Menoufia Medical Journal

ORIGINAL ARTICLE
Year
: 2014  |  Volume : 27  |  Issue : 1  |  Page : 44--49

The influence of phototherapy for neonatal hyperbilirubinemia on tumour necrosis factor-α


Magdy A. Saber1, Sameh A. Abd El Naby2, Mohamed A. Helwa3, Ramy N. Deghedy2,  
1 Department of Pediatrics, National Liver Institute, Menoufiya, Egypt
2 Department of Pediatrics, Faculty of Medicine, Menoufiya University, Menoufiya, Egypt
3 Department of Clinical Pathology, Faculty of Medicine, Menoufiya University, Menoufiya, Egypt

Correspondence Address:
Ramy N. Deghedy
MBBCh, Flat No. 5, 4th Floor, Block No. 3, Railway Street, Kom Hamada, El Behera
Egypt

Abstract

Objective The aim of the study was to investigate the influence of phototherapy in treatment of neonatal hyperbilirubinemia on the serum level of tumour necrosis factor-α (TNF-α). Background Jaundice is the most common clinical diagnosis in neonatal medicine that requires medical attention. Phototherapy is the most commonly used intervention to treat and prevent severe hyperbilirubinemia. Some investigations have expressed concern about potential toxic effects of phototherapy; one possible harmful consequence is affection of cytokines production and lymphocyte subtypes, which can affect the function of the immune system of the newborn. Recent research has provided evidence that phototherapy is associated with some long-term side effects such as melanocytic nevi and skin cancer, allergic diseases, asthma, patent ductus arteriosus and retinal damage. Patients and methods A total of 30 term neonates with neonatal jaundice were included in this study who had indirect bilirubin levels higher than 14 mg/dl, and 15 healthy matched newborns were selected as controls. Blood samples were obtained from hyperbilirubinemic newborns before exposure and at 72 h of exposure to phototherapy and from controls at the time of examination. Serum TNF-α levels were measured in the samples using enzyme-linked immunosorbent assay kits. Results Serum TNF-α levels in both patients before phototherapy and the control group did not differ significantly. Serum TNF-͍ levels significantly increased after 72 h of exposure to phototherapy, indicating the strong effect of phototherapy on TNF-α serum level. Conclusion These results demonstrate that, in addition to the well-known positive effect of phototherapy on the neonatal serum bilirubin level, this therapeutic modality increased serum TNF-α that can affect the function of the immune system in newborns.



How to cite this article:
Saber MA, Abd El Naby SA, Helwa MA, Deghedy RN. The influence of phototherapy for neonatal hyperbilirubinemia on tumour necrosis factor-α.Menoufia Med J 2014;27:44-49


How to cite this URL:
Saber MA, Abd El Naby SA, Helwa MA, Deghedy RN. The influence of phototherapy for neonatal hyperbilirubinemia on tumour necrosis factor-α. Menoufia Med J [serial online] 2014 [cited 2020 Apr 3 ];27:44-49
Available from: http://www.mmj.eg.net/text.asp?2014/27/1/44/132735


Full Text

 Introduction



Neonatal jaundice is one of the most common conditions confronting neonatologists daily. About 60% of term and 80% of preterm infants develop jaundice in the first week of life. Bilirubin encephalopathy is a devastating brain injury that can cause permanent neurodevelopmental handicaps [1].

Although most newborns with jaundice are otherwise healthy, they need to be monitored because bilirubin is potentially toxic to the central nervous system. Sufficiently elevated levels of bilirubin can lead to bilirubin encephalopathy and subsequently kernicterus [2].

Phototherapy is the most commonly used intervention to treat and prevent severe hyperbilirubinemia in term and large preterm infants [3]. Fortunately, phototherapy at wavelength of 425-475 nm is an effective method for treatment of neonatal hyperbilirubinemia [4].

Phototherapy is generally regarded as a safe method; the reported side effects have been subjected to extensive and controversial debate and include rash, loose green stools, water loss, oxidative injury, dehydration and ocular hazards [5].

Phototherapy may be associated with some long-term side effects such as melanocytic nevi and skin cancer, allergic diseases, patent ductus arteriosus and retinal damage [6]. Recently, phototherapy is one of the potent risk factors of childhood asthma [7]. Neonatal phototherapy (NNPT) is associated with allergic rhinitis and conjunctivitis [8].

