Understanding mechanisms underlying the pathology of immune reconstitution inflammatory syndrome (IRIS) by using animal models

Diagnostic clues in a stem cell transplant patient manifested with chronic central nervous system GVHD and IRIS

Transplant physicians should be aware of the immune deviation-related clinical conditions as allogeneic hematopoietic stem cell transplantation is widely used for the treatment of patients with malignant and non-malignant disorders. Neurological manifestations and graft-versus-host disease (GVHD) may commonly develop in transplant recipients. However, overlapping clinical immunological conditions may lead to diagnostic challenges. Herein, we discussed the differential diagnosis of a patient with immune reconstitution inflammatory syndrome (IRIS) developing on the basis of chronic GVHD.

Host immune responses in the central nervous system during fungal infections

Fungal infections in the central nervous system (CNS) cause high morbidity and mortality. The frequency of CNS mycosis has increased over the last two decades as more individuals go through immunocompromised conditions for various reasons. Nevertheless, options for clinical interventions for CNS mycoses are still limited. Thus, there is an urgent need to understand the host-pathogen interaction mechanisms in CNS mycoses for developing novel treatments. Although the CNS has been regarded as an immune-privileged site, recent studies demonstrate the critical involvement of immune responses elicited by CNS-resident and CNS-infiltrated cells during fungal infections. In this review, we discuss mechanisms of fungal invasion in the CNS, fungal pathogen detection by CNS-resident cells (microglia, astrocytes, oligodendrocytes, neurons), roles of CNS-infiltrated leukocytes, and host immune responses. We consider that understanding host immune responses in the CNS is crucial for endeavors to develop treatments for CNS mycosis.

Immune reconstitution inflammatory syndrome (IRIS) in a patient with neuro pulmonary nocardiosis following hematopoietic cells transplantation (HCT)

Immune reconstitution inflammatory syndrome (IRIS) is increasingly reported in various HIV negative patients with immunosuppression, but the relationship with hematopoietic cell transplantation (HCT) is not well defined. We report a case of IRIS in a patient infected with pulmonary and CNS Nocardiosis following HCT due to primary myelofibrosis.

Co-infections as Modulators of Disease Outcome: Minor Players or Major Players?

Human host and pathogen interaction is dynamic in nature and often modulated by co-pathogens with a functional role in delineating the physiological outcome of infection. Co-infection may present either as a pre-existing pathogen which is accentuated by the introduction of a new pathogen or may appear in the form of new infection acquired secondarily due to a compromised immune system. Using diverse examples of co-infecting pathogens such as Human Immunodeficiency Virus, Mycobacterium tuberculosis and Hepatitis C Virus, we have highlighted the role of co-infections in modulating disease severity and clinical outcome. This interaction happens at multiple hierarchies, which are inclusive of stress and immunological responses and together modulate the disease severity. Already published literature provides much evidence in favor of the occurrence of co-infections during SARS-CoV-2 infection, which eventually impacts the Coronavirus disease-19 outcome. The availability of biological models like 3D organoids, mice, cell lines and mathematical models provide us with an opportunity to understand the role and mechanism of specific co-infections. Exploration of multi-omics-based interactions across co-infecting pathogens may provide deeper insights into their role in disease modulation.

Predictors of glucose metabolism and blood pressure among Ethiopian individuals with HIV/AIDS after one-year of antiretroviral therapy

OBJECTIVE

Better understanding of glucose metabolism in patients with HIV after initiating antiretroviral therapy (ART) is important to target treatment and follow-up for diabetes risk and other non-communicable diseases in resource-limited settings. The aim of this study was to assess the changes and predictors of glucose metabolism and blood pressure among patients with HIV on ART for 12 months.

METHODS

One-year follow-up of Ethiopian patients with HIV after initiation of ART was done. Outcomes were changes in fasting plasma glucose (FPG), and 30-minute (30mPG) and 2-hour plasma glucose (2hPG) after oral glucose tolerance test, glycated haemoglobin (HbA1c), fasting plasma insulin (p-insulin), homeostatic model assessment index for insulin resistance (HOMA-IR) and blood pressure.   RESULTS: The mean age was 33 years, and the majority were women. During the first 12 months, levels of all plasma glucose parameters decreased, while p-insulin (10^B 3.1; 95% CI2.4, 4.0), HOMA-IR (10^B 3.1; 95% CI2.3, 4.0) and systolic blood pressure (B 4.0; 95% CI2.5, 5.5) increased. Fat-free mass at baseline predicted higher increments in p-insulin, HOMA-IR and blood pressure; whereas, fat mass predicted higher increment in HbA1c.

CONCLUSIONS

Among Ethiopian patients with HIV, blood pressure and insulin increased, and all glucose parameters declined during 12-month of ART. Only longer-term follow-up will tell us whether insulin increase is due to insulin resistance or from recovering β-cells.

