Extracellular 70-kd heat shock protein in mid-trimester amniotic fluid and its effect on cytokine production by ex vivo-cultured amniotic fluid cells.

Objective: The 70-kd heat shock protein is released from cells in response to stress and functions as a regulator of innate immunity. We hypothesized that 70-kd heat shock protein in mid-trimester amniotic fluid might regulate local immune system activation.

Study Design: Amniotic fluid that was obtained from 200 women who underwent amniocentesis at 15 to 19 weeks of gestation was tested by enzyme-linked immunosorbent assay for 70-kd heat shock protein, tumor necrosis factor-alpha, and interleukin-1beta and -6. The amniotic fluid cellular fraction also was evaluated for Mycoplasma hominis by gene amplification. Whole amniotic fluids were incubated ex vivo in medium alone or medium that contained peptidoglycan, a TLR2 ligand, or lipopolysaccharide, a TLR4 ligand. After 24 hours, the supernatants were collected and assayed for 70-kd heat shock protein. The influence of exogenous 70-kd heat shock protein on tumor necrosis factor-alpha and interleukin-1beta and -6 production by whole amniotic fluid was assessed similarly.

Results: The 70-kd heat shock protein was detected in all amniotic fluids with a median (range) of 11.5 ng/mL (1.2-76.7). The intra-amniotic 70-kd heat shock protein concentration was correlated positively only with amniotic fluid tumor necrosis factor-alpha levels (P = .0002). Detection of M hominis was associated with an increased 70-kd heat shock protein concentration (median, 17.2 ng/mL; P = .01). The addition of peptidoglycan resulted in a stimulation of 70-kd heat shock protein production, and exogenous 70-kd heat shock protein stimulated the release of tumor necrosis factor-alpha by amniotic fluid cells.

Conclusion: The 70-kd heat shock protein is released from cells in mid-trimester amniotic fluid as a consequence of TLR2 stimulation and potentiates tumor necrosis factor-alpha production.