Reactivation of Cytomegalovirus Increases Nitric Oxide and IL-10 Levels in Sepsis and is Associated with Changes in Renal Parameters and Worse Clinical Outcome

Neonatal Sepsis: Aetiology, Pathophysiology, Diagnostic Advances and Management Strategies

Neonatal sepsis, a bloodstream infection in the first 28 days of life, is a leading cause of morbidity and mortality among infants in both developing and developed countries. Additionally, sepsis is distinguished in neonates by unique pathophysiological and presentational factors relating to its development in immature neonatal immune systems. This review focuses on the current understanding of the mechanics and implications of neonatal sepsis, providing a comprehensive overview of the epidemiology, aetiology, pathophysiology, major risk factors, signs and symptoms and recent consensus on the diagnosis and management of both early-onset and late-onset neonatal sepsis. It also includes a discussion on novel biomarkers and upcoming treatment strategies for the condition as well as the potential of COVID-19 infection to progress to sepsis in infants.

Profiling the dysregulated immune response in sepsis: overcoming challenges to achieve the goal of precision medicine

Sepsis is characterised by a dysregulated host immune response to infection. Despite recognition of its significance, immune status monitoring is not implemented in clinical practice due in part to the current absence of direct therapeutic implications. Technological advances in immunological profiling could enhance our understanding of immune dysregulation and facilitate integration into clinical practice. In this Review, we provide an overview of the current state of immune profiling in sepsis, including its use, current challenges, and opportunities for progress. We highlight the important role of immunological biomarkers in facilitating predictive enrichment in current and future treatment scenarios. We propose that multiple immune and non-immune-related parameters, including clinical and microbiological data, be integrated into diagnostic and predictive combitypes, with the aid of machine learning and artificial intelligence techniques. These combitypes could form the basis of workable algorithms to guide clinical decisions that make precision medicine in sepsis a reality and improve patient outcomes.

Human Cytomegalovirus pUL11, a CD45 Ligand, Disrupts CD4 T Cell Control of Viral Spread in Epithelial Cells

Human cytomegalovirus (HCMV) encodes numerous immunomodulatory genes that facilitate its persistence. Previously described mechanisms by which HCMV avoids T cell control typically involve evasion of detection by infected cells. Here, we show that the virus also inhibits T cells directly via an interaction between the pUL11 glycoprotein on infected cells and the CD45 phosphatase on T cells. The antiviral functions of CD4 T cells are impaired as a result of this interaction, largely via induced interleukin 10 (IL-10) secretion in the CD4 T cell central memory compartment, resulting in enhanced viral spread. This establishes CD45 as an inhibitory receptor that regulates antiviral T cell functions and has parallels with the manipulation of natural killer (NK) cells by HCMV. By coculturing donor T cells with HCMV-infected epithelial cells, we observed that CD4 T cells can respond to epithelial cell antigen presentation and can control HCMV spread via cytolytic and cytokine-dependent mechanisms. pUL11 impairs both mechanisms. We showed that pUL11-induced IL-10 secretion requires IL-2, mTOR, and T cell receptor signaling. This characterization of the effects of the pUL11-CD45 interaction may allow for the development of new antiviral therapies and treatments for inflammatory disorders. IMPORTANCE Human cytomegalovirus (HCMV) is adept at avoiding its host's immune defenses, both by evading detection and by directly inhibiting immune cells. This can lead to a loss of control of the infection, and dangerous disease can result, particularly in cases in which an individual's immune system is immature, weak, or suppressed. T cells form a crucial part of the response to HCMV and are used in cellular HCMV therapies. We show that an interaction between a viral glycoprotein (pUL11) and a T cell surface receptor (CD45) impairs T cell memory functions and allows for increased viral spread. This defines a new immunomodulatory strategy for the virus as well as a new T cell regulatory mechanism. These results are important, as they increase our understanding of how T cells function and how HCMV disrupts them. This will allow for the development of new antiviral therapies that restore T cell functions and indicates a new target for controlling pathological T cell disorders.

