Nasal Foralumab downregulates the coronavirus pathogenesis pathway in T cells and the expression of CASP1 in T cells, monocytes, and B cells. To investigate the transcriptomic changes in immune cells following nasal Foralumab treatment in SARS-CoV-2 infected patients, we FACS-sorted CD3+ (Tcells), CD19+ (B cells) and CD14+ (monocytes) cells from Foralumab treated and untreated COVID-19 patients at baseline (day − 2) and day 10 as well as in healthy subjects (Figure. 1A; Supplementary Fig. 1A; Supplementary Table 1). To obtain a COVID-19 signature for the subjects in our study we performed bulk RNA sequencing (RNA-seq) in T cells, monocytes and B cells and compared all COVID-19 patients in our study at baseline versus healthy controls. (Supplementary Table 2). Ingenuity Pathway Analysis (IPA) of the top differently expressed genes (DEGs) showed upregulation of coronavirus pathogenesis pathways in all three immune cell populations (Supplementary Fig. 1B-D).
We then compared CD3+ cells isolated from COVID-19 infected subjects vs. healthy controls and found increased expression of activation markers including CD69, CD83, ICOS, RGS1 as well as other stress related genes including HIF1A, ATF4, NFKB1 and PR1. Genes related to T cell responsiveness such as IL21R, IL4R, CXCR4 were also upregulated in COVID-19 infected subjects (Supplementary Table 2). Gene set enrichment analysis (GSEA) of DEGs showed upregulation of IL-18 (p < 0.001), TNF (p < 0.0001) and VEGFA-VEGFR2 signaling pathways (p = 0.002) in COVID-19 subjects (Supplementary Table 3). In addition, activation of NLRP3 inflammasome by SARS-CoV-2 (p = 0.003) and host-pathogen interaction of human coronavirus-interferon induction (p < 0.0001) canonical pathways were upregulated in T cells of COVID-19 subjects vs. healthy controls (Supplementary Fig. 1B-D; Supplementary Table 3). Overall, our findings are consistent with the known immune response in subjects infected with SARS-CoV-2 20–23.
We next investigated the effect of nasal Foralumab on gene expression in T cells, B cells and monocytes by comparing pre-treatment (day-2) versus follow-up (day 10) in Foralumab treated versus untreated subjects. Unsurprisingly, as they are the target of the Foralumab treatment, the most pronounced changes were found in T cells (Fig. 1B). 306 genes were uniquely expressed in untreated subjects whereas 323 genes were uniquely expressed in Foralumab treated subjects 24 (Data File 1). IPA of the differentially expressed genes (DEGs) in the Foralumab group identified genes that are part of the coronavirus pathogenesis pathway that were downregulated in the Foralumab group but not in untreated controls. Amongst them, eight genes (CASP1, IRF9, IRF7, OAS3, STAT1, BST2, TRIM25, TP53) were downregulated, and 3 genes were upregulated (EEF1A1, FOS1, NUP98) (Fig. 1B; Supplementary Table 4). Of note, Caspase-1 was downregulated not only in T cells, but also in B cells and monocytes in Foralumab versus untreated subjects (Data file 1). Caspase-1 is associated with immune-related COVID pathogenicity and worse COVID-19 outcome 25. In monocytes from Foralumab treated individuals (Fig. 1C) we found that coronavirus pathogenesis pathway was slightly downregulated compared to untreated subjects (Supplementary Table 4).
We thus analysed the effect of nasal Foralumab on gene expression in B cells by comparing pre-treatment versus day 10 in Foralumab treated versus untreated subjects Fig. 1D (Data file 1). Although we found differences in gene expression in B cells, such as downregulation of IL-4 and IL-15 signaling in Foralumab treated subjects, these differences were of smaller statistical significance compared to those observed in T cells (Supplementary Table 4).
Taken together, our results suggest that nasal administration of Foralumab led to the downregulation of genes related to inflammation and coronavirus pathogenesis and that its immunomodulatory effects were mostly pronounced in CD3 + T cells, although we could find some evidence for changes indirectly affecting both monocytes and B cells.
