On 2020-06-15 02:32:20, user Sinai Immunol Review Project wrote:
Main findings<br />
Sex-based differences in the immune response have been reported for various types of infections. There is a growing body of epidemiological evidence that supports the finding that men experience more severe COVID-19 disease than women do, but the immune mechanisms underscoring such a difference remain unknown.
Here, Takahashi et al. analyze PBMCs, plasma, and nasopharyngeal swabs or saliva from 93 mild-to-moderate COVID-19 patients (n=93), comprised of 48 women (n=48) and 45 men (n=45), to characterize potential sex-based differences in the immune response to SARS-CoV-2 infection. It is important to note that patients on hydroxychloroquine and Remdesivir were not excluded from a sub-cohort of patients (n=39) evaluated as baseline measures for untampered immune responses to SARS-CoV-2 (these patients were not treated prior to first sample collection). In a second sub-cohort, 54 patients were assessed longitudinally for an undisclosed amount of time. Samples from uninfected healthcare workers were used as controls.
Viral Load (nasopharyngeal or saliva samples)<br />
No significant differences were identified between male and female patients. Still, median viral RNA was higher in male patients at first sample collection and generally throughout disease course.
Antibody production (plasma samples)<br />
Anti-SARS-CoV-2 S1 protein-specific IgG and IgM antibodies were measured in the plasma of male and female patients. Though anti-S1-IgG antibodies were higher in female patients, compared to male patients, no significant differences could be identified either in the baseline cohort or in longitudinal patients.
Cytokine analysis (plasma samples)<br />
Among baseline patients, who had not received immunomodulatory therapy prior to sample collection (except hydroxychloroquine), type I/II/III IFN levels were not significantly different between male and female patients. However, IL-8 was significantly higher in male than in female patients. Of note, among longitudinally evaluated patients, CCL5 levels were significantly higher in male than in female patients. CXCL10 levels show a similar trend, though this was not significant.
Immune cell landscape (PBMCs)<br />
Both male and female patients exhibited a reduction among T cells and an increase in B cells. No significant differences in T cell subtypes (naïve, central/effector memory, follicular, regulatory) were observed between male and female patients. Of note, however, female patients showed (1) a significantly greater proportion of CD38+HLA-DR+ activated CD8+ T cells and (2) a concomitant enrichment of PD-1+TIM-3+ terminally differentiated T cells, compared to male patients. Otherwise, no other significant differences were identified between male and female patients.
The authors subsequently interrogated the peripheral myeloid compartment. Female patients showed a greater increase in CD14+CD16+ intermediate monocytes than male patients, while both patients exhibited a marked increase in total monocytes, compared to the controls. However, male patients showed higher levels of CD14loCD16+ non-classical monocytes than female patients and their uninfected, healthy counterparts. The authors noted that this enrichment of non-classical monocytes was correlated with CCL5 levels only in male patients.
Clinical comparison<br />
Clinical outcomes were tracked for both male and female patients. Clinical scoring was used to separate each group into two sub-groups: patients that had remained stable throughout hospital stay (stabilized) and patients that had worsened since the first sample collection (deteriorated). Deteriorated male patients were significantly older than stabilized male patients; there was no significant difference in age between stabilized and deteriorated female patients. In terms of BMI, both deteriorated male and female patients tended to be higher in BMI than their respective stabilized counterparts. Interestingly, anti-S1-IgG antibodies were higher in stabilized female patients than their deteriorated counterparts, though this trend was not seen with male patients. Otherwise, no other significant differences in clinical parameters were observed.
Additional comparisons between deteriorated and stabilized patients of each sex revealed that certain innate cytokine mediators (TNFSF10 and IL-15) associated with worse outcome in female patients but not in male patients. In contrast, the proportion of CD38+HLA-DR+ activated CD8+ T cells was significantly reduced in deteriorated male patients compared to their stable counterparts, but this was not true for female patients. Indeed, poor CD8+ T cell activation and IFN? production were both negatively correlated with age in male patients, but not in female patients.
Limitations<br />
• A significant number of patients were diagnosed with underlying chronic conditions that have been previously described to associate with poorer COVID-19 outcomes or with a compromised immune system. <br />
• Approximately two-thirds of each group (men and women) were treated with tocilizumab, and nearly a sixth of each group were treated with corticosteroids. While these patients were excluded from the baseline cohort, it is unclear whether or not these patients contributed to the second cohort that was longitudinally examined.<br />
• The mean age for patients is notably higher than the mean age for the HCW control group.<br />
• Duration of hospital stay was not considered, so it is unclear how quickly certain subsets of male and female patients deteriorated. This may be a confounding variable, or at the very least, the kinetics of disease course in male and female patients is a parameter that warrants investigation.
Significance<br />
In summary, Takahashi et al. provide the first report-to-date that delineates immunological differences between male and female patients with mild-to-moderate COVID-19 disease during the initial stages of infection. For example, male patients deteriorate due to less robust T cell-mediated antiviral immunity, compared to their female counterparts. Several of the other findings substantiate previous reports, such as those of significant neutrophil chemotaxis in the lung of COVID-19 patients (and its association with poorer prognosis). This study, therefore, provides an important platform for additional inquiries into key signaling pathways and transcriptional programs that are differentially regulated between male and female COVID-19 patients by specific cell types (i.e. intermediate and non-classical monocytes, CD38+HLA-DR+ CD8+ T cells) identified in this report. These studies, alongside others, are warranted to better tailor therapies for male and female COVID-19 patients.
This review was undertaken by Matthew D. Park as part of a project by students, postdocs and faculty at the Immunology Institute of the Icahn School of Medicine, Mount Sinai.