Pneumocystis pneumonia can complicate medical treatment of hypercortisolism even in outpatients with Cushing's disease

Several cases of Pneumocystosis pneumonia (PCP) have been reported in patients with hypercortisolism, mainly in patients with severe ectopic ACTH syndrome (EAS). We report 2 cases of PCP that did not develop until after starting treatment with metyrapone, one of which occurred in an outpatient with Cushing's disease (CD) without pulmonary symptoms before medical treatment for CD. Patient 1 presented as an outpatient with CD and severe hypercortisolism but nonetheless in good general condition. Treatment with metyrapone was started before pituitary surgery. Patient 2 had EAS due to prostate cancer. Respiratory failure in the two patients occurred 4 days and 30 days, respectively, after the start of metyrapone treatment. In both cases, chest CT showed bilateral interstitial infiltrates, and Pneumocystis jirovecii was found on bronchoalveolar lavage (BAL). A literature review was performed to identify risk factors for PCP in patients with CD: we identified 20 other cases of PCP in patients treated for hypercortisolism, including 16 patients with EAS. Ninety percent of patients had free urinary cortisol greater than 6 times the upper limit of normal (ULN). In conclusion, onset of PCP after initiation of anticortisolic therapy is not limited to patients with EAS, and may occur in CD patients with elevated cortisol levels, even if the patient remains in good general condition and has no pulmonary symptoms before treatment. In such patients, routine prophylactic treatment with trimethoprim/sulfamethoxazole (TMP/SMX) should be considered.

Th1-Dependent Cryptococcus-Associated Immune Reconstitution Inflammatory Syndrome Model With Brain Damage

Cryptococcus-associated immune reconstitution inflammatory syndrome (C-IRIS) is identified upon immune reconstitution in immunocompromised patients, who have previously contracted an infection of Cryptococcus neoformans (Cn). C-IRIS can be lethal but how the immune system triggers life-threatening outcomes in patients is still poorly understood. Here, we establish a mouse model for C-IRIS with Cn serotype A strain H99, which is highly virulent and the most intensively studied. C-IRIS in mice is induced by the adoptive transfer of CD4+ T cells in immunocompromised Rag1-deficient mice infected with a low inoculum of Cn. The mice with C-IRIS exhibit symptoms which mimic clinical presentations of C-IRIS. This C-IRIS model is Th1-dependent and shows host mortality. This model is characterized with minimal lung injury, but infiltration of Th1 cells in the brain. C-IRIS mice also exhibited brain swelling with resemblance to edema and upregulation of aquaporin-4, a critical protein that regulates water flux in the brain in a Th1-dependent fashion. Our C-IRIS model may be used to advance our understanding of the paradoxical inflammatory phenomenon of C-IRIS in the context of neuroinflammation.

Niflumic Acid Reverses Airway Mucus Excess and Improves Survival in the Rat Model of Steroid-Induced Pneumocystis Pneumonia

Although the role of adaptive immunity in fighting Pneumocystis infection is well known, the role of the innate, airway epithelium, responses remains largely unexplored. The concerted interaction of innate and adaptive responses is essential to successfully eradicate infection. Increased expression of goblet-cell-derived CLCA1 protein plus excess mucus in infant autopsy lungs and in murine models of primary Pneumocystis infection alert of innate immune system immunopathology associated to Pneumocystis infection. Nonetheless, whether blocking mucus-associated innate immune pathways decreases Pneumocystis-related immunopathology is unknown. Furthermore, current treatment of Pneumocystis pneumonia (PcP) relying on anti-Pneumocystis drugs plus steroids is not ideal because removes cellular immune responses against the fungal pathogen. In this study, we used the steroid-induced rat model of PcP to evaluate inflammation and mucus progression, and tested the effect of niflumic acid (NFA), a fenamate-type drug with potent CLCA1 blocker activity, in decreasing Pneumocystis-associated immunopathology. In this model, animals acquire Pneumocystis spontaneously and pneumonia develops owing to the steroids-induced immunodeficiency. Steroids led to decreased animal weight evidencing severe immunosuppression and to significant Pneumocystis-associated pulmonary edema as evidenced by wet-to-dry lung ratios that doubled those of uninfected animals. Inflammatory cuffing infiltrates were noticed first around lung blood vessels followed by bronchi, and both increased progressively. Similarly, airway epithelial and lumen mucus progressively increased. This occurred in parallel to increasing levels of MUC5AC and mCLCA3, the murine homolog of hCLCA1. Administration of NFA caused a significant decrease in total mucus, MUC5AC and mCLCA3 and also, in Pneumocystis-associated inflammation. Most relevant, NFA treatment improved survival at 8 weeks of steroids. Results suggest an important role of innate immune responses in immunopathology of steroid-induced PcP. They warrant evaluation of CLCA1 blockers as adjunctive therapy in this condition and describe a simple model to evaluate therapeutic interventions for steroid resistant mucus, a common condition in patients with chronic lung disease like asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis.