Scientific corner

P106 Single-cell transcriptomic analysis reveals insights into the mechanism of action of Granulocyte-monocyte apheresis

D Kioroglou, J L Cabriada, U Martinez Marigorta, I Rodriguez-Lago. Journal of Crohn’s and Colitis, Volume 18, Issue Supplement_1, January 2024, Page i389,

Granulocyte-monocyte apheresis (GMA) is a non-pharmacological treatment approved for the management of ulcerative colitis (UC), particularly steroid-dependent cases. The exact mechanism of action and immunological changes associated with GMA remain undescribed. Gene expression analysis at the single-cell level (through scRNA-Seq) has emerged as a key tool of choice to characterize drug response at the molecular level. We used scRNA-Seq to characterize the transcriptomic effects and immune cell population alterations in GMA.

We generated scRNA-Seq from peripheral blood mononuclear cells (PBMC) of two ulcerative colitis (UC) patients undergoing GMA treatment. We compared the gene expression profile before and after 5 sessions of GMA treatment. The analytical pipeline included quality control and classical filtering steps, cell-type annotation, differential gene expression analysis and pathway enrichment profiling.

We report three main results. First, we observed significant reductions of cell types directly affected by GMA treatment in UC patients. This includes classical CD14+ monocytes and Natural killers, which are central components of the innate system. Of note, we observed a remarkable increase in Double-negative T cells (dnT) after 5 sessions of GMA treatment, suggesting potential expansion of protective populations involved in decreased inflammation. Second, we observe a variety of genes and regulatory pathways altered by GMA treatment. In total, we detect 86 differentially expressed genes (DEGs), which overall are biased towards downregulation (63%). Of note, we detected dnT-s exhibiting upregulation of NEFL that is associated with the MAPK cascade and downregulation of genes related to immune response and signaling pathways. Finally, the effects of GMA treatment extend beyond the above mentioned populations, with particular alterations in CD4+ T cell populations such as CD4+ central memory and CD4+ Naive (7 and 13 DEGs, respectively).

For the first time, we generated single-cell transcriptomic profiles to characterize the effects of GMA treatment in peripheral blood of UC patients. Our preliminary analysis detects important alterations in the gene regulation and cell type composition in samples obtained after 5 sessions of GMA. Through expansion of this dataset to include more time points and profiles for more individuals, we will discuss the longitudinal changes and molecular mechanisms involved in response to GMA treatment.

Scientific corner

Suppression of Inflammatory Cytokine Secretion by Granulocyte/Monocyte Adsorptive Apheresis in Active Ulcerative Colitis

Akira Andoh,Tomoyuki Tsujikawa,Osamu Inatomi,Yasuyuki Deguchi,Kazunori Hata,Katsuyuki Kitoh,Masaya Sasaki,Keiichi Mitsuyama,Yoshihide Fujiyama Therap Apher Dial(2005) 9, 2; 23-127,

To elucidate the molecular mechanisms involved in the therapeutic effects of granulocyte/monocyte adsorption apheresis, changes were investigated in the cytokine responses of peripheral blood mononuclear cells (PBMC) before and after granulocyte/monocyte adsorptive apheresis in ulcerative colitis (UC) patients. Four patients with active UC were enrolled. All patients responded to granulocyte/monocyte adsorptive apheresis. A total of 20 sessions of four patients were analyzed. Peripheral blood mononuclear cells were isolated from peripheral venous blood within 5min before and after each session of granulocyte/monocyte adsorptive apheresis. The cells were stimulated with interleukin (IL)-1β and tumor necrosis factor (TNF)-α for 24h, and the secreted IL-8 and IL-6 levels were determined by enzyme-linked immunosorbent assay (ELISA). IL-1β-induced IL-8 and IL-6 secretion was significantly decreased after granulocyte/monocyte adsorptive apheresis. TNF-α-induced IL-8 secretion was also significantly decreased after apheresis, but there was no significant difference in TNF-α-induced IL-6 secretion (P = 0.052). In conclusion, granulocyte/monocyte adsorptive apheresis down-regulates the IL-1β- and TNF-α-induced inflammatory responses in PBMC. The induction of hyporesponsiveness to pro-inflammatory cytokines may be an important factor mediating the clinical effects of granulocyte/macrophage adsorptive apheresis in UC patients.

Scientific corner

Anti-inflammatory effect of granulocyte and monocyte adsorption apheresis in a rabbit model of immune arthritis

Nobuhito Kashiwagi 1Minoru NakanoAbby R SaniabadiMasakazu AdachiToshikazu Yoshikawa

Inflammation 2002 Aug;26(4):199-205. doi: 10.1023/a:1016523914161.

In active rheumatoid arthritis, large numbers of granulocytes and macrophages are found in the inflamed joints. These leucocytes can promote inflammation and tissue injury by releasing inflammatory cytokines, proteinases and oxygen derivatives. To see if granulocyte and monocyte (GM) depletion produces anti-inflammatory effect, GM adsorption apheresis was performed in rabbits with immune arthritis by using a column (Adacolumn) filled with cellulose diacetate beads (G-1 beads) as adsorptive carriers which selectively adsorb CD11b positive GMs. Injection of ovalbumin into the knee joints of ovalbumin-sensitized rabbits caused a marked increase in peripheral blood leucocytes, joint swelling, increased granulocyte adhesion to G-1 beads and elevated TNF-alpha production by peripheral blood mononuclear cells (PBMC). When rabbits received a 60 min adsorption apheresis, there was suppression of CD11b positive leucocyte infiltration into the joint and reduced joint swelling (P < 0.01) compared with controls. Additionally, there was a significant (p < 0.01) suppression of TNF-alpha production by PBMC in the post column blood. These results suggest that GM depletion may serve as a non-pharmacological strategy to modify inflammatory disorders.

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