To compare the performances of these models, cross-validation procedures are also performed.

The natural history of HIV infection

Purpose of review

To review recent published literature around three areas: long-term nonprogression/viral control; predictors of viral load set point/disease progression; and the potential impact of antiretroviral therapy (ART) in early HIV infection.

Recent findings

The natural course of untreated HIV infection varies widely with some HIV-positive individuals able to maintain high CD4 cell counts and/or suppressed viral load in the absence of ART. Although similar, the underlying mechanistic processes leading to long-term nonprogression and viral control are likely to differ. Concerted ongoing research efforts will hopefully identify host factors that are causally related to these phenotypes, thus providing opportunities for the development of novel treatment or preventive strategies. Although there is increasing evidence that initiation of ART during primary infection may prevent the immunological deterioration which would otherwise be seen in untreated HIV infection, recent studies do not address the longer term clinical benefits of ART at this very early stage.

Summary

A better understanding of the relative influences of viral, host, and environmental factors on the natural course of HIV infection has the potential to identify novel targets for intervention to prevent and treat HIV-infected persons.