Christina Ekerfelt

Immunology of preeclampsia

Preeclampsia is a placenta-dependent disorder with both local and systemic anomalies with neonatal and maternal morbidity. It is manifested late in pregnancy, but the onset is during early stages of gestation. The current hypothesis regarding the aetiology of preeclampsia is focused on maladaptation of immune responses and defective trophoblast invasion. Thus, an excessive maternal inflammatory response, perhaps directed against foreign fetal antigens, results in a chain of events including shallow trophoblast invasion, defective spiral artery remodelling, placental infarction and release of pro-inflammatory cytokines and placental fragments in the systemic circulation. During normal pregnancy, trophoblasts interact in the decidua with the unique uterine NK cells, modifying their cytokine repertoire, regulating adhesion molecules and matrix metalloproteinases. The inability of trophoblasts to accomplish these changes might be a critical factor for the onset of preeclampsia. Several cytokines, produced at the maternal-fetal interface, have an impact on trophoblast invasion. It is suggested that deficiency of interleukin-10 may contribute to enhanced inflammatory responses towards the trophoblasts elicited by e.g. tumour necrosis factor-alpha and interferon-gamma. Consequently, trophoblasts subjected to a high rate of apoptosis are hampered in their invasive capacity resulting in defective transformation of spiral arteries, hypoxia, thrombosis and infarction of the placenta. The ensuing infarction of placenta leads to leakage of increasing amounts of placental fragments and cytokines in the maternal circulation and an exaggerated systemic endothelial activation as identified in preeclampsia. So far, treatment of preeclampsia is focused on signs like hypertension, whereas attempts of modifying immune responses may be a possibility in the future.

Cytokine secretion patterns of NK cells and macrophages in early human pregnancy decidua and blood : Implications for suppressor macrophages in decidua

Problem:  Local immune modulation has been shown to be of considerable importance for the maintenance of successful pregnancy. We have previously reported the secretion of interferon‐γ (IFN‐γ), interleukin‐4 (IL‐4) and IL‐10 in human decidua from early normal pregnancy. The aim of this study was to investigate the cellular source of cytokine secretion in the decidua, and compare this to secretion patterns in peripheral blood.

Detection of spontaneous and antigen-induced human interleukin-4 responses in vitro: comparison of ELISPOT, a novel ELISA and real-time RT-PCR

Interleukin-4 (IL-4) is an important T-helper cell type 2 (Th2) cytokine in man, driving Th2 polarisation and exerting the most antagonistic effects to the Th1 cytokine interferon-gamma (IFN-gamma). Nevertheless, few data on spontaneous and antigen-specific secretion of IL-4 in man are available, mainly due to difficulties in the detection of IL-4. In this study, we compared three assays that can detect antigen-induced IL-4 responses; ELISPOT, ELISA after blocking the IL-4 receptor during cell culture, and real-time reverse transcription polymerase chain reaction (RT-PCR). Spontaneous, antigen- and allergen-induced responses were analysed in peripheral blood mononuclear cells from three groups with different secretion patterns for IL-4: atopic individuals, nonatopic individuals and pregnant women. ELISPOT displayed the highest sensitivity and was the only assay that could detect spontaneous secretion of IL-4 in all analysed samples. The IL-4 receptor blocking ELISA was considered best for the detection of in vitro antigen- and allergen-induced responses, since the results obtained from the ELISPOT and real-time RT-PCR displayed lower specificity, possibly because of seemingly aberrant IL-4 responses in the group of pregnant women. The real-time RT-PCR for detection of IL-4 mRNA proved to be sensitive, but expression of IL-4 mRNA was not correlated with the secretion of IL-4.

Paternal leukocytes selectively increase secretion of IL-4 in peripheral blood during normal pregnancies: demonstrated by a novel one-way MLC measuring cytokine secretion.

PROBLEM: It has been proposed that immune responses in normal pregnancy are Th2‐like, thereby protecting the fetus and placenta from being rejected. Some studies have shown Th2‐deviated systemic responses to different antigens and mitogens. The aim of this study was to demonstrate the specific T cell cytokine responses directed toward paternal histocompatibility leukocyte antigen (HLA), because this is the most prominent target for rejection of the feto‐placental unit.

Increased Numbers of Circulating Interferon‐γ‐and Interleukin‐4‐Secreting Cells During Normal Pregnancy

PROBLEM: Systemic immune responses during normal pregnancy are suggested to deviate toward secretion of T helper (Th)2‐like cytokines.

Borrelia-Specific Interferon-γ and Interleukin-4 Secretion in Cerebrospinal Fluid and Blood during Lyme Borreliosis in Humans: Association with Clinical Outcome

The Borrelia-specific interferon (IFN)- gamma and interleukin (IL)-4 responses of 113 patients and control subjects were analyzed using the sensitive enzyme-linked immunospot method. Cerebrospinal fluid (CSF) and blood samples were obtained, during the course of disease, from patients with chronic or nonchronic neuroborreliosis (NB) and from control subjects without NB. Blood samples were obtained from patients with Lyme skin manifestations and from healthy blood donors. Early increased secretion of Borrelia-specific IFN- gamma (P<.05) and subsequent up-regulation of IL-4 (P<.05) were detected in the CSF cells of patients with nonchronic NB. In contrast, persistent Borrelia-specific IFN- gamma responses were observed in the CSF cells of patients with chronic NB (P<.05). In patients with erythema migrans, increased IFN- gamma (P<.001) was observed in blood samples obtained early during the course of disease, whereas increased IL-4 (P<.05) was observed after clearance. On the contrary, patients with acrodermatitis chronica atrophicans had Borrelia-specific IFN- gamma (P<.001), but not IL-4, detected in blood samples. The present data suggest that an initial IFN- gamma response, followed by up-regulation of IL-4, is associated with nonchronic manifestations, whereas a persistent IFN- gamma response may lead to chronic Lyme borreliosis.

