Immune reconstitution inflammatory syndrome in HIV infection: taking the bad with the good

Correlation Between CD4 Cell Count, HIV Viral Load, and Chest CT Findings of AIDS-associated Pulmonary Cryptococcosis

Background: The computed tomography (CT) features of acquired immune deficiency syndrome (AIDS)-associated pulmonary cryptococcosis (PC) are correlated with the viral load of human immunodeficiency virus (HIV). An increase in CD4-positive T lymphocyte (CD4) cell count in peripheral blood after a highly active antiretroviral therapy (HAART) can reflect the morphological changes of lung lesions. Objectives: This study aimed to evaluate the correlation between CT features and HIV viral load and to determine a cut-off value for CD4 cell count increment to investigate the prognosis of PC. It also aimed to examine the morphology of PC lesions and their prognosis following HAART. Methods: Sixty-two patients with AIDS-associated PC, confirmed by pathology or follow-up, were enrolled in this study. The CT findings were recorded and classified as nodular, cavitary, and consolidation groups and their subtypes. Forty HIV patients who had undergone HAART were screened in this study, and the outcomes of lung lesions were recorded in a follow-up of 3 - 6 months. The participants were divided into improvement and progression groups. The correlation analysis and the receiver operator characteristic (ROC) curve analysis were used to examine the correlation between CT morphology and HIV viral load and to determine the cut-off value for CD4 cell count increment. The intraclass correlation coefficient (ICC) for inter-observer agreement was also calculated. Results: In the nodular group, patients with miliary nodules had the highest HIV viral load in peripheral blood (miliary nodules vs. solitary nodules, P = 0.009; miliary nodules vs. multiple nodules; P = 0.024). In the cavitary group, thick-walled cavity lesions had a higher HIV viral load than thin-walled cavity lesions (thin-walled vs. thick-walled cavity lesions, P = 0.036). Changes in the morphology of lesions, indicating the progression or improvement of PC, had a positive correlation with the CD4 cell count increment (F = 4.260, P = 0.045). The cut-off value for CD4 cell count increment to differentiate the two outcomes (progression and improvement) was 44/µL. The area under the curve (AUC) was 0.851, and sensitivity, specificity, and accuracy were estimated at 0.815, 0.714, and 0.764, respectively. Conclusion: In AIDS-associated PC, different types of lesions were related to the HIV viral load, and CD4 cell count increment following HAART was associated with the morphological changes of lesions. This finding can be helpful for clinicians and radiologists to make an accurate diagnosis and evaluate the treatment outcomes, as well as disease progression.

Classical complement and inflammasome activation converge in CD14highCD16- monocytes in HIV associated TB-immune reconstitution inflammatory syndrome

Inflammasome-derived cytokines, IL-1β and IL-18, and complement cascade have been independently implicated in the pathogenesis of tuberculosis (TB)-immune reconstitution inflammatory syndrome (TB-IRIS), a complication affecting HIV⁺ individuals starting antiretroviral therapy (ART). Although sublytic deposition of the membrane attack complex (MAC) has been shown to promote NLRP3 inflammasome activation, it is unknown whether these pathways may cooperatively contribute to TB-IRIS. To evaluate the activation of inflammasome, peripheral blood mononuclear cells (PBMCs) from HIV-TB co-infected patients prior to ART and at the IRIS or equivalent timepoint were incubated with a probe used to assess active caspase-1/4/5 followed by screening of ASC (apoptosis-associated speck-like protein containing a CARD domain) specks as a readout of inflammasome activation by imaging flow cytometry. We found higher numbers of monocytes showing spontaneous caspase-1/4/5⁺ASC-speck formation in TB-IRIS compared to TB non-IRIS patients. Moreover, numbers of caspase-1/4/5⁺ASC-speck⁺ monocytes positively correlated with IL-1β/IL-18 plasma levels. Besides increased systemic levels of C1q and C5a, TB-IRIS patients also showed elevated C1q and C3 deposition on monocyte cell surface, suggesting aberrant classical complement activation. A clustering tSNE analysis revealed TB-IRIS patients are enriched in a CD14^highCD16^- monocyte population that undergoes MAC deposition and caspase-1/4/5 activation compared to TB non-IRIS patients, suggesting complement-associated inflammasome activation during IRIS events. Accordingly, PBMCs from patients were more sensitive to ex-vivo complement-mediated IL-1β secretion than healthy control cells in a NLRP3-dependent manner. Therefore, our data suggest complement-associated inflammasome activation may fuel the dysregulated TB-IRIS systemic inflammatory cascade and targeting this pathway may represent a novel therapeutic approach for IRIS or related inflammatory syndromes.

