This research reported that 45.3% out of the 95 pregnant women on their third trimester that came for prenatal care on healthcare providers were LTBI pregnant women. As much as 32.1% (27 people) out of the 84 pregnant women had low levels of vitamin D. This result is in accordance with a prior study in Indonesia where 95% of the 145 adult women had vitamin D deficiency in 2014.16 LTBI pregnant women had lower levels of vitamin D compared to their non-LTBI counterparts, and LTBI pregnant women had a 3.7 times higher risk to suffer from vitamin D deficiency. This result is in accordance with prior researches where the existence of a bacterial infection process significantly affected the vitamin D levels on pregnant women 17,18 and individuals that were infected with TB had lower levels of vitamin D compared to those who weren’t infected with TB. 19,20,21 The active metabolites of vitamin D works cellularly to the natural immune system and is adaptive in regulating the body’s immunity system towards the cell proliferation, cell differentiation, and bacterial phagocytosis. 8,20,22 The body’s immune response against M. tuberculosis involves the non-specific and specific natural immune system where there will be the increase of vitamin D’s active metabolite usage to help the immune cells phagocytizes bacteria, and thus would affect the vitamin D levels.
In this research, there was a significant relationship between the vitamin D levels on LTBI pregnant women and their newborn’s vitamin D levels (p = 0.038). The result of this research is in accordance with prior research in Poland, Nepal, Malaysia, and Indonesia, where almost of newborns had vitamin D deficiencies, and pregnant women with low levels of vitamin D will give birth to a baby that also has low levels of vitamin D. 23-26 Neonatal vitamin D were obtained from the mother’s vitamin D through transplacental route during the intrauterine growth. The main vitamin D metabolite that crosses the placenta are the inactive form of (25(OH)D), where the levels from the umbilical cord makes up 2/3 of the mother’s vitamin D levels, and therefore, if the mother suffered from vitamin D deficiency, or even insufficiency, it could affect the baby’s vitamin D levels. 27,28,29 During fetal period, the active vitamin D metabolites were utilized for fetal growth and development.30 Lack of vitamin D on the newborns that were delivered by mothers that had low or normal levels of vitamin D on this research could have happened because the value of the vitamin D levels on newborns were 2/3 of their mothers’ vitamin D supply, and the relatively high usage of active vitamin D metabolites for the growth and development during the fetal period and therefore, it could have affected the levels of inactive vitamin D that’s in the fetal blood circulation.
Cathelicidin plays an important role in the non-specific immune defense system and would usually increase during an inflammation process due to a bacterial infection.31 All of the mean value of the newborn’s cathelicidin value and the pregnant mother with LTBI’s cathelicidin value experienced an increase above the normal range (Normal range: 2,71±3,57 ng/mL32). In this research, the IFNγ on newborns could only have its value detected on all newborns, where it was obtained a higher mean IFNγ levels on the newborns from LTBI pregnant women compared to its non-LTBI counterpart (healthy neonate range: 17,5-38,5 pg/mL33), and the mean value of IFNγ levels on LTBI pregnant women were above the normal range (healthy adult range: 1,4±1,34 pg/mL34). This result is in accordance with prior researches where the increase of cathelicidin on the airway tract cells (trachea) on newborns with acute respiratory infection will established its function as one of the immune defense systems against respiratory infections, and TB infections.35,36,37 Interferon γ is a strong cytokine response on neonates that plays a role in lowering the incidence of respiratory infections9 and is an early cytokine response when infected with M. tuberculosis. The increase of cathelicidin and IFNγ levels on newborns happened because the newborn could have been exposed to bacteria during the delivery process. During the delivery process, bacteria or virus could enter the newborn’s respiratory tract when the newborn breathes (e.g., when crying) for the first time, which will activate the natural non-specific immune response on the newborns, with one of them being the increase of cathelicidin and IFNγ levels.
