The NAIP-NLRC4 inflammasome senses pathogenic bacteria by recognizing the cytosolic presence of bacterial proteins such as flagellin and type III secretion system (T3SS) subunits. In mice, the NAIP-NLRC4 inflammasome provides robust protection against bacterial pathogens that infect intestinal epithelial cells, including the gastrointestinal pathogen Shigella flexneri. By contrast, humans are highly susceptible to Shigella, despite the ability of human NAIP-NLRC4 to robustly detect Shigella T3SS proteins. Why the NAIP-NLRC4 inflammasome protects mice but not humans against Shigella infection remains unclear. We previously found that human THP-1 cells infected with Shigella lose responsiveness to NAIP-NLRC4 stimuli, while retaining sensitivity to other inflammasome agonists. Using mT3Sf, a "minimal Shigella" system, to express individual secreted Shigella effector proteins, we found that the OspF effector specifically suppresses NAIP-NLRC4-dependent cell death during infection. OspF was previously characterized as a phosphothreonine lyase that inactivates p38 and ERK MAP kinases. We found that p38 was critical for rapid priming of NAIP-NLRC4 activity, particularly in cells with low NAIP-NLRC4 expression. Overall, our results provide a mechanism by which Shigella evades inflammasome activation in humans, and describe a mechanism for rapid priming of the NAIP-NLRC4 inflammasome.

Innate immune recognition of double-stranded RNA (dsRNA) by germline-encoded receptors initiates antiviral defenses, including type I interferon (IFN) production. The inflammasome-forming sensor NLRP1 binds and is activated by dsRNA in a mitogen-activated protein kinase (MAPK) p38-dependent manner. How dsRNA initiates these events to induce NLRP1 inflammasome activation is unclear. Here we demonstrate that both exogenous and cellular dsRNA triggers NLRP1 inflammasome activation downstream of RIG-I/MDA5-MAVS and/or TLR3-TRIF signaling but is independent of type I IFN. In immortalized and primary human keratinocytes, we find that NLRP1 inflammasome activation by dsRNA, including during viral infection, requires the MAPK kinase kinase TAK1. Mechanistically, TAK1-dependent phosphorylation of the NLRP1 N-terminal disordered region is necessary and sufficient for inflammasome activation. Collectively, we reveal TAK1 as a novel activator of the NLRP1 inflammasome, functioning as a critical signaling hub linking NLRP1 to inflammatory responses in the context of viral infection and autoimmunity.

Our previous work demonstrated that CARD8 detects HIV-1 infection by sensing the enzymatic activity of the HIV protease, resulting in CARD8-dependent inflammasome activation (Kulsuptrakul et al., 2023). CARD8 harbors a motif in its N-terminus that functions as a HIV protease substrate mimic, permitting innate immune recognition of HIV-1 protease activity, which when cleaved by HIV protease triggers CARD8 inflammasome activation. Here, we sought to understand CARD8 responses in the context of HIV-1 cell-to-cell transmission via a viral synapse. We observed that cell-to-cell transmission of HIV-1 between infected T cells and primary human monocyte-derived macrophages induces CARD8 inflammasome activation in a manner that is dependent on viral protease activity and largely independent of the NLRP3 inflammasome. Additionally, to further evaluate the viral determinants of CARD8 sensing, we tested a panel of HIV protease inhibitor resistant clones to establish how variation in HIV protease affects CARD8 activation. We identified mutant HIV-1 proteases that differentially cleave and activate CARD8 compared to wildtype HIV-1, thus indicating that natural variation in HIV protease affects not only the cleavage of the viral Gag-Pol polyprotein but also likely impacts innate sensing and inflammation.

To distinguish pathogens from commensals, the intestinal epithelium employs cytosolic innate immune sensors. Activation of the NAIP-NLRC4 inflammasome initiates extrusion of infected intestinal epithelial cells (IEC) upon cytosolic bacterial sensing. We previously reported that activation of the inflammasome in tuft cells, which are primarily known for their role in parasitic infections, leads to the release of prostaglandin D2 (PGD2). We observe that NAIP-NLRC4 inflammasome activation in tuft cells leads to an antibacterial response with increased IL-22 and antimicrobial protein levels within the small intestine, which is dependent on PGD2 signaling. A NKp46+ subset of ILC3 expresses the PGD2 receptor CRTH2 and is the source of the increased IL-22. Inflammasome activation in tuft cells also leads to better control of Salmonella Typhimurium in the distal small intestine. However, tuft cells in the cecum and colon are dispensable for antibacterial immunity. These data support that intestinal tuft cells can also induce antibacterial responses, possibly in a tissue-specific manner.

Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) which is responsible for Coronavirus disease-19 (COVID-19), infects host cells through the cell surface receptor angiotensin-converting enzyme 2 (ACE2) in conjunction with the cell surface transmembrane protease serine 2 (TMPRSS2). In asthmatic patients, mRNA expression of these receptors are shown to be down regulated in upper airways compared to the lower airways.1 Additionally, it is evident that type 2 asthma (T2) inflammation influences the expression of ACE2 and TMPRSS2.2, 3 In the present study, we examined the levels of ACE2 and TMPRSS2 in upper and lower airways and investigated the relationship to T2 inflammation through measures of alarmin cytokines IL-33 and thymic stromal lymphopoietin (TSLP). Bronchial tissue from allergic asthmatics (AA) and healthy controls (HC), and nasal tissue from AA with additional co-morbid allergic rhinitis (AR), and HC (Table S1) was immuno-stained and analyzed by immunofluorescent microscopy for protein expression of ACE2, TMPRSS2, IL-33 and TSLP. Written consent was obtained from all the participants of this study. We found significantly more cells immuno-positive for ACE2 in the bronchial tissue of AA versus bronchial tissue of HC (p <.0001), and versus nasal tissue of AR (p =.007) (Figure 1A). There were significantly more TMPRSS2 immuno-positive cells in nasal tissue of AR compared to HC (p =.002), while co-expression of ACE2 and TMPRSS2 was more frequent in AA versus HC in bronchial tissue (p =.02), but not significantly so in nasal tissue (p =.09) (Figure 1A). IL-33 displayed the same pattern as ACE2, with highest levels measured in the bronchial tissue of AA (Figure 1B). There was a significantly higher number of TSLP immuno-positive cells in bronchial versus nasal tissue, and this was a consistent finding in both the allergic (p =.02) and the HC (p =.002) (Figure 1B). This higher expression of the SARS-CoV-2 receptors as well as alarmin cytokines in allergic tissue, particularly in the bronchial tissue compared to the nasal tissue, is consistent with previous literature demonstrating primary expression of these receptors in bronchial cells, and that ongoing exposure inhaled allergens upregulates alarmin cytokines in asthmatic individuals.3 A similar pattern in the expression of alarmins and SARS-CoV-2 receptors in allergic tissue led us to investigate whether there were any relationships. When including all tissue and donors we observed a weak positive correlation between ACE2 levels and IL-33 and (r = 0.35, p =.01) but not with TSLP. However, in the smaller datasets examining upper and lower airway tissue separately we did not find any significant correlations between the expression of alarmins and ACE2/TMPRSS2 (data not shown); additional experiments are required to explore this observation. Our study is the first to report higher protein levels of ACE2 and TMPRSS2 receptors in in allergic tissue, and these findings are consistent with measurements of RNA in previous studies,1, 4 together suggesting that individuals with allergic airways disease may have a higher number of viral entry receptors in airways compared to HC. Despite these findings, recent data have shown that asthmatic patients have a lower risk of COVID-19 infection.5 These findings could be affected by a variety of factors in asthmatic patients including increased mucus production and susceptibility and exposure of S1/S2 cleavage site to proteases, but other factors such as age, sex, genetic predisposition, expression of non-functional isoform of the ACE2 receptor, and different SARS-CoV-2 variants could also play a role.6 Our staining antibodies are unable to distinguish between the long and short isoforms of the ACE2 receptor, and additional research is required to explore whether asthmatic patients possess a higher prevalence of the short isoform. Overall, further research is needed to fully understand the mechanisms underlying the lower risk of COVID-19 in asthmatic patients, which may have important implications for the management of COVID-19 in individuals with allergic airway disease. All authors contributed to the study design, acquisition or analysis of data, were involved with drafting of this manuscript, and approved the final version and are accountable for all aspects of the work. We would like to acknowledge funding from AstraZeneca Canada (ESR 20-20723) and Mitacs (IT22844). The authors have no conflict of interest related to this manuscript. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. Data S1. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Journal Article Persistent diaphragmatic weakness and peripheral muscle weakness are associated with anosmia in the long-COVID syndrome Get access S O’Brien, S O’Brien Formal analysis, Investigation, Methodology, Writing - original draft, Writing - review & editing From the Department of Medicine, Tallaght University Hospital, Dublin, IrelandSchool of Medicine, Trinity College Dublin, Dublin, Ireland Address correspondence to Shane O’Brien, Department of Medicine, Tallaght University Hospital, Dublin, Ireland. email: obries71@tcd.ie https://orcid.org/0000-0001-5009-9350 Search for other works by this author on: Oxford Academic PubMed Google Scholar C Buckley, C Buckley Data curation, Investigation, Project administration From the Department of Medicine, Tallaght University Hospital, Dublin, IrelandSchool of Medicine, Trinity College Dublin, Dublin, Ireland Search for other works by this author on: Oxford Academic PubMed Google Scholar T Butler, T Butler Formal analysis, Investigation, Software From the Department of Medicine, Tallaght University Hospital, Dublin, IrelandSchool of Medicine, Trinity College Dublin, Dublin, Ireland Search for other works by this author on: Oxford Academic PubMed Google Scholar Z Cunningham, Z Cunningham Data curation, Investigation, Project administration From the Department of Medicine, Tallaght University Hospital, Dublin, IrelandSchool of Medicine, Trinity College Dublin, Dublin, Ireland Search for other works by this author on: Oxford Academic PubMed Google Scholar S Keane, S Keane Data curation, Investigation, Project administration From the Department of Medicine, Tallaght University Hospital, Dublin, IrelandSchool of Medicine, Trinity College Dublin, Dublin, Ireland Search for other works by this author on: Oxford Academic PubMed Google Scholar E McArdle, E McArdle Data curation, Investigation, Project administration From the Department of Medicine, Tallaght University Hospital, Dublin, IrelandSchool of Medicine, Trinity College Dublin, Dublin, Ireland Search for other works by this author on: Oxford Academic PubMed Google Scholar P Mitchell, P Mitchell Funding acquisition, Investigation, Methodology, Resources, Supervision, Writing - review & editing From the Department of Medicine, Tallaght University Hospital, Dublin, IrelandSchool of Medicine, Trinity College Dublin, Dublin, Ireland https://orcid.org/0000-0001-5705-9618 Search for other works by this author on: Oxford Academic PubMed Google Scholar S C Donnelly S C Donnelly Conceptualization, Formal analysis, Funding acquisition, Investigation, Methodology, Resources, Supervision, Writing - review & editing From the Department of Medicine, Tallaght University Hospital, Dublin, IrelandSchool of Medicine, Trinity College Dublin, Dublin, Ireland Search for other works by this author on: Oxford Academic PubMed Google Scholar QJM: An International Journal of Medicine, Volume 116, Issue 7, July 2023, Pages 603–604, https://doi.org/10.1093/qjmed/hcad025 Published: 16 February 2023 Article history Received: 01 February 2023 Revision received: 08 February 2023 Published: 16 February 2023 Corrected and typeset: 02 March 2023