Single cell sequencing identifies T effector subset changes in Foralumab treated subjects.
We performed droplet-based 10x CellRanger sequencing in FACS sorted cells from healthy controls, untreated COVID-19 subjects, and Foralumab treated COVID-19 subjects (Fig. 1A). Using graph-based clustering of uniform manifold approximation and projection (UMAP), we captured the transcriptomes of 12 cell types according to the expression of canonical gene markers (Fig. 2A). These included CD4+ and CD8+ naive T cells (LEF1+, LTB+), CD4+ and CD8+ effector memory T cells re-expressing CD45RA (TEMRA) (GZMH+, GNLY+, CST7+), CD8+ Central Memory (CM) (COTL1+, NELL2+) T cells, CD8+ Effector Memory (EM) (COTL1+, GZMH+, GNLY+), Non gamma VD2 gamma-delta (TRDV1+) T cells, VD2 gamma deltas (TRDV2+) T cells, NK-like cells (KLRD1+, FCER1G+), T regulatory (Treg) (FOXP3+), Thelper ( KLRD1−, TRDC− GNLY− FOXP3−) cells and mucosal-associated invariant T (MAIT) (KLRB1+) cells. (Fig. 2A; Supplementary Fig. 2A,B; Data file 2). Prior to treatment (day − 2) (Fig. 2B,C), subjects with COVID-19 displayed a reduction in both naïve CD4+ and CD8+ T cells compared to healthy controls, which was accompanied by an increase of other cell types including CD4+ and CD8+ TEMRA, CD8+ EM cells, nonVD2 gamma delta, VD2 gamma delta T cells and NK-like cells. No changes were observed in the frequency of Treg, MAIT and T helper cells. (Supplementary Fig. 2C). Following treatment with Foralumab, the COVID-19 associated changes in CD3+ T cells resembled the pattern observed in healthy subjects, particularly in naïve CD4+ cells, CD4+ and CD8+ TEMRAs, NonVD2 and VD2 gamma delta T cells and NK-like cells (Fig. 2C). Consistent with these observations, we found a reduction of effector cells in Foralumab treated subjects (Fig. 2D).
We then performed TCR sequencing on CD3+ cells (Supplementary Fig. 3A-D). We found that CD3+ T cells were distributed in the lower regions of the UMAP and showed the largest clonal expansion (clonal size 20 < X < 100) (Supplementary Fig. 3C), predominantly involving the CD8+ EM and TEMRA populations (Supplementary Fig. 3D). There were no differences in clonal expansion following Foralumab treatment suggesting that its effect was not associated with the expansion or contraction of specific selection T cell clones. Our TCR-sequencing data were not sufficiently powered to identify preferred TCR sharing patterns and immunodominance in T cells from Foralumab treated subjects versus control in SARS-CoV-2 infection.
We next compared gene expression of total CD3+ T cells in which we compared pre-treatment versus day 10 for both Foralumab treated subjects and untreated COVID-19 patients. We found significant downregulation of effector function genes including NKG7, CCL5, IL32, CST7, GZMH, GZMB, GZMA, PRF1, and CCL4 in the Foralumab treated subjects. (Fig. 3A, B; Data file 3). We further explored this effector gene distribution among the CD3 + subsets (Fig. 3C). Reduction of IL32 was observed in CM and EM CD8+ cells as well as in gamma delta T cells in Foralumab treated subjects. Downregulation of GZMH was observed in CD4+ effector cells and PRF1 was downregulated in CD8+ CM (Fig. 3C). Taken together, our findings demonstrate a reduction of effector features in multiple T cell subsets in Foralumab treated subjects when compared to untreated controls.
