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COVID-19 vaccine research in immune-deficient/disordered people (IDP) has primarily focused on cancer and organ transplantation populations. We followed 195 IDP with varied immune disorders and 35 healthy volunteers (HV) from April 2021-April 2022. Anti-spike IgG and angiotensin-converting enzyme 2 pseudo-neutralization were measured though six months post-dose 3. Anti-spike IgG was detected in 93% of IDP by six months post-dose 3. IgG dynamics in IDP and HV were similar, though median IgG levels for IDP were <33% of HV at all timepoints. IgG concentrations were lower against Omicron BA.1 than other variants at all timepoints. Pseudo-neutralization capacity was modestly correlated with anti-spike IgG concentration, but was especially low for Omicron BA.1. Post-vaccination adverse events were minimal. Results were largely unaffected by participants’ immunomodulatory medication and treatments. COVID-19 vaccines are safe, induce anti-spike IgG in most IDP, and should be more strongly recommended for people with immunodeficiencies.

Background Candida albicans is the single most common human fungal pathogen, and invasive candida infections carry a mortality rate of about 25%. C. albicans possesses a range of iron acquisition mechanisms that contribute to its persistence, and virulence. Patients with fungal infection have substantially increased transferrin saturation and serum iron concentrations independent of underlying hematological disorder, suggesting that host iron handling is critical to the outcome of the infection. Using a murine model of systemic iron overload, we investigated whether C.albicans-induced pathology is influenced by iron availability. Experiment Iron overloaded hepcidin knockout (Hamp−/−) and wild type (WT) litter mates were infected with C. albicans SC5314 and outcomes of infection were evaluated after 3 days. Results Compared to WT mice, Hamp−/− mice displayed increased renal fungal burden, had more renal injury, inflammation and mortality. C. albicans was in yeast form in the kidneys of WT mice but had transformed into hyphae in the iron rich renal tubular segments of Hamp−/− mice. Despite the greater pathogen burden, kidneys of Hamp−/− mice had reduced numbers of neutrophils with increased expression of p21. Conclusion Our data identify systemic iron overload as a susceptibility factor to C. albicans induced renal failure. Hepcidin deficiency was associated with increased renal iron burden and transformation of yeast into hyphae, suggesting increased virulence. Increased p21 expression in neutrophils suggests impaired NETosis and may possibly explain increased fungal burden. Our data highlight importance of dysregulated iron metabolism in disseminating candidiasis.

Background Patients receiving the Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib have an increased likelihood of systemic and central nervous system (CNS) fungal infections. Previous work has shown that BTK knockout (KO) mice have more severe Aspergillus infection compared to wild-type (WT) mice. We sought to determine: 1) if blocking BTK impacted Cryptococcus infection; 2) if the effect was strain-dependent; and 3) if the blood-brain barrier was impaired in BTK KO mice. Methods BTK KO C57 breeding pairs were obtained from Dr. Lionakis (NIH) and expanded in the Duke Breeding Core. We collected 4 clinical C. neoformans isolates from patients who developed cryptococcosis on ibrutinib and used virulent and avirulent control strains (H99 and A1-35-8, respectively). The following doses were used for infection: 1) 5x104 yeast for intranasal (IN); 2) 5x104 for oropharyngeal aspiration (OPA); and 3) 0.1 mL of 5x105 CFU/mL for tail vein injection. Mice were sacrificed on day 7 (IN infection, 6 infection strains; N=35 WT, 80 KO) and day 14 post-infection (OPA infection H99 only; N=15 WT, 20 KO). Lung and brain tissues were collected for yeast census. For tail vein injection, mice were sacrificed 48 hours post-infection (H99 only; N=10 WT, 8 KO). Yeast census was measured by colony forming units (CFUs) per gram of tissue weight. Survival experiments through day 28 were performed for OPA infection with H99 (N=12 WT, 17 KO) and analyzed by Kaplan Meier Curve. Results We observed no difference in infection severity as measured by lung and brain yeast census at days 7 and 14 post-infection or difference in survival between BTK KO and WT mice (Figure 1). We also did not observe a distinct pattern based on Cryptococcus strain to suggest that infection severity was strain-dependent (Figure 1A-B). For tail vein infection, there was no difference in brain yeast census at 48 hours post-infection (Figure 1F). Figure 1. Yeast Census and Survival. A) Lung yeast census day 7 post-intranasal infection with 6 clinical strains and 2 control strains; B) Brain yeast census day 7 post-intranasal infection with 6 clinical strains and 2 control strains; C) Lung yeast census day 14 post infection by oropharyngeal aspiration with H99; D) Brain yeast census day 14 post infection by oropharyngeal aspiration with H99; E) 28 day survival post-infection by oropharyngeal aspiration with H99; F) Brain yeast census 48 hours post infection by tail vein injection. Conclusion Our results in mice suggest that Ibrutinib target BTK is not a major contributing factor for controlling Cryptococcus, and that human susceptibility to cryptococcosis and CNS infection may be due to an off-target effect of ibrutinib. Future work will focus on pharmacologic inhibition of BTK with ibrutinib to determine if the off-target effects of the drug increase risk for cryptococcosis. Disclosures Julia A. Messina, MD, MHS, MS, Uptodate (Other Financial or Material Support) Julia A. Messina, MD, MHS, MS, Uptodate (Individual(s) Involved: Self): Author, Other Financial or Material Support John R. Perfect, MD, Astellas Pharma, Inc. (Consultant, Grant/Research Support, Other Financial or Material Support, Honorarium)Basilea (Consultant, Grant/Research Support)Enzon (Consultant, Grant/Research Support)F2G (Consultant, Grant/Research Support)Merck (Consultant, Research Grant or Support)MethylGene (Consultant, Grant/Research Support)Pfizer, Inc. (Consultant, Grant/Research Support)Schering-Plough Corp. (Consultant, Grant/Research Support)