This research reported no significant relationship between the levels of vitamin D on LTBI pregnant women and their newborn’s cathelicidin levels, but if it’s based on the newborn’s vitamin D status, then there is a significant relationship between insufficient levels of vitamin D on newborns of LTBI pregnant women compared to the deficient levels of vitamin D (p = 0.043). The analysis results on the mother’s vitamin D levels were in accordance with prior researches where they reported that there was no relationship between vitamin D levels and cathelidicin 39,40 and that the results of the newborn’s vitamin D levels were aligned with several researches’ report that reported the vitamin D’s role in cathelicidine. 41,42 In this research, there was not a significant relationship between the levels of vitamin D on LTBI pregnant women nor the vitamin D levels on the newborns with the IFNγ levels of newborns. This result is in accordance with several researches from Japan and Kuwait that found no statistically significant correlation between vitamin D levels and IFNγ34,43 and is different with several researches that stated that the vitamin D levels did affect the IFNγ.8,44,45
This research found a significant relationship between the cathelicidin levels on LTBI pregnant women and their newborn’s cathelicidin (p = 0.033), influencing around 69.2% (R2 = 0.692), where the newborn’s cathelicidin level would increase 1.357 times (coefficient number = 1.357) with every 1% increase of the pregnant mother with ILTB’s cathelicidin level. There was also a significant correlation between pregnant women with ILTB’s IFNγ level with their newborn’s IFNγ levels (p = 0.001), influencing around 64.1% (R2 = 0.641), where there will be 2.311 times (coefficient number = 2.311) increase in the newborn’s IFNγ levels with 1% increase of the pregnant mother with ILTB’s IFNγ levels. This result is in accordance with prior researches where the components of the natural immune response when the mother is exposed to pathogens would enter the fetal circulation through the placenta46-49, but this result is different from a research from India where the pregnant women with ILTB does not affect their newborn’s immune response.50
This research also shows that despite the vitamin D levels on LTBI pregnant women did not play a role towards their newborn’s cathelicidin and IFNγ, the newborn’s vitamin D status affects their own cathelicidine. In LTBI pregnant women that’s having an ongoing infection, the vitamin D plays an immunomodulator role to the mother where the immunity response component on the pregnant mother with LTBI, such as the cathelicidin and IFNγ, plays a role on their child since gestation. The high levels of cathelicidin and IFNγ on LTBI pregnant women also shows that there’s an immune response that works well towards fighting the infection, where this could be seen from the health condition of the pregnant mother with LTBI and her child. From the period where the LTBI pregnant women were admitted to the hospital until discharged after giving birth, the mothers and their newborns were in healthy condition without any clinical signs and symptoms of an illness.
In the respiratory tract, TLR activation starts from the alveolar macrophages as the first immune response to identify the pathogen molecules51 and TLR2 expression that plays the role of the peptidoglycan and lipopeptide receptor from positive-gram bacteria.52 In this research, the TLR2 gene expression from the newborns and the LTBI pregnant women increased 1.2 times than their non-LTBI counterpart. This result is in line with previous studies where it was reported that TLR2 is the very first inflammation mediator that plays the role during M. tuberculosis infection and lung TB risk factors53,54,55 but the aforementioned results were different from this one study in India.56 Despite TLR2 testing not conducted on LTBI pregnant women, but based on previous results, the natural immune response component from LTBI pregnant women that appears during pregnancy will enter the fetus through the placenta, so we would expect more TLR2 gene expressions on newborns compared to the pregnant women. This immunity role on LTBI pregnant women towards the TLR2 gene expression on their newborns become a strong reason because of the newborn have not been exposed to M. tuberculosis.
This research reported a statistically significant correlation between the vitamin D levels of pregnant women to the newborn’s TLR2 levels from mothers that had LTBI (p = 0.038) or mothers that were non-LTBI (p = 0.044), and the normal levels of vitamin D from newborns with non-LTBI mothers played a role on their newborn’s TLR2 levels (p = 0.005). This result is in accordance with prior studies that found a correlation between vitamin D and TLR2 expression9,57,58, but the results are different from a study that was conducted during summer that reported a decrease in TLR2 expression when there’s an increase in vitamin D levels.59 In this research, the vitamin D levels on pregnant women plays a role with the newborn’s natural immune response, which is the TLR2, without looking at whether they’re infected with M. tuberculosis or not, and the higher vitamin D levels in newborns with mothers that weren’t infected with M. tuberculosis plays a role on TLR2. This exemplified the fact that the vitamin D levels on pregnant women play a role when infected with M. tuberculosis and the vitamin D will have a more prominent role during the infection when there’s a normal levels of vitamin D or higher. The mother’s and the newborn’s vitamin D levels itself plays a role in the newborn’s immune response.
The limitations of this study are long-term monitoring on the mother and her child, interviews about the mother’s food intake, amount of sunlight exposure, IGRA testing on newborns, vitamin D metabolism gene, and other vitamin levels aside from vitamin D or other immunomodulator were not conducted in this research. Long-term monitoring on weight loss, fever, chronic cough, and other clinical signs of TB on the newborns were not done by the researches, but based on a study by Dosanjh et al.60, the aforementioned procedures should be conducted. All of the newborns received a BCG immunization before going home and were given education to do get vaccinated as well as routine child growth monitoring every month. These examinations can be conducted in the next research. In this research, we are still seeing a large number of subjects that are deficient in vitamin D despite having consumed the vitamin D 1000 IU supplement, and therefore, further research can be conducted on the comparison of higher vitamin D supplement dosage so that the right dosage of vitamin D supplementation can be achieved, especially for LTBI pregnant women so that they could obtain an adequate body defense mechanism. Education about the amount of time for sunlight exposure for newborns also needs to be done because higher levels of vitamin D plays a role in the newborn’s natural immune system aside from their mothers’.