Novel heterozygous PLCG2 variant presenting with very early-onset perianal abscess

Case report Background: Mutations in the PLCG2 gene can cause PLCG2-associated antibody deficiency and immune dysregulation (PLAID) or auto-inflammation with PLCG2-associated antibody deficiency and immune dysregulation (APLAID). PLAID is characterized by urticarial eruptions triggered by evaporative cooling along with cutaneous granulomas. APLAID may present with early-onset skin inflammation and non-infectious granulomas, uveitis, and colitis. Method(s): Case report and literature review. We performed in silico analysis for variants of uncertain significance (VUS). Result(s): A 29-day-old boy presented to emergency department for failure to thrive. He was found to be SARS-CoV2 positive, had an E. coli UTI in the setting of bilateral perinephric masses which subsequently resolved. He also had a perianal soft tissue abscess measuring 4cm in diameter. Mom reported a similar infection when she was age 2. She also reported intermittent diffuse urticaria triggered following perspiration evaporation.Abscess wall histology showed diffuse neutrophil and lymphocytic infiltration, with cultures growing polymicrobial enteric flora. His serum immunoglobulins G, A, M, and E were within reference range. Naive and memory CD4, CD8, CD19 lymphocyte subsets (including NK cells) were also within age-appropriate reference range. He had a normal neutrophil oxidative burst measured using dihydrorhodamine (DHR) flow cytometry following PMA stimulation, which ruled out a diagnosis of chronic granulomatous disease. On evaporative cooling, the patient had a 2mm wheal with surrounding erythema which resolved rapidly with warming. A targeted primary immunodeficiency panel showed a heterozygous VUS in PLCG2, c.688C > G (p.Leu230Val). The variant was absent from major databases and had a calculated CADD score of 17.77. He had symptomatic resolution after completing 3 weeks of ceftriaxone and metronidazole antimicrobials. Given the concern for PLCG2-associated very early-onset inflammatory bowel disease (VEO-IBD), a fecal calprotectin was obtained at 3 months and found to be elevated (157 mcg/g [ < = 49 mcg/g]). However, he had no symptomatic or macroscopic evidence for VEO-IBD. Conclusion(s): Presence of very early onset abscesses has not been previously described in patients with heterozygous PLCG2 deficiency. This case adds to the expanding variable phenotype of PLCG-2-associated immune dysregulation.

A discussion of heat generation during a fever

Fever can be caused by pathogen infection. We analyze the thermogenesis mechanism and reveal that heat is naturally generated during the immune system's fight against pathogen infection. Particularly, the heat production by reactive oxygen species that originates in the respiratory burst significantly contributes to the fever development. This analysis can help address mechanisms of SARS-CoV-2 pathogenesis or provide a foundation for future mechanistic inquiries.Copyright © 2022, Research Trends (P) LTD.. All rights reserved.