Immune Modulation and Cytomegalovirus Reactivation in Sepsis-induced Immunosuppression: A Pilot Study

Introduction

Sepsis is a life-threatening condition caused due to dysregulated immune response to an infection and progressive immunosuppression. Reactivation of cytomegalovirus (CMV) occurs frequently in sepsis and is found associated with adverse outcomes. The study objective was to evaluate the association between incidence of CMV reactivation and immune alteration in sepsis-induced immunosuppression in patients with prolonged sepsis.

Patients and methods

Patients admitted to intensive care unit (ICU), with severe sepsis and CMV immunoglobulin G (IgG) seropositivity, were prospectively enrolled. Other manifest immune suppression causes were excluded. Samples were collected on enrolment and further once a week until day 21 or death/discharge. CMV viral load was quantified using qPCR. Lymphocyte subset analysis (CD3+, CD4+, CD8+, CD19+, CD16+/CD56+, and CD25+CD127− regulatory T cells), human leukocyte antigen-DR isotype (HLA-DR) expression on monocytes, programmed death-1 (PD-1) expression on T lymphocytes, and proinflammatory (interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ)), anti-inflammatory cytokines levels (IL-2, IL-4, and IL-10) were analyzed by flow cytometry as markers for immunosuppression.

Results

A total of 25 CMV IgG-positive patients and 11 healthy controls were included. CMV reactivation occurred in 20 patients. Patients with CMV reactivation had T-cell lymphopenia. PD-1 expression on CD4+ and CD8+ T cells was markedly elevated (p <0.02) in CMV-reactivated patients compared to nonreactivated patients. HLA-DR expression was significantly low on monocytes in all septic patients (p <0.01) compared to healthy controls. IL-6 levels showed elevation at day 7, whereas IL-10 was found to be significantly higher from day 0 in CMV-reactivated group.

Conclusion

Our study concluded that immune suppression markers and cytokine levels in patients with severe sepsis were found to be significantly associated with the incidence of CMV reactivation.

How to cite this article

Lambe G, Mansukhani D, Khodaiji S, Shetty A, Rodrigues C, Kapadia F. Immune Modulation and Cytomegalovirus Reactivation in Sepsis-induced Immunosuppression: A Pilot Study. Indian J Crit Care Med 2022;26(1):53–61.

NK and CD8+ T cell phenotypes predict onset and control of CMV viremia after kidney transplant

CMV causes mostly asymptomatic but lifelong infection. Primary infection or reactivation in immunocompromised individuals can be life-threatening. CMV viremia often occurs in solid organ transplant recipients and associates with decreased graft survival and higher mortality. Furthering understanding of impaired immunity that allows CMV reactivation is critical to guiding antiviral therapy and examining the effect of CMV on solid organ transplant outcomes. This study characterized longitudinal immune responses to CMV in 31 kidney transplant recipients with CMV viremia and matched, nonviremic recipients. Recipients were sampled 3 and 12 months after transplant, with additional samples 1 week and 1 month after viremia. PBMCs were stained for NK and T cell markers. PBMC transcriptomes were characterized by RNA-Seq. Plasma proteins were quantified by Luminex. CD8⁺ T cell transcriptomes were characterized by single-cell RNA-Seq. Before viremia, patients had high levels of IL-15 with concurrent expansion of immature CD56^bright NK cells. After viremia, mature CD56^dim NK cells and CD28^–CD8⁺ T cells upregulating inhibitory and NK-associated receptors were expanded. Memory NK cells and NK-like CD28^–CD8⁺ T cells were associated with control of viremia. These findings suggest that signatures of innate activation may be prognostic for CMV reactivation after transplant, while CD8⁺ T cell functionality is critical for effective control of CMV.

Surviving Sepsis Campaign: Research Opportunities for Infection and Blood Purification Therapies

Patients with infection can develop sepsis, and their mortality can be high. An important aspect in the treatment of sepsis is adequate management of the infection.

