Provided are: a method for predicting the onset of pregnancy-induced hypertension (PIH) by precisely detecting abnormalities that occur before the onset of PIH (where such abnormalities have been impossible to detect by various conventional testing methods for PIH) while imposing less of a burden on a subject; a method for evaluating a fetus and placental functions in PIH; and a method for detecting PIH, which comprises measuring the level of human lipocalin-type prostaglandin D synthase (L-PGDS) in a body fluid sample collected from a subject.

Description of the Invention

An object of the present invention is to provide a method for conveniently and objectively determining the severity of PIH, which has been comprehensively determined by various testing methods. Another object of the present invention is to provide a method for predicting the onset of PIH by precisely detecting abnormalities that occur before the onset of PIH (such abnormalities have been impossible to detect by various conventional testing methods for PIH) while imposing less of a burden on a subject. Still another object of the present invention is to provide a method for evaluating a fetus and placental functions in PIH.

As a result of intensive studies to achieve the above objects, the present inventors have discovered that the severity of PIH can be determined by measuring L-PGDS levels in body fluids such as blood and urine and using the measured values as indexes. Furthermore, the present inventors have discovered that early prediction of PIH is possible with the use of such measured values as indexes. Thus, the present inventors have completed the research.

Specifically, the present invention relates to a method for determining the severity of or predicting PIH, which comprises measuring the level of L-PGDS in a body fluid sample collected from a subject.

Specifically, the present invention is as follows: [1] a method for detecting pregnancy-induced hypertension, which comprises measuring the level of human lipocalin-type prostaglandin D synthase in a body fluid sample collected from a subject; [2] the method for detecting pregnancy-induced hypertension according to [1], which comprises measuring the level of human lipocalin-type prostaglandin D synthase in a body fluid sample collected from a subject and comparing the measured value with a cut-off value that is determined based on measured values of human lipocalin-type prostaglandin D synthase in body fluid samples collected from normal pregnant women and/or pregnant women with pregnancy-induced hypertension; [3] a method for determining the severity of pregnancy-induced hypertension, which comprises measuring the level of human lipocalin-type prostaglandin D synthase in a body fluid sample collected from a subject; [4] the method for determining the severity of pregnancy-induced hypertension according to [3], which comprises measuring the level of human lipocalin-type prostaglandin D synthase in a body fluid sample collected from a subject and comparing the measured value with cut-off values that are determined according to the measured values of human lipocalin-type prostaglandin D synthase in the body fluid samples collected from pregnant women with various severities of pregnancy-induced hypertension; [5] a method for predicting pregnancy-induced hypertension, which comprises measuring the level of human lipocalin-type prostaglandin D synthase in a body fluid sample collected from a subject; [6] the method for predicting pregnancy-induced hypertension according to [5], which comprises measuring the level of human lipocalin-type prostaglandin D synthase in a body fluid sample collected from a subject showing no hypertension, proteinuria, or edema; [7] the method for predicting pregnancy-induced hypertension according to [5] or [6], which comprises measuring the level of human lipocalin-type prostaglandin D synthase in a body fluid sample collected from a subject and comparing the measured value with a cut-off value that is determined from measured values of human lipocalin-type prostaglandin D synthase in body fluid samples collected from normal pregnant women and/or pregnant women with pregnancy-induced hypertension; [8] a method for evaluating a fetus and a placental function, which comprises measuring the level of human lipocalin-type prostaglandin D synthase in a body fluid sample collected from a patient with pregnancy-induced hypertension; [9] the method for detecting pregnancy-induced hypertension according to [1] or [2], wherein the level of human lipocalin-type prostaglandin D synthase in a body fluid sample is measured by an immunological assay method; [10] the method for determining the severity of pregnancy-induced hypertension according to [3] or [4], wherein the level of human lipocalin-type prostaglandin D synthase in a body fluid sample is measured by an immunological assay method; [11] the method for predicting pregnancy-induced hypertension according to any one of [5] to [7], wherein the level of human lipocalin-type prostaglandin D synthase in a body fluid sample is measured by an immunological assay method; [12] the method for evaluating a fetus and a placental function according to [8], wherein the level of human lipocalin-type prostaglandin D synthase in a body fluid sample is measured by an immunological assay method; [13] the method according to any one of [1] to [12], wherein the body fluid sample is blood; [14] the method according to any one of [1] to [12], wherein the body fluid sample is urine; and [15] a kit for detecting pregnancy-induced hypertension, which contains an anti-human lipocalin-type prostaglandin D synthase antibody.