During the last few decades, some investigations have expressed concern about potential toxic effects of phototherapy; one possible harmful consequence is affection of cytokines production and lymphocyte subtypes, which can affect the function of the immune system of the newborn [9].

Phototherapy can affect the synthesis and release of cytokines from the peripheral immune system [10]. Exposure to ultraviolet (UV) radiation initiates a complex cascade of responses that affect the immune system. Various immune mediators such as interleukin (IL)-1, IL-6, IL-10 and tumour necrosis factor-α (TNF-α) are secreted by the immune system of skin to support the systemic immunologic response [11].

Cytokines are hormone-like proteins that enable immune cells to communicate, and they play an integral role in the initiation, perpetuation and subsequent downregulation of the immune response [12].

TNF-α is one of the most important cytokines secreted in patients with infection or in those exposed to acute UV radiation [9].

TNF-α is a glycoprotein hormone with important functions in inflammation and apoptosis. It plays a significant role as a proinflammatory cytokine in the defense against viral, bacterial and parasitic infections and autoimmune disorders [13].

 Patients and methods



This study was conducted prospectively on 30 term neonates with neonatal jaundice, who had indirect bilirubin levels higher than 14 mg/dl. There were 15 male and 15 female patients, with a mean gestational age of 37 weeks and a mean postnatal age of 4 days [Table 1]. Fifteen healthy matched newborns were selected as controls. There were seven female patients and eight male patients, with a mean gestational age of 37 weeks and a mean postnatal age of 2 days [Table 1].{Table 1}

All patient samples were collected from neonatal ICU in Kom Hamada Central Hospital, El Beheira Governorate from January 2013 to April 2013. Parental consent was obtained before inclusion and the study was approved by the local ethics commission.

Inclusion criteria for the study group were patients with neonatal hyperbilirubinemia in whom the use of phototherapy had begun according to the guidelines of the American Academy of Pediatrics.

Exclusion criteria were as follows:

Congenital malformations.Congenital infections associated with the TORCH complex.Hypoxia.Respiratory distress.Exchange transfusion.Direct bilirubin levels higher than 2 mg/dl.Newborn of mothers with pre-eclampsia, steroid treatment or diabetes mellitus.

All participants were subjected to complete history taking, complete clinical examination and laboratory investigations including complete blood count, C-reactive protein (CRP), total and direct serum bilirubin (patients only) and serum TNF-α level.

Phototherapy treatment was administered for 72 h.

Two samples were taken each time: one sample was for complete blood count and serum was separated from the other sample for CRP, total and direct serum bilirubin and TNF-α. Samples from controls were collected at the time of examination. For TNF-α, sera were kept at -20°C until they were assayed by solid-phase enzyme immunoassay (enzyme-linked immunosorbent assay) using kits (Assay Pro, Camarillo, California, USA).

CRP was assayed by latex agglutination test kits.

Principle of the test

The CRP latex particles are coated with antibodies to human CRP. When the latex suspension is mixed with serum containing elevated CRP levels on a slide, clear agglutination is seen within 2 min. The serum CRP concentration can then be calculated approximately by multiplying the dilution factor (i.e. 2, 4, 8 or 16) by the detection limit (i.e. 6 mg/l) to give the concentration in mg/l - for example, if the agglutination titre appears at 1/8, the approximate serum CRP concentration is 8 × 6 = 48 mg/l.

Principle of tumour necrosis factor-α measurement

TNF-α enzyme-linked immunosorbent assay kit is designed for detection of TNF-α in human plasma, serum or cell culture supernatants. This assay uses a quantitative sandwich enzyme immunoassay technique that measures TNF-α in less than 5 h. A murine monoclonal antibody specific for human TNF-α has been precoated into a microplate. TNF-α in standards and samples is sandwiched by the immobilized antibody and a biotinylated polyclonal antibody specific for human TNF-α, which is recognized by a streptavidin-peroxidase conjugate. All unbound material is then washed away and a peroxidase enzyme substrate is added. The colour development is stopped and the intensity of the colour is measured.

