Syndrome inflammatoire lié à la reconstitution immunitaire chez le patient coinfecté par le VIH et la tuberculose est une complication du traitement par des antirétroviraux, appelé TB-IRIS. Ce syndrome est souvent rencontré dans les pays en voie de développement. Son diagnostic se pose essentiellement sur la présentation clinique et nécessiter de se différentier des autres pathologies. Son évolution est souvent favorable ou sous corticoïde mais certaine forme est sévère et/ou mortelle. L'étude de leur mécanisme permettra d'identifier de marqueur prédictif, applicable à leur diagnostic précoce et à l'amélioration de leur prise en charge. Alors, nous avons proposés d'étudier le rôle de cellule NK et le rôle de lymphocyte T dans l'essai clinique de CAMELIA au Cambodge. Le résultat a montré l'élévation de la capacité de dégranulation de cellule NK est associé à la survenu de TB-IRIS et il peut être un marqueur prédictif. De plus, l'hyperactivation de cellule T effectrice et la diminution de cellule T régulatrice sont aussi observées. Le rôle de cellule T régulatrice n'est pas encore préciser. Le mécanisme régulateur de ce phénomène doit être ultérieurement exploré. / Inflammatory syndrome associated with immune reconstitution in patients coinfected with HIV and TB is one complication of antiretroviral treatment, called TB-IRIS. This syndrome more often encountered in developing countries. Diagnosis of this syndrome is mainly based of clinical presentation and needs to differentiate from other diseases. Their evolution is usually favorable or under corticosteroids, but some cases are severe and / or fatal. The study of their mechanism could lead to identify predictive markers, applicable to their early diagnosis and improved their management. Thus, we proposed to study the role of NK cell and T cell in the CAMELIA clinical trials which have conducted in Cambodia. The result showed that higher increase of NK cell degranulation capacity was associated with the occurrence of TB-IRIS and it could be a predictive marker. Furthermore, the hyperactivation of effector T cell and decrease of regulatory T cell were also observed. The implication of the regulatory T cell in this syndrome was not clear yet. The regulatory mechanism of this phenomenon should be further explored

Tuberculosis (TB) is the most common opportunistic infection in HIV-infected patients and the emergence of drug-resistant tuberculosis (DR-TB) is a growing problem in resource-limited settings (RLS). TB diagnosis in most RLS still depends on smear microscopy for acid-fast bacilli (AFB) while adequate infrastructure for testing drug sensitivity is unavailable. However, molecular diagnostics that detect Mycobacterium tuberculosis (Mtb) DNA and its genetic markers of drug resistance were recently developed. In this thesis I describe the use of a molecular diagnostic, Genotype MTBDRplus, for characterizing DR-TB and patterns of tuberculosis-like infection in two cities in south-west and north-central Nigeria. I found high rates of DR-TB in Nigerian HIV-infected individuals (9.3% for RIF or INH) with significantly different amounts by location (18.18% in south-west vs. 3.91% in north-central Nigeria, p=0.01). RIF resistance, indicative of MDR-TB, was found in 5.52% treatment-naïve patients, far exceeding the WHO predictions (0-4.3%). Furthermore, RIF resistance was genetically distinct, suggesting location-specific transmission of drug resistance (p=0.04). Genotype MTBDRplus correctly identified the drug-resistant samples compared to sequencing in 96.8% of cases. Mtb was confirmed in 56% of patients and was less likely to be found in patients on ART, while controlling for other relevant demographic characteristics (OR 0.29, P=0.02). Only abnormal respiratory findings on auscultation and the direct sputum smear grade greater than 3/100 were significant predictors of Mtb infection (OR 3.28, P=0.03; OR 6.40, p<0.01 respectively). Concentrated sputum smear was not significantly correlated with Mtb infection, except at the highest grades (>2+). Furthermore, in 49% of samples that were not confirmed for Mtb other actinomycetes were found: atypical Mycobacteria (ATM), Rhodococcus spp., Nocardia spp., Corynebacterium spp. I conclude that concentrated sputum AFB smears may misidentify bacteria as Mtb in a subset of HIV-infected patients. These individuals may have a different, even uncharacterized, actinomycete infection in the respiratory tract. Furthermore, total DR-TB in HIV-infection is high and transmission of DR-TB in HIV-infected patients in Nigeria is higher than estimated by the WHO. Molecular diagnostics are a rapid method for identifying Mtb and monitoring DR-TB, and can guide appropriate treatment decisions for respiratory infections in RLS with a high HIV burden.

<p dir="ltr">Tuberculosis (TB), caused by <i>Mycobacterium tuberculosis</i> (<i>Mtb</i>), and human immunodeficiency virus-1 (HIV) are major public health concerns, individually and in combination. The status of the host immune system, previous <i>Mtb</i> infection and HIV-mediated T cell exhaustion, can have significant impacts on immune dynamics during reinfection. Individuals with asymptomatic latent TB infection (LTBI) may be protected against <i>Mtb </i>reinfection, as demonstrated by animal and <i>in vitro </i>studies. However, the underlying dynamics and protective mechanisms of LTBI are poorly understood. In HIV, long-term infection in children and associated T cell exhaustion leads to weakened immune responses to HIV reinfection. The complexity of these infections, particularly in the context of the heightened vulnerability of HIV+ individuals to TB, underscores the need for novel investigative approaches to study host-pathogen and pathogen-pathogen interactions. To this, we have developed an agent-based model (ABM) as a mechanistic computational tool to simulate the immune response to <i>Mtb </i>and HIV, separately and during coinfection. Our ABM integrates clinical and experimental data; simulates immune cell dynamics between macrophages, CD4+ and CD8+ T cells; and produces emergent granuloma-like structures – a critical response to <i>Mtb</i>. This <i>in silico</i> approach allows us to efficiently explore host-pathogen interactions and their clinical implications. By unraveling the complex interplay of immune cell activation, T cell exhaustion, and pathogen dynamics, our model offers insights that could guide the development of targeted therapies. By quantifying the multifaceted nature of these diseases and their interactions, we highlight the potential of computational approaches in understanding and treating complex diseases, individually and in combination.</p>