ABSTRACT Pathogenesis of Pseudomonas aeruginosa infections can include bacterial survival inside epithelial cells. Previously, we showed that this involves multiple roles played by the type three secretion system (T3SS), and specifically the effector ExoS. This includes ExoS-dependent inhibition of a lytic host cell response that subsequently enables intracellular replication. Here, we studied the underlying cell death response to intracellular P. aeruginosa, comparing wild-type to T3SS mutants varying in capacity to induce cell death and that localize to different intracellular compartments. Results showed that corneal epithelial cell death induced by intracellular P. aeruginosa lacking the T3SS, which remains in vacuoles, correlated with the activation of nuclear factor-κB as measured by p65 relocalization and tumor necrosis factor alpha transcription and secretion. Deletion of caspase-4 through CRISPR-Cas9 mutagenesis delayed cell death caused by these intracellular T3SS mutants. Caspase-4 deletion also countered more rapid cell death caused by T3SS effector-null mutants still expressing the T3SS apparatus that traffic to the host cell cytoplasm, and in doing so rescued intracellular replication normally dependent on ExoS. While HeLa cells lacked a lytic death response to T3SS mutants, it was found to be enabled by interferon gamma treatment. Together, these results show that epithelial cells can activate the noncanonical inflammasome pathway to limit proliferation of intracellular P. aeruginosa, not fully dependent on bacterially driven vacuole escape. Since ExoS inhibits the lytic response, the data implicate targeting of caspase-4, an intracellular pattern recognition receptor, as another contributor to the role of ExoS in the intracellular lifestyle of P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa can exhibit an intracellular lifestyle within epithelial cells in vivo and in vitro. The type three secretion system (T3SS) effector ExoS contributes via multiple mechanisms, including extending the life of invaded host cells. Here, we aimed to understand the underlying cell death inhibited by ExoS when P. aeruginosa is intracellular. Results showed that intracellular P. aeruginosa lacking T3SS effectors could elicit rapid cell lysis via the noncanonical inflammasome pathway. Caspase-4 contributed to cell lysis even when the intracellular bacteria lacked the entire T33S and were consequently unable to escape vacuoles, representing a naturally occurring subpopulation during wild-type infection. Together, the data show the caspase-4 inflammasome as an epithelial cell defense against intracellular P. aeruginosa, and implicate its targeting as another mechanism by which ExoS preserves the host cell replicative niche.