 Results



Comparison between patients and controls regarding demographic data showed no statistically significant differences between them, except for postnatal days that were highly statistically significantly different [Table 1].

Anthropometry regarding weight, length and head circumference showed no statistically significant difference between patients and controls [Table 2].{Table 2}

Laboratory data including serum TNF-α showed no statistically significant difference between patients and controls [Table 3].{Table 3}

White blood cell (WBC) count in patients before and after phototherapy showed no statistically significant difference [Table 4]. Haemoglobin level and haematocrit values were statistically significantly lowered after phototherapy [Table 4].{Table 4}

CRP levels were statistically significantly higher after phototherapy [Table 4]. Total serum bilirubin levels were statistically significantly lowered after phototherapy [Table 4].

Serum levels of TNF-α were statistically significantly higher after phototherapy (P≥0.001) [Table 5].{Table 5}

Demographic data have no statistically significant effect on serum level of TNF-α in patients both before phototherapy [Table 6] and after phototherapy [Table 7].{Table 6}{Table 7}

 Discussion



Phototherapy is the most commonly used intervention to treat and prevent severe hyperbilirubinemia [3]. Exposure to UV radiation initiates a complex cascade of responses resulting in the downregulation of the immune system. Various immune mediators such as IL-1, IL-6, IL-10 and TNF-α are secreted by the immune system of skin to support the systemic immunologic response [11].

Comparison between patients and controls regarding TNF-α level showed no statistically significant difference. These results suggest that neonatal hyperbilirubinemia does not influence the serum levels of TNF-α. These results are in agreement with that of Kurt et al. [9] who stated that neonatal hyperbilirubinemia may have no effect on TNF-α level.

Correlation of demographic data with TNF-α before and after phototherapy among patients showed no statistically significant difference. These results suggest that sex, consanguinity and mode of delivery have no effect on TNF-α serum level, only with respect to phototherapy.

In our study, comparison of WBCs count in patients before and after phototherapy showed no statistically significant difference [Table 4]. These results are in agreement with that of Kurt et al. [9] who stated that WBCs did not show any important changes. In contrast with our study, Jahanshahifard et al. [10] stated that phototherapy in term neonate can raise peripheral WBC count. Mrkaiζ et al. [14] observed that phototherapy may cause higher incidence of infections in neonate. They examined the effects of phototherapy on the immune system of neonates without signs of infection. Their results showed an increase in the total number of peripheral WBCs. They concluded that phototherapy may complicate the existing infection, although those findings were temporary. In contrast with the study by Mrkaiζ et al. [14], Erduran et al. [15] stated that WBCs were significantly decreased after exposure to UV radiation.

Haemoglobin levels and haematocrit values were statistically significantly lowered after phototherapy [Table 4]. These results may be explained by frequent blood sampling, besides the physiological decrement postnatally. Total serum bilirubin levels were highly statistically significantly lowered after phototherapy among patients (P≥0.001) [Table 4]. This means that UV phototherapy has lowered neonatal hyperbilirubinemia.

These results are in agreement with that of Jahanshahifard et al. [10], Kurt et al. [9] as well as Sirota et al. [16], who stated that UV phototherapy is a potent and effective treatment for neonatal jaundice while studying the effect of phototherapy for neonatal hyperbilirubinemia on cytokines.

CRP levels were statistically significantly higher after phototherapy (P≥0.017), indicating a relationship between CRP as one of the inflammatory indices and TNF-α as a proinflammatory mediator.

Serum TNF-α level in both patients before phototherapy and the control group did not differ significantly. Serum TNF-α level significantly increased after 72 h of exposure to phototherapy and this change was statistically significant (P≥0.001) as shown in [Table 5], indicating the strong effect of phototherapy on TNF-α serum level.