Comparison of Transplantation Outcomes after Foscarnet and Ganciclovir Administration as First-Line Anti-Cytomegalovirus Preemptive Therapy

Ganciclovir (GCV) and foscarnet (FCN) are effective anti-cytomegalovirus (CMV) preemptive therapies; however, the impact of the 2 agents on various clinical outcomes of allogeneic hematopoietic stem cell transplantation (HSCT) remains unclear. We retrospectively analyzed data on 532 patients undergoing allogeneic HSCT from unrelated donors and administered FCN (n = 86) or GCV (n = 446) as first-line anti-CMV preemptive therapy. Overall survival, relapse, and nonrelapse mortality (NRM) did not differ between the FCN and GCV groups, whereas the GCV group had a higher risk of chronic graft-versus-host disease (cGVHD) (hazard ratio [HR], 2.38; 95% confidence interval [CI], 1.28 to 4.39; P = .006) and extensive cGVHD (HR, 3.94; 95% CI, 1.43 to 10.9; P = .008). All 13 patients with cGVHD in the FCN group survived. Switching to the other agent was done mainly due to hematologic adverse events in the GCV group and mainly due to insufficient efficacy in the FCN group. The incidence of end-organ CMV disease was similar in the 2 groups. Selection of FCN or GCV as first-line preemptive anti-CMV therapy did not affect survival, relapse, or NRM. Physicians can select either of the agents, depending on the clinical situation; however, the selection may influence the cGVHD-related clinical course in HSCT recipients.

A 21st Century Evil: Immunopathology and New Therapies of COVID-19

Coronavirus Disease 2019 (COVID-19) has been classified as a global threat, affecting millions of people and killing thousands. It is caused by the SARS-CoV-2 virus, which emerged at the end of 2019 in Wuhan, China, quickly spreading worldwide. COVID-19 is a disease with symptoms that range from fever and breathing difficulty to acute respiratory distress and death, critically affecting older patients and people with previous comorbidities. SARS-CoV-2 uses the angiotensin-converting enzyme 2 (ACE2) receptor and mainly spreads through the respiratory tract, which it then uses to reach several organs. The immune system of infected patients has been demonstrated to suffer important alterations, such as lymphopenia, exhausted lymphocytes, excessive amounts of inflammatory monocytes and macrophages, especially in the lungs, and cytokine storms, which may contribute to its severity and difficulty of establishing an effective treatment. Even though no specific treatment is currently available, several studies have been investigating potential therapeutic strategies, including the use of previously approved drugs and immunotherapy. In this context, this review addresses the interaction between SARS-CoV-2 and the patient's host immune system during infection, in addition to discussing the main immunopathological mechanisms involved in the development of the disease and potential new therapeutic approaches.

Human Cytomegalovirus Interleukin 10 Homologs: Facing the Immune System

Human Cytomegalovirus (HCMV) can cause a variety of health disorders that can lead to death in immunocompromised individuals and neonates. The HCMV lifecycle comprises both a lytic (productive) and a latent (non-productive) phase. HCMV lytic infection occurs in a wide range of terminally differentiated cell types. HCMV latency has been less well-studied, but one characterized site of latency is in precursor cells of the myeloid lineage. All known viral genes are expressed during a lytic infection and a subset of these are also transcribed during latency. The UL111A gene which encodes the viral IL-10, a homolog of the human IL-10, is one of these genes. During infection, different transcript isoforms of UL111A are generated by alternative splicing. The most studied of the UL111A isoforms are cmvIL-10 (also termed the "A" transcript) and LAcmvIL-10 (also termed the "B" transcript), the latter being a well-characterized latency associated transcript. Both isoforms can downregulate MHC class II, however they differ in a number of other immunomodulatory properties, such as the ability to bind the IL10 receptor and induce signaling through STAT3. There are also a number of other isoforms which have been identified which are expressed by differential splicing during lytic infection termed C, D, E, F, and G, although these have been less extensively studied. HCMV uses the viral IL-10 proteins to manipulate the immune system during lytic and latent phases of infection. In this review, we will discuss the literature on the viral IL-10 transcripts identified to date, their encoded proteins and the structures of these proteins as well as the functional properties of all the different isoforms of viral IL-10.