The present invention will be explained in detail as follows.

This description includes part or all of the contents as disclosed in the description and/or drawings of Japanese Patent Application No. 2003-332084, which is a priority document of the present application.

BEST MODE OF CARRYING OUT THE INVENTION

In the present invention, a sample containing L-PGDS to be measured is a body fluid collected from a subject. Specific examples of such sample include blood (e.g., serum or plasma), urine (e.g., spot urine specimens or timed urine specimens), amniotic fluids, cervical mucus, uterine luminal fluids, and oviduct luminal fluids. Of these examples, blood and urine are particularly preferable because they can be easily collected. In this case, a subject may be any pregnant woman regardless of her pregnancy stage (weeks that have passed after conception). Regarding a pregnant woman in the early stages of pregnancy, when PIH has not yet been developed, her future risk of developing PIH can be determined by the method of the present invention. Regarding a pregnant woman who has already shown symptoms of PIH, the severity of PIH can be determined by the method of the present invention. A method for measuring L-PGDS levels in the above samples is not particularly limited, as long as it can precisely reflect such L-PGDS levels. Examples of such method include an immunological assay method, an enzyme activity assay method, and a capillary electrophoresis method. However, in view of the necessity of simultaneously and conveniently measuring large amounts of samples at an actual clinical site, an immunological assay method using a monoclonal antibody or a polyclonal antibody specific to L-PGDS, such as an enzyme immunoassay method, a radio-immunoassay method, a latex agglutination assay method, or a fluorescence immunoassay method is preferable. A monoclonal antibody that can be preferably used herein is produced by a hybridoma strain 1B7 (FERM BP-5709), 7F5 (FERM BP-5711), 6F5 (FERM BP-5710), 9A6 (FERM BP-5712), 10A3 (FERM BP-5713), or the like. The hybridoma strain 1B7 was deposited on Sep. 21, 1995 (original deposition date) under FERM BP-5709, 7F5 was deposited on Jun. 6, 1996 (original deposition date) under FERM BP-5711, 6F5 was deposited on Sep. 21, 1995 (original deposition date) under FERM BP-5710, 9A6 was deposited on Jun. 6, 1996 (original deposition date) under FERM BP-5712, and 10A3 was deposited on Jun. 6, 1996 (original deposition date) under FERM BP-5713 with the International Patent Organism Depositary, National Institute of Advanced Industrial Science and Technology (Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki, Japan). For example, an L-PGDS detection kit (WO97/16461) that the present inventors have already established as a kit to be used for a sandwich ELISA method using a monoclonal antibody may be used.

According to the present invention, PIH at the initial stage can be detected using an L-PGDS level measured by the above methods as an indicator. Furthermore, severe PIH can be predicted at an early stage. Furthermore, decreased placental functions in the case of PIH can be determined using an L-PGDS level measured by the above methods as an indicator.

PIH that is detected by the method of the present invention is limited to neither preeclampsia, gestational hypertension nor superimposed preeclampsia. Eclampsia associated with cerebral vasospasm seizure is also included. Moreover, PIH associated with HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome, which induces pulmonary edema, encephalorrhagy, premature ablation of normally implanted placenta, or hepatic vasospasm is also included.