Inflammasomes are cytosolic innate immune complexes that assemble upon detection of diverse pathogen-associated cues and play a critical role in host defense and inflammatory pathogenesis. Here, we find that the human inflammasome-forming sensor CARD8 senses HIV-1 infection via site-specific cleavage of the CARD8 N-terminus by the HIV protease (HIV-1PR). HIV-1PR cleavage of CARD8 induces pyroptotic cell death and the release of pro-inflammatory cytokines from infected cells, processes regulated by Toll-like receptor stimulation prior to viral infection. In acutely infected cells, CARD8 senses the activity of both de novo translated HIV-1PR and packaged HIV-1PR that is released from the incoming virion. Moreover, our evolutionary analyses reveal that the HIV-1PR cleavage site in human CARD8 arose after the divergence of chimpanzees and humans. Although chimpanzee CARD8 does not recognize proteases from HIV or simian immunodeficiency viruses from chimpanzees (SIVcpz), SIVcpz does cleave human CARD8, suggesting that SIVcpz was poised to activate the human CARD8 inflammasome prior to its cross-species transmission into humans. Our findings suggest a unique role for CARD8 inflammasome activation in response to lentiviral infection of humans.

PDF file - 2066K, S1. MiR-103 and miR-107 inhibit DNA damage-induced RAD51 foci formation in cancer cells. S2. MiR-103 and miR-107 promote chemosensitivity in U2OS cells. S3. MiR-103 and miR-107 promote chemosensitivity to cisplatin and a PARP inhibitor in HeLa and PEO1 C4-2 cells. S4. MiR-107 promotes chemosensitivity in H1299, HeLa and PEO1 C4-2 cells. S5. MiR-103 and miR-107 regulate RAD51 and RAD51D. S6. RAD51 is critical for cellular resistance to cisplatin and a PARP inhibitor. S7. RAD51 downregulation is critical for miR-103/107-mediated regulation of HR. S8. RAD51D downregulation is relevant to miR-103/107-mediated chemosensitivity. S9. Inhibition of miR-103 and miR-107 mildly de-represses RAD51D expression. S10. MiR-103 and miR-107 are inversely correlated with RAD51D mRNA expression in several tumor subtypes. Table S1. Summary of library screening to identify microRNAs that regulate IR-induced RAD51 foci formation. Table S2. Correlation between miR-103 or miR-107 and target gene expression in the NCI-60 panel of cancer cell lines. Table S3. Correlation between miR-103 or miR-107 and target gene expression in several tumor subtypes from TCGA.

XLSX file - 86K, Summary of TCGA sample patient information used in correlation analyses.