We next investigated the cell state score of predefined gene sets associated to T cell exhaustion and activation in COVID-19 9. By aggregating the expression values of co-inhibitors molecules associated with T cell exhaustion, we were able to score and compare baseline (day − 2) versus follow-up (day 10) (Fig. 3D,E). As shown in Fig. 3F, Foralumab treated subjects showed greater reduction of T cell exhaustion scores when compared to untreated controls. Of note, MAF and TGFb1 gene expression was increased in highly exhausted cells when compared to non-exhausted cells while IL2, TNFa and IFNg was unchanged (Supplementary Fig. 4A). The exhaustion score was higher in Tregs, effector memory CD8+, CD8 + TEMRAS and non VD2 gamma delta T cells (Supplementary Fig. 4B).
We further investigated the level of expression of genes that were present in the coronavirus pathogenesis pathway that were found to be decreased in T cell of Foralumab treated subjects in our bulk-RNA-seq data set. CASP1, OAS3, BST2 and IRF7 were found to be highly expressed in the T cells subsets found in our single cell dataset and were modulated by disease (Fig. 3G, H; Supplementary Fig. 5A). In accordance with our bulk-RNA-seq of T cells sorted from Foralumab treated subjects, CASP1 was also significantly downregulated in our single-cell dataset (Fig. 3H). CD4+ TEMRA represents the major CD3+ subset driving this effect (Fig. 3H). OAS3 and IRF7 genes expression were significantly increased in all CD3+ cell subsets at the baseline time point (day-2) when compared to healthy controls and decreased at day 10. We were not able to elect a major CD3 + subset that could alone be associated with the downregulation of these genes expressions in the bulk RNA-seq dataset. Collectively, OAS3 was downregulated in CD8+ EM, nonVD and VD2 gamma delta T cells. Finally, nonVD2 gamma delta T cells were found to be the major contributor of BST2 downregulation in Foralumab-treated subjects. (Fig. 3G).
Changes in serum cytokines, growth factors and chemokines in Foralumab treated subjects. We quantified serum cytokines, growth factors and chemokines in COVID-19 subjects following Foralumab treatment as well as in untreated COVID-19 and healthy controls using both OLINK and Multiplex technology.
IL-18 is a product of inflammasome activation that plays a role in COVID-19 26. We found that serum IL-18 was increased in COVID-19 subjects compared to healthy controls (p = 0.003) (Supplementary Fig. 6A,B) and a reduction of serum IL-18 in subjects that received Foralumab (p = 0.05) (Fig. 4A; Supplementary Table 5).
Brain derived neurotrophic factor (BDNF) is a neuronal growth factor produced by immune cells including T cells 27. Increased BDNF secretion has been associated with recovery in COVID-19 28. We found an increase in serum BDNF in Foralumab treated patients (p = 0.01) that was not observed in untreated COVID-19 subjects or healthy controls (Fig. 4A, Supplementary Table 5). In addition to BDNF, an increased in other growth factors was observed following Foralumab treatment that did not occur in untreated COVID-19 patients including vascular endothelial growth factor A (VEGF-A) (p = 0.003), placental growth factor (PIGF) (p = 0.004), and stem cell factor (SCF) (p = 0.023) (Supplementary Table 5). We observed changes in hepatocyte growth factor (HGF), platelet derived growth factor-BB (PDGF-BB), and serum interferon gamma inducible protein-1 (IP-10) in both Foralumab treated and untreated COVID-19 subjects (Supplementary Table 5). Altogether, these results suggest that Foralumab administration induces the secretion of factors related to tissue repair and re-vascularization, as well as growth factor involved in restoring the damage caused by the inflammatory processes related to COVID-19 infection.
