SARS-CoV-2 infection elucidates unique features of pregnancy-specific immunity

Pregnancy is a risk factor for increased severity of SARS-CoV-2 and other respiratory infections. The mechanisms underlying this risk have not been well-established, partly due to a limited understanding of how pregnancy shapes immune responses. To gain insight into the role of pregnancy in modulating immune responses at steady state and upon perturbation, we collected peripheral blood mononuclear cells (PBMC), plasma, and stool from 226 women, including 152 pregnant individuals (n = 96 with SARS-CoV-2 infection and n = 56 healthy controls) and 74 non-pregnant women (n = 55 with SARS-CoV-2 and n = 19 healthy controls). We found that SARS-CoV-2 infection was associated with altered T cell responses in pregnant compared to non-pregnant women. Differences included a lower percentage of memory T cells, a distinct clonal expansion of CD4-expressing CD8 + T cells, and the enhanced expression of T cell exhaustion markers, such as programmed cell death-1 (PD-1) and T cell immunoglobulin and mucin domain-3 (Tim-3), in pregnant women. We identified additional evidence of immune dysfunction in severely and critically ill pregnant women, including a lack of expected elevation in regulatory T cell (Treg) levels, diminished interferon responses, and profound suppression of monocyte function. Consistent with earlier data, we found maternal obesity was also associated with altered immune responses to SARS-CoV-2 infection, including enhanced production of inflammatory cytokines by T cells. Certain gut bacterial species were altered in pregnancy and upon SARS-CoV-2 infection in pregnant individuals compared to non-pregnant women. Shifts in cytokine and chemokine levels were also identified in the sera of pregnant individuals, most notably a robust increase of interleukin-27 (IL-27), a cytokine known to drive T cell exhaustion, in the pregnant uninfected control group compared to all non-pregnant groups. IL-27 levels were also significantly higher in uninfected pregnant controls compared to pregnant SARS-CoV-2-infected individuals. Using two different preclinical mouse models of inflammation-induced fetal demise and respiratory influenza viral infection, we found that enhanced IL-27 protects developing fetuses from maternal inflammation but renders adult female mice vulnerable to viral infection. These combined findings from human and murine studies reveal nuanced pregnancy-associated immune responses, suggesting mechanisms underlying the increased susceptibility of pregnant individuals to viral respiratory infections.

Alcohol and opiate misuse in adults with cystic fibrosis

BACKGROUND

International consensus statements on depression and anxiety in adolescents and adults with cystic fibrosis (awCF) recommend assessment for comorbid substance misuse. However, at CF centers, the frequency and impact of substance misuse have not been well characterized, and best practices for prevention, identification, and evidence-based treatment have not been routinely implemented.

METHODS

Medical records of 148 awCF over 3 years were reviewed to determine the prevalence of substance misuse (alcohol or opiates) and its relationship with clinical variables and healthcare utilization. Independent sample t test for continuous outcomes and χ2 test for binary outcomes were used to compare groups with and without substance misuse.

RESULTS

Substance misuse was documented in 28 (19%) awCF, equally distributed between alcohol (n = 13) and opiates (n = 15). Adults with substance misuse were more likely to be male. The prevalence of diagnosed anxiety and depression did not differ significantly between groups, but those with substance misuse had more severe anxiety (Generalized Anxiety Disorder-7 Item [GAD-7]: 10.0 ± 6.1 vs. 3.3 ± 4.4; p < 0.001) and depressive symptoms (Patient Health Questionnaire-9: 10.4 ± 6.5 vs. 4.0 ± 4.8; p < 0.001). Adults with substance misuse had higher annual rates of missed outpatient CF visits, more frequent "sick" visits, more frequent and longer hospitalizations, and a higher mortality rate.

CONCLUSIONS

In awCF, substance misuse is common and associated with adverse indicators of emotional and physical health, including via proxy of service utilization, suggesting that systematic approaches to addressing substance misuse in CF clinics should be considered. Prospective, longitudinal study is warranted to elucidate the complex relationships between depression, anxiety, substance misuse, and health outcomes in individuals with CF.

299. Systems immunology profiling of treatment-naïve children with multisystem inflammatory syndrome

Background

Multisystem inflammatory syndrome in children (MIS-C) is a severe post-infectious complication occurring weeks after SARS-CoV-2 infection. The exact mechanisms leading to immune dysregulation and organ damage remain incompletely understood. Progress in understanding the immunopathology underlying MIS-C has been halted by limited availability of pre-treatment patient samples and confounding effects of immunomodulatory treatment on previously studied specimens.

Methods

In this study, we have restricted enrollment to treatment-naïve patients with MIS-C and used a systems biology approach combining CyTOF, single cell transcriptomics, serum cytokine profiling and T cell receptor sequencing to dissect how immune responses in children with MIS-C differ from children with mild SARS-CoV2 infection, adults with severe COVID-19 and healthy individuals. We also integrated single cell transcriptomics datasets from post-treatment MIS-C samples to study how immune responses change along disease course.

Results

We identified increased activation markers and antigen presentation across multiple immune cell types in MIS-C patients from both CyTOF and single cell transcriptomics data. Importantly, in PBMCs of MIS-C patients, we identified a distinct subset of proinflammatory monocytes, with increased expression of interferon gamma response genes combined with a signature of enhanced complement expression, antigen processing and presentation, which was not observed in post-treatment MIS-C samples. Interestingly, this monocyte population bears resemblance to a subset of monocytes that emerges after the BNT162b2 mRNA vaccine booster. In addition, in PBMCs of MIS-C patients, we identify increased proportion of proliferating T/NK cells, suggesting distinct T cell expansions in MIS-C. T and NK cells in MIS-C samples also showed increased cell cytotoxicity markers.

Conclusion

Taken together, treatment-naïve MIS-C samples display distinct monocyte clusters, activated antigen presentation and complement expression, and increased T and NK cell cytotoxicity, which may account for the clinical presentation of MIS-C.

Disclosures

Purvesh Khatri, PhD, Cepheid, Inc.: Advisor/Consultant|Inflammatix, Inc.: Advisor/Consultant|Inflammatix, Inc.: Inflammatix is in negotiations to license the 9-gene signature discussed here.|Inflammatix, Inc.: Stocks/Bonds.