A combination therapy using IL-12 and soluble IL-4 receptor on herpes simplex virus Type 1 infection in a human-SCID chimera model of thermal injury

The "T" in trauma: the helper T-cell response and the role of immunomodulation in trauma and burn patients

BACKGROUND

The immune system undergoes numerous changes after traumatic and burn injuries, including a down-regulation of the TH1 response and up-regulation of the TH2 response.

METHODS

The PubMed, Medline, and Ovid search engines were queried for relevant human studies. Bibliographies were also meticulously reviewed.

RESULTS

An interesting and potentially clinically relevant pattern of immune dysregulation exists after injury. The type 1 T-helper cell (TH1) response is suppressed as illustrated by diminished interleukin (IL)-2, interferon (IFN)-gamma, and IL-12 levels after major injury. The enhancement of the TH2 response is marked by elevated IL-10 and IL-4. Certain cytokine profiles, ratios, and polymorphisms may help identify patients at increased risk of systemic inflammatory response syndrome (SIRS), sepsis, multiple organ failure (MOF), and deep venous thrombosis. The most promising prognostic indicators to date are decreased production of the IL-12, elevated IL-10, soluble IL-2 receptor-a (sIL-2Ra), and IL-18 levels, IL-18 promoter polymorphisms, the IL-6:IL-10 ratio, and the degree of TH1 suppression as measured by diminished IL-2 and IFN-gamma. The Cytokine sections are subdivided into basic science, human studies, animal studies (when necessary), and directed therapeutics. The outcomes of sepsis, SIRS, or MOF are generally discussed together.

CONCLUSIONS

T-cell-specific immunologic changes occur after major injury. Identification of those TH1/TH2 cytokine profiles associated with worse prognosis may one day allow clinicians to risk stratify injured patients and identify those at increased risk of developing SIRS, sepsis, MOF, and deep venous thrombosis. Immune-targeted therapies may eventually serve as effective treatments in the acute setting to decrease morbidity and mortality, and to improve the management and prognosis of those patients at risk for developing postinjury complications.

Role of natural killer T (NKT) cells lacking interleukin (IL)-4 producing abilities on the CC-chemokine ligand 2-associated herpes simplex virus type 1 infection in human severe combined immunodeficiency (SCID) mouse chimeras

CC-chemokine ligand 2 (CCL2/monocyte chemoattractant protein 1) is known to have an important role on T helper type 2 (Th2) cell generation and described to induce interleukin (IL)-4 production by activated T cells. In the present study, an increase of CCL2 production in cultures of peripheral blood lymphocytes (PBL) from patients with severe thermal injuries was demonstrated. Severe combined immunodeficiency (SCID) mice reconstituted with PBL from healthy donors (PBL-SCID chimeras) were resistant to infection with herpes simplex virus type 1 (HSV-1). Treatment of these chimeras with recombinant human CCL2 resulted in an increased susceptibility to the same HSV-1 infection. However, human SCID mouse chimeras created by PBL depleted of natural killer T (NKT) cells (NKT(-) PBL-SCID chimeras) were resistant to HSV-1 infection, even though they were treated with CCL2. IL-4 was not detected in the sera of NKT(-) PBL-SCID chimeras treated with CCL2, while IL-4 was detected in the sera of PBL-SCID chimeras under the same CCL2 administration. NKT cells isolated from PBL were shown to be cells not responsible for CCL2-stimulated IL-4 production. However, in the presence of CCL2, IL-4 was detected in culture fluids of NKT cells co-cultured with naive T cells. This cytokine was produced in co-cultures of NKT cells pretreated with CCL2 (CCL2-NKT cells) and naive T cells. In addition, IL-4 production was demonstrated in transwell cultures of CCL2-NKT cells and naive T cells. These results suggest that NKT cells lacking IL-4 producing abilities contribute to the CCL2-associated increase in the susceptibility of thermally injured patients to HSV-1 infection through the induction of Th2 cell generation.

Effect of IL‐12 and soluble IL‐4 receptor on the herpesvirus infection in human SCID chimeras whose Th2 cells predominate

Th2 cytokines, commonly detected in burn patients, have been shown as inhibitors for the generation of Th1 cells that are essential for the host's resistance against herpes simplex virus type 1 (HSV-1) infection. In this study, the possibility of immunological treatment through the regulation of Th1/Th2 responses was examined in two kinds of human severe combined immunodeficiency (SCID) chimera models reflecting human immune functions. SCID mice injected with a mixture of PBMC from a healthy donor and Th2 cells experimentally generated from the same healthy PBMC (Th2 SCID chimeras) were more susceptible to HSV-1 infection when compared with SCID mice injected with healthy donor PBMC (healthy SCID chimeras). When Th2 SCID chimeras were individually treated with human IL-12 (hIL-12) or human soluble IL-4 receptor (hsIL-4R), hIFN-gamma was not produced in their sera after antihuman CD3 mAb stimulation. However, hIFN-gamma production in sera of Th2 SCID chimeras treated with the combination therapy of hIL-12 and hsIL-4R was recovered at levels observed in healthy SCID chimeras. When Th2 SCID chimeras infected with HSV-1 were treated with saline, hIL-12, hsIL-4R or a combination of hIL-12 and hsIL-4R, 13%, 13%, 25% or 100% of them survived, respectively. Also, Th1 responses (hIFN-gamma production) were demonstrated in Th2 SCID chimeras that became resistant against HSV-1 infection after the combination treatment. These results suggest that individuals whose Th2 cells predominated may be immunologically controlled by the combination treatment between a Th1 response inducer and a Th2 response inhibitor.