Tuberculosis (TB) associated-immune reconstitution inflammatory syndrome (TB-IRIS) is a clinical complication affecting HIV⁺ individuals previously co-infected with Mycobacterium tuberculosis (Mtb), upon antiretroviral therapy (ART) initiation. TB-IRIS is characterized by an exacerbated inflammatory response and can be associated with high morbidity and mortality rates in resource-limited countries with high TB prevalence. So far, there is no targeted TB-IRIS therapy, and corticosteroids are frequently used to prevent or alleviate IRIS related-symptoms. Here we found inflammasome activation (i.e. caspase1/4/5⁺ASC speck complex formation) on circulating classical CD14^highCD16^- monocytes may contribute to TB-IRIS immunopathology, since it correlates with pro-inflammatory cytokine plasma levels and its decay is associated with dampening in IRIS-related symptoms promoted by anti-inflammatory therapy. We also found TB-IRIS monocytes display higher surface complement deposition, being more sensitive to external complement-mediated NLRP3 inflammasome activation than healthy control cells. In fact, complement MAC molecule C9 and caspase-1/4/5 activation were associated on classical monocytes in TB-IRIS patients, suggesting complement-mediated inflammasome activation may lead to a positive feedback loop in the inflammatory responses observed in TB-IRIS. Therefore, our findings support that complement-NLRP3/ASC/caspase1/4/5 axis may be considered as a potential target for host-directed therapy of TB-IRIS.

The controversial natural history of oral herpes simplex virus type 1 infection

The natural history of oral herpes simplex virus type 1 (HSV-1) infection in the immunocompetent host is complex and rich in controversial phenomena, namely the role of unapparent transmission in primary infection acquisition, the high frequency of asymptomatic primary and recurrent infections, the lack of immunogenicity of HSV-1 internalized in the soma (cell body) of the sensory neurons of the trigeminal ganglion, the lytic activity of HSV-1 in the soma of neurons that is inhibited in the sensory neurons of the trigeminal ganglion and often uncontrolled in the other neurons, the role of keratin in promoting the development of recurrence episodes in immunocompetent hosts, the virus-host Nash equilibrium, the paradoxical HSV-1-seronegative individuals who shed HSV-1 through saliva, the limited efficacy of anti-HSV vaccines, and why the oral route of infection is the least likely to produce severe complications. The natural history of oral HSV-1 infection is also a history of symbiosis between humans and virus that may switch from mutualism to parasitism and vice versa. This balance is typical of microorganisms that are highly coevolved with humans, and its knowledge is essential to oral healthcare providers to perform adequate diagnosis and provide proper individual-based HSV-1 infection therapy.

Immune reconstitution inflammatory syndrome associated with secondary syphilis: dermatologic, neurologic and ophthalmologic compromise in an HIV patient

The presentation of syphilis as a manifestation of immune reconstitution inflammatory syndrome in patients with human immunodeficiency virus (HIV) infection is rare and can be associated with the varied clinical expression of unusual syphilitic manifestations. We report a case of immune reconstitution syndrome with dermatologic, ophthalmologic and neurologic compromise of secondary syphilis in a patient with HIV infection.