COVID-19-INDUCED IMMUNOSUPPRESSION LEADING TO SECONDARY INFECTION AS DISSEMINATED COCCIDIOIDOMYCOSIS

SESSION TITLE: Post-COVID-19 Infection Complications SESSION TYPE: Case Report Posters PRESENTED ON: 10/17/2022 12:15 pm - 01:15 pm INTRODUCTION: Coccidioidomycosis caused by the fungi C. immitis and C. Posadasii is well known to be endemic to the Southwest United States. Less than 1% of these infections will manifest as extrapulmonary symptoms and multiple sites causing dissemination fungemia [1]. Risk factors for disseminated infection include exogenous immunosuppression, immunodeficiency, pregnancy, and ethnic backgrounds of African and Filipino descent [2]. CASE PRESENTATION: A 39-year-old previously immunocompetent Congolese male with recent onset of recurrent skin abscess, and positive testing for COVID-19 three week prior (not treated with steroids). He presents with shortness of breath, back pain, fevers after recently migrating from the Southwest region to the Midwest. Upon admission imaging with Computed Tomography (CT) revealed extensive pulmonary infiltrates (Fig 1), intra-abdominal abscesses, and magnetic resonance imaging revealing (MRI) osteomyelitis of the thoracic (Fig 2) and lumbar spine (Fig 3). His work of breathing continued to worsen, requiring prompt intubation, and he was initiated on a broad-spectrum antimicrobial regimen, including fluconazole, voriconazole, cefepime and vancomycin. Immunoglobulins, HIV and oxidative burst testing was unremarkable. Cultures from image-guided aspiration of the psoas abscess, incision, and drainages of skin abscess and bronchoalveolar lavage fluid were all positive for coccidioidomycosis, transitioned to amphotericin B. Course complicated with the development of multidrug-resistance pseudomonas aerogenes VAP treated with inhaled tobramycin and meropenem. He developed progressive acute respiratory distress syndrome with refractory hypoxemia. After 3 weeks of antimicrobial and anti-fungal treatment, a decision was made to transfer the patient to a lung transplant center, however, due to ongoing fungemia, he was deemed to be not a candidate for extracorporeal membrane exchange and lung transplantation. About a month into his hospitalization, the family decided to withdraw care. DISCUSSION: Reactivation of latent coccidiomycosis has been largely studied in the immunosuppressed population that includes HIV, hematological malignancies, and diabetes mellitus, however little is known about this fungal infection in the immunosuppressed state in the setting of COVID-19. Thus far only two case reports have been reported of co-infection if COVID-19 and pulmonary coccidioidomycosis [3]. The days of the COVID-19 pandemic might contribute to further delays in diagnosing this fungal infection due to similarities of pulmonary manifestation. CONCLUSIONS: This case demonstrates a COVID-19 infection leading to an immunosuppressed status resulting in disseminated infection from reactivation of latent coccidiomycosis. As a result, physicians must maintain a high level of suspicion for superimposed fungal infections in those with even relative immunosuppression from a recent COVID infection. Reference #1: Odio CD, Marciano BE, Galgiani JN, Holland SM. Risk Factors for Disseminated Coccidioidomycosis, United States. Emerg Infect Dis. 2017;23(2):308-311. doi:10.3201/eid2302.160505 Reference #2: Hector RF, Laniado-Laborin R. Coccidioidomycosis–a fungal disease of the Americas. PLoS Med. 2005;2(1):e2. doi:10.1371/journal.pmed.0020002 Reference #3: Shah AS, Heidari A, Civelli VF, et al. The Coincidence of 2 Epidemics, Coccidioidomycosis and SARS-CoV-2: A Case Report. Journal of Investigative Medicine High Impact Case Reports. January 2020. doi:10.1177/2324709620930540 DISCLOSURES: No relevant relationships by Stephen Doyle No relevant relationships by Connor McCalmon No relevant relationships by John Parent No relevant relationships by Jay Patel No relevant relationships by Angela Peraino No relevant relationships by Keval Ray

Intravenous Immunoglobulin but Not Dexamethasone Inhibits Neutrophil Pro-Inflammatory Activity While Maintaining Key Antimicrobial Functions

Rationale. Acute respiratory distress syndrome (ARDS) is a heterogeneous clinical disease. ARDS immunopathology due to lung infection involves an array of immune cells and the importance of granulocytes, and in particular neutrophils and neutrophil extracellular trap production (NETosis), has recently come to light. Despite over 20 well run, randomized, controlled trials, no specific therapies for ARDS are available and mortality remains high. Current treatments for ARDS are primarily limited to supportive therapies, including lung protective ventilation, and in certain situations, systemic steroid administration. Recently, clinical studies adding intravenous immunoglobulin (IVIG), an FDA approved drug, to standard ARDS therapy have shown faster recovery with less severe symptoms, suggesting a complementary beneficial effect, but the mechanism(s) remain unknown. Interestingly, previous in vitro studies found that IVIG can impair some inflammatory pathways in neutrophils. Our study assessed effects of IVIG with and without dexamethasone (a key glucocorticoid used in COVID-19 ARDS) in neutrophils ex vivo and in vivo in COVID-19 patients. Methods. Ex vivo treatment of neutrophils with IVIG or dexamethasone was conducted, followed by assessment of NETosis, oxidative burst and phagocytosis. Additionally, cell-free DNA was quantified in the blood of COVID-19 patients before and after treatment with IVIG. Ex vivo NETosis and plasma cell-free DNA was quantified using the QuantiT ™ PicoGreen™ dsDNA Assay Kit (Invitrogen). Oxidative burst was assessed by OxyBURST™ Green H2DCFDA, SE (Invitrogen) and phagocytosis of pHrodo™ Red S. aureus Bioparticles™ (Invitrogen) was quantified. Results. IVIG inhibits crucial neutrophil inflammatory pathways such as NETosis and oxidative burst while concomitantly enhancing phagocytic activity (Figure panels A-C). Notably, dexamethasone does not impact any of these critical pathways. Moreover, COVID-19 patients undergoing standard treatment plus IVIG had decreased cell-free DNA in the circulation 5 days after initiation of a 4 day treatment course, suggesting decreased NETs in circulation (Figure panel D) which possibly reverted at a later timepoint. Conclusion. Our data demonstrate potential targeted beneficial effects of IVIG in the context of neutrophil-mediated immunopathology. We demonstrate an ex vivo inhibitory effect of IVIG on pro-inflammatory pathways in neutrophils, which may lead to diminished immunopathology in disease states worsened by neutrophil-driven destruction. Based on the compelling evidence of the contribution of neutrophils to development and severity in ARDS, our evidence of IVIG impairing key pro-inflammatory functions in neutrophils (where dexamethasone does not) suggests a theoretical potential complementary beneficial effect of adding IVIG to standard treatment for infection induced ARDS although further research is needed.