To determine by the method of the present invention whether or not a pregnant woman is affected with PIH, first a cut-off value is determined. For example, the levels of L-PGDS in body fluid samples collected from normal pregnant women and/or pregnant women who are already showing hypertension, proteinuria, or edema as a symptom and have been clinically diagnosed to have PIH are measured. Then, based on distribution of L-PGDS level in normal pregnant women or diagnostic accuracy, such as sensitivity and specificity in the detection of PIH, an appropriate cut-off value for L-PGDS is determined. Subsequently, the level of L-PGDS in a body fluid sample collected from a pregnant woman who is a subject is measured, followed by comparison of the measured value with the cut-off value. When the L-PGDS level in a subject is higher than the cut-off value, it can be determined that the subject is affected with PIH. Cut-off values may be previously determined according to various severities of PIH. Through comparison of a measured L-PGDS value in a subject with each of such cut-off values, the severity of PIH can be determined. For example, subjects with PIH are divided into a group of those with severe-type or a group of those with mild-type PIH based on clinical symptoms such as hypertension, proteinuria, and edema. Distribution of L-PGDS level in each group and diagnostic accuracy for determination of the severity are examined, so that appropriate cut-off values may be determined. The number of subjects for determination of the above cut-off values is not limited. The number of cases is preferably 5 or more and further preferably 10 or more.

According to the method of the present invention, PIH at the initial stage can also be determined, which is impossible to precisely determine based only on symptoms such as hypertension, proteinuria, and edema.

A cut-off value to be used in such case is not limited. Specifically, in the case of blood level, a cut-off value for determining whether or not a subject is affected with PIH can be determined to be between 50 and 70 .mu.g/dL, for example, for a pregnant woman at and before pregnancy week 31 and can be determined to be between 50 and 60 .mu.g/dL, for example, for a pregnant woman at and after pregnancy week 32. Moreover, in the case of urinary excretion (level), a cut-off value can be determined to be between 2.7 and 9 mg/g creatinine for a pregnant woman at and before pregnancy week 31, and can be determined to be between 3.5 and 7.5 mg/g creatinine for a pregnant woman at and after pregnancy week 32. Furthermore, a cut-off value for determining if PIH is mild-type or severe-type is also not limited. For example, in the case of blood level, such a cut-off value can be determined to be between 55 and 70 .mu.g/dL. In the case of urinary excretion, such a cut-off value can be determined to be between 4 and 9 mg/g creatinine. When a measured L-PGDS value in a subject is higher than a cut-off value used for determining whether or not a subject is affected with PIH and is lower than a cut-off value used for determining if PIH is mild-type or severe-type, it is determined that the relevant subject is affected with mild-type PIH. When a measured value is higher than a cut-off value used for determining if PIH is mild-type or severe-type, it is determined that the relevant subject is affected with severe-type PIH.

Moreover, the method of the present invention also encompasses a method for determining a risk of developing PIH in the pregnant woman who shows none of hypertension, proteinuria, and edema as symptoms and thus is thought not to be clinically affected with PIH, that is, a method for predicting PIH. In this case, L-PGDS levels in body fluid samples collected from normal pregnant women are measured. Subsequently, the conditions of pregnancy of the normal pregnant women are prospectively observed. Such subject pregnant women are divided into a group of pregnant women who have delivered their babies without developing PIH and a group of pregnant women who have developed PIH during pregnancy. A cut-off value for prediction is determined to be between the measured L-PGDS values of the former group and the measured L-PGDS values of the latter group. Alternatively, body fluid samples are collected from pregnant women with PIH before the onset of PIH. Body fluid samples are also collected from pregnant women who have delivered their babies without developing PIH. All of these samples are collected during the similar pregnancy period. These samples are stored by means such as freezing. Through measurement of L-PGDS levels in such stored samples, a cut-off value can also be determined retrospectively. Moreover, pregnant women are divided by the onset timing of PIH. L-PGDS levels are measured for each group of pregnant women and then a cut-off value can be determined for each onset timing. Thus, the onset timing of PIH can also be predicted. For example, pregnant women are divided into a group of pregnant women who have developed PIH in the early stage of pregnancy (pregnancy weeks 15 to 25) and a group of pregnant women who have developed PIH in the late stage of pregnancy (at and after pregnancy week 26). Through measurement of L-PGDS levels in body fluid samples of each group, it becomes possible to determine the risk of developing PIH in the early stage of pregnancy and the risk of developing PIH in the late stage of pregnancy. Furthermore, pregnant women are divided into a group of pregnant women who have developed mild-type PIH and a group of pregnant women who have developed severe-type PIH. L-PGDS levels in the body fluid samples of each group are measured. A cut-off value is then determined between L-PGDS levels (measured before the onset) of pregnant women who have developed severe-type PIH and L-PGDS levels (measured before onset) of pregnant women who have developed mild-type PIH. Hence, the risk of developing severe-type PIH can be determined.