Hosts have evolved diverse strategies to respond to microbial infections, including the detection of pathogen-encoded proteases by inflammasome-forming sensors such as NLRP1 and CARD8. Here, we find that the 3CL protease (3CL(pro)) encoded by diverse coronaviruses, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), cleaves a rapidly evolving region of human CARD8 and activates a robust inflammasome response. CARD8 is required for cell death and the release of pro-inflammatory cytokines during SARS-CoV-2 infection. We further find that natural variation alters CARD8 sensing of 3CL(pro), including 3CL(pro)-mediated antagonism rather than activation of megabat CARD8. Likewise, we find that a single nucleotide polymorphism (SNP) in humans reduces CARD8's ability to sense coronavirus 3CL(pros) and, instead, enables sensing of 3C proteases (3C(pro)) from select picornaviruses. Our findings demonstrate that CARD8 is a broad sensor of viral protease activities and suggests that CARD8 diversity contributes to inter- and intraspecies variation in inflammasome-mediated viral sensing and immunopathology.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilizes the angiotensin-converting enzyme 2 (ACE2) receptor in conjunction with the cell surface transmembrane protease serine 2 (TMPRSS2) to enter host cells.1 The type 2 (T2) cytokine IL-13 has been shown to downregulate ACE2 mRNA levels in cultured epithelial cells of asthmatic donors,2, 3 however, whether environmental triggers causing elevated airway IL-13 levels in vivo translates to changes in protein levels in asthmatic airways is unknown. By immunofluorescence microscopy, we assessed protein expression of ACE2 and TMPRSS2 under T2 high conditions after allergen challenge of the upper and lower airways of subjects with allergic asthmatics and allergic rhinitis, respectively (Table S1 Supporting Information). The study was approved by the Hamilton Integrated Research Ethics Board, and participants provided informed written consent. Eleven participants with mild allergic asthma (FEV1 ≥ 70% predicted, methacholine PC20 ≤ 16 mg/mL, skin prick test positive) underwent whole lung allergen inhalation challenges (AIC), resulting in early and late bronchoconstriction responses, sputum eosinophilia (Figure 1A,B), and increased sputum eotaxin-1, eosinophil-derived neurotoxin (EDN) and the T2 cytokines IL-5, and IL-13 post-challenge (p < .05) (Table S2 supplementary material). Ten participants underwent a second AIC using the same dose of allergen, and endobronchial biopsies were obtained before and again at 24 h post-AIC. There was a significant reduction in the number of bronchial tissue cells immuno-positive for ACE2, TMPRSS2, and double positive for ACE2/TMPRSS2 (p = .002, p = .014, p = .002, respectively) measured 24 h post-AIC (Figure 1C,D). There was no correlation between SARS-CoV-2 receptor immuno-positive cells and levels of biomarkers in sputum. Ten allergic asthmatics with co-morbid allergic rhinitis completed a crossover study with nasal allergen challenge (NAC) conducted after 21 days of intranasal placebo or triamcinolone (220 mcg BID) treatment. The NAC-induced changes in peak nasal inspiratory flow rate, nasal lavage eosinophils (Figure 2A,B) IL-5, IL-13, and eotaxin-1 (Table S2 Supporting Information) observed during placebo treatment were all significantly attenuated by triamcinolone (p < .05). In biopsies of inferior nasal turbinate, NAC did not change the number of cells immuno-positive for ACE2 or TMPRSS2 (Figure 2C,D), and we did not observe a relationship between immunopositivity for ACE2, TMPRSS2, and biomarkers in nasal lavage. Previous studies have reported that nasal and bronchial allergen challenges lower ACE2 mRNA transcript in epithelium of nasal and bronchial brushing, respectively.3 Using in vitro model data sourced from Gene Expression Omnibus, Jackson et al found that IL-13 reduced ACE2 mRNA expression in differentiated nasal and bronchial epithelium. Using cultured primary human bronchial epithelial cells Stocker et al reported that IL-13 decreases long ACE2 mRNA isoforms and reduces glycosylation of full length ACE2 protein, thereby limiting expression on the apical side of ciliated cells exposed to viral infection.2 We therefore hypothesized that elevation of IL-13 levels after allergen challenge and lowering of IL-13 with corticosteroid treatment would correspondingly regulate ACE2 protein expression in airways. Indeed, ACE2 and TMPRSS2 immunopositivity was significantly reduced in bronchial tissue after AIC. In nasal tissue, however, interpretation of the data is inconclusive due to low ACE2 and TMPRSS2 protein levels measured at baseline in inferior nasal turbinate tissue, and by the small study sample size. The proposed protective mechanisms of IL-13 raise the possibility that T2 high airways may be protective against SARS-CoV-2, but to date, this has not been supported by clinical observations. In general populations, there is no clear association between asthma and SARS-CoV-2 infectivity or hospitalization.4, 5 Counterintuitive to a proposed protective role of IL-13, treatment with dupilumab, a monoclonal antibody that blocks IL-13 signaling, was reported to improve survival in asthmatic patients compared with matched controls after SARS-CoV-2 infection.6 Collectively, these data suggest that despite dampening of ACE2 and TMPRSS2 receptor expression in airways by IL-13, there are other factors contributing meaningfully to the rate of SARS-CoV-2 infectivity and hospitalization in asthmatic patients. All authors contributed to the study design, acquisition or analysis of data, were involved with drafting of this manuscript, and approved the final version and are accountable for all aspects of the work. We would like to acknowledge funding from AstraZeneca Canada (ESR 20-20723) and Mitacs (IT22844). The authors have no conflict of interest related to this manuscript. Outside of this work, MD reports research funding from Gilead and Janssen; DDS reports Advisory Board, research funding, speaking fees from GSK, Sanofi, Stryker; PMB reports personal fees for consulting or speaker fees from AstraZeneca, GSK, MedImmune, Chiesi, Menarini and Covis and research grants from AstraZeneca, MedImmune, Biohaven, Merck and Bayer; GMG reports personal fees for consulting or speaker fees from AstraZeneca, Sanofi–Regeneron and research grants from Biohaven, Genentech, BioGaia, Novartis. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. Data S1. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

