Respiratory virus infections in the immunocompromised host

HMGB1: A Potential Target of Nervus Vagus Stimulation in Pediatric SARS-CoV-2-Induced ALI/ARDS

From the start of pandemics, children were described as the ones who were less affected by SARS-Cov-2 or COVID-19, which was mild in most of the cases. However, with the growing vaccination rate of the adult population, children became more exposed to the virus and more cases of severe SARS-CoV-2-induced ARDS are being diagnosed with the disabling consequences or lethal outcomes associated with the cytokine storm. Thus, we do hypothesize that some of the children could benefit from nervus vagus stimulation during COVID-19 ARDS through the inhibition of HMGB1 release and interaction with the receptor, resulting in decreased neutrophil accumulation, oxidative stress, and coagulopathy as well as lung vascular permeability. Moreover, stimulation through alpha-7 nicotinic acetylcholine receptors could boost macrophage phagocytosis and increase the clearance of DAMPs and PAMPs. Further rise of FGF10 could contribute to lung stem cell proliferation and potential regeneration of the injured lung. However, this stimulation should be very specific, timely, and of proper duration, as it could lead to such adverse effects as increased viral spread and systemic infection, especially in small children or infants due to specific pediatric immunity state and anatomical features of the respiratory system.

Prevalence and clinical outcome of respiratory viral infections among children with cancer and febrile neutropenia

Background: The role of respiratory viruses (RV) in children with cancer having febrile neutropenic episodes has not been well studied. The objectives of our study were to investigate the prevalence and clinical outcomes of Respiratory viral infection (RVI). Methods: Children with cancer and febrile neutropenia (FN) having acute respiratory infections (ARI) were considered as cases and febrile neutropenic cancer patients without ARI were considered as controls. A throat swab sample was obtained for the detection of 21-respiratory pathogens. Results: A total of 81 episodes of FN in cases and 37 episodes of FN in controls were included. Prevalence of RVI (at least 1 RV) was seen in 76.5% of cases and 48.6% of controls (p = 0.005). The mixed-respiratory viruses (co-infections of ≥2 viruses) were seen only in cases (26%) (p = 0.00). Rhinovirus (36.8%) and respiratory syncytial virus (13.6%) were the most frequently detected viruses. Median duration of fever before presentation was more in cases with RVI compared to without RVI [2 (1-5) days vs 1 (1-5) day (p = 0.012)]. The median total duration of febrile period was 4 (IQR, 3-6) days in cases with RVI and 3 (IQR, 1-4) days in cases without RVI (p = 0.005). The median duration of antibiotic days were longer in cases with RVI as compared to patients without RVI [9 (IQR, 7-17) days vs 7 (IQR, 6-10) days (p = 0.046)] respectively. Conclusion: There was high prevalence of RVI in children with cancer and FN; more in association with ARI. The RVI were associated with prolonged febrile period and days of antibiotics therapy.

Inhibitors of Measles Virus

Measles virus (MV) infections have been almost eradicated in some industrialized nations. However, MV continues to cause severe disease and mortality in the world and is responsible for clusters of exogenous-borne disease in essentially disease-free countries. Because of the ebb and flow of immunization campaigns, especially in the poverty-stricken and war-torn Third World, and the ominous potential for severe disease and mortality, it is vital that research for discovery of therapeutic countermeasures should continue. To that end, a number of compounds have been evaluated for efficacy in vitro and in animal models, and several therapeutic modalities have been tested in the clinic. The only current therapies used in the clinic include ribavirin administered orally or intravenously, alone or in combination with immune serum globulin; these therapies have demonstrated variable efficacy. Therefore, drug discovery efforts have been launched to supplement the existing treatments for MV infections. Antisense molecules, adenosine and guanosine nucleosides, including ring-expanded ‘fat’ nucleoside analogues, brassinosteroids, coumarins, peptide inhibitors, modulators of cholesterol synthesis and a variety of natural products have been screened for efficacy and toxicity both in vitro and in animals. However, none of these agents has gone into human clinical trials and most will not merit further development due to toxicity concerns and/or low potency. Thus, further research is needed to develop more potent and less toxic drugs that could be used for treating MV infections to supplement the existing MV vaccine campaigns.