We also used the OLINK to measure 96 inflammatory proteins in the serum. Consistent with the inflammatory nature of COVID-19 infection, we found an elevation in 19 inflammatory proteins including IL-18, IL-8, IL-10, IL-6, IFNg, CSF-1, CXCL11, CXCL10 and CSF-1 in COVID-19 subjects vs. healthy controls (Supplementary Table 6; Supplementary Fig. 6B; Data file 4). We then asked whether any of the proteins measured by the OLINK panel were changed by Foralumab treatment and identified 6 proteins (Fig. 4B). Two proteins were reduced by Foralumab treatment (FLT3L and IL-12B) and 4 proteins were increased following treatment (NT-3, ST1A1, AXIN1 and SIRT2). FLT3L and IL-12B are immune stimulatory cytokines that promote dendritic cell maturation. Neurotrophin-3 (NT-3) is a member of the BDNF family that we also found increased in Foralumab treated subjects. SIRT2 plays a role in T cell metabolism and effector function 29.
Given that Foralumab modulates T cells, we asked which proteomic changes we observed with Foralumab treatment were related to genes expressed in T cell subsets as defined by our scRNA-seq analysis. We found that FLT3LG, SIRT2, SULT1A1 and AXIN 1 were expressed in T cell subsets (Fig. 4C). Of note, even though IL-18, BDNF, and other growth factors changed with Foralumab treatment, they were not selected for this analysis as they were poorly expressed in T cell subsets in our dataset.
We found that FLT3 was decreased in serum samples from Foralumab treated subjects when compared to untreated controls (Fig. 4B; Supplementary Fig. 5B). Several hematopoietic and nonhematopoietic cells can produce FLT3L 30. We could not find any FLT3L gene expression decrease in any CD3+ subset when comparing untreated and Foralumab subjects suggesting the involvement of other cell types in the observed effect (Supplementary Fig. 5B). Similarly, we did not find any major changes in SULT1A1 and AXIN1 gene expression among CD3+ cells subsets when comparing untreated vs Foralumab treated subjects. In Fig. 4D, we showed that SIRT2 was increased in NK-like cells in Foralumab treated subjects (Fig. 4D).
Changes in T cell expression of GIMAP7, NKG7, and TGFb1 are associated with immunomodulatory effects of nasal Foralumab.
We found that NKG7 was downregulated in CD8+ TEMRAs, CD8+ EM, nonVD2 gamma deltas and gamma delta T cells when compared to baseline (day − 2) in COVID-19 treated subjects but not untreated controls (Supplementary Fig. 7A). TGFb1 was increased in multiple CD3+ subsets including CD4+ TEMRA, CD8+ TEMRA, CD8+ EM, nonVD2 gamma-delta and VD2 gamma-delta T cells following Foralumab treatment when compared to both healthy controls and untreated COVID-19 subjects. The TGFb1 gene expression increase was found in cell types with known effector function that not classical Treg cells (Supplementary Fig. 7B).
In addition to COVID-19 subjects, we have treated healthy volunteers and multiple sclerosis (MS) subjects with nasal Foralumab and performed scRNA-seq analysis on CD3 + subsets in these subjects. This provided the opportunity to ask whether there were common mechanisms by which nasal anti-CD3 modulated T cell function in different human conditions. We found that GIMAP7 and TGF- b1 were upregulated whereas NKG7 was downregulated in all 3 cohorts (Fig. 5A, 5B). Furthermore, we found these same changes in CD3 + cells sorted from the cervical lymph nodes of C57BL/6J mice treated with nasal anti-CD3 (Fig. 5C). Although the immunologic role of GIMAPs is not well defined, they define stages of T-cell development, survival and cell identity 31,32 and have been reported to be associated with T cell regulatory function 33.
Lastly, we found that the gene expression of RhoA, ROCK1and CFL1, which are negatively regulated by GTPases was downregulated in Foralumab treated individuals. By aggregating the expression values of these genes, we were able to score the changes in the Rhoa/ROCK1 pathway and found a decrease of this pathway in Foralumab treated subjects (Fig. 5D).
Taken together, we found that nasal anti-CD3 (Foralumab) induces naïve-like cells and restrains effector features in CD3+ T cells as exemplified by decreased gene expression of CASP1, CCL4 and NKG7, while TGFb1 gene expression increased. Notably, this effect was not limited to subjects with COVID-19 but was also observed in healthy and MS subjects treated with nasal Foralumab.