In this issue of JEM, companion articles from Pinilla et al. (2023. J. Exp. Med.https://doi.org/10.1084/jem.20230104) and Robinson et al. (2023. J. Exp. Med.https://doi.org/10.1084/jem.20230105) demonstrate that ribotoxic stress induced by Pseudomonas aeruginosa and Corynebacterium diphtheriae EEF2-targeting exotoxins leads to NLRP1 inflammasome activation, representing a new mechanism of effector-triggered immunity.

Background Patients with severe asthma may present with characteristics representing overlapping phenotypes, making them eligible for more than one class of biologic. Our aim was to describe the profile of severe adult asthma patients eligible for both anti-IgE and anti-IL5/5R and to compare the effectiveness of both classes of treatment in real life. Methods This was a prospective cohort study that included adult severe asthma patients from 22 countries enrolled into the International Severe Asthma registry (ISAR) who were eligible for both anti-IgE and anti-IL5/5R. The effectiveness of anti-IgE and anti-IL5/5R was compared in a 1:1 matched cohort. Exacerbation rate was the primary effectiveness endpoint. Secondary endpoints included long-term-oral corticosteroid (LTOCS) use, asthma-related emergency room (ER) attendance and hospital admissions. Results In the matched analysis (n=350/group), the mean annualized exacerbation rate decreased by 47.1% in the anti-IL5/5R group and 38.7% in the anti-IgE group. Patients treated with anti-IL5/5R were less likely to experience a future exacerbation (adjusted IRR 0.76; 95% CI 0.64, 0.89; p<0.001) and experienced a greater reduction in mean LTOCS dose than those treated with anti-IgE (37.44% vs 20.55% reduction; p=0.023).) There was some evidence to suggest that patients treated with anti-IL5/5R experienced fewer asthma-related hospitalizations (IRR 0.64; 95% CI 0.38, 1.08), but not ER visits (IRR 0.94, 95% CI 0.61, 1.43). Conclusions In real life, both anti-IgE and anti-IL5/5R improve asthma outcomes in patients eligible for both biologic classes, however anti-IL5/5R was superior in terms of reducing asthma exacerbations and LTOCS use.

Introduction: Anosmia has emerged as a clinical feature of Covid-19. It is estimated over half of patients with Covid-19 report anosmia. It is primarily transient, but can persist over a month in around 20% of cases. There is a hypothetical interaction between hypovitaminosis D and diminished smell. A deficiency may lead to neurologic decline in cranial nerves, including the olfactory nerve. Few studies investigating this are available. Loss of smell is a common occurrence through adulthood, with many physiologic and anatomic contributing factors. Limited data is available addressing anosmia post Covid-19. Aims: To assess the correlation between vitamin D (VD) and anosmia, in patients referred to post acute COVID syndrome (PACS) clinic, and to assess the variation of data across age groups. Methods: A “Sniffin’ Sticks” test was undertaken for all patients referred to the PACS clinic. This was correlated with a recent serum VD level. Results: 143 patients presented to the PACS clinic over a 10 month period. 84% were under 65 years. 60% of these patients who developed anosmia were found to have VD insufficiency. A similar proportion of patients with hyposmia, and patients with normal smell were found to be VD insufficient (36% vs 34.7%). Within the older cohort, none of the patients with anosmia were deficient in VD, and 7.7% of patients with smell dysfunction had insufficiency. Conclusion: There is an association between anosmia and VD deficiency in patients under 65 years of age seen at PACS clinic. This did not reflect in the cohort with hyposmia. In the older age group, the majority of patients had normal VD levels, which may indicate other contributing factors towards the decrease in smell.