Immunodeficiency scoring index to predict poor outcomes in hematopoietic cell transplant recipients with RSV infections

We developed an immunodeficiency scoring index for respiratory syncytial virus (ISI-RSV) infection, based on a cohort of 237 allogeneic hematopoietic cell transplant (allo-HCT) recipients, that can predict the risk of progression to lower respiratory tract infection (LRTI) and RSV-associated mortality. A weighted index was calculated using adjusted hazard ratios for immunodeficiency markers. Based on the ISI-RSV (range, 0-12), patients were stratified into low (0-2), moderate (3-6), and high (7-12) risk groups. A significant trend of increasing incidence of LRTI and RSV-associated mortality was observed as the risk increased from low to moderate to high (P < .001). Patients in the high-risk group had the greatest benefit of ribavirin-based therapy at the upper respiratory tract infection stage and the highest risk for progression to LRTI and death when antiviral therapy was not given (6.5 [95% confidence interval (CI), 1.8-23.6] and 8.1 [95% CI, 1.1-57.6], respectively). The ISI-RSV is designed to stratify allo-HCT recipients with RSV infection into groups according to their risk for progression to LRTI and RSV-associated mortality. Identification of high-risk groups using this index would distinguish patients who would benefit the most from antiviral therapy, mainly with aerosolized ribavirin. The ISI-RSV should be validated in a multi-institutional study.

Management of patients with multidrug-resistant/extensively drug-resistant tuberculosis in Europe: a TBNET consensus statement

The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) substantially challenges TB control, especially in the European Region of the World Health Organization, where the highest prevalence of MDR/XDR cases is reported. The current management of patients with MDR/XDR-TB is extremely complex for medical, social and public health systems. The treatment with currently available anti-TB therapies to achieve relapse-free cure is long and undermined by a high frequency of adverse drug events, suboptimal treatment adherence, high costs and low treatment success rates. Availability of optimal management for patients with MDR/XDR-TB is limited even in the European Region. In the absence of a preventive vaccine, more effective diagnostic tools and novel therapeutic interventions the control of MDR/XDR-TB will be extremely difficult. Despite recent scientific advances in MDR/XDR-TB care, decisions for the management of patients with MDR/XDR-TB and their contacts often rely on expert opinions, rather than on clinical evidence.

This document summarises the current knowledge on the prevention, diagnosis and treatment of adults and children with MDR/XDR-TB and their contacts, and provides expert consensus recommendations on questions where scientific evidence is still lacking.

TBNET consensus statement on the management of patients with MDR/XDR-TB has been released in theEur Respir Jhttp://ow.ly/uizRD

Immune cell profile in infants' lung tissue

Little is known about the normal immune cell profile in the lungs of infants without pulmonary disease. Normal lung samples obtained at autopsy of 10 infants that died either due to incidental or inflicted causes or non-pulmonary diseases were stained for antibodies against B and T lymphocytes, macrophages, NK cells, cytotoxic cells, dendritic cells and mast cells. Cells were quantified in the airway epithelial layer, inner layer (between the epithelium and the outer smooth muscle border), outer layer (between the outer smooth muscle border and the external limits of the airway) and alveolar septa. Basement membrane or alveolar septa lengths were assessed by image analysis. Results were expressed as cells/mm. The median age of patients was 6.8 months, ranging from 11 to 840 days. The inner layer of the airways was the region with the smallest density of cells. There was a predominance of cells related to the innate immunity such as CD56+, Granzyme B+ and CD68+ cells in the epithelial layer and alveolar parenchyma. The outer layer and the lung parenchyma presented the highest cellular density. There were very few CD4+ T cells or dendritic cells in most of the lung compartments. The numbers of CD3+ T and granzyme B+ cells correlated positively with age. There was a compartmentalization of immune cells along airways and parenchyma, which may be related to the development of innate and acquired lung defense mechanisms.

Utility of bronchoalveolar lavage in the diagnosis of pulmonary infection in children with haematological malignancies

BACKGROUND

Fibre-optic bronchoscopy with bronchoalveolar lavage (BAL) is a safe procedure and is associated with low morbidity and mortality in immunocompromised children. Although many studies have highlighted the advantages of positive BAL results in the diagnosis of pulmonary infections, there have been few reports examining the impact of a negative BAL result on clinical management in immunocompromised children on empiric broad-spectrum antimicrobial therapy.

AIM

The aim of this study was to evaluate BAL in the diagnosis of pulmonary infections in children with haematological malignancies who develop pneumonia unresponsive to empiric antimicrobial therapy, and also to determine whether a negative BAL result contributed to the clinical management of these patients.

MATERIALS AND METHODS

A retrospective review of 44 BAL procedures performed in 33 children with haematological malignancy diagnosed and treated at Our Lady's Children Hospital, Crumlin, Dublin 12, Ireland, over a 10-year period was carried out.

RESULTS

We identified a pathogen causing pneumonia in 24 of 44 BAL procedures (54.5 %). The BAL procedure resulted in modification of antimicrobial treatment after 20 of 24 procedures with positive results (83.3 %) in 16 of 20 patients (80 %). Management was changed after 8 of 20 procedures with negative results (40 %) in 8 of 18 patients (44.4 %). The procedure was well tolerated in all patients.

CONCLUSIONS

Our study supports the use of bronchoscopy with BAL as a diagnostic intervention in this patient population. We consider BAL a safe procedure from which both positive and negative results contribute to the patient's clinical management.

