Severe coronavirus disease 2019 (COVID-19) can occur in younger, predominantly male, patients without preexisting medical conditions. Some individuals may have primary immunodeficiencies that ...predispose to severe infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
To explore the presence of genetic variants associated with primary immunodeficiencies among young patients with COVID-19.
Case series of pairs of brothers without medical history meeting the selection criteria of young (age <35 years) brother pairs admitted to the intensive care unit (ICU) due to severe COVID-19. Four men from 2 unrelated families were admitted to the ICUs of 4 hospitals in the Netherlands between March 23 and April 12, 2020. The final date of follow-up was May 16, 2020. Available family members were included for genetic variant segregation analysis and as controls for functional experiments.
Severe COVID-19.
Results of rapid clinical whole-exome sequencing, performed to identify a potential monogenic cause. Subsequently, basic genetic and immunological tests were performed in primary immune cells isolated from the patients and family members to characterize any immune defects.
The 4 male patients had a mean age of 26 years (range, 21-32), with no history of major chronic disease. They were previously well before developing respiratory insufficiency due to severe COVID-19, requiring mechanical ventilation in the ICU. The mean duration of ventilatory support was 10 days (range, 9-11); the mean duration of ICU stay was 13 days (range, 10-16). One patient died. Rapid clinical whole-exome sequencing of the patients and segregation in available family members identified loss-of-function variants of the X-chromosomal TLR7. In members of family 1, a maternally inherited 4-nucleotide deletion was identified (c.2129_2132del; p.Gln710Argfs*18); the affected members of family 2 carried a missense variant (c.2383G>T; p.Val795Phe). In primary peripheral blood mononuclear cells from the patients, downstream type I interferon (IFN) signaling was transcriptionally downregulated, as measured by significantly decreased mRNA expression of IRF7, IFNB1, and ISG15 on stimulation with the TLR7 agonist imiquimod as compared with family members and controls. The production of IFN-γ, a type II IFN, was decreased in patients in response to stimulation with imiquimod.
In this case series of 4 young male patients with severe COVID-19, rare putative loss-of-function variants of X-chromosomal TLR7 were identified that were associated with impaired type I and II IFN responses. These preliminary findings provide insights into the pathogenesis of COVID-19.
Interleukin-1 (IL-1) is a highly active pro-inflammatory cytokine that lowers pain thresholds and damages tissues. Monotherapy blocking IL-1 activity in autoinflammatory syndromes results in a rapid ...and sustained reduction in disease severity, including reversal of inflammation-mediated loss of sight, hearing and organ function. This approach can therefore be effective in treating common conditions such as post-infarction heart failure, and trials targeting a broad spectrum of new indications are underway. So far, three IL-1-targeted agents have been approved: the IL-1 receptor antagonist anakinra, the soluble decoy receptor rilonacept and the neutralizing monoclonal anti-IL-1β antibody canakinumab. In addition, a monoclonal antibody directed against the IL-1 receptor and a neutralizing anti-IL-1α antibody are in clinical trials.
Epigenetic reprogramming of myeloid cells, also known as trained immunity, confers nonspecific protection from secondary infections. Using histone modification profiles of human monocytes trained ...with the Candida albicans cell wall constituent β-glucan, together with a genome-wide transcriptome, we identified the induced expression of genes involved in glucose metabolism. Trained monocytes display high glucose consumption, high lactate production, and a high ratio of nicotinamide adenine dinucleotide (NAD(+)) to its reduced form (NADH), reflecting a shift in metabolism with an increase in glycolysis dependent on the activation of mammalian target of rapamycin (mTOR) through a dectin-1-Akt-HIF-1α (hypoxia-inducible factor-1α) pathway. Inhibition of Akt, mTOR, or HIF-1α blocked monocyte induction of trained immunity, whereas the adenosine monophosphate-activated protein kinase activator metformin inhibited the innate immune response to fungal infection. Mice with a myeloid cell-specific defect in HIF-1α were unable to mount trained immunity against bacterial sepsis. Our results indicate that induction of aerobic glycolysis through an Akt-mTOR-HIF-1α pathway represents the metabolic basis of trained immunity.
COVID-19 patients can present with pulmonary edema early in disease. We propose that this is due to a local vascular problem because of activation of bradykinin 1 receptor (B1R) and B2R on ...endothelial cells in the lungs. SARS-CoV-2 enters the cell via ACE2 that next to its role in RAAS is needed to inactivate des-Arg9 bradykinin, the potent ligand of the B1R. Without ACE2 acting as a guardian to inactivate the ligands of B1R, the lung environment is prone for local vascular leakage leading to angioedema. Here, we hypothesize that a kinin-dependent local lung angioedema via B1R and eventually B2R is an important feature of COVID-19. We propose that blocking the B2R and inhibiting plasma kallikrein activity might have an ameliorating effect on early disease caused by COVID-19 and might prevent acute respiratory distress syndrome (ARDS). In addition, this pathway might indirectly be responsive to anti-inflammatory agents.
A guide to immunotherapy for COVID-19 van de Veerdonk, Frank L; Giamarellos-Bourboulis, Evangelos; Pickkers, Peter ...