Differential Functional Responses of Neutrophil Subsets in Severe COVID-19 Patients.

Neutrophils play a significant role in determining disease severity following SARS-CoV-2 infection. Gene and protein expression defines several neutrophil clusters in COVID-19, including the emergence of low density neutrophils (LDN) that are associated with severe disease. The functional capabilities of these neutrophil clusters and correlation with gene and protein expression are unknown. To define host defense and immunosuppressive functions of normal density neutrophils (NDN) and LDN from COVID-19 patients, we recruited 64 patients with severe COVID-19 and 26 healthy donors (HD). Phagocytosis, respiratory burst activity, degranulation, neutrophil extracellular trap (NET) formation, and T-cell suppression in those neutrophil subsets were measured. NDN from severe/critical COVID-19 patients showed evidence of priming with enhanced phagocytosis, respiratory burst activity, and degranulation of secretory vesicles and gelatinase and specific granules, while NET formation was similar to HD NDN. COVID LDN response was impaired except for enhanced NET formation. A subset of COVID LDN with intermediate CD16 expression (CD16Int LDN) promoted T cell proliferation to a level similar to HD NDN, while COVID NDN and the CD16Hi LDN failed to stimulate T-cell activation. All 3 COVID-19 neutrophil populations suppressed stimulation of IFN-γ production, compared to HD NDN. We conclude that NDN and LDN from COVID-19 patients possess complementary functional capabilities that may act cooperatively to determine disease severity. We predict that global neutrophil responses that induce COVID-19 ARDS will vary depending on the proportion of neutrophil subsets.

Reaction Cycles of Halogen Species in the Immune Defense: Implications for Human Health and Diseases and the Pathology and Treatment of COVID-19.

There is no vaccine or specific antiviral treatment for COVID-19, which is causing a global pandemic. One current focus is drug repurposing research, but those drugs have limited therapeutic efficacies and known adverse effects. The pathology of COVID-19 is essentially unknown. Without this understanding, it is challenging to discover a successful treatment to be approved for clinical use. This paper addresses several key biological processes of reactive oxygen, halogen and nitrogen species (ROS, RHS and RNS) that play crucial physiological roles in organisms from plants to humans. These include why superoxide dismutases, the enzymes to catalyze the formation of H2O2, are required for protecting ROS-induced injury in cell metabolism, why the amount of ROS/RNS produced by ionizing radiation at clinically relevant doses is ~1000 fold lower than the endogenous ROS/RNS level routinely produced in the cell and why a low level of endogenous RHS plays a crucial role in phagocytosis for immune defense. Herein we propose a plausible amplification mechanism in immune defense: ozone-depleting-like halogen cyclic reactions enhancing RHS effects are responsible for all the mentioned physiological functions, which are activated by H2O2 and deactivated by NO signaling molecule. Our results show that the reaction cycles can be repeated thousands of times and amplify the RHS pathogen-killing (defense) effects by 100,000 fold in phagocytosis, resembling the cyclic ozone-depleting reactions in the stratosphere. It is unraveled that H2O2 is a required protective signaling molecule (angel) in the defense system for human health and its dysfunction can cause many diseases or conditions such as autoimmune disorders, aging and cancer. We also identify a class of potent drugs for effective treatment of invading pathogens such as HIV and SARS-CoV-2 (COVID-19), cancer and other diseases, and provide a molecular mechanism of action of the drugs or candidates.