Subsequently, a body fluid sample is collected from a pregnant woman showing none of hypertension, proteinuria, and edema as symptoms and then the L-PGDS level is measured. The measured L-PGDS value is compared with the above cut-off value for prediction. Thus, the risk of developing PIH is determined. For example, when a measured value is higher than such a cut-off value, it is determined that the risk of developing PIH in the future is high. When the same is lower than such a cut-off value, it is determined that the risk of developing PIH in the future is low. Furthermore, when there is no difference between a measured value and such a cut-off value, determination is suspended. Reexamination may be performed if necessary.

A cut-off value in this case is not limited. For example, a cut-off value for predicting whether or not a subject develops PIH during pregnancy can be determined to be between 55 and 75 .mu.g/dL in the case of blood level, and between 3.0 and 10 mg/g creatinine in the case of urinary excretion. Moreover, a cut-off value for predicting whether or not a subject develops severe-type PIH during pregnancy can be determined to be between 60 and 75 .mu.g/dL in the case of blood level and between 5.0 and 10 mg/g creatinine in the case of urinary excretion.

As described above, the risk of developing PIH is determined. When such risk is determined to be high, the relevant pregnant woman is appropriately treated, so that the risk of developing PIH later or the risk of developing more severe PIH can be reduced. The number of subjects needed for determination of the above cut-off value is not limited. The number of cases is preferably 5 or more and further preferably 10 or more.

Furthermore, the present invention encompasses a method for evaluating a fetus and placental functions, which comprises measuring the level of L-PGDS in a body fluid sample collected from a pregnant woman who has developed PIH. Here, the term "evaluation of a fetus and placental functions" means evaluation of whether or not placental functions for supplying nutrition and oxygen to a fetus decrease or means to evaluate whether or not any injury such as organ damage occurs in the fetus. When the L-PGDS level in a body fluid sample is low, the fetus and placental functions are evaluated to be in a good state. When the same is high, the fetus and placental functions are evaluated to be in a sub-optimal state.

Furthermore, the present invention encompasses a reagent for detecting or a kit for detecting PIH, which comprises an anti-L-PGDS antibody. The reagent or the kit may contain a carrier to which an antibody is immobilized when such kit is based on an enzyme immunoassay method. Such an antibody may be previously bound to a carrier. Furthermore, the kit may also appropriately contain a blocking solution, a reaction solution, a stop solution, a reagent for treating a sample, instructions containing each cut-off value listed therein, a standard reagent wherein the L-PGDS level is prepared to be the same as a cut-off value, and the like.
 

Claim 1 of 6 Claims

1. A method for predicting pregnancy-induced hypertension, which comprises measuring the level of human lipocalin-type prostaglandin D synthase in a body fluid sample collected from a subject and comparing the measured value with a cut-off value that is determined from measured values of human lipocalin-type prostaglandin D synthase in body fluid samples collected from normal pregnant women not exhibiting symptoms of hypertension, proteinuria, and edema and not thought to be clinically affected with PIH and/or pregnant women with pregnancy-induced hypertension, wherein it is determined that the risk of developing PIH in the future is high when the measured value of human lipocalin-type prostaglandin D synthase is higher than the cut-off value.

____________________________________________
If you want to learn more about this patent, please go directly to the U.S. Patent and Trademark Office Web site to access the full patent.