Compartmentalization of antigen specific cytokine responses to the central nervous system in CNS borreliosis: secretion of IFN-γ predominates over IL-4 secretion in response to outer surface proteins of Lyme disease Borrelia spirochetes

The neurological manifestations of Lyme disease have been proposed to be partly due to cytokine-mediated immunopathological mechanisms. In this study, the number of Borrelia-specific cells secreting interferon-gamma and interleukin-4 was determined in blood and cerebrospinal fluid from patients with CNS borreliosis (n = 23), other neurological diseases (n = 20), and in blood from healthy controls (n = 10), utilizing an ELISPOT-assay. Elevated specific secretion of IFN-gamma was found in CNS borreliosis, most pronounced in cerebrospinal fluid, whereas secretion of IL-4 was strikingly low. This may indicate that symptoms are due to side effects of the immune response, since IFN-gamma secretion in the absence of corresponding levels of IL-4 may be associated with tissue destruction.

Deficiency of decidual IL-10 in first trimester missed abortion: a lack of correlation with the decidual immune cell profile.

PROBLEM: To determine if first trimester missed abortion decidua is characterized by an altered immune cell profile and/or a modified interleukin (IL)‐10 and interferon (IFN)‐γ production pattern compared with decidua from elective termination.

The outer surface proteins of Lyme disease borrelia spirochetes stimulate T cells to secrete interferon-gamma (IFN-γ) : diagnostic and pathogenic implications

Late stages of borrelia Lyme disease infections may be difficult to diagnose because of unspecific symptoms and unreliable laboratory tests, being too unspecific or insensitive. The T cell immune response was thus evaluated in these patients by using a sensitive ELISPOT T cell assay that detects the secretion of IFN‐γ, i.e. a T helper 1 (Th1) response on the single‐cell level. Three subcellular fractions of the Lyme borreliosis strain Borrelia afzelii were used for antigenic stimulation. The outer surface protein (Osp) fraction elicited the strongest response, discriminating between borrelia infections (n= 15) compared with other neurological diseases (n= 10) and normal controls (n= 12) (P= 0.0001). The more heterogeneous sonicated borrelia fraction also elicited a strong response, however, also in some of the controls. The flagellin fraction did not have a similar T cell‐stimulating effect. When looking at subgroups of borrelia infections, central nervous system (CNS) infections (n= 7) revealed a lower T cell response in blood (P= 0.0128) compared with other borrelia manifestations (n= 8). Cerebrospinal fluid (CSF) lymphocytes were available from three patients with CNS borreliosis, and all showed a compartmentalization with higher responses to the Osp fraction in CSF compared with blood, also in the two patients without any intrathecal‐specific antibody synthesis. The ELISPOT method is feasible for detecting a specific IFN‐γ T cell response in borrelia infections. This Th1 response may well be of pathogenic relevance.

Cord blood cytokines and chemokines and development of allergic disease.

Exposure to ubiquitous allergens early in life, even before birth, may influence the incidence of allergic diseases later in life. During pregnancy, the fetomaternal interface is surrounded by high levels of T‐helper (Th)2‐like cytokines, possibly favouring the development of Th2‐like immune responses in the offspring. The aim of this study was to evaluate the relation between cord blood (CB) IgE antibodies, Th1‐ and Th2‐like cytokines and chemokines, maternal allergy and development of allergic disease during the first 2 yr of life in the offspring. The CB cytokine and chemokine levels from children of 20 allergic and 36 non‐allergic women were determined by a multiplexed Luminex assay and ELISA. Total CB and maternal IgE antibody concentrations were quantified using ImmunoCAP technology. The maternal IgE levels during and after pregnancy correlated with CB IgE and Th2‐associated macrophage‐derived chemokine [MDC (CCL22)] levels. Development of allergic disease and sensitization was associated with increased CB IgE and MDC (CCL22) levels, as well as high ratios of MDC (CCL22) to Th1‐associated interferon‐γ inducible protein 10 [IP‐10 (CXCL10)] and interferon‐γ inducible T‐cell α‐chemoattractant [I‐TAC (CXCL11) (n = 7 allergic vs. n = 25 non‐allergic)]. The correlations between maternal IgE and CB IgE and MDC (CCL22) levels possibly indicate that the maternal immunity can affect the Th1/Th2 profile in the neonate. Development of allergic disease is associated with a more marked Th2‐like deviation already at birth, shown as increased levels of CB IgE and MDC (CCL22) and higher ratios of MDC (CCL22) to IP‐10 (CXCL10) and I‐TAC (CXCL11).