CD4⁺CD25⁺ T regulatory (Treg) cells play a central role in the suppression of immune response and prevention of autoimmune reactions. Pathogen recognition receptors expressed by immune cells, such as TLRs, may provide a critical link between the innate and adaptive immune systems. There is also evidence that TLR ligands can directly modulate the suppressive capacity of Treg cells. Here, we showed that CD4⁺CD25⁺ Treg cells affect neutrophil function and survival and that the TLR4 ligand is involved in the regulation of the cell interactions. We found that LPS-activated Treg cells inhibit reactive oxygen intermediates and cytokine production by neutrophils. Moreover, Treg cells reverse LPS-induced survival of neutrophils and promote their apoptosis and death. We also found that TCR-activated Treg cells induce the same effects on polymorphonuclear neutrophils as those achieved by TLR4 stimulation. Importantly, the suppressive potential of CD4⁺CD25⁺ Treg cells induced by LPS seems to be partially IL-10 and TGF-β dependent, whereas anti-CD3/CD28 stimulation is rather contact dependent. Together, these observations suggest that Treg cells have the ability to directly regulate neutrophil function and life span when both types of the cells are exposed to LPS.

This study tested the hypothesis that CD4(+)CD25(+)CD127(low) regulatory T (Treg) cells might induce immunosuppressive properties in apoptotic neutrophils. Treg cells are recognized as a major subset of immune cells possessing potent suppressive properties directed at T effector cells. However, Treg cells have recently been found to inhibit neutrophil function and promote their apoptosis. One of the mechanisms of action of Treg cells is the induction of other suppressor cell populations according to an infectious tolerance model. We showed that LPS-activated Treg cells promote generation of IL-10 and TGF-β1, inhibit IL-6 production by PMNs and induce the expression of heme oxygenase-1 (HO-1) and the suppressor of cytokine signaling 3 molecule (SOCS3). However, CD3/CD28-activated Treg cells were seen to promote TGF-β1 production, as well as IDO and HO-1 expression by PMNs. These findings suggest that Treg cells might play an important role in the direct control of innate immune responses through the induction of neutrophils with immunosuppressive properties that generate IL-10, TGF-β1, IDO and HO-1.

The dysfunction of oligodendrocytes (OLs) is regarded as one of the major causes of inefficient remyelination in multiple sclerosis, resulting gradually in disease progression. Oligodendrocytes are derived from oligodendrocyte progenitor cells (OPCs), which populate the adult central nervous system, but their physiological capability to myelin synthesis is limited. The low intake of essential lipids for sphingomyelin synthesis in the human diet may account for increased demyelination and the reduced efficiency of the remyelination process. In our study on lipid profiling in an experimental autoimmune encephalomyelitis brain, we revealed that during acute inflammation, nervonic acid synthesis is silenced, which is the effect of shifting the lipid metabolism pathway of common substrates into proinflammatory arachidonic acid production. In the experiments on the human model of maturating oligodendrocyte precursor cells (hOPCs) in vitro, we demonstrated that fish oil mixture (FOM) affected the function of hOPCs, resulting in the improved synthesis of myelin basic protein, myelin oligodendrocyte glycoprotein, and proteolipid protein, as well as sphingomyelin. Additionally, FOM reduces proinflammatory cytokines and chemokines, and enhances fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor (VEGF) synthesis by hOPCs was also demonstrated. Based on these observations, we propose that the intake of FOM rich in the nervonic acid ester may improve OL function, affecting OPC maturation and limiting inflammation.

Periodontitis is a chronic multifactorial inflammatory disease that leads to the loss of supportive tissues around the teeth with gradual deterioration of masticatory function and esthetics, resulting eventually in the decrease of the life quality. Host immune response triggered by bacterial biofilm is responsible for the chronic periodontal inflammation and ongoing tissue loss. Omega-3 polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have anti-inflammatory properties, thus may be used for the treatment of chronic inflammatory diseases. In this study, we aimed to evaluate the effect of dietary supplementation with omega-3 PUFA in the patients with stage III and IV periodontitis. Thirty otherwise healthy patients were treated with scaling and root planning (SRP). In the test group (n = 16), patients were additionally supplemented with 2.6 g of EPA and 1.8 g of DHA. In the control group (n = 14), patients received only SRP. Periodontal examination was performed at baseline and three months following initial therapy. Salivary samples were taken twice at baseline and at the end of the experiment. We found that there was a statistically significant reduction in the bleeding on probing (BOP) and improvement of clinical attachment loss (CAL) at three months in the test group compared to the control group. Moreover, a statistically significant higher percentage of closed pockets (probing depth ≤ 4 mm without BOP) was achieved in the test group vs. control group after three months of treatment. Accordingly, the levels of pro-inflammatory cytokines/chemokines interleukin (IL)-8 and IL-17 were markedly lower, while the level of anti-inflammatory IL-10 was significantly higher in the salivary samples of the patients supplemented with omega-3 PUFA at three months in comparison to the patients treated with SRP alone. Our findings demonstrate that dietary intervention with high-dose of omega-3 PUFA during non-surgical therapy may have potential benefits in the management of periodontitis.