These results are in agreement with that of Jahanshahifard et al. [10] who stated that exposure to phototherapy in the treatment of neonates with hyperbilirubinemia can affect the synthesis and release of cytokines from the peripheral immune system, as it increases serum TNF-α. In addition, these results are also in agreement with that of Maisels and McDonagh [17] who stated that an imbalance in the production of different cytokines induces immune system failure. UV radiation for treatment of neonatal hyperbilirubinemia induces an increase in IL-6, IL-8 and TNF-α. Moreover, this result is in agreement with that of Kurt et al. [9] who stated that usage of phototherapy in neonate with jaundice as a treatment affects the function of the immune system in newborns through alterations in TNF-α production. These results are in agreement with that of Narbutt et al. [11] who stated that exposure of healthy term neonates to repeated doses of UV radiations shows a statistically significant increase in serum level of TNF-α. In addition, these results are in agreement with that of Naderi-Hachtroudi et al. [18] who showed that irradiation of the epidermal cells with UV phototherapy induced a release of TNF-α, as well as with that of Kennedy et al. [19] who stated that acute UV exposure leads to a significant increase in the production of TNF-α in human corneal stroma cells. In addition, our results are in agreement with that of Kφck et al. [20] who stated that human keratinocytes release TNF-α to support the crucial role of the epidermis and, in particular, of the keratinocyte in the pathogenesis of both local and systemic inflammation after UV irradiation, as well as in the host defense against microbial organisms and tumours. Moreover, our results are in agreement with that of Sirota et al. [16] who stated that phototherapy affects the function of the immune system in newborns by alterations in cytokine production. Exposure to UV radiation results in higher TNF-α production and suppression of many cell-mediated immune responses.

In contrast, our results are not in agreement with that of Procianoy et al. [21] who studied the influence of phototherapy on serum cytokine concentrations in newborn infants; there were no statistical differences in TNF-α concentrations before and after 24 h of phototherapy.

NNPT inhibits the immune system, ultimately causing allergic diseases during childhood and later in life. NNPT can significantly increase the levels of TNF-a, IL-1b and IL-8, in newborn infants. UV light in NNPT significantly decreases circulating CD4+ T lymphocyte counts, interferes with CD8+ cytotoxic T lymphocytes and reduces natural killer cell activity. Therefore, it affects the immune system and leads to allergy and autoimmunity disorders [1].

NNPT can activate the inflammatory pathways, leading to allergy or autoimmunity disorders [22]. Recently, phototherapy is one of the potent risk factors of childhood asthma. It was concluded that birth time events such as phototherapy result in an increased risk for autoimmune diabetes [7]. NNPT is associated with allergic rhinitis and conjunctivitis [8]. With the increasing rates of allergic diseases such as asthma and allergic rhinitis, much interest is currently focused on the immunologic mechanisms of NNPT for allergic diseases during early development. Immune competence is considered to be a state of equilibrium between humoral immunity (Th-2 cells) and cellular immunity (Th-1 cells). Normally, the immune system shifts from mainly Th-2 immune responses towards more Th-1 responses after birth. Environmental stimuli easily affect immune regulation in early life [23]. The evidence that NNPT inhibits the immune system is supported by the findings that NNPT affects the Th-2/Th-1 switch, ultimately causing allergic diseases during childhood and later in life. There are a few possible mechanisms for the Th-2/Th-1 switch disorders. First, NNPT can significantly increase the levels of TNF-a, IL-1b and IL-8 in newborn infants [1]. This change in cytokine levels is thought to be the principal cause of Th-2/Th-1 switch disorder. Second, NNPT directly causes DNA damage to lymphocytes in infants with jaundice [24]. This injury could affect the genes regulating the Th-2/Th-1 switch and contribute to the disorder. UV light, although a small component of NNPT, can activate the inflammatory pathways, leading to allergy or autoimmunity disorders [22].

TNF-α was subsequently shown to promote proliferation and survival of some tumour cell lines [25]. NNPT was associated with a significantly higher prevalence of clinically multiple common nevi and atypical nevi, which is the most important risk factor for the development of malignant melanoma [26].

NNPT to prevent infants from bilirubin encephalopathy has been overused by neonatologists in clinical practice, possibly resulting in many unnecessarily irradiated babies in the neonatal ICUs [27].

Therefore, it is necessary to develop evidence-based guidelines, new light devices and alternative agents, as well as individualized treatments to minimize the side effects of phototherapy [6].

 Conclusion



These results demonstrate that, in addition to the well-known positive effect of phototherapy on the neonatal serum bilirubin level, this therapeutic modality increased serum TNF-αα level that can affect the function of the immune system in newborns.

 Acknowledgements



Conflicts of interest

There are no conflicts of interest.

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