Lysosomal storage diseases (LSDs) are a large family of inherited disorders characterized by abnormal endolysosomal accumulation of cellular material due to catabolic enzyme or transporter deficiencies. Depending on the affected metabolic pathway, these diseases manifest with somatic or central nervous system signs and symptoms. Neuroinflammation is a hallmark feature of LSDs with neurologic involvement such as mucolipidosis type IV (Mcoln1) or Niemann-Pick disease, type C1 (Npc1), but not Fabry disease (Gla). We investigated the properties of microglia from these three disorders using mouse models and a combination of flow cytometric, RNA sequencing, biochemical and immunofluorescence analyses. Stored material is present in the microglia of the different mice however only in Niemann-Pick disease, type C1 did we observe that neuroinflammation increases with disease progression. Fabry disease mice do not have neurological manifestation, and this is reflected by the minor changes in microglial properties. Lastly, mucolipidosis type IV mice have an early gliosis which decreases with disease progression. Comparison among microglia transcriptome profiles form these 3 diseases, and other disorders where transcriptome data is available, showed similarities with other neurodegenerative diseases. The phenotypic similarities between microglia from rare monogenic disorders, where the primary metabolic disturbance is known, and common neuroinflammatory diseases may provide novel insights for therapeutic intervention.

Background—The chemokine receptor CCR6 and its ligand CCL20 are both expressed in human atheroma; however, their functional roles in atherogenesis remain undefined. Here, we addressed this question in the apolipoprotein E-deficient (ApoE-/-) mouse model of atherosclerosis. Methods and Results—Both Ccr6 and Ccl20 are expressed in atherosclerotic aorta from ApoE-/- mice. Atherosclerotic lesion area in the aorta in Ccr6-/-ApoE-/- mice was ~40% and ~30% smaller than in Ccr6+/+ApoE-/- mice at 16 and 24 weeks of age, respectively. In addition, lesions of Ccr6-/-ApoE-/- mice had 44% less macrophage content compared to Ccr6+/+ApoE-/- mice. Since monocytes are the source of lesional macrophages, we tested whether monocytes express Ccr6 and the effect of Ccr6 deletion on monocyte function. We found that Ccr6 was expressed on a subset of primary mouse monocytes and on the mouse monocyte/macrophage cell line RAW 264.7. The receptor was functional, as defined by Ccl20-induced chemotaxis of primary monocytes from wild type but not Ccr6-/- mice; moreover, Ccl20 induced monocytosis in ApoE-/- mice in vivo. Consistent with this, we observed 30% fewer monocytes in the circulating blood of Ccr6-/-ApoE-/- mice, mainly due to fewer CD11b+Ly6Chigh inflammatory monocytes. Conclusions—We conclude that Ccr6 promotes atherosclerosis in ApoE-deficient mice. This may be due in part to Ccr6 support of normal monocyte levels in blood in the model, as well as direct Ccr6-dependent monocyte migration.

The protozoan parasite Trypanosoma cruzi is the etiological agent of Chagas’ Disease, which affects ~12 million people in Latin America despite coordinated international control efforts. Cardiomyopathy due to chronic inflammation and fibrosis is the most common and serious presentation of Chagas’ Disease, but its pathogenesis is poorly understood. Several inflammatory chemokines and chemokine receptors have been implicated in mouse models of T. cruzi infection; however, roles for homeostatic chemokines have not previously been reported. Here, we found that mRNA for the homeostatic chemokine Ccl19 and its receptor Ccr7 were both increased in the heart during the acute phase after infection of WT C57BL/6 mice. Consistent with an important functional role, infection was uniformly fatal during the acute phase in infected Ccr7-/- mice, whereas mortality was only 10% in WT control mice. Death in infected KO mice was associated with uncontrolled parasitemia and increased parasite burden in both heart and liver, whereas infected WT mice controlled parasite burden in all 3 compartments. Leukocyte infiltration was also greater in the hearts of infected KO mice compared to infected WT controls, and was characterized by a lower frequency of CD8+ T cells and a greater frequency of Gr-1hiCD11b+IA- cells. Thus Ccr7 is a critical factor for survival and control of T. cruzi infection in C57BL/6 mice. The mechanisms of resistance conferred by Ccr7 are currently under investigation.