Management of RSV infections in adult recipients of hematopoietic stem cell transplantation

Respiratory syncytial virus (RSV) is a common cause of seasonal respiratory viral infection in patients who have undergone hematopoietic stem cell transplantation. RSV usually presents as an upper respiratory tract infection in this patient population but may progress rapidly to lower respiratory tract infection. Available therapies that have been used for the treatment of RSV infections are limited to ribavirin, intravenous immunoglobulin, and palivizumab. The use of aerosolized ribavirin, alone or in combination with either palivizumab or intravenous immunoglobulin, remains controversial. In this comprehensive review, we present and discuss the available literature on management of RSV infections in adult hematopoietic stem cell transplantation recipients with a focus on therapeutic modalities and outcomes.

Infections in the immunocompromised

Infections in the immunocompromised differ significantly from those in the immunocompetent. They can be more serious, more often life threatening, more difficult to diagnose and are caused by more unusual organisms. Children can be immunocompromised for a variety of reasons and the numbers, worldwide, are growing.

Long-term therapy with aerosolized ribavirin for parainfluenza 3 virus respiratory tract infection in an infant with severe combined immunodeficiency

We report the case of an infant with severe combined immunodeficiency who was presented with PIV3 infection. Aerosolized ribavirin was administered for 10 months until the child gained a functional immune system through an allogeneic hematopoietic stem cell transplant and cleared PIV3 infection. No adverse effect was observed in the child and in healthcare personnel, with a follow-up of three years. Despite the burden of aerosolized administration, early and prolonged administration of aerosolized ribavirin was feasible, well tolerated, and safe for the patient and the caregivers. This is a case report and no definite conclusions can be drawn. However, our experience suggests that prolonged aerosolized ribavirin administration should be considered for the treatment of PIV3 infection in the context of primary immunodeficiency, where there is no currently available alternative treatment, until a functional immune system is gained.

Respiratory virus infections in children with cancer or HIV infection

Most studies focusing on respiratory infections in immunocompromised children have been addressed to bacterial etiology. However, respiratory virus infections in this population can also lead to severe disease. The objective of this study is to evaluate the clinical significance of respiratory virus infections in children with cancer or human immunodeficiency virus (HIV) infection. Retrospective study conducted in a teaching hospital in Madrid. Medical records from children <or=14 years diagnosed with cancer or with HIV infection were reviewed. We analyzed demographic characteristics, clinical syndromes associated with the infection, need for hospitalization, treatment prescribed, and outcome. Fifty-three respiratory viral infections were identified: 26 (20%) in 129 HIV-infected children and 27 (12%) in 218 children with cancer. Twenty (38%) of the respiratory infections were nosocomial. Causal viruses were: respiratory syncytial virus, 43%; influenza A, 26%; adenovirus, 13%; parainfluenza virus, 13%; and influenza B, 4%. Thirty-three children were hospitalized: 14 (54%) with HIV infection and 19 (70%) receiving anticancer chemotherapy. Pneumonia occurred in 11 (34%) of the 33 hospitalized children. Four (21%) of the 19 hospitalized children with cancer, but none of the HIV-infected children, were admitted to the Pediatric Intensive Care Unit (P=0.096). Two children with cancer died. Common respiratory virus infections in children with cancer or HIV infection have a relevant morbidity. The fact that 40% of these infections are hospital-acquired emphasizes the need for isolation and preventive measures.

Targeting CD45RB alters T cell migration and delays viral clearance

CD45 is a receptor tyrosine phosphatase essential for TCR signaling. One isoform, CD45RB, is down-regulated in memory cells and targeting CD45RB with a specific antibody has been shown to inhibit graft rejection. Its role in immunity to infection, however, has not been tested. Here, we report the effect of anti-CD45RB antibody treatment on the induction of anti-influenza CD8+ T cells and viral clearance. Anti-CD45RB-treated mice had delayed pulmonary viral clearance compared with untreated mice whose infection was completely cleared by day 8 post-infection. In anti-CD45RB-treated mice, the total CD4+ and CD8+ T cell numbers in both the lungs and mediastinal nodes were substantially reduced at days 5 and 8; this effect was less marked for the spleen. CD8+ T cells specific for influenza virus were also reduced compared with the control group in all three organs at day 8. By day 11, when both treated and control groups showed no virus remaining in the lungs, specific CD8+ T cell numbers were at similar low levels. Homing to lymph nodes and lung of dye-labeled T cells was greatly inhibited (by >80%) by anti-CD45RB treatment. This reduced homing corresponded with reduced CD62L and beta1-integrin expression in both uninfected and infected mice. Since CD62L plays a critical role in homing lymphocytes to lymph nodes, and high levels of CD62L and alpha4beta1-integrin are expressed by lymphocytes that home to bronchus-associated lymphoid tissue, we suggest that reduced expression of these molecules is a key explanation for the delay in immune responses.