Nature medicine,
01/2022, Volume:
28, Issue:
1
Journal Article
Peer reviewed
Open access
Immune dysregulation is an important component of the pathophysiology of COVID-19. A large body of literature has reported the effect of immune-based therapies in patients with COVID-19, with some ...remarkable successes such as the use of steroids or anti-cytokine therapies. However, challenges in clinical decision-making arise from the complexity of the disease phenotypes and patient heterogeneity, as well as the variable quality of evidence from immunotherapy studies. This Review aims to support clinical decision-making by providing an overview of the evidence generated by major clinical trials of host-directed therapy. We discuss patient stratification and propose an algorithm to guide the use of immunotherapy strategies in the clinic. This will not only help guide treatment decisions, but may also help to design future trials that investigate immunotherapy in other severe infections.
Summary
Over the last decades, there was increasing evidence for the presence of innate immune memory in living organisms. In this review, we compare the innate immune memory of various organisms ...with a focus on phylogenetics. We discuss the acquisition and molecular basis of immune memory and we describe the innate immune memory paradigm and its role in host defense during evolution. The molecular characterization of innate immunological memory in diverse organisms and host‐parasite systems reconciles mechanisms with phenomena and paves the way to molecular comprehension of innate immune memory. We also revise the traditional classification of innate and adaptive immunity in jawed vertebrates. We emphasize that innate immune responses have the capacity to be “primed” or “trained”, thereby exerting a yet unknown type of immunological memory upon re‐infection.
Chronic mucocutaneous candidiasis (CMC) is characterized by susceptibility to candida infection of skin, nails, and mucous membranes. Patients with recessive CMC and autoimmunity have mutations in ...the autoimmune regulator AIRE. The cause of autosomal dominant CMC is unknown.
We evaluated 14 patients from five families with autosomal dominant CMC. We incubated their peripheral-blood mononuclear cells with different combinations of stimuli to test the integrity of pathways that mediate immunity, which led to the selection of 100 genes that were most likely to contain the genetic defect. We used an array-based sequence-capture assay, followed by next-generation sequencing, to identify mutations.
The mononuclear cells from the affected patients were characterized by poor production of interferon-γ, interleukin-17, and interleukin-22, suggesting that the defect lay within the interleukin-12 receptor and interleukin-23 receptor signaling pathways. We identified heterozygous missense mutations in the DNA sequence encoding the coiled-coil (CC) domain of signal transducer and activator of transcription 1 (STAT1) in the patients. These mutations lead to defective responses in type 1 and type 17 helper T cells (Th1 and Th17). The interferon-γ receptor pathway was intact in these patients.
Mutations in the CC domain of STAT1 underlie autosomal dominant CMC and lead to defective Th1 and Th17 responses, which may explain the increased susceptibility to fungal infection. (Funded by the Netherlands Organization for Scientific Research and others.).
Induction, production, and release of proinflammatory cytokines are essential steps to establish an effective host defense. Cytokines of the interleukin-1 (IL-1) family induce inflammation and ...regulate T lymphocyte responses while also displaying homeostatic and metabolic activities. With the exception of the IL-1 receptor antagonist, all IL-1 family cytokines lack a signal peptide and require proteolytic processing into an active molecule. One such unique protease is caspase-1, which is activated by protein platforms called the inflammasomes. However, increasing evidence suggests that inflammasomes and caspase-1 are not the only mechanism for processing IL-1 cytokines. IL-1 cytokines are often released as precursors and require extracellular processing for activity. Here we review the inflammasome-independent enzymatic processes that are able to activate IL-1 cytokines, paying special attention to neutrophil-derived serine proteases, which subsequently induce inflammation and modulate host defense. The inflammasome-independent processing of IL-1 cytokines has important consequences for understanding inflammatory diseases, and it impacts the design of IL-1-based modulatory therapies.
The immune response to Candida species is shaped by the commensal character of the fungus. There is a crucial role for discerning between colonization and invasion at mucosal surfaces, with the ...antifungal host defence mechanisms used during mucosal or systemic infection with Candida species differing substantially. Here, we describe how innate sensing of fungi by pattern recognition receptors and the interplay of immune cells (both myeloid and lymphoid) with non-immune cells, including platelets and epithelial cells, shapes host immunity to Candida species. Furthermore, we discuss emerging data suggesting that both the innate and adaptive immune systems display memory characteristics after encountering Candida species.
Abstract Adaptive features of innate immunity, also termed ‘ trained immunity ’, have recently been shown to characterize monocytes of BCG vaccinated healthy volunteers. Trained immunity leads to ...increased cytokine production in response to non-related pathogens via epigenetic reprogramming of monocytes. Recently, memory-like properties were also observed in NK cells during viral infections, but it is unknown if memory properties of NK cells contribute to trained immunity due to BCG vaccination. BCG vaccination of healthy volunteers increased proinflammatory cytokine production following ex vivo stimulation of NK cells with mycobacteria and other unrelated pathogens up until at least three months after vaccination. In addition, in a murine model of disseminated candidiasis, BCG vaccination led to an increased survival in SCID mice, which was partially dependent on NK cells. These findings suggest that NK cells may contribute to the non-specific (heterologous) beneficial effects of BCG vaccination.
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