Study of the Sex Differences in Inflammatory Diseases in Children
Study of the Sex Differences in Inflammatory Diseases in Children
Sexual differences in innate immune response have been demonstrated and were mainly
 attributed to the influence of the sex steroids (1-18). However, recent clinical data
 revealed significant differences in inflammatory markers between boys and girls suffering
 from acute and chronic inflammatory diseases (19-23). Sex hormone levels in prepubertal
 children are particularly low and insufficient to explain the gender differences observed in
 inflammatory conditions from neonates to the elderly, suggesting the contribution of another
 mechanism, such as the influence of genes situated on the sex chromosomes and involved in the
 inflammatory response.

 The aim of this work is to evaluate the role of the X chromosome in the sex differences in
 inflammatory diseases in children. In order to discriminate more precisely the role of the X
 chromosome relatively to the sex steroids in the sex-specific inflammatory response, some
 innate immune functions related to X-linked genes will be evaluated in whole blood from
 prepubertal children of both sexes, suffering from acute inflammatory processes such as
 pyelonephritis caused by Escherichia coli, pneumonia with pleural effusion caused by
 Streptococcus pneumoniae or sepsis
Many studies demonstrated immune differences between men and women suffering from acute and
 chronic inflammatory processes. In cases of acute inflammatory diseases, such as sepsis,
 females have better prognosis comparing to males (1,24-28).

 On the contrary, worse prognosis for women is observed in chronic inflammatory diseases such
 as asthma or cystic fibrosis (8-10,12,13,29).

 Sex-depended inflammatory response was attributed to the influence of sex hormones on the
 immune system. (2,15-18). However recent studies revealed differences in the clinical outcome
 but also in inflammatory markers between boys and girls suffering from acute and chronic
 inflammatory diseases (19-23). Sex hormone levels in prepubertal children are particularly
 low and insufficient to explain the gender differences observed in inflammatory conditions
 from neonates to the elderly, suggesting the contribution of another mechanism, such as the
 influence of genes situated on the sex chromosomes and involved in the inflammatory response.

 The aim of this work is to identify the potential X-linked mechanisms responsible for some of
 the differences between boys and girls in the inflammatory response, making the girls more at
 risk of developing complications in chronic inflammatory diseases and the boys more at risk
 of lethal complications in severe acute inflammatory diseases like sepsis. Several genes
 coding for innate immunity components are linked to the X chromosome such as diapedesis
 molecule CD99 or TLR pathway proteins genes. (30-33). X chromosome is also highly enriched in
 genes encoding micro RNAs (miRNAs) involved in the post-transcriptional regulation of gene
 expression which play a critical role in immune inflammatory response (34-36).

 Thus, in order to discriminate more precisely the role of the X chromosome relatively to the
 sex steroids in the sex-specific inflammatory response, some innate immune functions related
 to X-linked genes will be evaluated in whole blood from prepubertal children of both sexes,
 suffering from acute inflammatory processes such as pyelonephritis caused by Escherichia
 coli, pneumonia with pleural effusion caused by Streptococcus pneumoniae or sepsis. We will
 also study the correlations between inflammatory and clinical markers of the disease activity
 to identify prognosis indicators depending on the sex. Additionally, to delineate microbiome
 contribution, we will study the gut microbiota in stool samples obtained from the recruited
 patients.
Inclusion Criteria of Experimental group :

 -  Male (XY) and female (XX) aged from 6 months to 7 years old.

 -  Subject hospitalized either for:

 (1) Urinary tract infection caused by Escherichia Coli, with:

 -  Temperature ≥ to 38,5°C

 -  Urinalysis

 -  Leukocyte esterase +

 -  AND/OR Nitrites +

 -  AND/OR pyuria (≥ 100WBC/mm³)

 -  AND/OR bacteriuria.

 -  Urinalysis

 -  Clean catch voided urine: > 10^4 Escherichia Coli colony form unit (CFU)/mm
 (urine collection method for children >3 years old or toilet trained children or
 by stimulation for children <3 years old)

 -  Transurethral bladder catheterisation: > 10^4 Escherichia Coli colony form unit
 (CFU)/mm³ (urine collection method for children <3 years old).

 -  Suprapubic aspiration: > 1 Escherichia Coli colony form unit (CFU)/mm³ (urine
 collection method for children <3 years old).

 (2) Pneumonia with pleural effusion with :

 -  Temperature ≥ 38,5°C

 -  Chest radiography/ultrasound: Pleural effusion

 -  Streptococcus pneumoniae identified on blood or pleural fluid culture or by PCR

 (3) Sepsis with:

 -  Documented or suspected infection

 -  Temperature < 36° or > 38.3°C

 -  Heart rhythm:

 -  2 SD above normal for age

 -  6-23 months: >180/min

 -  24-71 months: >140/min

 -  72-84 months: >130/min

 -  Respiratory Rate:

 -  6-23 months: >35/min

 -  24 - 71 months: >30/min

 -  72-84 months: >20/min

 -  WBC:

 -  6-23 months: >17500/µL or <5000/µL

 -  24-71 months: >15500/µL or <6000/µL

 -  72-84 months: >13500/µL or <4500/µL

 -  and/or CRP (blood) > 2SD above normal

 -  And at least two of the following:

 -  PaO2/FiO2 <300

 -  Proven need for >50% FiO2 to maintain saturation ≥ 92%

 -  Need for mechanical ventilation

 -  Glasgow score < 11

 -  Urine output < 0,5mL/kg/h for at least 2h

 -  Creatinine:

 -  6-11 months: >0,4mg/dL

 -  12-23 months: >0,5mg/dL

 -  24-59 months: >0,8mg/dL

 -  60-84 months: >1mg/dL

 -  Or creatinine increase more than 0,5 mg/dL

 -  Platelet count <100000/mL

 -  Bilirubin >2 mg/dL

 -  Mean arterial pressure (MAP)

 -  6-11 months: <55 mmHg

 -  12 -23 months: <60 mmHg

 -  24-59 months: <62 mmHg

 -  60-84 months: <65 mmHg

 -  SBP less than two SD below normal for age

 -  Prolonged capillary refill: > 5 sec

 Inclusion Criteria of Control group :

 -  Male (XY) and female (XX) aged from 6 months to 7 years old.

 -  Scheduled surgical intervention for a non-infectious pathology.

 Exclusion Criteria:

 -  Use of antithrombotic drugs (acetylsalicylic acid, thienopyridines, dipyridamol,
 glycoprotein IIb / IIIa antagonists, vitamin K antagonists, heparins).

 -  Congenital or acquired immunodeficiency: immunosuppressive drugs, hematopoietic stem
 cells transplantation, immunoglobulin therapy, extracorporeal membrane oxygenation
 (ECMO).

 -  Hemodialysis.

 -  48h following cardiac operation of any type.

 -  Malignant cancer.

 -  HIV.